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Production and service systems often rely on stationary queueing formulas to determine the number of agents that need to be scheduled. However, this results in over-staffing decisions when the system starts empty. To address this issue, we propose a solution called transient staffing, which involves providing appointment times for agents to ensure that the expected queue length remains below a certain threshold. We model the system as a transient Erlang-A queue. To compute the appointment times, we employ a uniformized approximation that discretizes the elapsed time, which can be made as accurate as desired. We prove that the appointment times decrease with the arrival rate and traffic intensity, while increasing with the abandonment rate. Through numerical investigations, we find that adopting a transient staffing strategy leads to substantial cost savings, especially in scenarios where demand is high, customers are patient, traffic intensity is low, and the service level objective is intermediate. Furthermore, we use a fluid approximation to derive closed-form expressions for the agents' appointment times, and prove the impact of the system parameters. We show that this approximation performs well in predicting the first appointment times in contexts with high demand, low traffic intensity, and lax service level objective. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals have been under intense investigation for their promise in optoelectronic devices due to their remarkable physics, such as liquid/solid duality. This liquid/solid duality may give rise to their defect tolerance and other such useful properties. This duality means that the electronic states are fluctuating in time, on a distribution of timescales from femtoseconds to picoseconds. Hence, these lattice induced energy fluctuations that are connected to polaron formation are also connected to exciton formation and dynamics. We observe these correlations and dynamics in metal halide perovskite nanocrystals of CsPbI3 and CsPbBr3 using two-dimensional electronic (2DE) spectroscopy, with its unique ability to resolve dynamics in heterogeneously broadened systems. The 2DE spectra immediately reveal a previously unobserved excitonic splitting in these 15 nm NCs that may have a coarse excitonic structure. 2D lineshape dynamics reveal a glassy response on the 300 fs timescale due to polaron formation. The lighter Br system shows larger amplitude and faster timescale fluctuations that give rise to dynamic line broadening. The 2DE signals enable 1D transient absorption analysis of exciton cooling dynamics. Exciton cooling within this doublet is shown to take place on a slower timescale than within the excitonic continuum. The energy dissipation rates are the same for the I and Br systems for incoherent exciton cooling but are very different for the coherent dynamics that give rise to line broadening. Exciton cooling is shown to take place on the same timescale as polaron formation, revealing both as coupled many-body excitation. [ABSTRACT FROM AUTHOR]

SUMMARY Hexokinases (HXKs), which sense and catalyze cellular sugar, play a critical role in the growth and development of various plants, including wheat, a primary source of human calories frequently attacked by fungal pathogens. However, the evolutionary dynamics and functional diversification of HXKs in wheat, particularly their roles in plant defense, remain unclear. Here, we discovered that the wheat hexokinase gene family originated through multiple ancient gene duplications across different plant lineages and has undergone comprehensive, multidimensional functional specialization in gene expression, subcellular localization, enzyme activity, and regulation of plant defense responses. Gene expression analysis suggests that two‐thirds of the TaHXK genes are responsive to fungal infection. Subcellular analysis reveals that while six TaHXKs are localized in mitochondria, three TaHXKs from different phylogenetic branches are sorted into other cellular compartments. Notably, biochemical analysis shows that TaHXKs in mitochondria differ in their glucose‐catalyzing activity, with TaHXK5 and TaHXK3 exhibiting the highest and lowest enzyme activity, respectively. Consistently, transient expression analysis suggests that TaHXK5 induces various plant defense responses, while TaHXK3 is defective in activating some plant defense responses. Furthermore, inactivation of the glucokinase activity of TaHXK5 compromised its function in defense activation, suggesting that mitochondrial TaHXKs display functional divergence in both enzyme activity and defense‐inducing activity that are intrinsically connected. Overall, our findings reveal that the multidimensional specialization events following the ancient duplication events may have shaped the functional diversity of HXKs in wheat, shedding light on their evolutionary dynamics and potentially contributing to the improvement of wheat defense. [ABSTRACT FROM AUTHOR]

The internal flow field of the hydrogen circulation pump becomes more complex and flow process becomes more intense during the stopping process, strong vibration is generated to the pump and the working life of the pump is shortened. Therefore, the pressure pulsation at the inlet and outlet section, the radial force characteristics of the active rotor and the transient flow mechanism of the internal flow under different stopping modes are studied in this paper. The results show that the intake pressure and exhaust flow change greatly in exponential stopping mode, while the pressure pulsation amplitude decreases with the increase of stopping time in linear stopping mode. In addition, the radial force value of the active rotor in the exponential stopping mode is significantly smaller than that in the linear stopping mode, and the direction of the radial force F x and F y point to the negative direction of their respective axes. In this paper, the dynamic mesh technology is used to design the corresponding rotating speed UDF according to different stopping functions, and then the transient simulation of the hydrogen circulation pump under different stopping modes is completed. Finally, the change law of pressure and flow pulsation, radial force characteristics and internal flow field under different stopping modes are analyzed. [Display omitted] • Effects of different stopping modes on flow characteristics are studied. • Pressure variation under different stopping modes are discussed. • Radial force of the rotor under different stopping modes are analyzed. • Working process is researched from the pressure and velocity distribution. [ABSTRACT FROM AUTHOR]

