Simulation Test System Research Articles

Research on Automatic Driving Simulation Test System Based on Digital Twin

With the rapid development of 5G infrastructure, cloud computing and other technologies to enhance the rapid development of autonomous vehicles. How to quickly, safely and efficiently test and evaluate the autonomous vehicles is the only way for that to have the ability to drive on real public road. This paper build a set of automatic driving simulation test system based on digital twin technology, describing the necessary steps taken for the system design, system implementation, and testing of a autonomous vehicle. In the system the real traffic scene in the digital space re-emerged, to achieve the real vehicle running in the real environment, while mapping to the virtual environment to achieve the vehicle in the loop, making it possible to define driving test scenarios for different types of tractor and trailer combinations and providing the free test site for autonomous vehicles. At the same time, the system provides an open interface, to verify and test various autonomous algorithms. The sensor device of the tested autonomous system is flexibly configured, and the test cost is low and the efficiency is high.

Simulation Test System for Coal and Gas Outburst Triggered by Tunneling under Gas-Filling Condition and Its Application

Abstract The physical simulation test is an important means for studying the conditions of outburst occurrence and understanding the evolutionary pattern of outburst. However, the existing physical simulation test device cannot realize the real simulation of coal and gas outburst. In this study, a simulation test system for coal and gas outburst triggered by tunneling under a gas-filling condition was developed. This system consists of five key units: a sealed counterforce unit, a stress-loading unit, a gas-filling unit, a tunneling unit, and an information-acquisition unit. Through the cooperation of these units, the technical difficulties, such as high-pressure gas filling and rapid-pressure replenishment, high-pressure gas sealing, servo tunneling and slag discharge, information acquisition, and inclined model preparation, were overcome. The test system can be used to simulate the outburst triggered by tunnel (Φ150 mm) excavation in a coal-rock model (dimensions: 1,300 mm × 730 mm × 730 mm) under stress loading (maximum of 5 MPa) and gas-filling (maximum of 3 MPa). The proposed test system was employed to simulate the “6.12” coal and gas outburst incident in Huainan, China. The simulated outburst was similar to the original outburst in the following ways: phenomenon and duration of outburst (4.36 s); the shape and location (above the tunneling face) of the outburst holes; the mass (24.5 kg) and ejection distance (16 m) of the coal rock; and the sorting behavior of the ejected coal and rock. Additionally, the information of several physical quantities, including stress, gas pressure, and temperature, was also obtained. The development of this test system is important for an in-depth investigation of the information and patterns of outburst precursors, and for understanding the mechanism of outburst occurrence.

Analysis of the Influence of the Breaking Radiation Magnetic Field of a 10 kV Intelligent Circuit Breaker on an Electronic Transformer.

The development of the smart grid requires the distribution switch to not be limited to the original breaking function. More functional requirements lead to more complex switch structures, especially the intelligent processing unit on the secondary side. A technology called primary and secondary integration optimizes the structure of the switch, which greatly increases the intelligence level of the switch, but also has disadvantages. The secondary intelligent unit is arranged close to the primary high-voltage electromagnetic environment, and the distribution switch is prone to failure due to electromagnetic interference. In order to explore the influence of electromagnetic interference on it, a transient electromagnetic interference simulation test platform was built for a 10 kV intelligent distribution switch based on the principle of spherical gap arc discharge, and the interference signal of the intelligent distribution switch was measured; the law of the spatial magnetic field near the electronic transformer is mainly studied in this paper. The shielding effectiveness of the distribution terminal of the switch was analyzed, and the interference of the power line of the sensor merging unit circuit board was calculated. The results show that the electronic transformer may have serious faults under continuous strong transient electromagnetic interference. The electromagnetic transient simulation test system studied in this paper can evaluate the anti strong electromagnetic interference ability of the electronic transformer.

