Mass Variation Research Articles

Revealing High‐Temporal‐Resolution Flood Evolution With Low Latency Using GRACE Follow‐On Ranging Data

AbstractAn emerging approach is utilizing the line‐of‐sight gravity difference (LGD) between the twin Gravity Recovery and Climate Experiment Follow‐On (GFO) satellites to refine the temporal resolution of water storage estimates from 1 month to days, thus making the data applicable to transient extreme climate events like floods. However, applying the approach to medium‐scale climate events (with mass changes of several tens of gigatons) is challenging due to surrounding signal contamination and low signal‐to‐noise ratios. To address this problem, this study develops an improved algorithm accounting for peripheral signal sources and temporal correlations in mass variation. Two floods in July 2021 in Western Europe and Central China (CC) are chosen as case studies to demonstrate our approach's applicability to moderate floods in complex hydrological settings. The results present the temporal progression of the floods up to a maximum of ∼40 Gt with a scale of 3–5 days. However, the GFO‐derived water gain in CC is much lower than expected values from land surface models, indicating a mass deficit during the flood. We find that the potent manipulation of water resources by human activities might impact the predictive capabilities of these models, thereby misrepresenting the hydrological evolution during the flood event. This study refines the viability of applying GFO data to restore transient dynamics characterizing extreme climate events of ∼20 Gt magnitude. We also provide insights on the use of LGD data for high‐temporal‐resolution estimation of water storage changes and underscore the non‐negligible influence of human interventions on short‐term hydrological dynamics.

Optimization Through Artificial Neural Network and Compare with Response Surface Methodology for Multiples Yield

Cotton slub yarn is widely used in denomination and any other casual, physical and mechanical Conditions. The data for the underlying purpose was collected from the Department of Polymer Engineering, National Textile University, and Faisalabad. R-Programming language software is used for analysis. The output of cotton depends on several factors whose cumulative influence on Process efficiency has a direct influence. The purpose of the research was to optimize the 100% cotton slub yarn model (slub length, slub thickness, pause length and linear density) for multiples yield (elongation, imperfection, strength, coefficient of mass variation and hairiness) as Optimizing is a way of identifying and enhancing the performance of the constructed framework by assessing a set of quality parameters, such as process efficiency using two methods response- surface methodology (RSM) and artificial neural network (ANN) and the results are compared using mean square error (MSE). Furthermore, coefficients of determination () and the mean square error root (RMSE) are used for greater accuracy. However, the ANN has consistently performed better than the RSM in all the aspects. The final selected ANN model was able to simultaneously predict the five output parameters with an RMSE of 0.229.

Synthesis of Composite Photocatalyst Derived from Medical Mask Waste/TiO2 for Degradation of Rhodamine-B Textile Waste

Abstract The Covid-19 case requires the use of masks followed by an increase in the amount of waste in Indonesia. Another type of waste that continues to increase and is harmful to waters is Rhodamine-B (RhB). One way to treat this waste is by photodegradation method. In this research, the synthesis of S-doped porous carbon (SDPC) derived from medical mask waste was composited with TiO2, a semiconductor material, to be used as photocatalyst material. The aim of this research is to determine the effect of SDPC mass on the structure and morphology of the SDPC/TiO2 composite and the performance of Rhodamine-B degradation. The mass variations of SDPC used were 25%; 37.5%; and 50%. The process of synthesizing porous carbon by sulfonation method at a temperature of 200 °C for 6 hours and continued activation using KOH to form activated SDPC. Then the composite synthesis process was carried out by sonification process. The result show 50% SDPC/TiO2 composite has the best degradation performance with degradation percentage of 54.21% in 2 hours of irradiation time.

