Search Results (53)

Current internal dose assessments in nuclear emergencies rely on static, upright voxel phantoms, often neglecting realistic human postures and physiological factors—such as breathing rates specific to emergency scenarios—that influence radionuclide intake and biokinetics. We present a voxel deformation method based on an improved as-rigid-as-possible (ARAP) algorithm incorporating a novel smoothing term to generate anatomically consistent stooping and swivelling models. Coupled with Geant4 Monte Carlo simulations using the full decay spectra of radionuclides relevant to simulated nuclear accident scenarios (i.e., ¹³¹I and ¹³⁷Cs), and incorporating scenario-specific respiratory parameters into activity calculations, our results demonstrate that body posture significantly influences internal dose distributions: for ¹³⁷Cs, the specific absorbed fraction (SAF) of the liver increases by up to 24.9% in the stooping posture, while swivelling induces variations of up to 15.1%. In contrast, dose metrics for ¹³¹I show minimal sensitivity to posture (<5%). These findings highlight the importance of incorporating realistic postures and context-aware physiological parameters into emergency dosimetry. Our method enables behaviorally realistic internal dose reconstruction and provides a robust foundation for integrating human motion and respiratory data into rapid triage and risk assessment protocols. Full article

The article presents an approach to designing a low-orbit remote Earth sensing spacecraft. The low operational orbit of the satellite is maintained using a corrective electric propulsion system. The comprises an optical imaging system based on the Richey-Cretien telescope design augmented with an additional swivel reflection mirror. The optical system’s layout was optimized to minimize the spacecraft’s midsection area. This reduction in the frontal cross-sectional area decreases the aerodynamic drag forces exerted by the upper atmosphere, thereby reducing the propellant mass required for orbit maintenance. The article presents a model of constraints imposed by the satellite’s power supply system on the operating modes of the electric propulsion system and the orbit correction modes. Finally, a preliminary design of a low-orbit satellite, derived from the proposed approach, is presented. Full article

The article is devoted to the synthesis, implementation, simulation and experimental study of a real-time Lyapunov-based two-degree-of-freedom model reference adaptive controller (MRAC) for an axial-piston pump. The controller of the developed real-time system determinates control signal values applied to the electro-hydraulic proportional valve. The proportional valve is an actuator for driving the swash plate swivel angle of the pump. The swash plate swivel angle determines the displacement volume of the flow rate of the pump. The MRAC is synthesized based on the experimentally identified mathematical model. To conduct the identification and experimental investigation of the controller, the authors have used an existing laboratory test setup. The comparison of the designed MRAC with conventional PI controller is performed. The control performance analysis is based on integral square error (ISE) in transient responses of the pump flow rate at different flow rate references and loads. Full article

The complex jet-ground interactions of Short Take-off and Vertical Landing (STOVL) aircraft are critical to flight safety and performance, yet studying them with traditional full-scale wind tunnel tests is prohibitively expensive and time-consuming, hindering design optimization. This study addresses this challenge by developing and numerically verifying a “pressure ratio–momentum–geometry” multi-dimensional similarity framework, enabling accurate and efficient scaled-model analysis. Systematic simulations of an F-35B-like configuration demonstrate the framework’s high fidelity. For a representative curved nozzle configuration (e.g., the F-35B three-bearing swivel duct nozzle, 3BSD), across scale factors ranging from 1:1 to 1:15, the plume deflection angle remains stable at 12° ± 1°. Concurrently, axial force (F) and mass flow rate (Q) strictly follow the square scaling relationship ($F\propto 1/n^2, Q\propto 1/n^2)$, with deviations from theory remaining below 0.15% and 0.58%, respectively, even at the 1:15 scale, confirming high-fidelity momentum similarity, particularly in the near-field flow direction. Second, a 1:13.25 scale aircraft model, constructed using Froude similarity principles, exhibits critical parameter agreement (intake total pressure and total temperature) of the prototype-including vertical axial force, lift fan mass flow, and intake total temperature—all less than 1.5%, while the critical intake total pressure error is only 2.2%. Fountain flow structures and ground temperature distributions show high consistency with the full-scale aircraft, validating the reliability of the proposed “pressure ratio–momentum–geometry” multi-dimensional similarity criterion. The framework developed herein has the potential to reduce wind tunnel testing costs and shorten development cycles, offering an efficient experimental strategy for STOVL aircraft research and development. Full article

