Speed Research Articles

Tension fracture delamination analysis on a hot rolled Nb-bearing high-strength steel for vehicle wheel application

A comparative analysis was conducted on post-tensile specimens with and without delamination to investigate the causes of tensile delamination in hot rolled steel with a 600 MPa ultimate tensile strength (UTS) for automotive wheel applications. The tensile specimens were sampled from the hot rolled coils in the transverse direction per ASTM A370 standards, and Tensile tests were performed at room temperature with a constant crosshead speed of 0.5 mm/min. The results indicate that normal segregation is not the sole factor contributing to delamination; rather, the presence of Nb lumps within the central segregation area increased the susceptibility to tensile delamination. The statistical analysis indicates that there is a more intense presence of Nb lumps in specimens with tension delamination, tension delamination will occur during specimen stretching when there are Nb lumps with an average size greater than 6.5 μm and a quantity greater than 3 in the central segregation region. Meanwhile, the sources of lumps are also analyzed indicates that these Nb lumps originate from the ferroniobium alloy added during BOF tapping and ladle refining.

Long railway track modelling – A parallel computing approach

This paper presents the development of a dynamics model for long track sections. It is based on an established short track model that utilises the Finite Element Method to describe rails and block models to describe sleepers, ballast and subballast. By implementing a parallel computing method, this innovation enables the construction of a true long track model: by segmenting the long track into shorter segments that are easier to compute. The model facilitates simulations to be run in parallel, thereby permitting simultaneous calculations of various numerical track variables. The model employs a Message Passing Interface framework to seamlessly link the track segments, handling the flow of data among the computing cores designated to each subdivided section. This strategic framework allows the long track model with the capability to simulate tracks of virtually any length, with the only constraints being the available computational resources and time. The claimed contribution about modelling capability is verified using two case studies on a 6km-long track involving different practical and conceptual train operational scenarios: emergency braking and constant braking force with constant train speed. These case studies show the flexibility and scalability of the method and its capability to handle complex track dynamic systems.

Mathematical Model of the Electronic Cam in Terms of Application in a Dosing Machine

The article analyses the use of servomotors in the control systems of industrial equipment, focusing on the alternative offered by position and speed synchronization in relation to classical mechanical mechanisms. A complete methodology is presented to determine the dynamic parameters of the adopted kinematic system using electronic motion profiles. The results obtained constitute a mathematical model of the execution chain and an analysis of the basic quantities for linear motion, supported by actual measurements of the drive parameters. The merit of the article is to show that the servomotors can significantly simplify the design of the device, make it more flexible in adaptation to different assortments, and allow integration with systems predicting the technical condition of the device. The analysis of the results revealed significant differences in the constant rotational speed of the servomotor, which do not align with previous findings. The results suggest that changing the angular working range of the assembly to the range (205°;270°) could significantly affect the generated linear acceleration, reducing the risk of stalling. The calculations and graphs conducted allowed for the accurate representation of the actual mechanical system, considering its dynamic characteristics. The key conclusion is that precise mathematical modelling is essential to ensure the stability and durability of engineering components.

Sustainable Biodiesel Production via Biogenic Catalyzed Transesterification of Baobab Oil Methyl Ester and Optimization Process

Biomass diesel is one of the sustainable and renewable sources of energy envisaged to hold a prominent position in the world energy infrastructure. In this study, biodiesel was production from baobab seed oil by transesterification using biogenic heterogeneous catalyst, derived from mixed wastes of white chicken eggshells and banana fruit peels. The production process was analyzed and statistically analyzed using Box-Behnken Design-Response Surface Methodology (BBD-RSM). The influential transesterification reaction parameters investigated with their ranges include reaction time (40–80 min), molar ratio of oil to methanol (1:9–1:15) and catalyst weight (3–5 wt%). The nano-catalyst (CaO-BFP-850 NPs) was prepared by calcination at high temperature of 850 °C for 4 h, and its properties were found to contain majorly the basic elements of Ca and K when investigated with analytical instruments such as SEM, EDS, DSC-TGA, FT-IR, and XRD. The regeneration test of the CaO-BFP-850 NPs conducted showed it could be reused for more than four cycles with less catalytic efficiency reduction. The ideal conditions instituted by BBD-RSM was 75 min of reaction time, 12.8:1 molar ratio of oil to methanol, and 4.08 wt% CaO-BFP-850 at 65 °C and 650 rpm constant temperature and agitation speed respectively, with the validated biodiesel yield of 96.70 wt%. The assessment of the quality of the biodiesel produced showed compliance with the standard specifications of ASTM D6751, EN 14241, and SANS 833.