Chinese-style greenhouses (CSGs), characterized by a distinct geometric shape compared to traditional greenhouses, are extensively utilized in China. In this study, this type of greenhouse was modeled using TRNSYS software version 18 and experimentally validated. The model can transiently determine the indoor conditions of the greenhouse and the requirement for additional heating. It calculates the heat loss due to plant evapotranspiration as well as all the heat gains and losses from the surfaces. The application of this greenhouse has been investigated from the southernmost to the northernmost regions of Europe. For this purpose, cities located at different latitudes (between 32.63° N and 69.65° N) were entered into the model, and the results were obtained and compared. The analysis conducted over the entire year demonstrated that the CSG indoor temperature is more dependent on solar energy during the day and on outdoor temperature at night. The two southernmost cities in our survey, Funchal, Portugal (32.63° N) and Luqa, Malta (35.83° N), had no winter heating requirement. The thermal covering was sufficient to minimize night heat loss and maintain a suitable indoor temperature. In northern cities, the heating requirement was relatively high due to the lower outdoor temperature and solar radiation. Consequently, the duration of the heating season increases towards the north. In the northernmost city, Tromso, Norway (69.65° N), the heating season was determined to last 12 months. In the absence of solar energy, the transparent surface of the greenhouse is covered with thermal insulation to prevent heat loss. It has been shown that with the appropriate selection of this thermal covering, which is controlled based on the presence of instantaneous solar energy, up to 80% savings can be achieved from additional heating in southern cities. In the north, this rate can be increased up to a maximum of 70% by increasing the thermal covering thickness. [ABSTRACT FROM AUTHOR]

A study based on the transient responses of bio-inspired helicoidal laminated composite plates is performed by using a higher-order finite element model (HOFEM) consisting of the thickness stretching effect. The obtained results show good agreement with those available in the open literature. The shear locking phenomena is not inspected by employing the developed HOFEM for the helicoidal lamination schemes. The effects of path of the concentrated moving load, lamination scheme, boundary condition, speed, aspect and orthotropy ratios on the transient responses are investigated. Dynamic dimensionless center deflections and dynamic amplification factors are affected by considering not only the lamination scheme but also the path of the load, boundary condition, orthotropy and aspect ratios. [ABSTRACT FROM AUTHOR]

The existing one-dimensional model is inadequate in predicting the dynamic interactions between hydraulic transients and inline air pockets in water pipelines, leading to underestimated pressure dissipation in the modeling results. In this study, a one-dimensional (1D)–three-dimensional (3D) coupling model was applied to analyze and explain the interactions between the hydraulic transients and inline air pockets observed in systematic laboratory experiments. In this model, the method of characteristics provides 1D modeling of hydraulic transients in the regions without the inline air pocket and the finite-volume method with volume of fluid approach provides 3D modeling of hydraulic transient interactions at the air pocket. The coupling between 1D and 3D models is achieved using the partly overlapped coupling method. The analysis of the transient velocity profile unveils unique velocity distributions on both sides of the air pocket due to reflection and transmission processes, which contribute to the compression and movement of the air pocket. The investigations of variation in the internal energy of the air pocket using the 1D–3D model demonstrate that the internal energy reduces in the slow compression process due to greater energy fluctuations and more rapid energy transfer between air and water, especially at the front of the air–water interface directly impacted by the incident wave. This explains why the existing 1D model underestimates the pressure damping. [ABSTRACT FROM AUTHOR]

In time domain to solve electromagnetic radiation and scattering problems, several numerical methods are available in literature. Among these numerical methods Finite Difference Time Domain (FDTD) method and Time Domain FEM (TDFEM) method are more popular. In the present work, we have proposed a quantity in continuum, which is conserved under certain boundary conditions. Additionally, we have also proposed a time marching scheme within edge element framework, which satisfy this conservation characteristic in algorithmic sense irrespective of the choice of time step. To facilitate this, we have used some conversion algorithm that transform nodal finite element data to edge finite element data. [ABSTRACT FROM AUTHOR]

This paper presents a detailed investigation into the application of transient Fourier analysis in select electrical engineering contexts. Two novel approaches for addressing transient analysis are introduced. The first approach combines the Fourier series with the Laplace–Carson ( L - C ) transform in the complex domain, utilizing complex time vectors to streamline the computation of the original function. The inverse transformation back into the time domain is achieved using the Cauchy-Heaviside ( C - H ) method. The second approach applies the Fourier transform ( F - Τ ) for the transient analysis of a power converter circuit with both passive and active loads. The method of complex conjugate amplitudes is employed for steady-state analysis. Both contributions represent innovative approaches within this study. The process begins with Fourier series expansions and the computation of Fourier coefficients, followed by solving the system's steady-state and transient responses. The transient states are then confirmed using the Fourier transform. To validate these findings, the analytical results are verified through simulations conducted in the Matlab/Simulink R2023b environment. [ABSTRACT FROM AUTHOR]

Thermal transient problems, essential for modeling applications like welding and additive metal manufacturing, are characterized by a dynamic evolution of temperature. Accurately simulating these phenomena is often computationally expensive, thus limiting their applications, for example for model parameter estimation or online process control. Model order reduction, a solution to preserve the accuracy while reducing the computation time, is explored. This article addresses challenges in developing reduced order models using the proper generalized decomposition (PGD) for transient thermal problems with a specific treatment of the moving heat source within the reduced model. Factors affecting accuracy, convergence, and computational cost, such as discretization methods (finite element and finite difference), a dimensionless formulation, the size of the heat source, and the inclusion of material parameters as additional PGD variables are examined across progressively complex examples. The results demonstrate the influence of these factors on the PGD model's performance and emphasize the importance of their consideration when implementing such models. For thermal example, it is demonstrated that a PGD model with a finite difference discretization in time, a dimensionless representation, a mapping for a moving heat source, and a spatial domain non‐separation yields the best approximation to the full order model. [ABSTRACT FROM AUTHOR]