This article is devoted to the design of a real-time gain scheduling (adaptive) proportional–integral (PI) controller for the displacement volume regulation of a swash plate-type axial piston pump. The pump is intended for open circuit hydraulic drive applications without “secondary control”. In this type of pump, the displacement volume depends on the swash plate swivel angle. The swash plate is actuated by a hydraulic-driven mechanism. The classical control device is a hydro-mechanical type, which can realize different control laws (by pressure, flow rate, or power). In the present development, it is replaced by an electro-hydraulic proportional spool valve, which controls the swash plate-actuating mechanism. The designed digital gain scheduling controller evaluates control signal values applied to the proportional valve. The digital controller is based on the new linear parameter-varying mathematical model. This model is estimated and validated from experimental data for various loading modes by an identification procedure. The controller is implemented by a rapid prototyping system, and various real-time loading experiments are performed. The obtained results with the gain scheduling PI controller are compared with those obtained by other classical PI controllers. The developed control system achieves appropriate control performance for a wide working mode of the axial piston pump. The comparison analyses of the experimental results showed the advantages of the adaptive PI controller and confirmed the possibility for its implementation in a real-time control system of different types of variable displacement pumps. Full article

Acrylamide (ACR), utilized as a precursor for producing polyacrylamide for water purification, has demonstrated neurotoxic properties. However, the mechanisms underlying its neurotoxicity remain inadequately understood. In this investigation, Caenorhabditis elegans were exposed to ACR at concentrations ranging from 250 to 1000 μg/mL and then their locomotor behavior, neuronal development, neurotransmitter concentrations, and gene expression profiles were assessed. Exposure to 250–1000 μg/mL ACR resulted in observable behaviors such as head swiveling and body bending, accompanied by a significant reduction in body size. Furthermore, ACR exposure caused damage to serotonergic, cholinergic, dopaminergic, and glutamatergic neuronal structures. In this context, elevated levels of serotonin, dopamine, acetylcholine, and glutamate were detected, along with notable upregulation of the expression of genes associated with neurotransmitters, including tph-1, cat-4, mod-1, mod-5, cat-1, ser-1, dat-1, dop-1, dop-3, unc-17, cho-1, eat-4, and glr-2. Moreover, ACR exposure elevated reactive oxygen species (ROS), O₂, and H₂O₂ levels while concurrently depleting glutathione (GSH), thereby compromising the antioxidant defense system. This led to a significant upsurge in the expression of genes involved in the nematode ACR detoxification pathway, specifically daf-16, skn-1, mlt-1, sod-3, gst-4, gcs-1, hsf-1, and hsp-16.2. Additionally, Spearman correlation analysis revealed a significant inverse relationship between certain neurotransmitter and antioxidant genes and locomotor activities, highlighting the role of these genes in mediating ACR-induced neurotoxicity in C. elegans. Collectively, this research enhances the understanding of the mechanisms related to ACR neurotoxicity. Full article

Recently, an accelerometer-based device (Vienna Surface Tester (VST)) has been developed for testing the surface characteristics of floors, beddings and turf grounds. The accelerometers are placed in a sphere, which will be dropped in free fall on a test surface. By observing changes in acceleration during impact, researchers can deduce various material characteristics. A down-sized version of this device (Surface Tester of Food Resilience (STFR)) has been proposed for texture testing of foods. Whereas the movement of the VST can be described by the laws of free fall, the STFR follows a constrained circular path due to its attachment to a rod and swivel. We refined the mathematical representation of the different phases of the STFR spherical probe’s trajectory (fall, impact and rebound), and we modified the mathematical models for the STFR probe to extend the measurement range. Full article