Hot deformation of cast AZ31 and AZ80 magnesium alloys – Influence of Al content on microstructure and texture development

The present research studies and compares the hot deformation behaviour of the AZ31 and AZ80 magnesium alloys. Uniaxial compression tests using a Gleeble® 3500 thermal-mechanical simulation testing system were conducted at 400 °C and constant true strain rates in the range of 0.001 s−1 to 0.1 s−1. Samples were deformed to various levels of strain to assess the progression of dynamic recrystallization. Detailed microstructure and texture characterization were performed using optical microscopy, XRD macrotexture measurements, and electron backscatter diffraction (EBSD) microtexture measurements. Both the starting materials showed coarse dendritic microstructures and random texture. Both discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) occurred in both the alloys during deformation, although the AZ31 alloy showed a higher tendency towards CDRX compared to the AZ80 alloy, while reverse was true for DDRX. The AZ80 alloy showed initiation of DDRX at lower deformation strain levels, had coarser DDRX grain size and a higher DDRX% compared to the AZ31 alloy. These features resulted in the development of a homogeneous fine-grained microstructure in the AZ80 alloy for deformation to an equivalent strain of 1.0, while the microstructure of the AZ31 alloy sample became bimodal. The choice of the alloy also affected the texture development during the deformation, with the AZ31 alloy showing DDRX texture randomization, while the AZ80 alloy showing deformation texture preservation by the DDRXed grains. The study highlights the substantial effect the Al content in the α-Mg solid solution has on the microstructure and texture development during hot deformation of the AZ alloys.

Performance of N95 elastomeric respirators in high humidity and high coal dust concentration environment

High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal miners. This paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of miners. Based on the self-designed in-situ PM2.5 collector, controllable PM2.5 generator, human breathing simulator, and respirator simulation testing system, under the simulated deep mine working condition, this study investigated the effects of dust loading, wearing time, and dust concentration on the filtration efficiency, breathing resistance, and quality factor of N95 elastomeric respirators. With the increase of dust loading, the respirator filtration efficiency firstly decreased, then increased (minimum value 97.5%). The breathing resistance increased exponentially from 120 to 180 to 1020–1530 Pa, and the quality factor decreased logarithmically from 0.051 to 0.076 to 0.0058–0.0085 Pa−1. As the PM2.5 coal dust concentration increased from 5 to 50 mg/m3, the wearing time for the respirator breathing resistance to exceed 300 Pa reduced from 7 h to less than 1 h. One N95 elastomeric respirator is not able to perform an 8-h work shift. To avoid the excessive breathing resistance caused by dust loading, more filter cartridges are needed for coal miners.

An improved simulated load test system

A miniaturized analog load-checking relay protection test device is developed in this paper, in which a high-precision wireless phase volt-ampere test device is configured. This device, characterized by intelligence and ease of operation, realizes the detection of the transformation ratio, polarity, phase, etc. of the secondary wiring of the transformer in the smart substation merging unit and the conventional substation. It meets the testing requirements of smart substations, and can test bus differential protection, line protection, and various protections such as main transformer differential.

Study on enhancing hydrogen production potential from renewable energy in multi-terminal DC system

Renewable energy complementary hydrogen production can enhance the full consumption of renewable energy and reduce the abandonment of wind and solar power. The integration of renewable energy and hydrogen production equipment through existing multi-terminal DC systems can reduce new power lines construction and save investment in distribution equipment. For integrated renewable energy/hydrogen energy in an existing multi-terminal DC system, this paper investigates its potential of hydrogen production based on renewable energy, while ensuring the normal performance of the existing system being not affected. The typical structure and control strategy of the integrated renewable energy/hydrogen energy in multi-terminal DC system are firstly described. Then the state space model of the system is constructed, and the key parameters affecting the hydrogen production capacity are studied by using the eigenvalues analysis method. Finally, the corresponding system simulation model and test platform are built, and the theoretical analysis results are verified, and the potential of using multi-terminal DC system to enhance hydrogen production is quantitatively analyzed. The proposed scheme can enhance the hydrogen production potential from renewable energy, meanwhile the normal performance of the existing system is not affected.