A country‐wide examination of effects of urbanization on common birds

AbstractUrbanization forms one of the most drastic alterations of the environment and poses a major threat to wildlife. The human–induced modifications of the landscape may affect individual's fitness resulting in population declines. Research on how urbanization affects fitness traits has shown mixed results. However, studies typically contrasted data from a single species from few urban and non‐urban sites collected over short timeframes. Examining multiple species across a broad urbanization gradient enables a more robust comparison and understanding of how different species are impacted by urbanization‐knowledge crucial for generating population predictions, which are essential for conservation management. Here, we use data from a nation‐wide citizen science project to examine variation in survival and relative body mass and size (wing length) of common passerine birds, collected along an urbanization gradient in the Netherlands over an 8‐year period. Urbanization was measured as the distance from the city's border and the proportion of impervious surface area. Although the overall association between urbanization and survival was slightly negative, there was support for lower survival closer to the city in three species (chiffchaff Phylloscopus collybita, European robin Erithacus rubecula, European greenfinch Chloris chloris) and higher survival closer to the city in two (great tit Parus major and house sparrow Passer domesticus) of the 11 species examined. The contrasting survival successes among species suggest that ongoing urbanization may lead to shifts in community structure and loss of biodiversity. Impacts of urbanization on relative mass and size also exhibited varying effects, albeit less pronounced, and these effects were not correlated with the effects on survival. This implies that body mass and size cannot be used as indicators for urban‐associated patterns of survival. Our results further imply that effective conservation management targeting bird communities should involve a range of diverse actions, as focusing on single measures is unlikely to simultaneously impact multiple species due to the variation in responses to urbanization.

The potential of calcium oxide nanocatalyst from chicken eggshells for biodiesel production using chicken fat waste

This research aims to synthesize biodiesel using raw materials from chicken fat waste and a catalyst from eggshells (EGS). The eggshells used as a catalyst were calcined (EGS_calcined) and uncalcined (EGS_uncalcined). The calcination process was carried out at a temperature of 900 °C with a heating rate of 5 °C/minute under static air conditions for 24 h. The X-ray Diffraction diffractogram showed that the calcination process has successfully converted the calcium carbonate compound in the eggshell into calcium oxide. The particle sizes of EGS_uncalcined and EGS_calcined catalysts were 509.2 nm and 2.9 nm, respectively. Chicken fat transesterification reaction conditions were optimized to increase biodiesel yield, including variations in EGS catalyst mass (1–3 % of chicken fat extract (oil) weight), oil and methanol mole ratio (1:5–1:30), temperature (55–75 °C), and reaction time (30–180 min). The EGS catalyst mass conditions, oil and methanol mole ratio, temperature, and reaction time that produced the highest yield (93 %) were 1.5 % (w/w oil), 1:10, 65 °C, and 120 min, respectively. Research showed that the calcined EGS_catalyst performs better than the uncalcined EGS_catalyst.

Hydrodynamics of an underwater vehicle near the sea surface

The primary goal of this study is to evaluate the hydrodynamic characteristics and the wave exciting forces on a shallowly submerged vehicle. A thin, rigid plate, which is completely submerged beneath the free surface in waters of finite depth is considered herein. The examined body is similar to an unmanned vehicle which is developed in Cyprus Marine and Maritime Institute for ocean science applications. From the present analysis the phenomenon of negative added mass and rapid variations of the added mass and damping coefficients is verified due to the free surface effect which is explained in terms of near-resonant standing waves above the submerged body.

PRODUKSI BIOETANOL DARI BONGGOL PISANG DENGAN PENAMBAHAN BIJI NANGKA SEBAGAI SUBSTRAT

Bioethanol is a type of bioenergy that can be used as an alternative fuel. One of the ingredients that can be used is banana stems and jackfruit seeds. Banana stems and jackfruit seeds are materials that contain considerable potential as basic ingredients for bioethanol based on the availability of certain components (starch and cellulose) they contain. The starch and cellulose content found in banana humps and jackfruit seeds can be converted into bioethanol through hydrolysis and fermentation processes. This research aims to synthesize bioethanol from banana humps and jackfruit seeds, determine the effect of the combination of a mixture of banana humps and jackfruit seeds on the concentration of glucose produced from the hydrolysis process and bioethanol produced from the fermentation process. This research began with pretreatment of raw materials (washing, cutting, drying) with variations in the components of banana humps and jackfruit seeds 100% : 0%, 75% : 25%, 50% : 50%, 25% : 75%, 0% : 100 % and variations in starch mass of 1%, 2%, 3%, 4% and 5%. Then the hydrolysis process uses H2SO4 for 1 hour at a temperature of 95˚C-100˚C. Then the hydrolysis results are fermented using Saccharomyces Cerevisiae. The fermentation process lasts for 24 hours, 48 hours, 72 hours, 96 hours and 120 hours. The research results showed that the largest concentration of bioethanol was obtained in the 50%: 50% component with a starch mass of 100 grams of 7% (v/v).

