Compressibility Factor Research Articles

On the theory of spectral compression-assisted optical temporal differentiation

Bandwidth limitation represents a significant factor that degrades the performance of optical devices. The dimensions, composition and configuration of optical devices impose intrinsic constraints on processing broadband optical pulse signals. The enhancement of the response bandwidth of optical devices represents a significant challenge. In this study, we put forward the theory of self-similar spectral compression (SSSC), which involves solving the nonlinear Schrödinger equation with variable coefficients by using the Taylor expansion and residual theorem. The spectral waveform can be precisely preserved in the process of SSSC, leading to a predictable compression factor without pedestals. To demonstrate the effectiveness of the proposed SSSC, we present a case study by designing an on-chip optical time-domain differentiator (OTD) system including a silicon-based tapered spiral waveguide. A 200-fs chirped pulse is well differentiated at multiple orders in the OTD system. Although the linear loss of spiral waveguide has a detrimental impact on SSSC, the broadband spectrum can still be self-similarly compressed, leading to a reduction of differentiation deviation of 22.5 times. The proposed SSSC theory offers valuable guidance for designing all-optical signal processing systems with high spectral resolution and low signal error.

Measurement of spherical tokamak plasma compression in the PCS-16 magnetized target fusion experiment

Abstract A sequence of magnetized target fusion (MTF) devices built by General Fusion have compressed magnetically confined deuterium plasmas inside imploding aluminum liners. Here we describe the best-performing compression experiment, PCS-16, which was the fifth of the most recent experiments that compressed a spherical tokamak plasma configuration. In PCS-16 the plasma remained axisymmetric with δBpol/Bpol < 20% to a high radial compression factor (CR > 8) with significant poloidal flux conservation (77% up to CR = 1.7, and ≈30% up to CR = 8.65) and a total compression time of 167 μs. Magnetic energy of the plasma increased from 0.96 kJ poloidal and 17 kJ toroidal to a peak of 1.14 kJ poloidal and 29.9 kJ toroidal during the compression, while thermal energy was in the range of 350 ± 25 J. Plasma equilibrium was a low-β state with βtor ≈ 4% and βpol ≈ 15%. Ingress of impurities from the lithium coated aluminum wall was not a dominant effect. Neutron yield from D-D fusion increased significantly during compression. Thermodynamics during the early phase of compression (CR < 1.7) were consistent with increasing Ohmic heating of the electrons due to a geometric rise in the current density at near-constant resistivity, and with increasing ion cooling that approximately matched ion compressional heating power. Ion cooling by electrons was significant because the electrons were cooler than the ions (Te = 200 eV, Ti = 600 eV). Magnetohydrodynamic simulation was used to model the emergence of instabilities that increased electron thermal transport in the final phase of compression. Conditions for ideal stability were actively maintained during compression through a current ramp applied to the central shaft, and after this current ramp reached its peak two-thirds of the way through compression we measured a transition in plasma behavior across multiple diagnostics.

Generation of Wideband Signals Based on Continuous-Time Photonic Compression

A detailed study on continuous-time photonic compression (CTPC) for generating wideband signals is presented in this paper. CTPC enables the conversion of parallel analog waveforms from multiple channels into a time-compressed continuous-time waveform with increased bandwidth. We demonstrate a CTPC system with a compression factor of two in a proof-of-concept experiment. Subsequently, the origin of the distortion in the generated signals is investigated, and we proposed a method based on bandpass filtering to remove the periodic dips observed in the generated waveforms. In addition, a predistortion method is proposed to eliminate the distortion caused by the non-ideal spectral property of the multichannel system. Further simulation results are presented to show the potential of the proposed approach.