Fuel Cell Electric Vehicle Hydrogen Consumption and Battery Cycle Optimization Using Bald Eagle Search Algorithm

In this study, the Bald Eagle Search Algorithm performed hydrogen consumption and battery cycle optimization of a fuel cell electric vehicle. To save time and cost, the digital vehicle model created in Matlab/Simulink and validated with real-world driving data is the main platform of the optimization study. The digital vehicle model was run with the minimum and maximum battery charge states determined by the Bald Eagle Search Algorithm, and hydrogen consumption and battery cycle values were obtained. By using the algorithm and digital vehicle model together, hydrogen consumption was minimized and range was increased. It was aimed to extend the life of the parts by considering the battery cycle. At the same time, the number of battery packs was included in the optimization and its effect on consumption was investigated. According to the study results, the total hydrogen consumption of the fuel cell electric vehicle decreased by 57.8% in the hybrid driving condition, 23.3% with two battery packs, and 36.27% with three battery packs in the constant speed driving condition.

Performance study of dual heart assisted control system based on SL-SMC physiological combination controller.

The main challenges of Biventricular Assist Devices (BiVAD) as a treatment modality for patients with Bicardiac heart failure heart failure are the balance of systemic blood flow during changes in physiological activity and the prevention of ventricular suction. In this study, a model of the Biventricular Circulatory System (BCS) was constructed and a physiological combination controller based on Starling-Like controller and Sliding Mode Controller (SMC) was proposed. The effects of the physiological controller on the hemodynamics of the BCS were investigated by simulating two sets of physiological state change experiments: elevated pulmonary artery resistance and resting-exercise, with constant speed (CS) control and combined Starling-like and PI control (SL-PI) as controllers. Simulation and experimental results showed that the Starling-like and Sliding Mode Control (SL-SMC) physiological combination controller was effective in preventing the occurrence of ventricular suction, providing higher cardiac output, maintain balance of systemic blood flow, and have higher response speed and robustness in the face of physiological state changes.

Elastodynamic behaviors of steady moving straight dislocation within thin nano film

The elastodynamic dislocation behaviors are of great interest for understanding the performances of structural alloys under intense dynamic loading conditions. The formation, propagations, and interactions of dislocations (such as injected dislocation, accelerating dislocation, steady moving dislocation at high constant speed) are quite different from static dislocations. For steady-moving dislocation within the isotropic infinite medium, the effects of surface and interface on steady-moving dislocations within limited space are still known. In this paper, we investigate the elastodynamic image stress simulation of steady moving dislocation within film of limited thickness at constant speed using Eigenstrain theory, Lorentz transformation, and steady dynamic equilibrium equations. We propose an efficient solution method that involves complex Fourier series, transforming partial differential equations into ordinary differential equations, and ultimately into a set of algebraic equations in spectral space. The effects of dislocation speed and position near the free surface on the image stress of steady-moving climbing and gliding dislocations within the thin film are examined. The results show that relativistic effects are significant for certain dislocation configurations and stress components, whereas other stress components are less sensitive to relativistic effects near the transonic speed region.

