Three-dimensional Dynamics Model Research Articles

Second-Order Nanoscale Thermal Effects in Memristive Structures Based on Poly-p-Xylylene

Effects of second-order resistive switching in memristors based on poly-p-xylylene have been detected for the first time. It has been shown that these memristive structures constitute a dynamic system whose behavior significantly depends on second-order short-term effects. More precisely, the switching time of memristive structures decreases when a pair of pulses (not necessarily with the same polarities) are applied with a certain delay between the pulses. The second-order effects are explained by an increase in the local temperature of a metallic conducting bridge because of Joule heating. A three-dimensional numerical dynamic model involving the drift—diffusion of metal ions in the polymer matrix has been developed. The experimentally observed effects have been reproduced within this model. The results of this work demonstrate the possibility of using the revealed effects to develop neuromorphic computing systems.

A Comparison of Ride Performance of Hydro-Pneumatic Suspension System with Those of Rubber and Leaf Suspension Systems

The objectives of this study is to compare the performance of the hydro-pneumatic suspension system of heavy truck on cab ride comfort with rubber and leaf springs of suspension systems. To compare the three types of suspension systems, a three-dimensional dynamic model of heavy truck with 15 degrees of freedom (DOF) is established based on Zhou Changfeng model under random excitation of road surface for simulation and analysis. The root mean square (r. m. s) acceleration of the vertical cabin, pitch angle, and roll angle of cabin is chosen as objective functions. Matlab/Simulink software is used to simulate and calculate the values of objective functions. The ride performance of the hydro-pneumatic suspension system on vehicle is analyze and compared to two other supension systems when vehicle operates under different operating conditions. The results show that the values of objective functions with the hydro-pneumatic suspension system are significantly reduced in comparison with the rubber and leaf suspension system. The ride performance of Hydro-pneumatic suspension system is much better than that of the rubber and leaf suspension systems.

3D Dynamic Elastoplastic Constitutive Model of Concrete within the Framework of Rate-Dependent Consistency Condition

In this paper, the proposed yield function is the function of stress, hardening parameter, and strain rate. To fully describe the stress state and strain rate condition of material during dynamic loading, a new coordinate system, which is composed of a stress axis and strain rate axis, is employed to present the proposed rate-dependent yield surface. The strain rate is regarded as a variable in applying the consistency condition. The rate-dependent consistency is satisfied strictly during the whole dynamic loading. The nonassociated flow rule is employed to describe the dilatancy behavior of concrete. The loading–unloading criterion based on Ilyushin’s postulate is developed into the rate-dependent loading–unloading criterion that can consider reasonably the change of elastic domain caused by strain rate. Furthermore, a three-dimensional (3D) dynamic elastoplastic model of concrete is established within the framework of the rate-dependent consistency condition. Under the dynamic uniaxial compression loading condition, the model characteristics related to rate-dependent consistency condition are discussed and analyzed. Five sets of dynamic experiment results of concrete are employed to evaluate the performance of the model.

A novel design method of the impact zone of a high-speed train

The design of vehicle impact zone is of great significance for passive safety protection of trains. This study introduces a novel design method of impact zone based on the concept of linear impact force, which has a linear increase of impact force with the increase of displacement. A three-dimensional dynamic model of train collision was constructed and validated. Here, the linear impact force slope of energy absorbing devices were selected as design variables, whereas the total mean acceleration along the train (TMA) and the total crash displacement (TS) were set as objectives. The multi-objective particle swarm optimisation was used to seek for an optimal design of the impact zone, where the response surface method was adopted to formulate the TMA and TS. The results indicate that the optimised design has smaller impact acceleration peak value, higher utilisation efficiency of compression stroke, and more uniform distribution of crashing displacement.

Mechanical behavior of a drilling riser with buoyant blocks when it enters into deep water

A novel three-dimensional dynamic model is developed to investigate the vortex-induced vibrations (VIVs) in flexible risers with buoyant blocks conveying the internal fluid flow. The unsteady hydrodynamic forces associated with wake dynamics are modeled using two distributed van der Pol wake oscillators that consider the coupling between the structure and the fluid. Furthermore, our model considers the loads of buoyancy weight, tension, pressure, temperature, and seawater current owing to wind, tide, and waves, as well as the nonlinear effect of the large deflection of the riser on the loads. The riser is discretized into slender-beam elements, the distributed van der Pol wake oscillators are also discretized on the element nodes, and each node has six degrees of freedom, allowing it to describe the vibrations of the risers in lateral, axis, and torsion simultaneously. The boundary conditions include the displacements and rotations at the up end and free bottom end in the presence of additional weight. The computational program is prepared using Matlab (R2014a). The simulation results exhibit good agreement with the existing experimental data, verifying the validity of the model and the parameters. Finally, the VIV simulations are conducted for more realistic risers when they are entering 500–3000 m deep water, denoting the effects of buoyant blocks, entry speed, and water depth upon the drop-point offset of the bottom end of the risers, the tension stresses as well as the values and positions of the maximum bending stresses with respect to the risers. These data can be used to select a good operational condition for ensuring the entry of a riser. This study provides a computational framework for conducting subsequent research, and the obtained results can be applied to construct ocean-floating platforms more scientifically, safely, and economically.

