Evolution Of Parameters Research Articles

Pediatric spinal alignment and spinal development

BackgroundKnowledge of the growth spurt and remaining growth is essential for managing musculoskeletal diseases in children. Accurate prediction of curve progression and timely interventions are crucial, particularly for conditions like adolescent idiopathic scoliosis (AIS). MethodsThis study conducted a comprehensive review and synthesis of existing literature on spinal growth, skeletal maturity classifications, and the evolution of sagittal alignment parameters during childhood and adolescence. Key anatomical elements involved in spinal development, natural history of spinal growth, and skeletal maturity assessment systems were analyzed. ResultsThe analysis highlighted that key parameters such as Pelvic incidence (PI), Pelvic tilt (PT), and Lumbar lordosis (LL) increase significantly with growth, especially during the pubertal growth spurt. In contrast, Sacral slope (SS) remains relatively constant, and Thoracic kyphosis (TK) shows a slight increase. Additionally, there is a posterior shift in the center of gravity as children grow, reflecting progressive postural maturation. The study also reviewed and compared various maturity classification systems, noting the reliability and clinical implications of systems like the Sanders Maturity Stage (SMS) and Tanner-Whitehouse III. ConclusionsReliable maturity classification systems, such as the Sanders Maturity Stage (SMS) and Tanner-Whitehouse III, allow for tailored treatments to individual growth patterns. Integrating these classification systems into clinical practice enables precise prediction of curve progression and timely therapeutic interventions. This includes options from bracing to surgical techniques like growing rods or vertebral body tethering (VBT), with growth modulation being a key factor in achieving successful outcomes.

Coupling Phase Field Crystal and Field Dislocation Mechanics for a consistent description of dislocation structure and elasticity

This work addresses differences in predicted elastic fields created by dislocations either by the Phase Field Crystal (PFC) model, or by static Field Dislocation Mechanics (FDM). The PFC order parameter describes the topological content of the lattice, but it fails to correctly capture the elastic distortion. In contrast, static FDM correctly captures the latter but requires input about defect cores. The case of a dislocation dipole in two dimensional, isotropic, elastic medium is studied, and a weak coupling is introduced between the two models. The PFC model produces compact and stable dislocation cores, free of any singularity, i.e., diffuse. The PFC predicted dislocation density field (a measure of the topological defect content) is used as the source (input) for the static FDM problem. This coupling allows a critical analysis of the relative role played by configurational (from PFC) and elastic (from static FDM) fields in the theory, and of the consequences of the lack of elastic relaxation in the diffusive evolution of the PFC order parameter.

Simplified Physics-Based Battery Model for Stationary Energy-Storage Applications

To perform safe battery operation and avoid unnecessary degradation, battery models are needed. How complex, or close to reality the model should be, depends on the purpose of the model and the computational power available. The possibility for accurate parameterization before model implementation is another crucial aspect for the validity. Physics-based models have the advantage to solve for internal battery states, which includes important information to avoid accelerated degradation and to evaluate state of health. But the parameterization effort can be extensive and the computational cost too high to solve for in real time. Identifying the most essential processes and if possible, simplify the model is therefore motivated.Parameter sensitivity is a powerful tool to investigate how much certain parameters and the related processes effect the output signal, i.e. battery voltage. Under normal operating conditions the cells are rarely completely discharged, and as a result the diffusion processes show low sensitivity during operation [1]. In this work we therefore explore the utilization of a physics-based model solving for the electrolyte dynamics, rather than the solid phase diffusion commonly applied in the so-called single particle model. By neglecting the diffusion processes, the second dimension in the pseudo-two-dimensional (P2D) model can be ignored and the computational complexity simplified. The parameterization strategy and validation of the model is further discussed.We evaluate our model by comparing simulations with experimental data from batteries subjected to stationary energy storage applications. The cells are commercial 18650-type NMC/Graphite cells with 2.6 Ah capacity. Different service cycles have different needs in terms of current and voltage, see examples in Figure 1. Capturing these behaviours with a physics-based model might pose different challenges and will further affect the degradation of the cells [2]. A wide range of models exist in literature to capture degradation mechanisms during battery operation [3]. To keep the computational and parameterization effort as low as possible, our methodology is not to include more physics, but instead update the parameters to the processes already included in the model [4]. We explore this strategy comparing the behaviour from different types of services, as well as batteries where the application changes, to see the model response and analyse the battery state of health, see Figure 2. Electrochemical techniques such as differential voltage analysis and electrochemical impedance spectroscopy is included to support our conclusions.Our results highlight the value of application considerations when designing battery models, rather than only focusing on physical extreme points. We present an alternative physics-based model with the ability to capture crucial degradation phenomena and validate it against operational data. We believe our findings can be of value for smarter battery operating strategies and a greater understanding of application dependant lithium-ion battery degradation.Figure 1. Some of the application duty cycles part of the experimental study. a) Current profile peak shaving b) Current profile frequency regulation c) Voltage response peak shaving d) Voltage response frequency regulation.Figure 2. Degradation trends from the experimental study. Purple cell initially performing PS following application change to FR_high cycling a) Capacity evolution of the cycled cells b) tortuosity parameter evolution obtained from model parameter fitting c) Measured impedance response during cell reference performance tests d) Calculated charge transfer resistance from measured impedance data.