A comparative study on the parametrization of a time-variable geopotential model from GRACE monthly solutions

The gravity field of the Earth is time-dependent due to several types of mass variations which take place on different time scales. Usually, the time-variability of the gravitational potential of the Earth is expressed by the monthly determination of a static geopotential model based on data from gravity field missions. In this paper, the variability of the potential is parameterized by a functional approach which contains a polynomial trend and periodic contributions. The respective parameters are estimated based on the monthly solutions derived from the GRACE and GRACE-FO gravity field mission up to a maximum degree of expansion nmax=96\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n_\ ext {max}=96$$\\end{document}. As a preliminary data analysis, a Fourier analysis is performed on selected potential coefficients from the available monthly solutions of the GFZ. The indicated frequency components are then used to formulate a time-dependent analytical approach to describe each Stokes coefficient’s temporal behaviour. Different approaches are presented that include both polynomial and periodic components. The respective parameters for modelling the temporal variability of the coefficients are estimated in a Gauss-Markov model and tested for significance by statistical methods. Extensive comparative numerical studies are carried out between the newly generated model variants and the existing monthly GRACE, GRACE-FO and the existing time dependent EIGEN-6S4 solutions. The numerical comparisons make it clear that estimated models based on all available monthly solutions describe the essential periods very well, but such monthly events that deviate strongly from the mean behaviour of the signal show less precision in the space domain. Models that are estimated based on fourteen consecutive monthly solutions, covering one selected year, represent the amplitudes much more precise. The statements made apply to four initial data used, which are filtered to varying degrees. In particular, DDK2, DDK5 and DDK8, as well as unfiltered coefficients were used. For all the model approaches used, it can be seen that the potential coefficients contain up to about n≈40\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n\\approx 40$$\\end{document} in case of DDK5 periodically signals with annual, semi-annual or quarterly, as well as Luna nodal periods and do not vary significantly beyond that degree. Only an offset can be estimated significantly for all Stokes coefficients.

Ultrasound-assisted extraction and concentration of phenolic compounds from jabuticaba sabará (Plinia peruviana (Poir.) Govaerts) peel by nanofiltration membrane

Jabuticaba peel, rich in antioxidants, offering health benefits. In this study, the extraction of phenolic compounds from jabuticaba peel using ultrasound-assisted (UA) and their subsequent concentration by nanofiltration (NF) employing a polyamide 200 Da membrane was evaluated. The UA extractions were conducted using the Central Composite Rotatable Design (CCRD) 22 methodology, with independent variables extraction time (11.55 to 138 min) and temperature (16.87 to 53.3 °C), and fixed variables mass to ethanol solution concentration at pH 1.0 (1:25 g/mL), granulometry (1 mm), and ultrasonic power (52.8 W). The maximum concentrations obtained were 700.94 mg CE/100 g for anthocyanins, 945.21 mg QE/100 g for flavonoids, 133.19 mg GAE/g for phenols, and an antioxidant activity IC50 of 24.36 μg/mL. Key phenolic compounds identified included cyanidin-3-glucoside, delphinidin-3-glucoside, and various acids like syringic and gallic. NF successfully concentrated these compounds, enhancing their yield by up to 45%. UA and NF integrate for sustainable extraction.

Real-time estimation of vehicle inertia parameters based on Kalman-bucy filter

Vehicle inertial parameters such as mass and moments of inertia are required for most vehicle dynamic control systems. Due to the wide range variation of these parameters during vehicle operation, accurate estimation of their values in real-time plays an important role in improving the efficiency of vehicle control systems. In this article, the vehicle sprung mass and moments of inertia are estimated in real-time based on a Kalman-Bucy filter algorithm designed for a spatial vibration model of a two-axle truck. This proposed method requires measuring only the vertical, roll, and pitch velocity of the sprung mass and, therefore can reduce the sensor cost significantly. The simulation results for a random roughness road profile according to ISO 8608 class C with step variations in sprung mass and moments of inertia showed that the designed estimator rejected the process and measurement noises and tracked the real vehicle parameters effectively with acceptable errors

Microstructural Characterization, Mechanical Performance, and Anti-Corrosive Response of Zinc Multifaceted Coating on Mild Steel