Research on Control Method of Wet Desulfurization System for Coal-fired Boiler

In wet flue gas desulfurization technology, the key factor affecting flue gas SO2 absorption is the control of slurry pH value in the absorption tower. However, most of the commonly used pH value control methods have some defects and cannot fully meet the system control requirements. On the basis of the analysis for the problems in the control process, this paper discussed a control strategy based on internal model control algorithm. The system simulation test showed that this control method had good dynamic performance, robustness and anti-interference, which could realize the relatively accurate control of pH value for wet flue gas desulfurization system, and achieve the control goal.

A PI control strategy for Surface Permanent Magnet Synchronous Motor

In order to ensure the strong nonlinear parameter characteristics of Surface Permanent Magnet Synchronous Motor(SPMSM), which are commonly found at high speed and high power, and to ensure their good adaptability in the high speed range, this paper proposes a PI control algorithm for Surface Permanent Magnet Synchronous Motor adapted to high power and high speed types according to the characteristics of PI control. In order to verify the reliability, anti-interference and fast response of this control algorithm, system simulation tests were carried out by building a system simulation model, and the feasibility of this control strategy was verified by the simulation test results, which has a positive significance at a wide level for this type of motor.

Integration Control of Renewable Energy/Hydrogen Energy System Based on Flexible DC Interconnection

Wind/solar complementary for hydrogen production and hydrogen energy utilization have become one of the important directions for clean energy transformation and new economic growth point. This paper proposes a renewable energy/hydrogen energy system based on flexible DC interconnection and its coordinated control technology covering AC/DC voltage source converters and photovoltaic units, DC hydrogen production loads and energy storage devices. First, the typical structure of the renewable energy/ hydrogen energy system with low-voltage flexible DC interconnection is proposed, and the local control strategy of each unit is analysed, including the constant DC voltage control strategy and the constant active power control strategy. Then, coordinated control methods of renewable energy/hydrogen energy under different system operation states are proposed. Finally, a corresponding system simulation model and test platform are built, and then used to simulate and verify the proposed coordinated control method.

Deformation Failure and Support Test of Surrounding Rock in Deep Arched Roadway with Straight Wall

The deformation and failure of the uphill roadway on the 3rd horizontal track in the No. 6 Mine of Pingdingshan Coal Group was taken as the engineering background. The similar simulation material of the roadway surrounding rock with quartz sand as the aggregate, cement as the cementing agent, and gypsum powder as the regulator was selected. Through mechanical tests on 25 sets of specimens with different proportions, the best proportion of similar simulated materials for simulating the deformation and failure of the surrounding rock of the roadway was obtained. Later, a large-scale deep mine roadway simulation test system independently developed by the company was used to carry out the roadway deformation and failure test. First, load the test body to the set initial stress state, and then carry out the full-face excavation and unloading of the roadway; finally, load it in the vertical direction until the roadway wall is damaged. It can realize the actual effect of simulation of roadway deformation and failure under the path of “high stress + internal unloading + stress adjustment.” The results showed that after the deep roadway is excavated with preload and high stress, the surrounding rock deformation, failure, and instability of the roadway mainly experience 3 periods: the first period is the period of uniform deformation of the roadway surrounding rock, the second period is the development period of the roadway surrounding rock slab structure, and the third period is the period of instability of the roadway surrounding rock slab structure. Combined with the time period of deformation and failure of the surrounding rock of the roadway, the damage scope of the surrounding rock and the actual situation of the site engineering. A step-by-step combined roadway repair and support plan of “bolt mesh + shotcrete + full-face hollow grouting anchor cable” with hollow grouting anchor cable as the core was determined. The stability of the repaired roadway has been significantly improved, ensuring the long-term use of the roadway.