Modified Gravity in the Presence of Matter Creation: Scenario for the Late Universe.

We consider a dynamic scenario for characterizing the late Universe evolution, aiming to mitigate the Hubble tension. Specifically, we consider a metric f(R) gravity in the Jordan frame which is implemented to the dynamics of a flat isotropic Universe. This cosmological model incorporates a matter creation process, due to the time variation of the cosmological gravitational field. We model particle creation by representing the isotropic Universe (specifically, a given fiducial volume) as an open thermodynamic system. The resulting dynamical model involves four unknowns: the Hubble parameter, the non-minimally coupled scalar field, its potential, and the energy density of the matter component. We impose suitable conditions to derive a closed system for these functions of the redshift. In this model, the vacuum energy density of the present Universe is determined by the scalar field potential, in line with the modified gravity scenario. Hence, we construct a viable model, determining the form of the f(R) theory a posteriori and appropriately constraining the phenomenological parameters of the matter creation process to eliminate tachyon modes. Finally, by analyzing the allowed parameter space, we demonstrate that the Planck evolution of the Hubble parameter can be reconciled with the late Universe dynamics, thus alleviating the Hubble tension.

Study on the dynamic heating polymerization of PA MXD6: From thermal analysis to efficient polymerization

Optimizing a practical polymerization strategy for poly(m-xylylene adipamide) (PA MXD6) requires regulating the high-temperature residence time and preventing the solidification of the reaction mixture. Dynamic heating strategies have shown promise in addressing this issue. However, conventional polycondensation kinetics are not optimal for characterizing nonisothermal processes due to continuous changes in the reactant state. This study employed thermal analysis as a continuous monitoring method to comprehensively investigate the effects of pressure, temperature, and diffusion on polymerization. The results indicate that high heating rates lead to faster reaction rates, as evidenced by the evolution of the kinetic parameters throughout the reaction process. Nevertheless, excessively high heating rates increase the solidification risk. To resolve this contradiction, a low-rate heating process with pressure was developed for efficient polymerization and scale-up, resulting in superior products. This study provides new insights into polyamide polymerization and offers practical guidelines for enhancing polymerization efficiency and process stability.

A comparative study of overcharge thermal runaway force-electrical-thermal characteristics and safety assessment of lithium batteries with different cathode materials

This work compares the differences in thermal runaway (TR) behavior and force-electrical-thermal characteristics of three predominant types of lithium-ion batteries (LiNixCoyMn1-x-yO2 (NCM), LiFePO4 (LFP), LiCoO2 (LCO)) with the highest market share under various overcharge rates. The voltage and temperature of cells during the experiment are monitored. Early warning based on expansion force is currently a hot research topic. This study analyzes the evolution of expansion force from overcharging to TR, and lays the foundation for expansion force early warning. The results show that LFP batteries exhibit the lowest overcharging tolerance. However, LFP batteries exhibit the lowest TR hazard and only exhibit smoke release, no explosion or fire. NCM and LCO batteries exhibit more serious TR hazards. A novel safety assessment method based on seven experimental characteristics is proposed to evaluate the TR risks and hazards of three types of batteries qualitatively and quantitatively. Overall, this study compares the TR behaviors of three common lithium-ion batteries, introduces the expansion force parameter for comparative analysis, and reveals the mechanisms of multidimensional parameter evolution offering valuable insights for battery selection. The findings guide the safe use and risk management of lithium-ion batteries in electric vehicles.