Three-dimensional nonlinear response history analyses for earthquake damage assessment: A reinforced concrete wall building case study

Nonlinear dynamic analysis techniques have made significant progress in the last 20 years, providing powerful tools for assessing structural damage and potential building collapse mechanisms. The fact that several reinforced concrete shear wall residential buildings underwent severe structural damage in walls at the lower building levels during the 2010 Maule earthquake (Chile) presents a scientific opportunity to assess the predictive quality of these techniques. The objective of this research is to compare building responses using two completely different three-dimensional nonlinear dynamic models and study in detail the observed damage pattern and wall collapse of one reinforced concrete shear wall building in Santiago, Chile. The first model is a mixed fiber-shell model developed in MATLAB, and the second is a shell finite element model developed in the software DIANA. Results of both models are consistent with the hypothesis that high axial loads trigger a limited ductility failure in critical walls at roof-to-base drift ratios less than 0.34% with little capacity of hysteretic energy dissipation, which contradicts the ductile design philosophy of current code provisions.

Experimental and Numerical Study on the Formation Mechanism of Flow Field in a Side-Ported Rotary Engine Considering Apex Seal Leakage

Abstract The aim of this research is to investigate the influences of apex seal leakage on the formation mechanism of flow field in a side-ported rotary engine by particle image velocimetry (PIV) and computational fluid dynamics (CFD). In this study, a PIV was used to acquire the two-dimensional (2D) flow field on the rotor housing central plane at an engine speed of 700 rpm. A three-dimensional (3D) dynamic simulation model considering leakage through apex seals was established and verified by the 2D-PIV experiment results. Thereafter, CFD analysis was used to further understand the 3D flow field in combustion chamber under the action of apex seal leakage. The simulation results showed that for the three engine speeds (2000, 3500, and 5000 rpm), in the intake stroke, the vortex generated in the front end of combustion chamber under the condition with no leakage, was strengthened and destroyed by the effects of the small (0.02 mm) and the large (0.08 mm) apex seal leakage gaps, respectively. As the apex seal leakage gap increased, the volume efficiency and the peak pressure decreased continuously. The volume efficiency and the peak pressure caused by any fixed apex seal leakage gap decreased with the increase of the engine speed. Compared with the volumetric efficiency of the condition with no leakage at 2000 and 5000 rpm, the volumetric efficiency of apex seal leakage gap of 0.08 mm decreased only by 24.6% at 5000 rpm, but by 41.2% at 2000 rpm.

An implementation of Three-Dimensional Multi-Component Mooring Line Dynamics Model for Multi-Leg mooring line configuration

Multi-component mooring line (MCML) system is widely used and expected to be escalated for deep water mooring operation since it has several advantages comparing with conventional mooring line. The modelling of MCML involving its dynamic effects is strongly required to predict the dynamic behaviours of the mooring line precisely. In this paper, a proposed three-dimensional dynamics model of MCML system is presented and implemented to single point multi-leg mooring line configuration operated in deep water condition. An extending three-dimensional lumped mass method is elaborated to develop the model while the combination of Manoeuvring Modelling Group (MMG) and conventional floating body motion equations is used to perform simultaneous motion between floating structure and mooring lines. The simultaneous motion is performed with respect to wind, wave, and current. The motion of the floating structure and mooring line as well as mooring line tension can be analysed properly by using the presented model. The simulation results of the model show reasonable results for both floating structure and mooring line.