Small heat shock proteins (sHSPs) are molecular chaperones that are widely present in plants and play a vital role in the response of plants to various environmental stimuli. This study employed transgenic Arabidopsis to investigate the impact of the new tomato (Solanum lycopersicum) sHSP protein (SlHSP17.3) on salt stress tolerance. Transient conversion analysis of Arabidopsis protoplasts revealed that SlHSP17.3 localized to the cytoplasm. Furthermore, as suggested by expression analysis, salt stress stimulated SlHSP17.3 expression, suggesting that SlHSP17.3 is involved in the salt stress response of plants. SlHSP17.3-overexpressing plants presented greater germination rates, fresh weights, chlorophyll contents, and Fv/Fm ratios, as well as longer root lengths, lower reactive oxygen species (ROS) levels, and lighter cell membrane injury under salt stress. Furthermore, certain stress-related genes (AtCOR15, AtDREB1B, and AtHSFA2) were up-regulated in salt-stressed transgenic plants. Overall, SlHSP17.3 overexpression improved the salt stress resistance of transgenic plants, mainly through increasing AtCOR15, AtDREB1B, and AtHSFA2 expression. [ABSTRACT FROM AUTHOR]

There are many uncertainties in the actual use of thermal protection systems (TPSs). In this paper, an interval finite element model of a TPS under transient heat transfer is established by taking the uncertainties of TPSs as interval parameters. An affine interval finite element method (AIFEM) is proposed to study the temperature response bounds of uncertain TPSs under transient heat transfer conditions. Two numerical examples are given to verify the effectiveness and accuracy of the proposed AIFEM by comparison with the Monte Carlo method. The results show that the AIFEM can provide conservative and efficient calculation results in TPS transient heat transfer design with interval parameters. [ABSTRACT FROM AUTHOR]

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Purpose: The dosimetry of scalp dose was prospectively studied and correlated with alopecia following conventional cranial irradiation in primary brain tumors patients. Materials and methods: Patients with primary brain tumors who required conventional radiotherapy were enrolled. A hairline marker was applied to the patient's scalp to identify the entire scalp region. The maximal dose to 2% volume of interest (D2) for the entire scalp region were obtained. The radiation dosages at the localized hair-loss areas were evaluated during the final week of RT (transient alopecia) and six months after completing RT (permanent alopecia). Kruskal-Wallis tests were used to compare the dosimetric parameter values with statistical significance set as p < 0.05. Results: Forty-eight patients were included in the analysis. The prescribed radiation doses ranged from 50.4 to 60.0 Gy. Thirty-two patients experienced alopecia (27 transient and 5 permanent). The median D2 values adjusted for the entire scalp were higher in the alopecia group (38.40 Gy for transient alopecia and 47.84 Gy for permanent alopecia vs 11.90 Gy for no alopecia, p < 0.001). The D2 value was determined as a predictive parameter for alopecia. The threshold values for transient and permanent alopecia over the entire scalp were 22.15 Gy and 36.81 Gy, respectively. At the localized hair-loss areas, the D2 values for transient and permanent alopecia were higher at 44.82 Gy and 50.00 Gy, respectively. The radiation intensity at the localized hair-loss areas was also related to the severity of alopecia, with D2 values of 35.14 Gy and 46.39 Gy for clinically assigned grade 1 and grade 2 transient alopecia, respectively, with the D2 value being even higher for permanent alopecia. Conclusions: The D2 parameter value could be used to predict the type and severity of alopecia. [ABSTRACT FROM AUTHOR]

Centrifugal pumps are essential components in various industrial applications, where their stable and efficient operation is critical. The impeller, a key part of these pumps, plays a pivotal role in energy conversion; thus, any fracture in its blades can significantly impact the pump's performance. This study investigates the effects of a single-blade trailing edge fracture on the flow characteristics of a centrifugal pump, aiming to provide insights into fault diagnosis and performance optimization. By employing a combination of experimental analysis and numerical simulation, the study analyzes changes in pump performance, pressure distribution, vortex structures, entropy production, blade loading, transient radial force, and pressure pulsation. The results indicate that minor blade fractures have minimal impact on the pump's head and efficiency, while severe fractures cause a noticeable decrease in head across all flow rates, with efficiency remaining relatively stable at low-flow rates. Transient analyses reveal that blade fractures alter the distribution and magnitude of radial forces, leading to changes in pressure pulsation characteristics, with the shaft passing frequency amplitude increasing and gradually surpassing the blade passing frequency amplitude. These findings provide important references for diagnosing fluid-induced centrifugal pump failures, effectively enabling the extraction of hydraulic features to optimize the fault diagnosis process. [ABSTRACT FROM AUTHOR]

Transient Raman thermometry improves on its steady-state counterpart by eliminating the error-prone steps of temperature calibration and laser absorption measurement. However, the accompanying complex heat transfer process often requires numerical analysis, such as the finite element method, to decipher the measured data. This step can be time-consuming, inconvenient, and difficult to derive a physical understanding of the heat transfer process involved. In this work, the finite element method is replaced by fitting the measured data to an analytical three-dimensional heat transfer model. This process can be completed in a few seconds. Using this approach, the in-plane thermal conductivity of two bulk layered materials and the interfacial thermal conductance between two-dimensional materials and quartz have been successfully measured. Based on our model, we performed an analytical quantitative sensitivity analysis for transient Raman thermometry to discover new physical insights. The sensitivity of the in-plane thermal conductivity of bulk layered materials is dictated by the ratio between the spot radius and heat spreading distance. The sensitivity of the interfacial thermal conductance between two-dimensional materials and quartz is determined by its conductance value. In addition, the uncertainty of the measured value contributed by the uncertainty of the input parameters can be efficiently estimated using our model. Our model provides an efficient data and sensitivity analysis method for the transient Raman thermometry technique to enable high throughput measurements, facilitate designing experiments, and derive physical interpretations of the heat transfer process. [ABSTRACT FROM AUTHOR]