Research on Wellbore Integrity Evaluation Model of CO2 Enhanced Composite Fracturing

CO2 injection composite fracturing is an effective method for shale oil and gas well development. The downhole casing is prone to uniform corrosion, pitting, perforation, and even corrosion fracture in the CO2 environment. Therefore, it is particularly important to reveal the physical characteristics of CO2 under actual geological conditions and the impact of CO2 corrosion on the performance of casing. A mathematical model for the temperature and pressure field of CO2 in the wellbore under fracturing conditions is established in this paper, and the temperature and pressure distribution along the depth of the well is calculated. By optimizing the CO2 state equation and using the S-W equation, Lee model, and RK model to calculate the CO2 density, viscosity and compression factor, respectively, the phase distribution pattern of CO2 along the actual wellbore is obtained. Through CO2 corrosion tests on the casing, the influence of temperature and CO2 concentration on the corrosion rate of the casing is clarified. The peak corrosion rate of Q125 steel corresponds to 80 °C, and the corrosion rate increases with the increase in CO2 concentration. Finally, a prediction model for the uniform corrosion rate of casing under different temperatures and CO2 concentration conditions is obtained, which can provide technical support for the design of CO2-enhanced fracturing technology.

Deformability of filament-wound GFRP tubes filled with lightweight aggregate concrete: Experimental and improved analytical studies

Previous research indicates that lightweight aggregate (LWA) concrete exhibits more brittle failure under compression than conventional normal density (ND) concrete. In contrast, angle-ply fiber-reinforced polymer (FRP) filament-wound tubes filled with ND concrete show significant improvements in strength and deformability compared to hollow tubes. This study evaluates the impact of these tubes on LWA concrete to mitigate its brittle behavior. Sixteen concrete-filled FRP filament-wound tubes (CFFTs) made of ±55° filament-wound glass FRP (GFRP) were tested under axial compression. The GFRP tube’s mechanical properties and fiber winding angle of ±55° allowed for a compressive strength enhancement factor ranging from two to five for the CFFTs compared to unconfined specimens. Results also revealed substantial nonlinearity and deformability in the LWA-CFFTs due to the angle-ply tube orientation. An iterative analytical model predicted the CFFT’s nonlinear response, validated by experimental data. The findings demonstrate that angle-ply FRP tubes effectively enhance the bearing capacity and deformability of inherently brittle unconfined LWA concrete.

Multi-Color Spaceplates in the Visible.

The ultimate miniaturization of any optical system relies on the reduction or removal of free-space gaps between optical elements. Recently, nonlocal flat optic components named "spaceplates" were introduced to effectively compress space for light propagation. However, space compression over the visible spectrum remains beyond the reach of current spaceplate designs due to their inherently limited operating bandwidth and functional inefficiencies in the visible range. Here, we introduce "multi-color" spaceplates performing achromatic space compression at three distinct color channels across the visible spectrum to markedly miniaturize color imaging systems. In this approach, we first design monochromatic spaceplates with high compression factors and high transmission amplitudes at visible wavelengths based on a scalable structure and dielectric materials widely used in the fabrication of meta-optical components. We then show that the dispersion-engineered combination of monochromatic spaceplates with suitably designed transmission responses forms multicolor spaceplates that function achromatically. The proposed multicolor spaceplates, composed of amorphous titanium dioxide and silicon dioxide layers, efficiently replace free-space volumes with compression ratios as high as 4.6, beyond what would be achievable by a continuously broadband spaceplate made of the same materials. Our strategy for designing monochromatic and multicolor spaceplates, along with the presented theoretical and computational results, show that strong space-compression effects can be achieved in the visible range. Our findings may ultimately enable a new generation of ultrathin optical devices for various applications.

Dynamical and rheological analysis of gas condensate reservoir characteristics and multiphase flow behavior of a well

This manuscript proposes dynamical and rheological analysis of gas condensate reservoir characteristics and multiphase flow behavior of a well located at the lower Indus basin gas condensate reservoir in Sindh, Pakistan. The main objective is to analyze the compositional variation impacts on the liquid dropout, flow behavior and well productivity. For the sake of data analysis, constant composition expansion and constant volume depletion capabilities have been tested via pressure, volume and temperature cell under measurement of dew point and liquid dropout flow. By invoking CMG: Win prop simulator on the basis of equation of state namely Peng Robenson and Soave Redlish Kwong equations, phase diagram and well stream physical parameters have been analyzed. Our result suggested crucial significance for the behavior of flow and well productivity that liquid generation changes with the physical properties of flowing stream namely vapor viscosity, compressibility factor and vapor density due to pressure depletion showing decreasing trend. Mole percent of lighter components C1 mole percent increases from 54.567 to 62.153. While mole percent of heavier components C18+ decreases from 3.453 to 1.513 with 45% liquid dropout. In brevity, maximum well productivity has been observed in composition-1 which is 5.005 MMscf/day at pressure of 3131 psig.