Zinc has attracted significant attention in research due to its cost-effective use as an electrodeposited material, effectively protecting various types of steel from corrosion and wear. However, despite its advantages, zinc has limitations in fully guarding steel against corrosion. Recent studies propose that blending zinc with other metals during the coating process can proficiently shield mild steel from deterioration. The motivation for this study stems from recognizing the restrictions of zinc electrodeposition and the limited exploration of zinc multi-facet composite coatings for mild steel. In this study, the electrodeposition technique was employed to apply a coating to mild steel using zinc and nanoparticles of calcium oxide (CaO) and manganese oxide (MnO2). The coating bath's chemical composition included mass variations of 0-12 g/L for CaO and MnO2, along with 10 g/L each of boric acid, thiourea, and Na2SO4, and 15 g/L of K2SO4 and ZnSO4. The coating process occurred over a twenty-minute period, with a pH of 4.8, voltage set at 3.2V, current density at 1 A/cm2, temperature at 47°C, and stirring rate at 200 rpm. Results obtained from the coated mild steel demonstrated that Zn-6CaO-6MnO2 exhibited the greatest coating thickness at 0.2308 mm, and it showcased impressive corrosion resistance at 2.0618 mm/year. The Zn-CaO-MnO2 coating displayed a substantial deposit of crystallites in its microstructure, assisted by the presence of manganese, contributing to a smoother surface texture.

Cluster cosmology redux: a compact representation for the halo mass function

ABSTRACT Groups and clusters of galaxies imprint coherent, arcminute-scale features across the spectrophotometric sky, especially optical-IR clusters of galaxies, spectral distortions in the cosmic microwave background, and extended sources of X-ray emission. The space–time density of the host dark matter halo population – the halo mass function (HMF) – is a common theoretical basis for modelling such observable features. We explore a compact representation – a dual-quadratic (DQ-HMF) form – that features readily interpretable parameters representing polynomial expansions of the space–time number density surface, first in terms of log-mass, then in redshift. The DQ-HMF form fits Mira-Titan N-body emulator expectations for halo masses $10^{13.7-14.5} \, h^{-1}\, {\rm M}_\odot$ over redshifts, 0.1 < z < 1.5 to within $\sim \! 5~{{\ \rm per\ cent}}$. We provide best-fitting parameters for a Planck 2018 cosmology and demonstrate model self-similarity in the Ωm−$\, \sigma _8$ plane. Convolving with a minimal mass–observable relation (MOR) yields closed-form expressions for counts, mean mass, and mass variance of cluster samples characterized by an observable property. Performing information-matrix forecasts of potential parameter constraints from existing and future surveys, we demonstrate the potential for percent-level constraints on model parameters by an LSST-like optical cluster survey of 300 000 clusters and a richness–mass variance of 0.32. Even better constraints could potentially be achieved by a survey with one-tenth the sample size but with a reduced selection property variance of 0.12. Potential benefits and extensions to the basic MOR parametrization are discussed.

Simulation and electrification of a conventional vehicle into a battery electric vehicle for sustainability mobility

ABSTRACT This work explores converting a conventional 1996 Honda Civic Coupe into a battery-electric vehicle (BEV). A simulation model is developed to analyze the vehicle’s dynamic behavior under various conditions, including changes in vehicle mass and road slope. The system specifications are detailed based on a 50 kW AC induction motor, controller, battery, and battery management system. The battery comprises 2,376 NCR18650B cells with a capacity of 23 kWh based on inverter requirements. Energy consumption is simulated using the New European Driving Cycle (NEDC), resulting in 1.69 kWh to travel 10.8 km. Autonomy is estimated at 147 km. The environmental impact of 19.2 g CO2/km is calculated. The results illustrate the change in maximum speed, acceleration, and distance traveled based on changes in mass and slope. It is concluded that mass variation has a lesser impact on performance than road slope. The work demonstrates the feasibility of converting a conventional vehicle to a BEV with comparable dynamic capabilities using currently available technology. Future development plans include constructing a battery prototype, electrifying the vehicle, and incorporating instrumentation for validation.

Guiding Lunar Landers: Harnessing Neural Networks for Dynamic Flight Control with Adaptive Inertia and Mass Characteristics