A thermal model was developed based on finite element modeling analysis using the Transient Thermal module of Ansys. The objective of this study was to develop a thermal model for electrical discharge machining to address the discrepancies observed in the model proposed by Ming et al., which failed to accurately estimate Material Removal Rate (MRR) values for discharge powers exceeding 100 mJ. The MRR ratios derived from the model under consideration were observed to be within the range of 3.568–0.639. In comparison, the MRR ratios obtained from the models proposed by Ming et al. and Joshi et al. were found to be within the range of 3.566–1.186 and 40.433–0.652, respectively. Thus, the thermal model presented in this study demonstrates exceptional precision in predicting the MRR and surface roughness (SR) when compared to previously established models. The optimization of the readings was carried out through the application of Technique for Order of Preference by Similarity to Ideal Solution. The results indicated that an optimized MRR and SR were achieved at a pulse current (I) of 58 amps, pulse on time (Ton) of 420 μs, pulse off time (Toff) of 7.5 μs, and discharge power of 609 mJ. [ABSTRACT FROM AUTHOR]

Summary: Despite the performed progressive research work, the interpretation of the negative group delay (NGD) function remains not familiar to non‐specialist design and fabrication circuit engineers. The functionality misunderstanding limits the NGD circuit applications compared to other classical electronic functions. The present paper deals with the design of a tunable circuit by operating with positive and negative delay behaviors. The topology of the tunable circuit by using a low‐pass (LP) type NGD circuit is described. The design formulas for calculating the circuit resistor and capacitor parameters from the desired delay are expressed. The design feasibility of the tunable circuit composed of LP‐NGD cell and RC‐circuit is validated with a proof‐of‐concept (PoC) implemented on a test board. Two different signals with pulse and arbitrary waveforms having tens‐milliseconds duration were considered during the validation tests. As expected by tuning a varistor from 0.4 kΩ to 1 kΩ, the negative delay behavior varying from about −0.4 ms was verified thanks to the time‐advanced effect due to the LP‐NGD property. Then, the output signal delay was observed to become positive when the varistor was tuned from 1 kΩ to 3 kΩ. [ABSTRACT FROM AUTHOR]

In the paper, we consider the P H 2 -distribution, which is a particular case of the P H -distribution. In other words, The first service phase is exponentially distributed, and the service rate is μ. After the first service phase, the customer can to go away with probability p or continue the service with probability (1 − p) and service rate μ ′ . We study an analysis of an M / P H 2 / 1 queue model with catastrophes, which is regarded as a generalization of an M / M / 1 queue model with catastrophes. Whenever a catastrophe happens, all customers will be cleaned up immediately, and the queuing system is empty. The customers arrive at the queuing system based on a Poisson process, and the total service duration has two phases. Transient probabilities and steady-state probabilities of this queuing system are considered using practical applications of the modified Bessel function of the first kind, the Laplace transform, and probability-generating function techniques. Moreover, some important performance measures are obtained in the system. Finally, numerical illustrations are used to discuss the system's behavior, and conclusions and future directions of the model are given. [ABSTRACT FROM AUTHOR]

Most recently, metro rigid overhead wire-pantograph systems are subjected to severe wear of overhead wires and current collectors throughout China, which are difficult to completely solve up to now. The severe wear of metro rigid overhead wire-pantograph systems is probably brought about by the medium-high frequency vibration of the metro rigid overhead wire-pantograph systems. Coincidentally, corrugation is frequently found in rigid overhead wire systems, but rarely in flexible catenary systems. A frictional self-excited vibration model of a rigid overhead wire-pantograph system was set up. The self-excited vibration characteristics were investigated using the transient analysis and the motion stability analysis. Results show that when the friction coefficient is greater than 0.07, the rigid overhead wire-pantograph system is more prone to self-excited vibration. The self-excited vibration frequencies cover a range of 20–1000 Hz. The simulated overhead wire corrugation approaches the measured corrugation in wavelength. The influence factor analysis displays that the friction coefficient, zigzag layout of rigid catenary wires, and sliding direction of pantographs have significant effects on overhead wire corrugation, and but the train speed, normal force, main spring stiffness, and span of two positioning clips have a little effect. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) simulations are widely used to develop and analyze blood-contacting medical devices such as left ventricular assist devices (LVADs). This work presents an analysis of the transient behavior of two centrifugal LVADs with different designs: HeartWare VAD and HeartMate3. A scale-resolving methodology is followed through Large Eddy Simulations, which allows for the visualization of turbulent structures. The three-dimensional (3D) LVAD models are coupled to a zero-dimensional (0D) 2-element Windkessel model, which accounts for the vascular resistance and compliance of the arterial system downstream of the device. Furthermore, both continuous- and pulsatile-flow operation modes are analyzed. For the pulsatile conditions, the artificial pulse of HeartMate3 is imposed, leading to a larger variation of performance variables in HeartWare VAD than in HeartMate3. Moreover, CFD results of pulsatile-flow simulations are compared to those obtained by accessing the quasi-steady maps of the pumps. The quasi-steady approach is a predictive tool used to provide a preliminary approximation of the pulsatile evolution of flow rate, pressure head, and power, by only imposing a speed pulse and vascular parameters. This preliminary quasi-steady solution can be useful for deciding the characteristics of the pulsatile speed law before running a transient CFD simulation, as the former entails a significant reduction in computational cost in comparison to the latter. [ABSTRACT FROM AUTHOR]