Evaluation of Anchor Penetration Depth based on Numerical Analysis for Burial Protection Method of Submarine Cables

Submarine cables are installed and operated for the stable power supply of island regions, and feature protective measures to counter marine hazard factors. With regard to the protection techniques to prevent damage to submarine cables, the method of digging and embedding the submarine ground is applied the most. However, since there are no design criteria and techniques for such protection facilities, the burial depth of the submarine ground has been calculated only qualitatively and empirically after an ocean survey is conducted. Such an imperfect method has led to assorted damages to submarine cables. Therefore, in this study, to ensure the safety of submarine cables from marine hazard factors, the three-dimensional dynamic interaction analysis model was established for the ship anchor and ground, and the penetration depth of this anchor was calculated through numerical analysis for the burial protection method. These results were compared and evaluated with the results of the full scale test for anchoring and dragging anchor. As a result, the error rate(average) of the anchor penetration depth through the numerical analysis and test was 12.2% in the ground conditions of sand, clay and multi(clay/sand) layers. This error rate was analyzed to be caused by various uncertainties in the test, such as the dynamic impact of the anchor and ground conditions, and the numerical analysis was evaluated to ensure sufficient reliability. The results of this study are expected to be useful in the burial depth calculation of the burial protection method to ensure the safety of submarine cables.

Thermal and Fluid Dynamic Performance Comparison of Three Nanofluids in Microchannels Using Analytical and Computational Models

The fluid dynamic and thermal performance of three nanofluids containing aluminum oxide, copper oxide, and silicon dioxide nanoparticles dispersed in 60:40 ethylene glycol and water base fluid as a coolant in a microchannel heatsink are compared here by two methods. The first is a simple analytical analysis, which is acceptable for very low nanoparticle volumetric concentration (1–2%). The second method is a rigorous three-dimensional finite volume conjugate heat transfer and fluid dynamic model based upon a constant heat flux boundary condition, which is applicable for cooling electronic chips. The fluids’ thermophysical properties employed in the modeling are based on empirically derived, temperature dependent correlations from the literature. The analytical and computational results for pressure drop and Nusselt number were in good agreement with the nanofluids showing a maximum difference of 4.1% and 2.9%, respectively. Computations cover the practical range of Reynolds number from 20 to 200 in the laminar regime. Based on equal Reynolds number, all of the nanofluids examined generate a higher convective heat transfer coefficient in the microchannel than the base fluid, while copper oxide provided the most significant increase by 21%. Based on the analyses performed for this study, nanofluids can enhance the cooling performance of the heatsink by requiring a lower pumping power to maintain the same maximum wall temperature. Aluminum oxide and copper oxide nanofluids of 2% concentration reduce the pumping power by 23% and 22%, respectively, while maintaining the same maximum wall temperature as the base fluid.

Four-legged hunter (FLH) robot: design and shooting control to moving targets with SMC

The design and control of robotic shooting control systems in defense systems is one of the important research topics in recent years. This study focuses on the design, modeling, and success of the shooting control system of the 14 Degrees of Freedom (DoF) Four Legged Hunter Robot (FLH) system with 2 DoFs gun barrel systems. The three-dimensional dynamic model of the FLH-Robot with gun barrel system was created by the Simscape Multibody toolbox of the MATLAB program. The leg joints of FLH were controlled by the PID control method to perform the motion of the robot. Gun barrel stabilization was performed in order to ensure the orientation of the gun barrel system to the predetermined targets and to enhance the hitting success rate. Mechanical oscillations in the robot body were applied as a disruptive effect on the gun barrel system. The sliding-mode control (SMC) method was applied to 2 DOFs gun barrel system. Ballistic simulations were repeated for situations where the targets were fixed and mobile. While the robot was walking, in the first shooting scenario, the shots made on fixed targets placed in random coordinates were hit with a maximum error of 3.3 cm. In the second shooting scenario, shots were fired on moving targets at a speed of 0.1 to 1 rad / s, and hitting success was achieved with a maximum error of 0.387 m. When hit error rates are analyzed, the usability of FLH-Robot for the defense industry was demonstrated.

Dynamic interaction between rail vehicles and vibration-attenuating slab tracks

The ground vibration and noise induced by trains are among the most concerned issues in the field of urban railway transportation. Therefore, many types of vibration-attenuating slab tracks have been brough in urban railways to minimize train induced vibration and noise. Vibration-attenuating slab tracks usually have a soft support system than that of traditional slab tracks, which on the other hand affects the vehicle-track interaction. This paper presents a study on the dynamic interaction between urban railway vehicles and vibration-attenuating slab tracks, in which four typical elastic vibration-attenuating slab tracks including the resilient-fastener slab track, elastic-supporting-block track, ladder-type sleeper track and floating-slab track are considered. A three-dimensional dynamic model of a metro train running on different vibration-attenuating slab tracks is formulated. This model is capable of predicting the vehicle-track interactions under various wheel-rail excitations. The dynamic characteristics of wheel-rail interaction induced by impulsive, harmonic and random track defects of two metro vehicles travelling on the four vibration-attenuating slab tracks are compared in detail. The influence of track viscoelastic properties on vehicle-track interaction is reported. The results show that the properties of vibration-attenuating slab tracks have a significant effect on vehicle-track dynamic interactions. The dynamic responses of wheel-rail forces of the vehicles travelling on different vibration-attenuating slab tracks are significantly different. The elastic-supporting-block track has the best performance in absorbing mid- and high-frequency wheel-rail forces.