Assessment of dissociation enthalpies of methane hydrates in the absence and presence of ionic liquids using the Clausius-Clapeyron approach

The Clausius-Clapeyron (CC) equation is generally preferred to obtain dissociation enthalpies (ΔH) of hydrate-forming systems due to its ease of use. The application of other direct and indirect methods becomes more problematic if complex additives such as ionic liquids (ILs) are also present in the system. In this work, around 400 equilibrium data points for methane hydrates in the presence of over 80 ILs were collected from the literature in the temperature and pressure ranges of (272.10 – 306.07) K and (2.48 – 100.34) MPa, respectively. The ΔH of methane hydrates in the absence and presence of ionic liquids (ILs) have been calculated using the CC equation. The compressibility factor (z), required to calculate ΔH at each phase equilibrium condition has been obtained from three different approaches viz., Peng-Robinson (PR) equation of state, Soave-Redlich-Kwong (SRK) equation of state and Pitzer (Pz) correlation. The results were compared to the experimentally reported dissociation enthalpy (54.5 ± 1.5 kJ.mol−1) of methane hydrates. The role of the compressibility factor along with the slope of the equilibrium data set and the temperature/pressure range in determining the outcome of the CC equation has been discussed. The effect of molar mass, molar volume, and hydrate suppression temperature of the ILs on the ΔH of methane hydrates has been explored. The tested ILs do not show a systematic and significant influence on enthalpies, rather they show a large scattering in the ΔH values, which might mask any existing subtle effect of the ILs on the dissociation enthalpies. Therefore, this approach should be dealt with care to obtain molecular-level insights.

Prediction of pure and mixture thermodynamic properties and phase equilibria using an optimized equation of state – part 1: Parameter estimation

This study presents a novel three-parameter equation of state (EOS) wherein attraction parameter polynomial coefficients are optimized to enhance predictive capabilities. The performance of the proposed EOS is systematically compared with established models including Peng-Robinson, Patel-Teja, and Twu-Coon-Cunningham equations. Through comprehensive evaluation, it is demonstrated that the proposed EOS exhibits superior accuracy in vapor pressure and latent enthalpy predictions, while maintaining comparable precision in liquid density estimations. Notably, the fugacity expression of the proposed EOS closely resembles that of a two-parameter equation, resulting in significantly reduced computational overhead. Additionally, a comprehensive table of equation of state parameters for all four equations is available in an online repository, facilitating easy implementation and comparison. Furthermore, a reliable generalized polynomial correlation is provided for the proposed EOS parameters against the true compressibility factor and acentric factor, leveraging data accessibility and enhancing its applicability and versatility. These findings underscore the potential of the optimized attraction parameter polynomial coefficients approach in advancing the accuracy and efficiency of EOS modeling, thereby offering promising avenues for diverse applications in thermodynamics and process engineering.

Simulation of gas mixture dynamics in a pipeline network using explicit staggered-grid discretization

We develop an explicit staggered finite difference discretization scheme for simulating the transport of highly heterogeneous gas mixtures through pipeline networks. This study is motivated by the proposed blending of hydrogen into natural gas pipelines to reduce end use carbon emissions while using existing pipeline systems throughout their planned lifetimes. Our computational method accommodates an arbitrary number of constituent gases with very different physical properties that may be injected into a network with significant spatiotemporal variation. In this setting, the gas flow physics are highly location- and time- dependent, so that local composition and nodal mixing must be accounted for. The resulting conservation laws are formulated in terms of pressure, partial densities and flows, and volumetric and mass fractions of the constituents. We include non-ideal equations of state that employ linear approximations of gas compressibility factors, so that the pressure dynamics propagate locally according to a variable wave speed that depends on mixture composition and density. We derive compatibility relationships for network edge boundary values that are more complex than for a homogeneous gas. The simulation method is evaluated on initial boundary value problems for a single pipe and a small network, is cross-validated with a lumped element simulation, and used to demonstrate a local monitoring and control policy for maintaining allowable concentration levels.