Lubrication Characteristics of Dry-Gas Seals with Spiral Grooves

To obtain an optimal range of structural parameters for dry-gas seals with good performance, this study employed advanced sensing technology to monitor and analyze the internal flow characteristics of dry-gas seals in real time. Additionally, the validity of the calculation program was verified through experimentation. Using steady-state performance parameters as evaluation indices, a calculation model with lubrication characteristics was developed. The results indicate that when there are 12 grooves, the gas film pressure distribution is uniform and has a high value. At pressures greater than 2 MPa, the opening force, leakage, and gas film stiffness change significantly due to enhanced dynamic pressure effects with high-pressure differences, which reduces the local contact forces and frictional forces. At a constant speed, decreasing the gas film thickness increases the pressure difference while increasing both the opening force and film stiffness; however, at higher rotational speeds where the gas flow becomes non-uniform, the stability of the gas film is affected, leading to increased frictional forces. When there are between 10 and 16 grooves with depths ranging from 5.0 to 6.0 μm, dynamic pressure effects caused by pressure gradients become apparent, resulting in good dry-gas sealing performance being achieved. This research provides a theoretical reference for optimizing the design of dry-gas seals, as well as their steady-state seal performance.

Quasi-one-dimensional non-equilibrium method for shock tube and stagnation line flows

Shock tube experiments are used to investigate non-equilibrium thermochemistry and radiative processes in reacting gas hypersonic flows. Boundary layer and shock structure are known to influence the spatial variation of the test slug state properties. This work derives and validates a novel method for viscous, quasi-one-dimensional, non-equilibrium flow in a shock tube assuming constant shock speed. The proposed method fully resolves the shock structure. Mirels' estimate for boundary layer growth around the test slug determines the dilation rate at the centerline. This, along with relevant boundary conditions, appropriately models core flow in a shock tube. The flow equations are discretized by finite differences on a staggered grid. The resulting highly non-linear set of algebraic equations is solved by Newton iterations. The Jacobian matrix is block tridiagonal with a Schur complement, allowing efficient inversion. This culminates in a unique and computationally efficient quasi-one-dimensional method offering improved modeling of the physical characteristics of shock tube experiments. Results of a 3 km/s, 66.6 Pa argon test case solved by a viscous, axisymmetric Navier–Stokes solution had agreement with the proposed method in temperature and pressure profiles to within 2% and post-shock velocity to within 15%. Reacting gas shock tube experiments in synthetic air and synthetic Titan atmospheres were analyzed. Radiance values in the non-equilibrium and equilibrium regions were compared under various assumptions for the shock structure and radial velocity distribution. These results highlight the necessity of a dedicated shock tube solver when analyzing shock tube thermochemistry, particularly when determining reaction rates and relaxation parameters.

Managing lower extremity loading in distance running by altering sagittal plane trunk leaning

BackgroundTrunk lean angle is an underrepresented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries. The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose–response relationships between sagittal plane trunk lean angle and lower extremity (cumulative) joint loading to guide overuse load management in clinical practice. MethodsThirty recreational runners (15 males and 15 females) ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured. ResultsA change in trunk lean angle from –2° (extension) to 28° (flexion) resulted in a systematic increase in stance phase angular impulse, cumulative impulse, and peak moment at the hip joint in the sagittal and transversal plane. In contrast, a systematic decrease in these parameters at the knee joint in the sagittal plane and the hip joint in the frontal plane was found (p < 0.001). Linear fitting revealed that with every degree of anterior trunk leaning, the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m, while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m. ConclusionTrunk leaning can reduce knee joint loading and hip joint abduction loading, at the cost of hip joint loading in the sagittal and transversal planes during distance running. Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints. When implementing anterior trunk leaning in clinical practice, the increased demands on the hip musculature, dynamic stability, and the potential trade-off with running economy should be considered.