Physical Simulation Test on Temperature Field Distribution of Artificial Vertical Straight Multirow Freezing Inclined Shaft

This study investigated the temperature field distribution of a freezing inclined shaft. Thus, a three-dimensional physical simulation test system was developed, and the system consists of six parts, which are simulation box and shaft model, loading system, freezing system, external environment simulation system, and data acquisition system. From the results of physical and mechanical property test of artificially frozen sand, in the range of 25°C to -20°C, the heat capacity of sand decreases first, then increases, decreases, and finally tends to be stable; the thermal conductivity of sand gradually increases and finally becomes stable; and the cohesion, internal friction angle, uniaxial compressive strength, and elastic modulus of artificially frozen sand all increase as the freezing temperature decreases. The three-dimensional physical simulation test and field measurement showed that the distance from the freezing pipe is the main factor affecting freezing wall temperature, and the closer to the freezing pipe, the faster the cooling rates. Comparison of theoretical calculation results and field measurement results shows that the calculation formula of freezing wall temperature with time of the inclined shaft can reflect the general law of freezing wall temperature cooling. Therefore, the 3D physical simulation test system is reliable and the test method is feasible.

Upper and lower adjacent segment range of motion after fixation of different lumbar spine segments in the goat: an in vitro experiment.

ObjectivesThe purpose of this study was to examine the biomechanical effects of fixation on range of motion (ROM) in the upper and lower adjacent segments of different lumbar spine segments in a goat spine model.MethodsFifteen goat spine specimens (vertebrae T12–S1) were randomly divided into three groups: A (single-segment fixation), B (double-segment fixation), and C (triple-segment fixation). Motion in different directions was tested using a spinal motion simulation test system with five external loading forces. Transverse, forward–backward, and vertical displacement of the upper and lower adjacent segments were measured.ResultsAs the external load increased, the upper and lower adjacent segment ROM increased. A significantly greater ROM in group C compared with group A was found when the applied external force was greater than 75 N. The upper adjacent segment showed a significantly greater ROM than the lower adjacent segment ROM within each group.ConclusionsAdjacent segment ROM increased with an increasing number of fixed lumbar segments. The upper adjacent segment ROM was greater than that of the lower adjacent segments. Adjacent segment stability after lumbar internal fixation worsened with an increasing number of fixed segments.

Physical Model Test of Artificial Freezing-Inclined Shaft

Based on the vertical straight artificial freezing engineering in Northern Shaanxi, a three-dimensional (3D) physical simulation test system was developed, consisting of six parts, which are simulation box, shaft model, loading system, freezing system, external environment simulation system, and data acquisition system. The physical model and actual test results show that the 3D physical simulation test system is reasonable and reliable. The test model results show that the distance from the freezing pipe significantly affects the freezing wall temperature. For the case of four adjacent, two adjacent tangential freezing, and two adjacent axial freezing pipes, the cooling rates were 1.37, 2.79, and 1.96°C/h, respectively. The field measurement showed that the proximity to the freezing pipe increases the cooling rates. The cooling rates of points 1k#, 2k#, and 3k# were 25.61, 25.32, and 25.35 mm/d, respectively. The increment rates of vertical and horizontal freezing pressures with temperature were 8.78 and 2.97 kPa/°C, respectively. Furthermore, the freezing pressure time fitting formula was given. The calculated results of temperature and freezing pressure are consistent with the measured results, indicating the reasonability and reliability of the 3D physical simulation test scheme of the artificial freezing-inclined shaft in this work.

Dynamic safety measurement-control technology for intelligent connected vehicles based on digital twin system

As the number of connected vehicles increases, the intelligence levels become more and more uneven, so the problem how to determine the dynamic safety of autonomous driving behavior in the mixed-flow traffic system is significantly increased. To solve many difficult problems related to human-vehicle-road perception, decision, control coordination, and reliability evaluation in the intelligent networked scenario, this study establishes a dynamic Game model with multi-source information in the intelligent networked environment, to carry out the measurements and control evaluations for autonomous vehicle dynamics models, forward and backward active safety control, and mixed traffic trajectory optimization planning based on the optimal solution strategy. A digital twin test verification platform with semi-physical environment and hardware-in-the-loop (HIL) simulation to control the accuracy for making dynamic safety decision for the intelligent networked vehicle is developed by combining with the V2X real intelligent transportation system and smart laboratory virtual simulation test technology, which realizes the complex and dynamic safety decision goals for autonomous vehicle in different connected levels of the mixed-flow traffic environments, such as multi-agent perception, multi-source information transmission, vehicle control, vehicle-to-vehicle communication, and vehicle-to-road coordination. The study is conducive to improving the test efficiency and index evaluation integrity of the intelligent networked system, reducing the test costs, proving the behaviors of Game interaction and stress safety response under vehicle-to-road environment, enhancing the robustness and applicability of automatic driving technology, and improving the traffic efficiency and safety of mixed-flow traffic in the intelligent network.