The production performances of fractured tight gas wells are closely related to several complex and unknown factors, including the formation properties, fracture parameters, gas–water two-phase flow, and other nonlinear flow mechanisms. The rate transient analysis (RTA) results have significant uncertainties, which should be quantified to evaluate the formation and fracturing treatment better. This paper provides an efficient method for uncertainty quantification in the RTA of fractured tight gas wells with multiple unknown factors incorporated. The theoretical model for making forward predictions is based on a trilinear flow model, which incorporates the effects of two-phase flow and other nonlinear flow mechanisms. The normalized rates and material balance times of both water and gas phases are regarded as observations and matched with the theoretical model. The unknowns in the model are calibrated using the ensemble Kalman filter (EnKF), which applies an ensemble of multiple realizations to match the observations and updates the unknown parameters step by step. Finally, a comprehensive field case from Northwestern China is implemented to benchmark the proposed method. The results show that the parameters and rate transient responses have wide ranges and significant uncertainties before history matching, while all the realizations in the ensemble can have good matches to the field data after calibration. The posterior distribution of each unknown parameter in the model can be obtained after history matching, which can be used to quantify the uncertainties in the RTA of the fractured tight gas wells. The ranges and uncertainties of the parameters are significantly narrowed down, but the parameters are still with significant uncertainties. The main contribution of the paper is the provision of an efficient integrated workflow to quantify the uncertainties in RTA. It can be readily used in field applications of multi-fractured horizontal wells from tight gas reservoirs. [ABSTRACT FROM AUTHOR]

In this paper, we present various theoretical models that accurately approximate the spectral density of the optical capture cross-section ( σ e 0 ) obtained through the analysis of photo-capacitance transients using the deep-level optical spectroscopy (DLOS) technique applied to semi-transparent Ni/Au Schottky barrier diodes (SBDs) fabricated on n-GaN films. The theoretical models examined in this study involved a variety of approaches, from the Lucovsky model that assumes no lattice relaxation to more sophisticated models such as the Chantre–Bois and the Pässler models, which consider the electron–phonon coupling phenomenon. By applying theoretical models to the experimentally determined data, we were able to estimate the photoionization (E0), trap level position (ET), and Franck–Condon (dFC) energy, respectively. In addition, the results of our analysis confirm that the photoionization processes of deep traps in n-GaN grown by the metal–organic vapor-phase epitaxy technique (MOVPE) are strongly coupled to the lattice. Moreover, it was shown that the Pässler model is preferred for the accurate determination of the individual trap parameters of defects present in n-GaN films grown on an Ammono-GaN substrate. Finally, a new trap level, Ec-1.99 eV with dFC = 0.15, that has not been previously reported in n-GaN films grown by MOVPE was found. [ABSTRACT FROM AUTHOR]

A reduced-order homogenization framework is proposed, providing a macro-scale-enriched continuum model for locally resonant acoustic metamaterials operating in the subwavelength regime, for both time and frequency domain analyses. The homogenized continuum has a non-standard constitutive model, capturing a metamaterial behaviour such as negative effective bulk modulus, negative effective density and Willis coupling. A suitable reduced space is constructed based on the unit cell response in a steady-state regime and the local resonance regime. A frequency domain numerical example demonstrates the efficiency and suitability of the proposed framework. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 2)'. [ABSTRACT FROM AUTHOR]

The low specific speed centrifugal pump plays a crucial role in industrial applications, and ensuring its efficient and stable operation is extremely important for the safety of the whole system. The pump must operate with an extremely high head, an extremely low flow rate, and a very fast speed. The internal flow structure is complex and there is a strong interaction between dynamic and static components; consequently, the hydraulic excitation force produced becomes a significant factor that triggers abnormal vibrations in the pump. Therefore, this study focuses on a low specific speed centrifugal pump and uses a single-stage model pump to conduct PIV and pressure pulsation tests. The findings reveal that the PIV tests successfully captured the typical jet-wake structure at the outlet of the impeller, as well as the flow separation structure at the leading edge of the guide vanes and the suction surface. On the left side of the discharge pipe, large-scale flow separation and reverse flow happen as a result of the flow-through effect, producing a strong vortex zone. The flow field on the left side of the pressure chamber is relatively uniform, and the low-speed region on the suction surface of the guide vanes is reduced due to the reverse flow. The results of the pressure pulsation test showed that the energy of pressure pulsation in the flow passage of the guide vane occurs at the fBPF and its harmonics, and the interaction between the rotor and stator is significant. Under the same operating condition, the RMS value distribution and amplitude at fBPF of each measurement point are asymmetric in the circumferential direction. The amplitude of fBPF near the discharge pipe is lower, while the RMS value is higher. A complex flow structure is shown by the larger amplitude and RMS value of the fBPF on the left side of the pressure chamber. With the flow rate increasing, the energy at fBPF of each measurement point increases first and then decreases, while the RMS value decreases, indicating a more uniform flow field inside the pump. [ABSTRACT FROM AUTHOR]

Bluff-body wakes generally become three-dimensional (3-D) and then turbulent when the Reynolds number exceeds a few hundred. Other than an alternate shedding of the spanwise vortices behind the body and a gradual decay and annihilation of the vortices with distance downstream, whether a secondary vortex street would develop in the relatively far wake has been a long-standing argument in the literature. This argument is addressed in the present study. Specifically, direct numerical simulations and transient growth analysis are performed to examine the two-dimensional and 3-D wakes of different bluff bodies, including circular cylinder, square cylinder, diamond cylinder and rectangular cylinders with different cross-sectional aspect ratios. We found that a secondary vortex street is absent for most 3-D and turbulent wakes. The root cause is the weakening of spanwise vortices by 3-D wake instability modes and streamwise circulation/vorticity. The weakened spanwise vortices induce reduced mean shear in the intermediate wake, which then induces much smaller perturbation energy growth that is below the threshold for the emergence of a secondary vortex street. This finding suggests that the 3-D and turbulence characteristics, and the momentum, mass and heat transport in the relatively far wake of bluff bodies, would not be influenced by extra anisotropy or inhomogeneity caused by a secondary vortex street. [ABSTRACT FROM AUTHOR]