Development of coal geological information technologies in China

The history of coalfield geology and mine geology IT applications is over 30 years, which is gaining remarkable achievements. This paper sheds light on the development of geological and surveying spatial management information systems. Specifically, this study proposed the development trend, system structure and function design and sub-systems of the new generation of geological and surveying spatial management information system by benefitting from the recent advancements in computer and spatial information technologies. The sub-systems include the “One Map” online collaborative (2D-GIS) management platform, the geological survey mapping collaborative management system, the integrated service system based on “one map”, the three-dimensional dynamic geological model system, the three-dimensional transparent management platform, and water prevention and control information management system. This work is an important foundation to realize the IT information and intelligent management of coal industry. The successful development and application of the new generation of geological and surveying spatial management information system will provide the dynamic data support for the online decision-making of the intelligent coal mining.

An efficient three-dimensional dynamic contact model for cylindrical gear pairs with distributed tooth flank errors

Coupled loaded tooth contact analysis (LTCA) model and lumped-parameters model, an efficient three-dimensional dynamic contact model for cylindrical gear pairs with distributed tooth flank errors is established. The solution scheme of the proposed model is constructed using a combination of the loaded tooth contact algorithm and the Newmark integration method. The dynamic load distributions at different input speeds can be determined, and the dynamic time-dependent mesh stiffness and dynamic composite mesh error are proposed and calculated. The proposed model is validated by comparing the obtained numerical results with the experimental results from the published works, and has much higher efficiency compared with three-dimensional dynamic contact finite element method. The effects of helix angle, mesh damping, distributed tooth flank errors and output torque on the vibration behaviors and dynamic load distributions of cylindrical gear pairs under different working conditions are investigated and discussed. The proposed model can also be used to predict the vibration behaviors and the instantaneous three-dimensional dynamic contact state of cylindrical gear pairs with different distribution forms of tooth flank errors and various tooth surface modifications.

Dynamic performance of vehicle in high-speed freight EMU equipped with four double-axle bogies

Size and weight limitations mean that ordinary railway vehicles with two double-axle bogies cannot deliver some extremely heavy cargo and products. Thus, a newly designed high-speed freight electric multiple unit (EMU) equipped with two bogie groups each with two double-axle bogies connected by a transition frame is an alternative means of transporting heavy products because of its greater load capacity. However, because it is still in the design stage, its dynamic performance is yet to be researched, something that is urgently required because of the more-complicated structure and more-intensive wheel-rail interactions than those of traditional high-speed railway vehicles Therefore, to reveal the dynamic performance, this study establishes a three-dimensional dynamic model of a trailer vehicle in a high-speed freight EMU equipped with four double-axle bogies based on the classical theory of vehicle-track coupled dynamics. In this dynamic model, the vertical, horizontal, rolling, pitching, and yaw motions of the major components excited by random irregularities in the track geometry are considered fully. The results indicate that the derailment coefficient and stability index of this vehicle are both at excellent levels for the simulated conditions. The wheel unloading ratio appears to be larger but still within the safety range when the vehicle runs in a straight line, but it is close to or can even exceed the limit value when the vehicle runs at 400 km/h on a specified curved line.

Assessment of heat generation and risk of thermal necrosis during bone burring by means of three-dimensional dynamic elastoplastic finite element modelling

During bone burring, the heat generated due to friction at the bone-burr interface may cause thermal damage to the bone. Therefore, it is necessary to assess bone temperature distribution around a burring site and identify high-risk regions for thermal necrosis due to bone burring. In this study, a three-dimensional (3-D) dynamic elastoplastic finite element model for the burring process was developed and experimentally validated to investigate the influence of burring parameters (rotational speeds: 3,000, 10,000, 15,000 and 60,000 rpm; feed rates: 0.5, 0.9, 1.5 and 3.0 mm/s) on heat generation and evaluate the risk region for thermal necrosis. Calculated bone temperatures were compared with experimental values and found to be in good agreement with them. The analytical results demonstrated a linear relationship between the burring time and friction energy. In addition, the friction energy increased with the bone temperature. The high-risk thermal necrosis zone was measured from the edge of burring (y-direction) at feed rates of 0.5, 0.9, 1.5 and 3.0 mm/s and was found to be 7.8, 7.3, 6.6 and 5.5 mm, respectively. When the burr rotational speed increased from 3,000 to 60,000 rpm, the high-risk zone for thermal necrosis increased from 4.5 to 8.1 mm. We concluded that both the friction energy and the bone temperature increased in proportion with the burr rotational speed. Reducing burr rotational speeds and/or increasing feed rates may decrease the rise in bone temperature, thus decreasing the potential for thermal necrosis near the burring site. Our model can be used to select the optimal surgery parameters to minimise the risk of thermal necrosis due to bone burring and to assist in the design of optimal orthopaedic drill handpieces.