Clinical value and risk factors of compression supporting screwsin patients with femoral neck fractures

BackgroundThis study was performed with attempt to explore the clinical value and risk factors of compression supporting screws for the treatment of femoral neck fractures.MethodsThis retrospective analysis enrolled 102 patients with femoral neck fractures who admitted to our hospital from June 2020 to June 2022. Based on different screws during the operation, the participants were allocated into hollow screw group (52 cases, conventional fixation of parallel partial-thread hollow screw) and compression screw group (50 cases, compression screw fixation).ResultThe incidence of complications (including internal fixation failure, nonunion, a vascular necrosis of the femoral head, shortening of the femoral neck by less than 10 mm, and lateral screw withdrawal, of the affected limb) in the compression screw group were significantly lower than those in the hollow screw group (P < 0.05). Patients enrolled in this study were followed up for 9 to 14 months, with an average follow-up time of (12.09 ± 1.87) months.The pain degree at 3 days, 10 days, and the last follow-up after operation in the compression screw group was evidently lower than that in the hollow screw group (P < 0.05). At the last follow-up, the improvment in hip joint function was more significant in the compression screw group than in the hollow screw group (P < 0.05). Univariate logistic regression analysis showed that the risk factors for complications in the treatment of femoral neck fractures with compression supporting screws were age, Pauwels type III fracture (modified Pauwels classification), and hip joint (≥ 90 points). In addition, the result of multivariate logistic regression analysis showed that the risk factors for complications in the treatment of femoral neck fractures with compression supporting screws were age, Pauwels type III fracture (modified Pauwels classification).ConclusionOur findings demonstrated beneficial outcomes obtained by using compression supporting screw, in terms of effectively enhancing the recovery of patients with femoral neck fracture and reducing the associated complications.

Analysis of concrete damage at anchorage end of the high-speed railway bridge sound barrier under the 400 km/h train-induced wind loads

The sound barrier installed on high-speed railway bridges withstands repeated train-induced wind load, which may lead to concrete damage at its anchorage end. This paper focuses on the assessment of concrete static damage at the sound barrier anchorage end under train-induced wind loads. The nonlinear finite element model of the sound barrier anchorage system is established to analyze the stress distribution, strain distribution and static damage of concrete structure at the anchorage end under 400 km/h train-induced wind loads in respect of different bolt preloads. The simulated results illustrate that both mortar and concrete near bolt holes suffer a certain degree of tensile and compressive damage. The maximum tensile and compressive damage factor values for mortar and concrete are 0.930, 0.643 and 0.892, 0.434 respectively. In addition, the effects of train-induced wind load on the internal force of the sound barrier anchorage take nearly no account, with a maximum of only 0.68 %. The results indicate that bolt preload is the most significant factor for concrete static damage, while the train-induced wind load appears negligible. An appropriate bolt preload can avoid the concrete static damage of the sound barrier anchorage end, and guarantee the structural stability of the sound barrier.

An empirical model for predicting saturation pressure of pure hydrocarbons in nanopores