Since these large‐scale renewable power generation (RPGs) stations are always located far away from load centres, voltage source converters (VSCs) always operate in weak‐grid connected conditions, due to the long distance of transmission line and increasing capacity of RPGs. Large power disturbance of RPGs easily causes weak‐grid connected VSCs (WG‐VSCs) suffering from transient synchronization instability issue, which is lack of theoretical and quantitative analysis. This paper is motivated to fill this gap. By considering the dynamic interaction of outer DC voltage control, reactive power loop, and phase‐locked loop (PLL), an equivalent synchronization model of a WG‐VSC system is established first. Then, the mechanism of transient synchronization instability is revealed by the combination of equal area criterion and numerical integration method. Furthermore, the concept of feasible region of active power disturbance (FR‐APD) is introduced for the first time. With the constructed FR‐APD, the transient stability of the WG‐VSC system can be confirmed. Finally, experimental results based on the RT‐BOX hardware‐in‐the‐loop platform are presented to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

Protein kinases are key signaling nodes that regulate fundamental biological and disease processes. Illuminating kinase signaling from multiple angles can provide deeper insights into disease mechanisms and improve therapeutic targeting. While fluorescent biosensors are powerful tools for visualizing live-cell kinase activity dynamics in real time, new molecular tools are needed that enable recording of transient signaling activities for post hoc analysis and targeted manipulation. Here, we develop a light-gated kinase activity coupled transcriptional integrator (KINACT) that converts dynamic kinase signals into "permanent" fluorescent marks. KINACT enables robust monitoring of kinase activity across scales, accurately recording subcellular PKA activity, highlighting PKA activity distribution in 3D cultures, and identifying PKA activators and inhibitors in high-throughput screens. We further leverage the ability of KINACT to drive signaling effector expression to allow feedback manipulation of the balance of GαsR201C-induced PKA and ERK activation and dissect the mechanisms of oncogenic G protein signaling. Real-time biosensors have been developed for visualizing kinase activity dynamics, but they are confronted with many challenges. Here, the authors develop a light-gated KINACT integrator for post hoc analysis of transient kinase activity and signalling manipulation. [ABSTRACT FROM AUTHOR]

Inflow conditions dominate the process of root canal irrigation, and the application of pulsating inflow in dentistry is necessary to be explored due to its mass transfer enhancement capability. A prepared root canal model with a 30G side-vented needle is numerically investigated under pulsating inflow with different frequencies and amplitudes. Root canal apical pressure, extending depth, and effective cleaning area are adopted to evaluate the safety, mass transfer capacity, and clean efficiency of the irrigation system. Time-averaged results show that the irrigation performance is improved with pulsating flow maintaining safety. Compared with steady cases, the extending depth and effective cleaning area are increased by up to 43.6% and 11.42%, respectively. Three typical cases with significant improvement are selected for transient analysis. Transient results show that the apical pressure and extending depth have instant response features, while the effective cleaning area has a time-lag response characteristic. It is convinced that the transient characteristic of the system results from the coupling effects of the pulsating effect, instantaneous flow rate, and Coanda effect. The internal flow distribution of root canal system is prompted under the optimal parameters combinations of pulsating conditions, in which mass transfer capacity and clean efficiency are enhanced with guaranteed safety. [ABSTRACT FROM AUTHOR]

CO oxidation has been studied for more than a century; however, molecular-level understanding of its activation protocol and related intermediates remains elusive. Here, we present a unified mechanistic and kinetic picture of various electronic metal-support interactions within platinum-carbon catalysts via in situ spectroscopic/kinetic analyses and multi-scale simulations. Transient kinetic analysis and molecular dynamics simulations with a reactive force field provided a quantitative description of the competition between the oxygen association and oxygen dissociation mechanisms tuned by the interfacial charge distribution and CO coverage. Steady-state isotopic transient kinetic analysis and density functional theory calculations revealed a simultaneous shift in the rate-determining step (RDS) from O2 * dissociation to O* and CO* and O2 * and CO* association. A de novo strategy from the interfacial charge distribution to the reaction mechanism, kinetics/thermodynamics of RDS, and, ultimately, catalytic performance was developed to quantitatively map the above CO activation mechanism with an order-of-magnitude increase in reactivity. The proposed catalytic picture and de novo strategy are expected to prompt the development of theories and methodologies for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

A non-zero correlation between service times can be encountered in many real queueing systems. An attractive model for correlated service times is the Markovian service process, because it offers powerful fitting capabilities combined with analytical tractability. In this paper, a transient study of the queue length in a model with MSP services and a general distribution of interarrival times is performed. In particular, two theorems are proven: one on the queue length distribution at a particular time t, where t can be arbitrarily small or large, and another on the mean queue length at t. In addition to the theorems, multiple numerical examples are provided. They illustrate the development over time of the mean queue length and the standard deviation, along with the complete distribution, depending on the service correlation strength, initial system conditions, and the interarrival time variance. [ABSTRACT FROM AUTHOR]

Predicting the need for modeling and solutions is one of the largest difficulties in the electricity system. The static-constrained solution, which is not always powerful, is provided by the Gradient Method Power Flow (GMPF). Another benefit of using both dynamic and transient restrictions is that GMPF will increase transient stability against faults. The system is observed under contingency situations using the Dynamic Stability for Constrained Gradient Method Power Flow (DSCGMPF). The population optimization technique is the foundation of a recent algorithm called Training Learning Based Optimization (TLBO). The TLBO-based approach for obtaining DSCGMPF is implemented in this work. The total system losses and the cost of the individual generators have been optimized. Analysis of the stability limits under contingency conditions has been conducted as well. To illustrate the suggested approaches, a Standard 3 machine 5-bus system is simulated using the MATLAB 2022B platform. [ABSTRACT FROM AUTHOR]