Characterization of chaotic mixing effects in hydrometallurgical leaching process based on deep learning

Traditional stirring methods in the wet metallurgy leaching process suffer from low efficiency, high consumption, and low output, leading to increased production costs and energy consumption. Therefore, this study evaluates reactor performance using deep learning and introduces variable-speed stirring to enhance laminar mixing and reduce stirring reactor power consumption. An S-Type acceleration and deceleration control algorithm is constructed to ensure that stepper motors do not experience step loss, stalling, or overshoot when the frequency changes abruptly. A deep learning tracking model based on dual cameras is established to dynamically track tracer particles inside the stirring reactor, and a Euclidean distance evaluation method is proposed to characterize and evaluate the mixing performance of the stirring reactor. Experimental results demonstrate that the use of complex function variable-speed stirring and shortening the variable-speed cycle both contribute to improving mixing efficiency. Under a variable-speed cycle of 5 seconds, chaotic speed increases mixing efficiency by 53.1% compared to constant speed. This study provides a theoretical basis for optimizing the wet metallurgy leaching process.

The Benefits of Incorporating Vegetables and Fruits Flours into Grain-Based Foods

A study of food losses (flours) from vegetables and fruits obtained from production of juices from purple carrot, purple yams and red apple was conducted. The vegetables and fruits are with very good quality and good price. They are dried in a heat pump dryer, at an initial temperature of 45 ° C and circulating air with an initial moisture content of 20% at constant (5.6 m/s) and variable speed, in a thin layer, with transversely oriented air flow relative to the product layer.

Active cooling of hot integrated circuits using a rotating cylinder and NEPCM-water mixture: Numerical analysis of the impact of phase change and Magnetohydrodynamics on double-diffusive mixed convection

Efficient cooling of integrated circuits is crucial for maintaining optimal performance and longevity of electronic devices. This study addresses this challenge by investigating the double-diffusive mixed convection around a hot integrated circuit (using) a nano-encapsulated phase change material-water mixture for enhanced heat absorption. The cooling process is carried out by a cylinder rotating at a constant speed inside a square cavity surrounded by the NEPCM-water mixture. Using the Galerkin finite element method, we numerically analyzed the influence of various parameters, including the Reynolds number (10≤Re≤100), Richardson number (0.1≤Ri≤10), Hartmann number (0≤Ha≤80), NEPCM volume fraction (0.01≤ϕ≤0.035), Lewis number (0.1≤Le≤10), buoyancy ratio (1≤Nz≤5), fusion temperature (0.1≤ϴf≤0.9), and Stefan number (0.1≤Ste≤0.8), on the average Nusselt number (Nuav), average Sherwood number (Shav), total entropy generation (Stotal), and Bejan number (Be). The results demonstrate that increasing Re and Ri enhances Nuav and Shav by up to 175 % and 162 %, respectively, while applying a magnetic field (increasing Ha) suppresses heat and mass transfer rates by up to 58 % and 50 %, respectively. Increasing ϕ improves Nuav by up to 34 % with minimal impact on Shav. The Le and Nz govern the coupling between heat and mass transfer processes, with Le substantially influencing Shav and Nz affecting both Nuav and Shav. The ϴf exhibits a non-monotonic effect on Nuav, suggesting an optimal fusion temperature, while Ste shows an inverse relationship with Nuav. The Stotal is significantly influenced by Re, Ri, Ha, and ϕ, while Be is affected by Re, Ri, Ha, and ϕ to a lesser extent. These findings provide valuable insights into the complex interplay of forced and natural convection, magnetohydrodynamics, and NEPCMs in the active cooling of hot electrical elements. The results can be applied to optimize cooling system designs, potentially leading to more efficient and effective thermal management in electronic devices.

Silicon carbide-embedded AZ91E alloy nanocomposite hybridised with chopped basalt fibre: performance measures

ABSTRACT This study uses vacuum stir casting to manufacture magnesium alloy hybrid nanocomposites of silicon carbide nanoparticles (50 nm) and chopped basalt fibre. The different weight percentages (0 wt%, 3 wt%, 6 wt% and 9 wt%) of chopped basalt fibres with a constant weight percentage of 7.5 wt.% silicon carbide nanoparticles were added into molten AZ91E magnesium alloy at 600 rpm constant stirring speed. During the final casting process, 0.1 MPa vacuum pressure was applied to all the composites to reduce the casting defects. The prepared hybrid composite was characterised by physical, mechanical, microstructural and wear properties. The Quanta FEG model SEM apparatus was used to examine the distribution of silicon carbide nanoparticles and basalt fibre. The mechanical characteristics, such as ultimate tensile strength (UTS), yield strength and impact strength, were obtained for 7.5 wt% SiCnp/9 wt% basalt fibre reinforced AZ91E magnesium alloy matrix hybrid nanocomposite. Adding chopped basalt fibre enhanced the wear properties of conventional AZ91E magnesium alloy.