Methods of clutter modeling for development testing of hydroacoustic systems

The paper considers an approach to the construction of a clutter model used in software of the technological part of the test bench for simulation and development testing of hydroacoustic systems. Simulation of clutter on antenna arrays is a rather complex independent task important from the point of view of ensuring the correct SNR for the simulated noise sources at the antenna input. The existing methods of clutter simulation are presented and a new approach is proposed that eliminates the existing drawbacks while maintaining high performance.

Research on Simulation Experiment of Underwater Cluster Multi-source Information Fusion

Intelligent cluster information fusion technology is one of the key technologies to solve systematic cooperative operations in underwater manned and unmanned cooperative operations clusters. In this study, aiming at the multi-node hybrid multi-level hierarchical information fusion architecture and global optimization association algorithm based on cluster formation detection, the test scheme and evaluation method of multi-level information fusion are proposed, and the cluster information fusion simulation test system including sonar system, simulation deduction and evaluation system and multi-source information fusion system is constructed. For the first time, the system comprehensively verified the ability of multi-platform from orientation to positioning in the grouping of fusion algorithm, and proved the correctness and effectiveness of the fusion algorithm, which could greatly improve the accuracy of orientation and distance, and formed a highly credible simulation test evaluation ability. The system is extensible at the same time, and can also be applied to other simulation experiments.

A Phasor Estimation Algorithm Robust to Decaying DC Component

Phasor measurement is widely used in fault detection and localization of power systems. To improve the phasor measurement accuracy when the fault signal contains the decaying dc component (DDC), this article proposes a half-cycle DFT (HCDFT)-based phasor estimation algorithm. The error caused by DDC is estimated and removed from the phasor estimate by combining multiple HCDFT results that are computed using both the conventional basis vector and its corresponding complex conjugate. Both the numerical tests and the IEEE 39-bus system simulation tests are implemented to evaluate the performance of the proposed algorithm in comparison with four related phasor estimation algorithms. Test results show that the proposed algorithm can achieve accurate phasor estimation in the presence of DDC of a wide range of time constants under the interference of harmonics and noise. Moreover, the proposed algorithm is computationally efficient and its performance is independent of sampling rate. These merits make the proposed algorithm suitable to be applied in measurement and protection devices in real power systems.

Dynamic Behavior Analysis of Hose Operation in Deep-Sea Lift Mine

Based on the simulation test system of deep-sea mining hose transportation, the variation characteristics of the hose stress, strain and dynamic frequency are analyzed when the collector is in different positions under the condition of a certain hose length. It provides a reference for the design of hose in deep-sea mining system. The results show that the safety of the single arch structure is better than that of the Double Arch structure, the vibration displacement and stress of the hose increase with the increase of the working range of the dust collector, and the optimum working range of the dust collector is 30-60 m.

Research of a High Thermal-noise Test System Based on Progressive Wave Sound Field

Basing on the existing situation of the thermal source, this paper designed a thermal noise load simulation test system which can make the 1200 mm×1200 mm large panel structure meet the requirement of 165 dB (GJB 150.17 A - 2009) and 1200 °C. This paper introduced the overall design and the design method of the key components. In this paper, the acoustic field uniformity of progressive wave and the acoustic field distribution at the surface of the specimen under high temperature are analyzed by means of numerical simulation. Finally, the developed system was verified by using 1200 mm×1200 mm wallboard structure which led to a stable and good effect.