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"Environment simulation"
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Space environment simulation and analyses for the DAMPE mission
DAMPE was sent into space orbit for nearly nine years. Since its expected lifespan is only three years, DAMPE has surpassed its expected lifespan by almost six years. Due to its long stay in orbit, some of its components have met with such puzzles as the capabilities of the equipment are partially degrading. The effects of the space environment are responsible for some of its degradation. So, the knowledge of the space environment in the coming year is vital for DAMPE operation. We focus on the following factors: 1) electrons and protons trapped in Earth’s radiation belts; 2) solar proton effect; 3) cosmic ray effect; 4) atom oxygen distribution. Based on the powerful analytic software SPENVIS, some typical effects of space environments are simulated and analyzed respectively, providing supportive constraints when the task team of DAMPE decides when to lengthen the lifespan, or when to start the reentry to Earth’s atmosphere.
Journal Article
Multi-modal remote perception learning for object sensory data
When it comes to interpreting visual input, intelligent systems make use of contextual scene learning, which significantly improves both resilience and context awareness. The management of enormous amounts of data is a driving force behind the growing interest in computational frameworks, particularly in the context of autonomous cars.
The purpose of this study is to introduce a novel approach known as Deep Fused Networks (DFN), which improves contextual scene comprehension by merging multi-object detection and semantic analysis.
To enhance accuracy and comprehension in complex situations, DFN makes use of a combination of deep learning and fusion techniques. With a minimum gain of 6.4% in accuracy for the SUN-RGB-D dataset and 3.6% for the NYU-Dv2 dataset.
Findings demonstrate considerable enhancements in object detection and semantic analysis when compared to the methodologies that are currently being utilized.
Journal Article
Design and construction of the near-earth space plasma simulation system of the Space Plasma Environment Research Facility
Our earth is immersed in the near-earth space plasma environment, which plays a vital role in protecting our planet against the solar-wind impact and influencing space activities. It is significant to investigate the physical processes dominating the environment, for deepening our scientific understanding of it and improving the ability to forecast the space weather. As a crucial part of the National Major Scientific and Technological Infrastructure–Space Environment Simulation Research Infrastructure (SESRI) in Harbin, the Space Plasma Environment Research Facility (SPERF) builds a system to replicate the near-earth space plasma environment in the laboratory. The system aims to simulate the three-dimensional (3-D) structure and processes of the terrestrial magnetosphere for the first time in the world, providing a unique platform to reveal the physics of the 3-D asymmetric magnetic reconnection relevant to the earth's magnetopause, wave–particle interaction in the earth's radiation belt, particles’ dynamics during the geomagnetic storm, etc. The paper will present the engineering design and construction of the near-earth space plasma simulation system of the SPERF, with a focus on the critical technologies that have been resolved to achieve the scientific goals. Meanwhile, the possible physical issues that can be studied based on the apparatus are sketched briefly. The earth-based system is of great value in understanding the space plasma environment and supporting space exploration.
Journal Article
Research on leakage detection method of vacuum chamber flange in space environment simulation system under atmospheric pressure
To address the issue of the irreversible process once a leakage is detected in the vacuum chamber flange of the current spacecraft space environment simulation system after the rough pumping stage, this paper researches the leakage detection method of vacuum chamber flange under atmospheric pressure, that is, without pressure difference between inside and outside the chamber. Based on the principle of sound generation due to pressure difference at the leakage hole, an ultrasonic leakage detection system under atmospheric pressure is established. The detection capability for leakages caused by different-sized materials is studied, and millimeter-diameter steel wire inclusions are successfully detected. Combined with the helium mass spectrometry leakage detection method and limit leakage rate test method, the critical sound pressure level that affects the vacuum degree of the chamber is given to achieve early discovery, intervention, and elimination of chamber leakage failures.
Journal Article
Temperature Field Distribution Testing and Improvement of Near Space Environment Simulation Test System for Unmanned Aerial Vehicles
Temperature distribution inside the vacuum chamber of the TRX 2000(A) near space environment simulation test system (NSESTS) was investigated through both experimentation and computational fluid dynamics simulation. Comparison between the experimental result and the simulation result showed that these two results were very close to each other, validating the feasibility of using the simulation method to study the temperature distribution inside the NSESTS. Then, the effect of wind, either downwind or upwind, on temperature uniformity inside the NSESTS was investigated through the simulation method. The simulation result showed that the non-uniformity coefficient will be reduced from 0.2757 to 0.2012 (by 27.1%) in the case of downwind and to 0.2055 (by 25.5%) in the case of upwind. Then, the simulation result was validated by experiment. The result of this research indicates that the temperature uniformity can be greatly improved through installment of additional fans inside the NSESTS.