Interaction of Overweight and Pronated Foot on Ground Reaction Force Frequency Content During Running

Being overweight can influence the occurrence of pronated feet (PF). This research aimed to assess the interaction effect of overweight and PF along with sex on the frequency content of ground reaction forces (GRFs). 104 young male and female adults were allocated to four groups: normal body-mass-index/normal feet, normal body-mass-index/PF, excessive weight/normal feet, and excessive weight/PF. Subjects ran at constant speed over the walkway while an embedded force plate was located at the midpoint of the walkway. GRFs were recorded during 20 running trials. Findings demonstrated the significant main effect of “sex” (P

Energy cost of running uphill as compared to running on the level with impeding horizontal forces.

We have previously shown that accelerated running on flat terrain is biomechanically equivalent to running uphill at a constant speed. This hypothesis was further investigated comparing the energy cost of running at a constant speed either uphill, or on flat terrain against an equivalent horizontal impeding force, mimicking acceleration. Steady-state O2 consumption and the corresponding energy cost (per unit body mass and distance) were determined on 12 male subjects during treadmill running at speeds between 2.11 and 2.89 m/s: (i) on the level, (ii) uphill at 10 or 20% incline ( ), or (iii) on the level against a horizontal traction force of 10 or 20% of the subject's body weight ( ). This allowed us to estimate the net efficiency ( ) of running against horizontal or vertical forces, as given by the ratio between the additional mechanical work output under , or the corresponding condition, and the difference between the appropriate energy cost above that for running at constant speed on flat terrain. The values when running uphill ( ) amount to 0.35-0.40, whereas those for running against an equivalent impeding force ( ) are about 10% greater (0.45-0.50), a fact that may be due to a greater recovery of elastic energy in the as compared to the condition. Making allowance for these small differences, these data support the view of considering accelerated running on flat terrain biomechanically equivalent to running at a constant speed, up an equivalent slope.

Speed Strategy on High-Pressure Compressor for the Charging Process of Advanced Adiabatic Compressed Air Energy Storage During Dynamic Shutdown

Abstract Advanced adiabatic compressed air energy storage (AA-CAES) starts and shuts down frequently. A detailed charging process comprising three series of centrifugal compressors with intercoolers was constructed within the framework of UniSim® Design. The safety measures were meticulously considered by integrating anti-surge circuits, vent valves, and check valves. PI controllers were allocated to the primary component to govern the shutdown procedure. The speed strategy of the HP inverter motor during the load shedding stage is the focus of research. Six speed strategies, including decreasing speed, constant speed, and increasing speed, were discussed, respectively. The discussion focused on changes made to air injection, inlet mass flow of the HP, inlet and outlet pressure of both the middle-pressure compressor (MP) and HP, and energy efficiency. The study found that implementing the minimum allowable speed for the inverter motor speed (IMS) and increasing speed during the load shedding stage can cause fluctuations in the air injection. As IMS increases at the end of the load shedding stage, the pressure anomalies at the MP outlet and the HP inlet weaken, and the shutdown process's energy efficiency improves. The HP inlet flow fluctuations caused by various strategies were within an acceptable range. This study reveals that there is a mutual influence between components in the charging process of AA-CAES. An appropriate speed strategy for the HP inverter motor can mitigate the operational hazards. The results of this study can provide guidance for similar AA-CAES shutdowns.