The renormalization group for large-scale structure: primordial non-Gaussianities

The renormalization group for large-scale structure (RG-LSS) describes the evolution of galaxy bias and stochastic parameters as a function of the cutoff Λ. In this work, we introduce interaction vertices that describe primordial non-Gaussianity into the Wilson-Polchinski framework, thereby extending the free theory to the interacting case.The presence of these interactions forces us to include new operators and bias coefficients to the bias expansion to ensure closure under renormalization.We recover the previously-derived “scale-dependent bias” contributions, as well as a new (subdominant) stochastic contribution.We derive the renormalization group equations governing the RG-LSS for a large class of interactions which account for vertices at linear order in f NL that parametrize interacting scalar and massive spinning fields during inflation.Solving the RG equations, we show the evolution of the non-Gaussian contributions to galaxy clustering as a function of scale.

Spatial and temporal evolution of cost-competitive offshore hydrogen in China: A techno-economic analysis

China's ascendancy as the premier offshore wind power developer and principal hydrogen consumer underscores the expanding demand for green hydrogen, which is vital to its decarbonization trajectory. Offshore wind power is recognized as a crucial pathway for the future supply of green hydrogen, and further exploration of its development potential and economic viability can provide important insights for optimizing resource allocation, reducing greenhouse gas emissions, and ensuring energy security. This study analyzed the potential and regional economic differences in offshore wind energy for hydrogen production in China's coastal regions by considering the temporal evolution of techno-economic parameters and the spatial and temporal characteristics of geospatial resources. The findings suggest a potential hydrogen production capacity of 434–493 Mt/year in Chinese waters, with the average levelized cost of hydrogen projected to decline from 7.13 $/kgH2 in 2025 to 3.77 $/kgH2 by 2050, which is attributed to advancements in wind turbine technology and cost reductions in components. By 2030, hydrogen production of 40 Mt/year is expected to be cost-competitive, especially in Liaoning and Hebei, with projections indicating an increase to 435 Mt/year by 2050. Notably, floating wind power, contributing to 54 % of China's total offshore hydrogen capacity, holds significant promise for provinces such as Guangdong, Hainan, and Zhejiang. The study conclude that China's offshore hydrogen production has significant potential, with cost-competitive production achievable by 2030 and broad economic viability anticipated by 2050.

Influence of evolution in reinforcement scale characteristic parameters on the microstructure and properties of Ti6Al4V-TiBw composites fabricated by electron beam powder bed fusion

The size, aspect ratio, and distribution of reinforcement, referred to as the scale characteristic parameters (SCP), are critical factors that influence the mechanical properties of discontinuous reinforced titanium matrix composites (DRTMCs). To investigate the impact of SCP evolution on the microstructure and mechanical properties of TiBw, this study employed spherical Ti6Al4V-TiBw composite powder prepared by electrode induction melting gas atomization (EIGA) as feedstock for fabricating Ti6Al4V-TiBw composites through electron beam powder bed fusion (EB-PBF) process. By implementing a two-step rapid cooling approach in EIGA and EB-PBF processes to “freeze” the TiBw at nanoscale within Ti6Al4V-TiBw composites, a significantly wider regulation window for microstructure and mechanical properties was achieved. Subsequently, heat treatment was conducted at temperatures ranging from 850 to 1200 °C to systematically elucidate the mutual influence regulation among SCPs, microstructure, and mechanical properties of TiBw. Based on our findings, it can be concluded that when subjected to heat treatment temperatures higher than 950 °C, an orientation relationship between TiBw and α-Ti is observed: {0001} α-Ti//{001} TiBw, {11 2‾ 0} α-Ti//{010} TiBw, {10 1‾ 0} α-Ti//{100} TiBw. Additionally, the cross-section of columnar-shaped TiBw exhibits semi-coherent interfaces with coherent interfaces bonded to Ti along its (100) crystal plane while displaying incoherent interfaces with Ti matrix along its (101) and (10 1‾) crystal planes. The strength of Ti6Al4V-TiBw composites exhibited a trend of initial increase followed by decrease with the evolution of TiBw scale characteristic parameters, while the elongation demonstrated an overall decreasing pattern. This research aims to establish a foundation for microstructure and properties control of DRTMCs and provide experimental references and theoretical basis for high-performance DRTMCs research.