Journal Article
Space environment simulation for LEO spacecrafts devoted to a multimedia constellation
A constellation consisting of more than one thousand LEO satellites has been proposed in China in recent years. The purpose of this constellation is to provide an effective solution for space-based multimedia networks all over the world. The operational orbit is roughly defined as follows. Altitude is about one thousand kilometers, the inclination is about 90 degrees, and tens of orbit planes are designed for satellites to deploy in space. The space environment for satellites in such orbit altitude is particularly focused on to carry out such a huge space engineering successfully. Herein, such radiation causes as the Earth radiation belt, solar proton, and cosmic ray are considered. Based on internationally advanced space environment assessment software, SPENVIS, with the novelty of a multimedia network deployed at 1000 km altitude, the practical constraints to be suitable for tough space environment situations are simulated. Based on radiation simulations, it has shown that if the 7-year lifespan for LEO satellites is concerned, there is about 50.4 krad radiation dosage after 3mm Aluminium shielding; there is about 20.9 krad dosage with 6mm Aluminium shielding; and there is about 16.5 krad dosage with 9mm Aluminium shielding. Considering the design margin for radiation dosage, for 7-year lifespan satellites, the anti-total dose capacity is about 50.4×2 krad total dose with 3 mm Aluminium shielding; there is about 20.9×2 krad dosage with 6 mm Aluminium shielding; and there is about 16.5×2 krad total dose with 9 mm Aluminium shielding. If only the above space environment requirements are met, the proposed multimedia constellation would be in operation safe and sound in space during the lifespan of the satellites in question.
Journal Article
Fixed-Time Active Disturbance Rejection Temperature–Pressure Decoupling Control for a High-Flow Air Intake System
High-flow aeroengine transient tests involve strong coupling and external disturbances, which pose significant challenges for intake environment simulation systems (IESSs). This study proposes a compound control scheme that combines fixed-time active disturbance rejection with static decoupling methods. The scheme integrates a fixed-time sliding-mode controller (FT-SMC) and a super-twisting fixed-time extended-state observer (ST-FT-ESO). A decoupling transformation separates pressure and temperature dynamics into two independent loops. The observer estimates system states and total disturbances, including residual coupling, while the controller ensures fixed-time convergence. The method is deployed on a real-time programmable logic controller (PLC) and validated through hardware-in-the-loop (HIL) simulations under representative high-flow scenarios. Compared to conventional linear active disturbance rejection decoupling control (LADRDC), the proposed scheme reduces the absolute integral error (AIE) in pressure and temperature tracking by 71.9% and 77.9%, respectively, and reduces the mean-squared error (MSE) by 46.0% and 41.3%. The settling time improves from over 5 s to under 2 s. These results demonstrate improved tracking accuracy, faster convergence, and enhanced robustness against disturbances.
Journal Article
High Performance 18 GHz ECR Ion Sources Development
At present, ECR ion sources are developing towards higher frequency, higher magnetic field technology. However, 18 GHz is the highest optimal operation microwave frequency for room temperature ECR ion sources, which can meet the needs of most of the existing heavy ion facilities. After the success of the 18 GHz ECR ion source LECR4, we developed the upgraded version source LECR5 aiming for higher beam intensity and higher charge state ions. With a higher radial field, bigger plasma chamber volume, longer mirror length, and flexible Bmm field, promising results have been made at the power level of ∼2.1 kW@18 GHz, for instance, 81 eμA Bi 32 +, and 22 eμA Bi 41 +. This ion source has been recently used for the heavy ion facility SESRI (Space Environment Simulation Research Infrastructure) as the pre-injector ion source. High beam intensities and reasonable beam qualities have been demonstrated during the test platform. Inspired by this outcome, a hybrid 18 GHz ion source called HECRAL has been proposed aiming for the similar performance of SECRAL at 18 GHz. This paper will present the recent update of the LECR5 ion source commissioning. The design and preliminary results of the HECRAL ion source will be described.
Journal Article
Optimization of Neighborhood Public Space Design Based on Physical Environment Simulation and Crowd Simulation—A Case Study of Xiaomi’s Changping Campus
Digital technology has brought drastic changes to the design methods, values, and design tools of neighbourhood public spaces, thereby changing the behavioural patterns of people in neighbourhood public spaces. Therefore, people’s requirements for urban public space have changed and are characterised by high efficiency, high precision, humanization, and high aesthetics. Scholars at home and abroad have conducted many studies and practises on the application of digital technology to neighbourhood design, but there is a lack of systematic research practises on the use and analysis of multi-faceted data. This paper selects the Xiaomi Beijing Changping II design project, simulates and deduces the physical environment of its location, simulates the results of the natural environment by using the data of sunshine, wind, and water catchment in the physical environment, and then simulates the crowd’s action paths by combining kinetic algorithms and ant algorithms to optimise the design methods, processes, and results of the neighbourhood public space on the basis of this research. The research team designed five groups of programmes for the project based on different design methods and processes, and conducted a comparative study of the five groups of programmes through the hierarchical analysis method in conjunction with the fuzzy comprehensive evaluation method, as well as discussing them in conjunction with the actual bidding results of the project and the scoring conclusions of the industry experts. The results of the study show that the design scheme for neighbourhood public space based on physical environment simulation and crowd simulation is better able to take advantage of the analytical and predictive advantages of the technology and unite with the designer’s aesthetic interests, balancing the data objectivity and aesthetic subjectivity in the design process. The method is more likely to achieve a design solution that combines systematicity, foresight, rationality, and aesthetics, and provides an empirical case for the application of data simulation in public space, aiming to improve the rationality of public space design and solve the data-objective problems faced by the design of public space at this stage.
Journal Article