Augmented Reality-Enabled Education for Middle Schools

Augmented reality acts as an add-on to teachers while teaching students, and this helps the teachers and students to have an interactive session. Augmented reality’s usage in education is cited as one of the major changes in the educational sector. Thus, the work carried out makes a positive impact in the educational industry. Augmented reality provides features like image recogntion, motion tracking, facial recognition, plane detection, etc., to provide interactive sessions. Simultaneous localization and mapping and concurrent odometry and mapping have proved to be efficient algorithms for augmented reality on mobile devices. The work carried out allows students to view interactive newspapers while reading a specific article. It also allows them to view a dynamic three-dimensional model of the solar system on their smartphone using augmented reality.

Possibilities for Applying Information of Computerized Car Systems and Devices Installed thereon in the Process of Investigation

The paper draws attention to the development of computerized car systems and the expansion of their functionality. However, according to the author, the use of information recorded in these devices for the criminalistic purposes in crimes investigation is clearly not receiving enough attention in science and in practice. The paper discusses the main range of systems that allow you to obtain forensic information, as well as the possibility for practical application of electronic information from computerized car systems. The author draws the conclusion on the possibility of a forensic investigation of computerized car systems using forensic developments in the field of electronic traces and electronic evidence. A correctly conducted study can allow you to get a dynamic threedimensional model of a criminally committed traffic accident, as well as other criminal events recorded by car sensors. The paper also examines the prospects for the study of so-called smart cars. An increase in the effectiveness of expertise in the production of integrated computer-aided technical research is noted.

Application of distortion theory to tunnel physical modeling

With extensive developments in subway construction, tunnel lengths have also increased. Relative to this, existing experimental tunnel model which limited by large length–width ratios are only applicable to short tunnels with lengths that are less than 1000 m. In order to facilitate the development of research on extra-long tunnels, the use of distortion model with different linear length scales in the longitudinal direction is proposed in this research. A three-dimensional dynamic mesh model of a tunnel is established and validated by experiments to investigate the tunnel flow field. A multiple dynamic mesh coupling model is also created to study the piston wind effect of multiple trains simultaneously traversing the same tunnel. The distortion theory is introduced. Considering the structure of tunnel, the ratio of longitudinal direction is varied which is bigger than the ratios of transverse and vertical directions to shorten the length of tunnel model. The maximum permissible distortion ratio, which can reflect the application range of distortion, is elaborated. Distortion models applied to tunnels with one train and two trains are investigated. The results show that distortion models are capable of reflecting the flow field variation trend in full-size tunnels. The errors in distortion models, however, increase with the distortion ratio, which has a maximum permissible value of 4. The results are expected to provide reference for the design of tunnel physical models.

CFD performance analysis of finned-tube CO2 gas coolers with various inlet air flow patterns

A detailed model of three-dimensional computational fluid dynamics (CFD) on a finned-tube CO2 gas cooler has been developed and validated. The model is then applied to investigate the effect of uniform and mal-distribution inlet airflow profiles on the coil performance. The airflow mal-distribution velocity profiles include linear-up, linear-down and parabolic while the effected coil performance parameters contain airside pressure drop, average airside heat transfer coefficient, approach temperature and coil heating capacity. The model also enables to predict the CO2 refrigerant temperature profile along the coil pipes from refrigerant inlet to outlet at different operation conditions. The simulation results reveal that different types of inlet airflow velocity profiles have significant effects on the gas cooler performance. The uniform airflow velocity profile case shows the best thermal performance of gas cooler. Compared with the cases of linear-up and parabolic air velocity profiles, the linear-down airflow profile can influence more on the coil heat transfer performance. Due to the thermal conduction between neighbour tubes through coil fins, reversed heat transfer phenomenon exists which can be detected and simulated by the CFD model. It is predicted that the linear-down airflow profile can increase greatly the reversed heat transfer phenomenon and thus lead to the highest approach temperature and the lowest heating capacity amongst these four types of airflow profiles. The research method and outcomes presented in this paper can have great potentials to optimize the performance of a CO2 gas cooler and its associated refrigeration system.