The autonomous control of landing procedures can provide the efficiency and precision that are vital for the successful, safe completion of space operations missions. Controlling a lander with this precision is challenging because the propellants, which will be expended during the operations, represent a significant fraction of the lander’s mass. The mass variation of each tank profoundly influences the inertia and mass characteristics as thrust is generated and complicates the precise control of the lander state. This factor is a crucial consideration in our research and methodology. The dynamics model for our lander was developed where the mass, inertia, and center of mass (COM) vary with time. A feed-forward neural network (NN) is incorporated into the dynamics to capture the time-varying inertia tensor and COM. Moreover, the propellant takes time to travel through the feed lines from the storage tanks to the engine; also, the solenoid valves require time to open and close. Therefore, there are time delays between the actuator and the engine response. To take into account these sources of variations, a combined time delay is also included in the control loop to evaluate the effect of delays by fluid and mechanisms on the performance of the controller. The time delay is estimated numerically by a Computational Fluid Dynamics (CFD) model. As part of the lander’s control mechanism, a thrust vector control (TVC) with two rotational gimbals and a reaction control system (RCS) are incorporated into the dynamics. Simple proportional, integral, and derivative (PID) controllers are designed to control the thrust, the gimbal angles of the TVC, and the torque required by the RCS to manipulate the lander’s rotation and altitude. A complex mission with several numerical examples is presented to verify the hover and rotational motion control.

Investigating Carded Yarn Quality through Cross-Doubling in the Draw frame: A Comprehensive Analysis

A carding machine's performance has an impact on the quality of the carded sliver, which in turn affects the quality of the carded yarn produced. Several factors can influence a machine's efficiency, resulting in fluctuations in the slivers generated over time. To achieve consistent and reproducible quality levels, slivers from all carding machines must be blended homogeneously. This blending process is vital for achieving homogeneity in the final product and maintaining a high quality standard. This can be achieved by cross-doubling. In this technique, carded slivers are arranged into categories of good, medium and low quality based on the nep removal efficiency of the carding machine behind the breaker draw frame. This is a specific type of doubling process. The focus of this research was the effectiveness of the aforementioned practice. Three carding machines were selected out of seven based on the quality level of the produced carded sliver, which was measured by nep removal efficiency. Yarn samples of 29.5 tex were produced from the slivers of the individual carding machines and by cross-doubling them at the breaker draw frame. Samples were collected at each stage of processing and tested. The results showed that cross-doubling significantly reduced variation in the imperfection level and yarn strength, but had very little effect on the mass variation level of the strands. Furthermore, the categorization of the four samples for selection was carried out using the Analytic Hierarchy Process method. This study will provide a guideline for new spinners to enhance yarn quality through cross-doubling on a draw frame machine.

Numerical investigation of heat transfer enhancement in magnetohydrodynamics ternary ferrofluids on nonlinear stretching sheet

The current study examines the complex interaction between mass and thermal energy variations, considering factors including activation energy, chemical reactions, and thermal radiation across a nonlinear stretching sheet. The ternary nanofluid comprises titanium, single-walled carbon nanotubes, and multi-walled carbon nanotubes to improve the heat transfer characteristics of the fluidic system. Partial differential equations are utilized to represent the system’s dynamic behavior mathematically. Following this, similarity transformations are used to convert these governing partial differential equations into ordinary differential equations. The numerical solution for the transformed boundary value equations is derived using MATLAB. The graphical representations explain the results of these calculations, providing clear insights into the behavior of important variables in various conditions. It is concluded that an increase in the flexibility parameter improves the thermal behavior of a fluid, while an increase in the Prandtl parameter decreases it. Furthermore, applying a magnetic field to the dynamics of fluid heating enhances temperature and energy transfer.

A Regionally Refined and Mass‐Consistent Atmospheric and Hydrological De‐Aliasing Product for GRACE, GRACE‐FO and Future Gravity Missions

AbstractDe‐aliasing products are used in the estimation process of satellite‐based gravity field computation to reduce errors from high‐frequency mass variations that alias into monthly gravity fields. The latest official product is AOD1B RL07 and describes non‐tidal atmosphere and oceanic mass variations at 3‐hourly resolution. However, the model‐based de‐aliasing products are inevitably incomplete and prone to temporally and spatially correlated errors that substantially contribute to errors in the estimated gravity fields. Here, we investigate possible enhancement of current de‐aliasing products by nesting a regional high‐resolution atmospheric reanalysis over Europe into a global reanalysis. As further novelty we include almost mass consistent terrestrial water storage variability from a regional hydrological model nested into a global model as additional component of the de‐aliasing product. While we find in agreement with earlier studies only minor contributions from increasing the temporal resolution beyond 3‐hourly data, our investigations suggest that contributions from continental hydrology and from regional non‐hydrostatic atmospheric modeling to sub‐monthly mass variations could be relevant already for gravity fields estimated from current gravity missions. Moreover, in the context of extreme events, we find regionally contributions from additional moisture fields, such as cloud liquid water, in the order of a few mm over Europe. We suggest this needs to be taken into account when preparing data analysis schemes for future space gravimetric missions.