The Absolute Age of NGC 3201 Derived from Detached Eclipsing Binaries and the Hess Diagram

We estimate the absolute age of the globular cluster NGC 3201 using 10,000 sets of theoretical isochrones constructed through Monte Carlo simulation using the Dartmouth Stellar Evolution Program. These isochrones take into consideration the uncertainty introduced by the choice of stellar evolution parameters. We fit isochrones with three detached eclipsing binaries and obtained an age independent of distance. We also fit isochrones with differential reddening corrected Hubble Space Telescope photometry data utilizing two different Hess diagram-based fitting methods. Results from three different methods analyzing two different types of data agree to within 1σ, and we find the absolute age of NGC 3201 = 11.85 ± 0.74 Gyr. We also perform a variable importance analysis to study the uncertainty contribution from individual parameters, and we find the distance is the dominant source of uncertainty in photometry-based analysis, while total metallicity, helium abundance, α-element abundance, mixing length, and treatment of helium diffusion are an important source of uncertainties for all three methods.

A Frequency Domain PID Control Strategy for an In-House Friction and Wear Test Rig

The contact behavior greatly influences the damping performance of frictional interfaces. Numerous experimental studies on friction and fretting wear have investigated the evolution of contact parameters. An in-house friction and wear test rig has been developed to obtain hysteresis loops at certain normal forces. However, the test rig lacks load control and is thus unable to ensure precise stabilization at a preset normal force, which affected the hysteresis behavior. In this paper, we developed a frequency-domain PID controller to ensure the stable application of a target normal force with constant (0–300 N) and harmonic (0–50 N) components. Compared to the commonly used time-domain strategy, the control signal error is reduced from 6.30% to 0.54% at 50 Hz. With a 3% error as the standard, the controller enables stabilized control of signals with frequencies up to 300 Hz. Friction experiments on various typical materials are conducted using this improved test rig. The results indicate a general tendency for contact stiffness to increase with a rising normal force, while the relationship between the friction coefficient and the normal force does not exhibit a clear pattern. The contact stiffness is not sensitive to the relative displacement or vibration frequency.

Effects of alkali-silica reaction on the fracture energy of mass concrete: Experimental investigations using the wedge splitting test

This work aims to study the effects of alkali-silica reaction (ASR) on the fracture energy of reactive mass concrete mixtures (maximum aggregate sizes of 38 mm and 76 mm), characteristic of an existing hydro-electric facility. More than 40 large concrete blocks were casted and stored in a controlled environmental chamber for more than 1100 days. The blocks as well as cylindrical reference cores were monitored in expansion. Wedge splitting (WS) tests with different notch to depth ratios, were performed at different ASR advancements to assess the evolution of mechanical and fracture parameters of concrete. Digital Image Correlation (DIC) technique was used to monitor the tests. Damage Rate Index (DRI) technique was also performed on cores extracted from the blocks, following the completion of the splitting tests. Important size and heterogeneity effects were observed on the assessed ASR expansion and fracture energy. By filtering these effects, it was possible to assess for the first time in literature the evolution of size-independent fracture energy with respect to intrinsic volumetric expansion of concrete. The findings suggest that fracture energy increases for moderate levels of expansion, due to crack branching within the splitting crack, interacting with pre-existing ASR-induced cracks. This phenomenon was not observed for the case of a few horizontally cast blocks where the splitting crack ran parallel to pre-existing ASR cracks, indicating an anisotropy in ASR damage effects on the fracture energy of concrete.