Due to the confinement and strong adsorption to the pore wall in meso‑ and nano pores, fluid phase behavior in the confined media, such as the tight and shale reservoirs, can be significantly different from that in the bulk phase. A large amount of work has been done on the theoretical modeling of the phase behavior of hydrocarbons in the confined media. However, there are still inconsistencies in the theoretical models developed and validations of those models against experimental data are inadequate.In this study, we conducted a comprehensive review of experimental work on the phase behavior of hydrocarbons under confinement and analyzed various theoretical phase-behavior models. Emphasis was given to the modifications to the Peng-Robinson equation of state (PR EoS). Through the comparative analysis, we developed a modified alpha-function in PR EoS for accurate prediction of the saturation pressures of hydrocarbons in porous media. This modified alpha-function accounts for the pore size and was derived based on the regression results through minimizing the deviation between the experimentally measured and numerically calculated saturation pressure data. Meanwhile, the thermodynamic properties of propane were calculated in the bulk phase and in the nanopores. Finally, we validated the newly developed model using the experimental data in synthesized mesoporous materials and real reservoir rocks.By applying the modified PR EoS, a more accurate representation of the experimentally measured saturation pressure data in confined nanopores was achieved. This newly developed model not only enhanced the accuracy of the predictions but also provided valuable insights into the confinement effects on the phase behavior of hydrocarbons in nanopores. Notably, we observed significant changes in the properties of propane within confined nanopores, including suppressed saturation pressure and fugacity, indicating a greater tendency for the gas to remain in the liquid phase. Enthalpy of vaporization was found to increase highlighting increased difficulty in transitioning from liquid to gas phase under confinement. Additionally, the new model predicts an increased gas compressibility factor in the nanopores suggesting a close resemblance of ideal gas due to the counterbalance between the attractive and repulsive forces. To validate the model, new datasets containing saturation pressures of propane and ethane under a wide range of temperatures and pore sizes were employed. The newly developed model was further applied to the experimental data obtained in real rock samples (sandstones, limestones, and shales). Interestingly, it was observed that the phase change in these samples predominantly occurred in the smallest pores. This finding highlights the importance of considering the pore size distribution when studying the phase behavior of hydrocarbons in a capillary medium even if the rock has high permeability.This study provided a simple and easy-to-implement modification to the PR EoS for accurate prediction of the phase behavior of petroleum fluids under confinement. The newly developed model for calculating saturation pressures of hydrocarbons demonstrates improved accuracy in representing experimental data compared to the previous models, while offering a more straightforward and simplified approach.

A method for compressing AIS trajectory based on the adaptive core threshold difference Douglas–Peucker algorithm

Traditional trajectory compression algorithms, such as the siliding window (SW) algorithm and the Douglas–Peucker (DP) algorithm, typically use static thresholds based on fixed parameters like ship dimensions or predetermined distances, which limits their adaptive capabilities. In this paper, the adaptive core threshold difference-DP (ACTD-DP) algorithm is proposed based on traditional DP algorithm. Firstly, according to the course value of automatic identification system (AIS) data, the original trajectory data is preprocessed and some redundant points are discarded. Then the number of compressed trajectory points corresponding to different thresholds is quantified. The function relationship between them is established by curve fitting method. The characteristics of the function curve are analyzed, and the core threshold and core threshold difference are solved. Finally, the compression factor is introduced to determine the optimal core threshold difference, which is the key parameter to control the accuracy and efficiency of the algorithm. Five different algorithms are used to compress the all ship trajectories in the experimental water area. The average compression ratio (ACR) of the ACTD-DP algorithm is 87.53%, the average length loss ratio (ALLR) is 23.20%, the AMSED (mean synchronous Euclidean distance of all trajectories) is 68.9747 mx, and the TIME is 25.6869 s. Compared with the other four algorithms, the ACTD-DP algorithm shows that the algorithm can not only achieve high compression ratio, but also maintain the integrity of trajectory shape. At the same time, the compression results of four different trajectories show that ACTD-DP algorithm has good robustness and applicability. Therefore, ACTD-DP algorithm has the best compression effect.

Theoretical Studies of Supercritical Real-Fluid Oxidations of Diverse Fuels by Using the 3rd-order Virial Equation of State with Nonlinear Effects