In this study, the temperature change and its control measures caused by hydration heat in the construction process of bridge mass concrete cap in severe cold area are discussed. The finite element analysis method was used to simulate the temperature field of the mass pile cap concrete of the No. 13 pier of the swivel bridge in Dehui City under different construction conditions. The effects of different pouring methods, cooling water pipe layout, and its parameters on temperature control were investigated. The research shows that layered pouring combined with multi-layer cooling water pipe arrangement can effectively reduce the core temperature of concrete, thereby reducing the temperature gradient and stress concentration. Among them, the four-layer metal cooling water pipe scheme can significantly reduce the temperature peak, improve the temperature field distribution, and reduce the risk of cracks. In this study, a ‘layered pouring and four-layer metal cooling water pipe collaborative temperature control system’ was proposed for the first time. Combined with the environmental characteristics of severe cold regions, the core temperature of concrete was reduced from 63.55 °C without control to 40.70 °C, and the temperature decreased by 22.85 °C (about 36%). At the same time, the temperature gradient and temperature stress are significantly reduced, which inhibits the stress concentration caused by the temperature gradient and effectively controls the risk of crack formation. In addition, this study explores the influence of cooling water pipe diameter, material and water flow rate on the internal temperature of concrete, and proposes an optimized construction strategy that provides a scientific basis and engineering reference for the construction of mass concrete caps under cold climate conditions. Full article

This paper addresses the unclear bearing force of an RV reducer shaft by establishing a transmission model and analyzing the force situation of each component. Three force models for the crank support bearing, swivel arm bearing, and main bearing are developed. The force variations under different working conditions and the impact of structural parameters on shaft bearing forces are analyzed. Structural optimization is performed using Kriging-NSGA-II to minimize bearing forces. The results show similar load patterns for the bearings, with the force magnitude being ranked in the following order: rotating arm > crank support > main bearing. After optimization, the bearing forces are reduced by 8.26% for the crank support shaft, 10.35% for the rotating arm shaft, and 5.15% for the main shaft. Full article

This paper presents the results of investigations on the accuracy of contact point identification during coordinate measurement, which is crucial in the context of the Industry 4.0 concept. In particular, the effects of swivel length and probe declination angle during measurement were analyzed. In the experiments, deviations from the expected coordinates (0,0,0) of the contact point were analyzed for different rotational angles of the probing head. It was found that the recommended vertical positioning of the stylus at an angle of A = 0° might have introduced some insignificant errors. Increasing angle A up to 15° generated additional errors of negligible values in comparison with the measurement accuracy of the CMM. However, an increase in angle A up to 90° introduced additional errors as high as 10 μm. This contact point identification error will have a certain effect on the best fitting element and subsequent calculations and on the respective measurement results. Full article

The article is devoted to designing novel multivariable robust μ-control of an open-circuit axial piston pump. In contrast with classical solutions of displacement volume control, in our case, the hydro-mechanical controller (by pressure, flow rate, or power) is replaced by an electro-hydraulic proportional valve which receives a control signal from an industrial microcontroller. The valve is used as the actuator of the pump swash plate. The pump swash plate swivel angle determines the displacement volume and the flow rate of the pump. The μ-controller design is performed on the basis of a one-input, two-output model with multiplicative output uncertainty. This model is estimated and validated from experimental data at various loads by multivariable identification. The designed control system achieves robust stability and robust performance for the wide working mode of an axial piston pump. To conduct this experimental study, the authors have developed a laboratory test bench, enabling a real-time function of the control system via USB/CAN communication. The designed controller is implemented in a rapid prototyping system, and real-time experiments are performed. They show the advantages of μ-control and confirm the possibility of its implementation in the case of the real-time control of an axial piston pump. Full article

The Mecanum-wheeled robot has four special wheels. It can control four wheels independently and has seven turning axes. The robot can translate in all directions and travel in curves without changing its direction by means of the control commands for turning ratio, speed, and direction of travel. However, no model has been proposed that can accurately simulate the output of the actual machine for the three types of inputs, even when the characteristics of the motor and motor driver are unknown. In this study, we synthesized and simplified transfer functions and estimated the undetermined coefficients that minimize the sum of squared errors to construct a model of the robot that can output the position and posture equivalent to those of the actual robot for the input commands for turning ratio, speed, and the direction of travel. We modeled a Mecanum-wheeled robot using the proposed modeling method and parameter determination method and compared the outputs of the real robot to the step and ramp inputs. The results showed that the errors between the two outputs were very small and accurate enough to simulate AI learning, such as reinforcement learning, using the model of the robot. Full article