太阳能-热泵联合干燥条件下紫花苜蓿动态干燥特性

To promote the application of solar energy-heat pump combined drying technology in forage processing and enhance the drying efficiency of alfalfa, an experimental study was conducted. The research utilized a solar energy-heat pump drying system and a mesh belt dynamic drying device to investigate the drying characteristics of alfalfa. Drying characteristic curves were obtained, and the drying model and parameters were determined through model comparison. The study also analysed the impact of factors such as hot air velocity, temperature, alfalfa stacking thickness, turning angle of the spinner rack, and conveyor belt speed on the drying characteristic curves and parameters of alfalfa. A predictive model for alfalfa moisture content was developed, and the effective moisture diffusivity and activation energy were calculated. The findings revealed that alfalfa does not exhibit a constant speed drying stage, and its drying primarily occurs during the deceleration drying stage. The Logarithmic model was found to accurately describe the moisture change pattern during the dynamic drying process of alfalfa, with a model fitting coefficient R^2 exceeding 0.994, with an effective moisture diffusivity ranging from 2.776×10-10 m2/s to 4.7324×10-9 m2/s, and an activation energy of 37.02 kJ/mol. The study suggests that increasing the hot air velocity and temperature, reducing the conveyor belt speed, and adjusting the alfalfa stacking thickness can further enhance the drying rate and reduce the drying time.

Model-Based Inference of Flame Transfer Matrices from Acoustic Measurements in an Aero-Engine Test Rig

Abstract Flame dynamics, represented as a flame transfer matrix (FTM), is not directly measurable in test rigs and must be deduced from transfer matrix measurements of the combustion system. The burner-flame transfer matrix (BFTM) approach for FTM estimation is based on local pressure signals from microphones located upstream and downstream of the combustor. It combines acoustic measurements in non-reacting and reacting conditions, with the latter implicitly including flame dynamics. A simple matrix operation yields the FTM. However, this approach assumes loss-free wave propagation at constant speed of sound with no change in cross-sectional area between the microphones and the burner/flame. The present work demonstrates the limitations of these assumptions when applied to a test rig with effusion cooling, bypass annulus, and end contraction. This work proposes a method to infer the FTM for complex combustors by combining reactive transfer matrix measurements of the entire combustor with an accurate low-order model (LOM) of the test rig. This generalized method reduces to the BFTM approach as a special case. The Rolls-Royce SCARLET test rig, operating under realistic engine conditions, is used to analyze the capabilities of the proposed model-based inference method and the limitations of the BFTM approach. First, a LOM based on SCARLET's geometry and operating point is formulated using a generic FTM. This model visualizes the limitations of the BFTM approach concerning various physical and geometrical parameters. Finally, experimental data is used to infer the FTM of SCARLET using the proposed approach.

A Whole-Spine Radiography Study to Reduce Patient Exposure Dose and Artifacts Using the EOS Imaging System.

Whole-spine radiography can be accomplished through two methods: (1) segmented imaging employing X-ray tube angulation and detectors, or (2) the Euronext Paris Advanced Orthopedic Solutions (EOS) 2D Imaging system that can capture the entire spine in a single image using X-ray tubes and detectors oriented at a 90-degree angle. This study aimed to establish optimal EOS examination parameters based on patient morphotype and scan speed to reduce patient radiation exposure, repeat examinations, heat stress on equipment, and X-ray tube cooling time. X-ray exposure conditions involved adjustments of scan speed ranging from two to four steps, contingent upon the patient's morphotype ('S', small body; 'M', medium body; and 'L', large body. Patient dose measurements were conducted 20 times for each set of conditions. When transitioning from an 'S' to an 'M' morphotype at a constant scan speed, the entrance skin dose (ESD) exhibited an increase of approximately 41.25 ± 4.57%. A similar change from an 'M' to an 'L' morphotype resulted in an ESD increase of roughly 59.56 ± 24.00%. A transition from an 'S' to an 'L' morphotype at the same scan speed manifested an ESD elevation of approximately 124.21 ± 26.96%. This study underscores significant variations in radiation dose, ranging from 40% to 50%, when altering morphotype while maintaining a consistent scan speed.