The 3rd-order Virial equation of state (EoS) with nonlinear effects was constructed and applied to simulate various real-fluid fuel oxidations, including hydrocarbons and oxygenated fuels under supercritical conditions. The real-fluid effects for hydrocarbon and oxygenated fuel oxidations have been discussed by using the Redlich-Kwong (RK) and the 3rd-order Virial methods. The compressibility factors calculated using the 3rd-order Virial EoS possess better agreements with experimental data for H2, N2, and H2O at different temperatures and below 300 atm than the previous 2nd-order Virial EoS and the RK EoS. The calculations of thermodynamic properties by using the 3rd-order Virial EoS also showed a better agreement with experimental data for H2O than using the RK EoS. The RK method exhibited contradictory speciation predictions against the ideal-gas 0-D and 1-D simulations in H2O and N2/CO2 diluent gases, respectively, while the 3rd-order Virial method kept its consistency. Especially, the ignition delay simulation by using the 3rd Virial EoS is extended to the operation conditions relevant to the recent SpaceX Starship Raptor engines in CH4/O2 mixture at 600 atm. It shows the decreases in the ignition delay times by 3 times by including the real-fluid impact. The simulation results were also compared with a series of existing experimental data for ammonia, larger alkanes, and gasoline blends, which show significant real-fluid effects at low temperatures. Instead of inputting critical pressure and temperature parameters of different species manually in the typical empirical methods with high inconvenience and uncertainties, the required parameters in the 3rd-order Virial method can be directly obtained from the input transport document for real-fluid computations.

Cylindrical compression of thin wires by irradiation with a Joule-class short-pulse laser

Equation of state measurements at Jovian or stellar conditions are currently conducted by dynamic shock compression driven by multi-kilojoule multi-beam nanosecond-duration lasers. These experiments require precise design of the target and specific tailoring of the spatial and temporal laser profiles to reach the highest pressures. At the same time, the studies are limited by the low repetition rate of the lasers. Here, we show that by the irradiation of a thin wire with single-beam Joule-class short-pulse laser, a converging cylindrical shock is generated compressing the wire material to conditions relevant to the above applications. The shockwave was observed using Phase Contrast Imaging employing a hard X-ray Free Electron Laser with unprecedented temporal and spatial sensitivity. The data collected for Cu wires is in agreement with hydrodynamic simulations of an ablative shock launched by highly impulsive and transient resistive heating of the wire surface. The subsequent cylindrical shockwave travels toward the wire axis and is predicted to reach a compression factor of 9 and pressures above 800 Mbar. Simulations for astrophysical relevant materials underline the potential of this compression technique as a new tool for high energy density studies at high repetition rates.

Accuracy assessment of the turbomachinery performance maps correction models used in dynamic characteristics of supercritical CO2 Brayton power cycle

The supercritical CO2 Brayton cycle (SCO2BC) has emerged as a promising next-generation power generation technology due to its potential for high thermal efficiency and compact components design. Dynamic modeling of SCO2BC is crucial for understanding and analyzing its performance under design and off-design conditions. Turbomachines are critical components in SCO2BC dynamic models. While turbomachinery components are often modeled using their design-point turbomachinery performance maps (TPM), these maps become less accurate during off-design operations. Despite the existence of various TPM correction methods that ensure model validity, the implementation of the accurate ones within dynamic SCO2BC models remains scarce in the literature. This is crucial as it potentially compromises the accuracy of the obtained results. Therefore, there is a need to investigate the errors in the existing literature TPM correction models (in dynamic SCO2BC simulation) by comparing them against dynamic SCO2BC models employing a highly accurate correction method. Thus, in the current work, the common TPM correction methods from the literature are implemented in SCO2BC dynamic models and compared against a baseline mode, which uses the highly-accurate Pham method (at both the component and cycle levels). To the authors’ knowledge, this is the first work to address this research gap for the SCO2BC dynamic simulations and on both component and cycle levels. Additionally, another novelty is the usage of Simcenter Amesim software to dynamically model the SCO2BC aided with Pham model. Multible dynamic models for both the turbomachines of SCO2BC and the whole cycle are constructed and equipped with the different TPM correction methods found in literature to compare their dynamic behaviour that of Pham model. The Ideal Gas Compressibility factor (IGZ) method demonstrates a better performance than the other tested methods, as it exhibits the lowest discrepancy compared to the Pham model. Many of the other tested methods show significant errors. Furthermore, a popular hybrid correction combining IGZ and Pham (IGZ-Ph) is also investigated. Surprisingly, while seemingly beneficial, this hybrid approach negatively impacts accuracy, even resulting in predictions as if no correction was applied.