Transient stability analysis is critical for maintaining the reliability and security of power systems. This paper provides a comprehensive review of research methods for transient stability analysis under large disturbances, detailing the modeling concepts and implementation approaches. The research methods for large disturbance transient stability analysis are categorized into five main types: simulation methods, direct methods, data-driven methods, analytical methods, and other methods. Within the analytical method category, several common analytical strategies are introduced, including the asymptotic expansion method, intrusive approximation method, and other analytical methods. The fundamental principles, characteristics, and recent research advancements of these methods are detailed, with particular attention to their performance in various aspects such as computational efficiency, accuracy, applicability to different system models, and stability region estimation. The advantages and disadvantages of each method are compared, offering insights to support further research into transient stability analysis for hybrid power grids under large disturbances. [ABSTRACT FROM AUTHOR]

The rapid technological progress of large-scale CNC (computer numerical control) systems for Screw Extrusion Additive Manufacturing (SEAM) has made the overprinting of composite laminates a much-discussed topic. It offers the potential to efficiently produce functionalised high-performance structures. However, bonding the 3D-printed structure to the laminate has proven to be a critical point. In particular, the bonding mechanisms must be precisely understood and controlled to ensure in situ bonding. This work investigates the applicability of healing models from 3D printing to the overprinting of thermoplastic laminates using semi-crystalline, high-performance material like PEEK (polyether ether ketone). For this purpose, a simulation methodology for predicting the bonding behaviour is developed and tested using experimental data from a previous study. The simulation consists of a transient heat analysis and a diffusion healing model. Using this model, a qualitative prediction of the bond strength could be made by considering the influence of wetting. It was shown that the thermal history of the interface and, in particular, the tolerance of the deposition of the first layer are decisive for in situ bonding. The results show basic requirements for future process and component developments and should further advance the maturation of overprinting. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the individual electrochemical transients arising from local anodic events on stainless steel, to uncover the potential mechanisms producing different types of transients and to derive appropriate parameters indicative of the corrosion severity of such transient events. Design/methodology/approach: An equivalent circuit model was used for the transient analysis, which was performed using a local current allocation rule based on the relative instant cathodic resistance of the coupled electrodes, as well as the kinetic parameters derived from the electrochemical polarization measurement. Findings: The shape and size of the electrochemical current transients arising from SS 316 L were influenced by the film stability, local anodic dissolution kinetics and the symmetry of the cathodic kinetics between the coupled electrodes, where the ultralong transient might correspond to the propagation of film damage with a slow anodic dissolution rate. The dynamic cathodic resistance during the final stage of transient current growth can serve as a characteristic parameter that reflects the loss of passive film protection. Originality/value: Estimation of the local anodic current trace opens a new way for individual electrochemical transient analysis associated with the charges involved, local current densities and changes in film resistance throughout localized corrosion processes. [ABSTRACT FROM AUTHOR]

The system integration of cross‐industrial networks in the Carbon2Chem® project relies on numerical simulations. Hence, this study validates the methanol synthesis loop models vs. the measurements from a demonstration plant, focusing on the thermodynamic, kinetic, and dynamic aspects. The plant can produce up to 500 L per week of methanol from real blast furnace gases of the thyssenkrupp steel plant in Duisburg. Despite its small size, it comprises a recycle gas loop and an original reactor tube of 6 m in length. After validation, the simulation models are used to analyze the dynamic operation limits of the plant, and they are transferred to the model of an industrial size to analyze the operation of cross‐industrial networks with volatile boundary conditions. [ABSTRACT FROM AUTHOR]

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A virtual synchronous generator (VSG) is prone to transient instability under a grid fault, which leads to the loss of synchronization between the new energy converter and grid, and threatens the operation safety of high-proportion new energy grids. There are a variety of control models in the existing VSG control, including active and reactive power models, which lead to their different transient stabilities. However, the evolution characteristics, correlation between different models of VSG, and the internal mechanism affecting transient stability have not been fully studied. To this effect, this paper analyzes their evolution characteristics based on the existing mainstream VSG control models and establishes a unified VSG model and its equivalent correspondence with other models. Then, the phase plane method is used to comprehensively analyze and compare the transient stability of the VSG unified model with other models. It is pointed out that the key factors affecting the transient stability of different models are three links of primary frequency regulation, reactive power regulation and reactive power tracking. Finally, the correctness of the established VSG unified model and the conclusion of transient stability analysis is verified by experiments. [ABSTRACT FROM AUTHOR]

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As large-scale renewable energy sources are increasingly integrated into AC grids via voltage source converters (VSCs), the transient synchronization stability of phase-locked loop (PLL)-based VSCs during fault ride-through is gaining more attention. Most existing studies assume that the positive and negative sequence separation and current control dynamics are much faster than the PLL dynamics, thereby neglecting their impact on the transient synchronization stability of the system. However, when the PLL bandwidth is relatively large, ignoring the positive and negative sequence separation and current control dynamics may result in incorrect stability assessments. To address this issue, this paper first considers the multiple control loop coupling, including positive and negative sequence separation, current control, and PLL, to construct a full-order nonlinear mathematical model of the VSC grid-connected system under asymmetric fault conditions. Based on this, the phase trajectory method is employed to analyze the transient synchronization stability of the system. Additionally, this full-order mathematical model is used to determine the PLL bandwidth boundary beyond which the effects of positive and negative sequence separation and current control dynamics cannot be neglected. Finally, PSCAD/EMTDC simulation results validate the effectiveness of the theoretical analysis presented in this paper. [ABSTRACT FROM AUTHOR]