Using partial discharge data to identify highly sensitive electrochemical parameters of aged lithium-ion batteries

Highly sensitive (HS) electrochemical parameters can serve as battery aging indicators, deserving thorough examination. To identify these parameters and determine their cycle evolution across a wide range of battery state of health, this study conducts a three-stage analysis. First, after a detailed evaluation, a global sensitivity analysis is performed to evaluate the sensitivity values of ten selected parameters across five intervals of discharge voltage curves simulated through the Doyle-Fuller-Newman theory. Such analysis facilitates the classification of these parameters into HS and low sensitive (LS) groups. Next, a deep learning (DL) model is developed for parameter identification, employing as minimal data as possible, specifically only partial discharge curves and their corresponding first-order derivatives, as inputs, while the electrochemical parameters are generated as outputs. It is found that utilizing the model built with the HS parameters achieves a remarkably low mean absolute percentage error (MAPE) of 0.25 % for output prediction. On the contrary, adopting the LS parameters yields a MAPE of 13.30 %, highlighting the significant impact of parameter sensitivity on the model outputs. Lastly, the well-trained DL model is directly applied to identify the five HS parameters pertaining to real-world commercial batteries, whose state of health spans approximately from 97 % down to 55 %. With the experimentally recorded partial discharge voltage data, the model generates the cycle evolutions of the HS parameters, revealing a noticeable decrease in their values ranging from 12 % to 40 % with aging.

Experimental hot-wire characterisation of the turbulent jet produced by a sweeping jet actuator in a quiescent environment

The present work presents the design and the characterisation of a sweeping jet, a fluidic actuator that has been shown to be able to enhance the aerodynamic performance of flow applications as transportation vehicles. The principles and operation of this type of actuator are detailed here. An experimental apparatus with hot-wire anemometry was installed to describe the flow topology produced by the sweeping jet. Basic analysis shows that the jet generates a flow with an average velocity of 60<Umean<100ms−1, a flow rate between 1.3 and 3 gs−1, and an oscillating frequency up to 2200Hz. The produced jet geometry is also analysed and shows interesting behaviour. The evolution of geometrical parameters is influenced by a transonic transition inside the actuator. To analyse the turbulent properties of the external flow, spectral triple decomposition is developed and used on the experimental data. A strong impact of the transition from a subsonic to a transonic regime on the produced flow is highlighted. The analysis of the turbulence produced by the sweeping jet shows a separation of the flow in three different zones detailed in the article. The study highlights promising results for future flow control implementations.

Redshift evolution and covariances for joint lensing and clustering studies with DESI Y1

ABSTRACT Galaxy–galaxy lensing (GGL) and clustering measurements from the Dark Energy Spectroscopic Instrument Year 1 (DESI Y1) data set promise to yield unprecedented combined-probe tests of cosmology and the galaxy–halo connection. In such analyses, it is essential to identify and characterize all relevant statistical and systematic errors. We forecast the covariances of DESI Y1 GGL + clustering measurements and the systematic bias due to redshift evolution in the lens samples. Focusing on the projected clustering and GGL correlations, we compute a Gaussian analytical covariance, using a suite of N-body and lognormal simulations to characterize the effect of the survey footprint. Using the DESI one percent survey data, we measure the evolution of galaxy bias parameters for the DESI luminous red galaxy (LRG) and bright galaxy survey (BGS) samples. We find mild evolution in the LRGs in $0.4 &amp;lt; z &amp;lt; 0.8$, subdominant to the expected statistical errors. For BGS, we find less evolution for brighter absolute magnitude cuts, at the cost of reduced sample size. We find that for a redshift bin width $\Delta z = 0.1$, evolution effects on DESI Y1 GGL is negligible across all scales, all fiducial selection cuts, all fiducial redshift bins. Galaxy clustering is more sensitive to evolution due to the bias squared scaling. Nevertheless the redshift evolution effect is insignificant for clustering above the 1-halo scale of $0.1h^{-1}$ Mpc. For studies that wish to reliably access smaller scales, additional treatment of redshift evolution is likely needed. This study serves as a reference for GGL and clustering studies using the DESI Y1 sample.

Study on the early warning of cracking and water inrush risk of coal mine roof and floor

Microseismic monitoring has proven to be an effective approach for detecting and preempting water inrush incidents within mining operations. However, challenges persist, particularly in terms of relying on a singular early warning index and the complexities involved in quantification. In response to these obstacles, a dedicated investigation was undertaken against the backdrop of mining activities at the 11,023 working face of Paner Coal Mine. Primarily, a novel methodology for categorizing the roof and floor into distinct zones was established based on the vertical distribution of microseismic events. Furthermore, this study delves into the dynamic evolution of key source parameters, such as microseismic energy, apparent stress, and apparent volume, amidst mining disturbances, enabling a comprehensive evaluation of the risk associated with roof and floor cracking, as well as potential water inrush incidents. A groundbreaking approach to early warning was proposed, operating on three pivotal dimensions: the depth of fractures, the intensity of fractures, and the likelihood of water inrush. Through rigorous validation during mining operations at the 11,023 working face, the efficacy was substantiated. Ultimately, the achievements offer invaluable insights and practical guidance for the advancement and implementation of water inrush early warning systems in coal mining contexts.