Multi-objective adaptive energy management strategy for fuel cell hybrid electric vehicles considering fuel cell health state

This study proposes a multi-objective adaptive energy management strategy for fuel cell hybrid electric vehicles considering fuel cell health state. By integrating rule-based control with multi-objective optimization methods, the strategy aims to improve system efficiency, extend the lifespan of proton exchange membrane fuel cells (PEMFC), and reduce operating costs. Based on a comprehensive model of PEMFC output characteristics and lifetime degradation, this study introduces an optimized point line (OPL) strategy. This strategy dynamically adjusts operating constraints according to the state of health (SOH) of the PEMFC, ensuring optimal vehicle performance throughout its lifecycle. To optimize the OPL strategy parameters, a particle swarm optimization algorithm with compression factor was employed, enhancing the strategy’s optimization efficiency, adaptability, and robustness to better handle various real-world operating conditions. The strategy was evaluated under US06 and WLTC driving cycles and compared with traditional power following (PF) and point line (PL) strategies. Results show that compared to the PL strategy, the OPL strategy achieved a 36.4% and 34.2% reduction in operating costs under US06 and WLTC cycles, respectively. Moreover, PEMFC lifetime degradation decreased by 44.9% and 39.4% in these cycles. In high-power regions, the average operating efficiency of PEMFC improved by 2%. The strategy demonstrated good adaptability to different driving conditions, providing an effective solution for optimizing the performance and durability of fuel cell hybrid electric vehicles.

Tapered photonic crystal fiber based on artificial intelligence-design for pulse compression

In this study, we employ a deep neural network(DNN) to achieve rapid prediction of dispersion and effective mode area in Pb-silicate photonic crystal fiber. Subsequently, this prediction model is used to drive a particle swarm optimization(PSO) algorithm to design tapered Pb-silicate photonic crystal fibers for pulse compression. The designed fibers exhibit an increasing nonlinear index profile, enabling self-similar pulse compression(SSPC) of pulses at a wavelength of 2μm. In compliance with fundamental soliton conditions, a 0.566 m tapered PCF achieves notable pulse compression. It reduces the initial pulse width of 1.76 ps to 52 fs, achieving a remarkable compression factor of 33.92, while maintaining a quality factor of 1.01 and less than 5.4% pedestal energy. In scenarios where fundamental soliton conditions are not met, a 1.74 m tapered PCF also achieves significant compression. It compresses a pulse with a width of 1.76 ps and a peak power of 1 kW to a pulse width of 13.7 fs and a peak power of 24.82 kW, resulting in a compression factor of 129. The proposed approach overcomes the empirical reliance inherent in manual design and significantly reduces computational demands, enabling the design of pulse compression fiber tapers tailored to input pulse shapes.

Simulation of January 22, 2024 Mw=7.0 Uqturpan earthquake consequences with the "Extremum" system application

This paper reports the use of intensity attenuation equations for the territory of the Northern Tien Shan by modeling the impact of a powerful destructive earthquake of January 22, 2024 in China. The relevance of the study follows from the needed reliable estimates of possible losses due to earthquakes in order to aid the decision making process for the response and the proper choice of a search and rescue strategy for the heavily affected settlements. The paper has as its goal the calibration of the Extremum system models for the territory of the Northern Tien Shan. Our study is the first to analyze the seismic intensity attenuation equations obtained by researchers at different times with a view to their applicability to near real time loss assessment for strong events occurring in the area of study. We investigate how the results of seismic attenuation modeling are affected by the ellipse compression factor k. and the source parameters of a strong event as determined by different seismological agencies in the alert mode. Computer simulation was applied to assess the possible impact of the January 22, 2024 earthquake using the "Extremum" system developed with our participation. This paper provides results of modeling the impact of the 2024 Uqturpan earthquake, as well as an assessment of the convergence achieved by calculated and observed intensities for various intensity prediction equations obtained before for China, Kyrgyzstan and adjacent areas within the Gissar-Kokshaalsky seismically active belt.