Thermal transients of small or thermally well-conducting components typically relax with a very short time constant. In some cases, the fastest changes occur on a time scale of a few tens to hundreds of microseconds. Providing a sampling rate higher than 1 kHz is challenging, even for modern infrared cameras. This work presents a periodic non-uniform sampling technique for measuring thermographic transients, which increases the effective sampling rate by one order of magnitude to 10 kHz, resulting in a temporal resolution of 100 μs. The practical application of this technique captures parts of the thermal transient that would otherwise be missed for standard sampling rates. The results confirm the algorithm's ability to enhance the effective sampling rate, providing a more detailed thermal analysis of rapid transient processes in small-scale electronic components. [ABSTRACT FROM AUTHOR]

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Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the assumption of acceleration variation in traditional step-by-step integration methods such as Newmark, sufficiently small time steps are required to ensure numerical stability and accuracy in dynamic systems. In contrast, the state-space approach, based on piecewise interpolation of discrete load functions, does not rely on predetermined acceleration assumptions and has demonstrated high efficiency in terms of stability and accuracy. The original state-space method requires the calculation of the inverse of the structural mass in the transition matrix. However, when a lumped mass matrix is used, this computation renders the entire mass matrix singular, resulting in an invalid solution expression. To address this issue, this study proposes an improved state-space approach for the transient analysis of large-scale structural systems with local nonlinearities. In this approach, a nonlinear force corrector is introduced as an external force term applied to the linear elastic system to account for the nonlinear behavior of locally yielding components. Consequently, the original nonlinear dynamic system can be transformed into an equivalent linear elastic transient system. Furthermore, based on the lumped mass matrix, a first-order ordinary differential state-space equation for such an equivalent linear elastic transient system is derived. Simulation results from three transient system examples show that the state-space approach outperforms the Newmark method in terms of accuracy and stability for dynamic systems characterized by high frequency and low damping. The prediction results show that the state-space approach appears to be insignificantly affected by the choice of the consistent or lumped mass matrix. The numerical results show that the root-mean-square errors between the consistent and lumped matrices in the top displacement time histories of a 15-storey plane frame under various seismic intensities are all less than 1%, and in the base reaction time histories responses the discrepancies are only about 0.5%, indicating that the use of lumped mass matrices is quite reliable. When many nodes or degrees of freedom have no assigned mass, the dimensionality of the state-space equation can be significantly reduced using the lumped mass approach. Therefore, the simulation of large-scale systems can be simplified by employing the improved state-space approach with lumped mass matrices, yielding results nearly identical to those obtained using traditional methods. In conclusion, the improved state-space approach has great potential for the simulation of transient behavior in large-scale systems with local nonlinearities. [ABSTRACT FROM AUTHOR]

This research article presents the design and development of a custom-made inside-mouth support for microphone placement, aiming to improve sound quality and minimize background noise. The support was designed to ensure proper articulation and pronunciation. To ensure biocompatibility, a medical-grade polymer poly methyl methacrylate (PMMA) was chosen due to its low melting temperature and ability to manufacture clear and transparent pieces suitable for 3D printing. The design of the support is done using Fusion 360, and later analysis is done on the support in ANSYS workbench software to analyse the behaviour of the support subjected to dynamic and static loads. The support was subjected to transient structural, explicit dynamic, and static structural analysis to investigate its response to different loading conditions and evaluate its performance in real-world scenarios. The transient response of the PMMA material was found to be safer and more reliable. The maximum average values of total deformation, maximum principal elastic strain, and maximum principal stress obtained from the transient structural analysis were 3.5258e-003 mm, 2.1363e-005 mm/mm, and 0.035209 MPa, respectively. The explicit dynamic analysis resulted in maximum average values of 1.2917e-003 mm, 5.9808e-006 mm/mm, and 5.3201e-003 MPa, respectively. The static structural analysis gave average values of 2.7015e-003 mm, 2.0882e-005 mm/mm, and 2.9142e-002 MPa, respectively. Additionally, the support was tested using two different materials, silicone rubber, and PMMA, for comparison. The results showed that PMMA had several advantages over silicone rubber, including lower total deformation and maximum principal stress, making it more reliable for use in real-world scenarios. In conclusion, the inside-mouth support designed and developed in this study can improve sound quality and minimize background noise in areas where high noise predominates. Using PMMA as the material of choice for the support ensures biocompatibility and improves the overall performance and reliability of the device. [ABSTRACT FROM AUTHOR]

Abstract Since these large‐scale renewable power generation (RPGs) stations are always located far away from load centres, voltage source converters (VSCs) always operate in weak‐grid connected conditions, due to the long distance of transmission line and increasing capacity of RPGs. Large power disturbance of RPGs easily causes weak‐grid connected VSCs (WG‐VSCs) suffering from transient synchronization instability issue, which is lack of theoretical and quantitative analysis. This paper is motivated to fill this gap. By considering the dynamic interaction of outer DC voltage control, reactive power loop, and phase‐locked loop (PLL), an equivalent synchronization model of a WG‐VSC system is established first. Then, the mechanism of transient synchronization instability is revealed by the combination of equal area criterion and numerical integration method. Furthermore, the concept of feasible region of active power disturbance (FR‐APD) is introduced for the first time. With the constructed FR‐APD, the transient stability of the WG‐VSC system can be confirmed. Finally, experimental results based on the RT‐BOX hardware‐in‐the‐loop platform are presented to verify the theoretical analysis.