As part of improving road safety around trucks, a solution was proposed to reduce the swept path width of a moving tractor–semi-trailer. This article presents a mathematical analysis of the movement of a tractor unit with a traditional semi-trailer with fixed axles and steered wheels. A simulation analysis of both presented vehicles was carried out. The core of the algorithm controlling the steering angle of the semi-trailer wheels is presented. The influence of controlling the semi-trailer’s swivel wheels on the swept path width of a tractor–trailer with a semi-trailer equipped with swivel wheels is discussed. The assumptions for building the control algorithm are presented. The article presents the advantages of the solution used along with the control algorithm. Measurable benefits resulting from the use of the presented solution are presented, such as increasing cargo space, reducing cargo transport costs, and reducing aerodynamic resistance and fuel consumption. It is worth emphasizing that reducing fuel consumption is very important because it reduces the emission of harmful exhaust gases into the atmosphere. The swept path width is important especially in the case of vehicles moving in a limited area, for example in the parking lots of transhipment and logistics centers, between urban buildings. Vehicles admitted to traffic meet the minimum conditions imposed by homologation regulations, but reducing the swept path width allows for improving the operational properties of the tractor–semi-trailer. The use of the proposed control algorithm to control the turn of the semi-trailer’s steered wheels brings tangible benefits both in improving road safety and in reducing the emission of harmful substances into the environment. Full article

In order to study the change law of mechanical characteristic parameters of the steel spherical hinge of swiveling bridges in the process of rotation, a T-shaped rigid swiveling bridge over railway is used as a research target in this paper, and a three-dimensional bridge finite element model was constructed. The process of bridge turning was numerically simulated by Ansys software(Ansys Release 16.0); the patterns of change in the upper turntable and steel spherical hinge stresses for specific rotational angles were obtained, the effect of bias loads on the stress distribution in the upper turntable and steel spherical hinge was analyzed, and the stress data of the steel spherical hinge of numerical simulation and real-time monitoring were compared. The results illustrated: During rotation, the maximum compressive stress in the upper turntable is located in the contact area with the outer edge of the upper steel spherical hinge; the maximum compressive stress in the steel spherical hinge is at the edge of its own circumference. The overall stress in the upper steel spherical hinge is slightly greater than the stress in the lower steel spherical hinge. Under the eccentricity condition, the maximum compressive stress in the steel spherical hinge increases with increasing eccentricity, and the stress concentration is more significant. The eccentric limit position of swiveling bridges is determined by the strength of the upper turntable. The monitoring method of deploying stress gauges at the steel support structure of the lower bearing platform provides a new method to obtain the stress pattern of the steel spherical hinge and even the bridge as a whole. Full article

In the design of cantilever method bridge anti-overturning structures, the appropriate gap between the supporting foot and the lower rotating table is a crucial factor. It affects the distribution of the upper load and the friction force of the rotating structure, playing a key role in stability control. Currently, a reasonably defined range for this gap based on engineering practice has not been established. This study, set against the backdrop of practical engineering for large-tonnage rotational bridges, analyzes potential overturning instability forms during rotation. It provides a detailed examination of the stability performance of bridges in unbalanced states under single-side joint support configurations and analyzes the mechanical performance and stability under different gaps and impact velocities during rotation. The result is that the impact acceleration, angular acceleration of rotation, and tilt angle (gap) increase displacement and stress in the support system, posing a significant safety risk. The present research demonstrates the safety and rationality of the proposed unbalanced rotation and provides control limits for tilt angle and rotation acceleration during the rotation process. These results demonstrate that the proposed support mode ensures safety requirements during unbalanced rotation, offering insights for the design and construction of large-tonnage rotational bridges. Full article