Using Shelf‐Edge Transport Composition and Sensitivity Experiments to Understand Processes Driving Sea Level on the Northwest European Shelf

AbstractVariability in ocean currents, temperature and salinity drive dynamic sea level (DSL) variability on the Northwest European Shelf (NWES). It is dominated by mass variations, with steric signals relatively small. A mechanistic explanation of how ocean dynamics relates to the mass component of NWES sea level variability is required. We use regional ocean model experiments to isolate sources of variability and then investigate the effect on monthly to‐interannual DSL variability together with the simulated momentum budgets along the shelfbreak. Regional (local) wind and non‐regional (remote) forcing are important on the NWES. For the local wind forcing, the net mass flux onto the shelf, which drives a shelf‐mean mode of DSL variability, results from a combination of surface Ekman, bottom Ekman and geostrophic flows and explains 73% of the variance in transport across the shelf‐edge. The geostrophic flow is closely related to wind stress with a flow about half that of surface Ekman transport but in the opposite direction. For the remotely forced mass‐flux across the shelf‐edge, the geostrophic component explains 62% of the variance and bottom friction plays an important indirect role. The remotely forced variability, while relatively spatially uniform, is more important for explaining DSL variance over the western NWES. This mode of variability is sensitive to signals propagating northward via a thin strip of the southern boundary near the Portuguese coast, consistent with coastal trapped wave signals. It also appears to drive steric height in the Bay of Biscay, which is related to DSL on the shelf.

Plant mass variations of Leymus chinensis (Poaceae) and their relationships with environmental factors on a large-scale gradient, northeastern China.

Body size (or mass) variations and their relationships with environmental variability have been well documented for many species at the local scale, while the effects of climate, combined with soil nutrients, on plant mass in large-scale gradient remain unclear. Herein, detailed surveys were conducted to investigate plant mass (PM, aboveground mass per plant) variations of Leymus chinensis and their relationship with environmental factors (e.g., climate, soil nutrient, and microbial diversity) at 18 wild sites along a large-scale gradient from 114 to 124° E in northeastern China. Based on site-by-site analyses, the plant mass of the species varied significantly from east to west along the gradient. It initially increased, peaking at middle sites, and then dropped with the increase of drought in both dry and rainy seasons. Plant mass at the eastern end was almost equal to that at the western end and was equivalent to 1/2 and 1/3 of middle sites. The average plant mass in the rainy season was about 50% greater than that in the dry season (F 1,1078 = 489.80, p < .001). The effects of environmental variables on plant mass differed in dry and rainy seasons. Mean annual temperature and temperature seasonality were the critical restrictions of plant mass in the dry season, while temperature and precipitation seasonality and soil resources (total C, Mn, Zn) had significant impacts in the rainy season (p < .05). In general, plant mass had not dropped linearly with the increase of drought along large-scale gradient, suggesting that precipitation decrease was not the critical restriction regulating the growth and settlement of the species.

The evolution of femoral morphology in giant non-avian theropod dinosaurs.

Theropods are obligate bipedal dinosaurs that appeared 230 million years ago and are still extant as birds. Their history is characterized by extreme variations in body mass, with gigantism evolving convergently between many lineages. However, no quantification of hindlimb functional morphology has shown if these body mass increases led to similar specializations between distinct lineages. Here we studied femoral shape variation across 41 species of theropods (n= 68 specimens) using a high-density 3D geometric morphometric approach. We demonstrated that the heaviest theropods evolved wider epiphyses and a more distally located fourth trochanter, as previously demonstrated in early archosaurs, along with an upturned femoral head and a mediodistal crest that extended proximally along the shaft. Phylogenetically informed analyses highlighted that these traits evolved convergently within six major theropod lineages, regardless of their maximum body mass. Conversely, the most gracile femora were distinct from the rest of the dataset, which we interpret as a femoral specialization to "miniaturization" evolving close to Avialae (bird lineage). Our results support a gradual evolution of known "avian" features, such as the fusion between lesser and greater trochanters and a reduction of the epiphyses' offset, independently from body mass variations, which may relate to a more "avian" type of locomotion (more knee-than hip-driven). The distinction between body mass variations and a more "avian" locomotion is represented by a decoupling in the mediodistal crest morphology, whose biomechanical nature should be studied to better understand the importance of its functional role in gigantism, miniaturization and higher parasagittal abilities.