Dipole cosmology in [formula omitted]-gravity

Symmetric teleparallel f(Q)-gravity allows for the presence of a perfect fluid with a tilted velocity in the Kantowski–Sachs geometry. In this dipole model, we consider an ideal gas and we investigate the evolution of the physical parameters. The tilt parameter is constrained by the nonlinear function f(Q) through the non-diagonal equations of the field equations. We find that the dynamics always reduce to the vacuum solutions of STEGR. This includes the Kasner universe, when no cosmological term is introduced by the f(Q) function, and the isotropic de Sitter universe, where fQ plays the role of the cosmological constant. In the extreme tilt limit, the universe is consistently anisotropic and accelerated. However, the final solution matches that of STEGR.

Significance of a quadratically varying deceleration parameter in scalar field-dominated model and cosmic acceleration

In this study, we explore the enigma of late-time cosmic acceleration in the framework of a general scalar field playing the role of dark energy. Our investigation yields an exact solution to Einstein’s field equations, achieved through a parametrization of the deceleration parameter [Formula: see text] in quadratic form in the homogeneous and isotropic background geometry represented by Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime. This parametrization unveils a seamless transition from a decelerated to an accelerated phase in the cosmic evolution. Furthermore, we leverage this parametrization to reconstruct cosmological parameters with respect to redshift z, elucidating their dependency on certain model parameters that govern the universe’s evolutionary trajectory. The model parameters are subsequently constrained using diverse observational datasets. We provide a comprehensive analysis of the evolution of geometrical and physical parameters, complete with the numerically constrained values. To gain deeper insights into the nature of dark energy, we employ Statefinder diagnostics, conducting a thorough examination. Our findings shed light on the intricate interplay between cosmic acceleration, quintessential dark energy and the parametrization of deceleration parameter, offering valuable insights into the fundamental dynamics of the universe.

Deposition characteristics and influence regularity of sputtered products in a low-power RF gridded ion thruster

RF ion thruster has a broad prospect of development via its simple structure, high specific impulse and electrode-less discharge. During the RF operating process, an important but ignored generally issue is that the high-energy metal particles generated by sputtering grid system can diffuse towards the ionization chamber and then deposit on the wall to form a conductive film. As a result, the RF power feed can be significantly inhibited which affects the thruster perform and reliability. In this work, the axial distribution of film thickness on the ionization chamber has been measured which has the characteristic of nonlinear distribution. And the film roughness can be significantly affected due to the gradient of film thickness and deposition temperature. Another corresponding measurement of plasma parameter evolutions in the ionization chamber has been carried out within 6000 min of thruster operation. Results shows that the presence of the deposited film can result in a ∼30 % decrease in the plasma density, which weakens the grid sputtering erosion and subsequently leads to a decrease in film growth rate. The combination of contributed to the degradation of the thruster performance, with the effect of deposited film accounting for about 41 %.

Stabilizing Donor/Acceptor Interfaces with Ordered Polymer Layers in Planar‐Heterojunction Organic Solar Cells Under Thermal Stress

AbstractAs the efficiency of single‐junction organic solar cells (OSCs) is about to break 20%, more research effort is needed to achieve long‐term device stability for commercialization. The complex active layer microstructure of bulk‐heterojunctions challenges the degradation mechanism study, especially for the morphological changes under thermal stress. In this work, this issue can be overcome by employing planar‐heterojunction (PHJ) OSCs with well‐defined bi‐layered structures, which enables effective control of the microstructure of polymer donor layers. The evolution of photovoltaic parameters of the PHJ OSCs under thermal stress is specifically revealed, which is strongly related to the inter diffusion of small molecular acceptors into the amorphous phases of the polymer donors. Increasing the crystallinity of polymer donors can effectively stabilize the donor/acceptor interfaces and the photovoltaic performances. The work puts forward effective strategies to improve the morphological stability of OSCs and alternative approaches for mechanistic studies on the thermal stability of OSCs.