Ground Simulation Experiments Research Articles

Research on the underground ignition mechanism of ignition fuel and ground simulation experiments

Abstract In the increasingly severe environment of the “dual carbon” situation and the urgent objective demand for national energy transformation and upgrading, the development and use of clean energy have become a new research field and direction. Underground coal gasification technology (UCG) is a clean coal technology that completely bypasses the traditional coal combustion process by converting coal underground into gas and then classifying and recycling it. This method removes sulfur before fuel combustion Nitrogen compounds and particles make it clean like natural gas. The most commonly used ignition method in this technology is chemical ignition. A certain proportion of ignition fuel and main fuel is injected into the underground through pipelines, and then combustion supporting gas is introduced to cause a chemical reaction and generate an open flame to ignite the coal. However, due to the complex internal environment of the pipeline, uneven bending of the pipeline column, and the length of the pipeline exceeding one kilometer, the concentration threshold of the ignition fuel when it reaches the underground igniter cannot be accurately controlled, resulting in ignition failure. In response to the above difficulties, this article has conducted research on the ignition mechanism of ignition fuel, and developed a dedicated ground simulation test bench to conduct ground simulation experiments. The research has strong support for the on-site pilot testing and engineering services of underground coal gasification technology.

Continuous charge management scheme for TianQin

TianQin is a proposed Chinese space-borne gravitational wave detection mission, which will consist of three earth-orbiting spacecraft in equilateral triangle constellation. Due to the ‘3 months on + 3 months off’ observation scheme, the continuous scientific observation period of TianQin is much shorter than LISA, it is highly preferred that other on-board operations, such as charge management, will not interrupt gravitational wave detection. This paper presents a torsion pendulum system on the ground to investigate the continuous discharge method in detail. It is found that the difference in surface characteristics between the test mass and the surrounding housing is the most critical to the success of continuous discharge method. Consequently, the effect of this difference on the continuous discharge process was evaluated in ground simulation experiments, and based on the research results, we also proposed a more feasible spatial continuous charge management strategy for TianQin.

Automatic Cutting Speed Control System of Boom-Type Roadheader Based on Geological Strength Index

The boom-type roadheader is the foremost mining equipment in coal mines. At present, the automatic cutting technology is still immature for adjusting cutting speed automatically in accordance with rock strength, resulting in energy dissipation. In this study, we put forward a method with respect to detecting the geological strength index of coal seam profile through visual inspection, as well as characterize the geological strength index and control the cutting head for adjusting speed automatically based on inspecting fracture features on coal rock’s surface, aiming at achieving energy conservation control of boom-type roadheader. The image processing algorithm is adopted for detecting joint characteristics of palisades fracture, and a quantitative model of the geological strength index is established. The fractal dimension is used to obtain the distribution of geological strength indicators of a coal seam, and the heading machine’s cutting head is controlled for adjusting speed automatically. A vision control platform of boom-type roadheader is built in the laboratory to perform ground simulation experiments. According to experimental results, the difference between the geological strength index of the coal seam detected through visual inspection and the set value in the geological strength index chart is up to 3.5%, and the results are basically consistent, so the quantification of geological strength index can be performed rapidly and effectively. The average energy consumption of boom-type roadheader decreases by 5.4% after adopting self-adaptation control, realizing energy conservation and consumption reduction as well as intelligent control of coal mine machinery.

Space Exposure of Amino Acids and Their Precursors during the Tanpopo Mission.

Amino acids have been detected in extraterrestrial bodies such as carbonaceous chondrites (CCs), which suggests that extraterrestrial organics could be the source of the first life on Earth, and interplanetary dust particles (IDPs) or micrometeorites (MMs) are promising carriers of extraterrestrial organic carbon. Some amino acids found in CCs are amino acid precursors, but these have not been well characterized. The Tanpopo mission was conducted in Earth orbit from 2015 to 2019, and the stability of glycine (Gly), hydantoin (Hyd), isovaline (Ival), 5-ethyl-5-methylhydantoin (EMHyd), and complex organics formed by proton irradiation from CO, NH3, and H2O (CAW) in space were analyzed by high-performance liquid chromatography and/or gas chromatography/mass spectrometry. The target substances showed a logarithmic decomposition over 1-3 years upon space exposure. Recoveries of Gly and CAW were higher than those of Hyd, Ival, and EMHyd. Ground simulation experiments showed different results: Hyd was more stable than Gly. Solar ultraviolet light was fatal to all organics, and they required protection when carried by IDPs/MMs. Thus, complex amino acid precursors (such as CAW) were possibly more robust than simple precursors during transportation to primitive Earth. The Tanpopo 2 mission is currently being conducted to expose organics to more probable space conditions.

The effects of combined environmental factors on the intestinal flora of mice based on ground simulation experiments

The composition and function of intestinal microbial communities are important for human health. However, these intestinal floras are sensitive to changes in the environment. Adverse changes to intestinal flora can affect the health of astronauts, resulting in difficulties in implementing space missions. We randomly divided mice into three groups and placed each group in either a normal environment, simulated microgravity environment or a combined effects environment, which included simulated microgravity, low pressure and noise. Fecal samples of the mice were collected for follow-up analysis based on metagenomics technology. With the influence of different space environmental factors, the species composition at the phylum and genus levels were significantly affected by the combined effects environment, especially the abundance of the Firmicutes and Bacteroidetes. Furthermore, screening was conducted to identify biomarkers that could be regarded as environmental markers. And there have also been some noticeable changes in the function of intestinal floras. Moreover, the abundance of antibiotic resistance genes (ARGs) was also found to be changed under different environmental conditions, such as bacitracin and vancomycin. The combined effects environment could significantly affect the species composition, function, and the expression of ARGs of intestinal flora of mice which may provide a theoretical basis for space medical supervision and healthcare.

Experiments on Simulation Microgravity of Composite Deployable Antenna

After the satellite is launched into a special orbit in space, its space environment is zero gravity or microgravity. Therefore, in ground simulation experiments, it is necessary to consider overcoming the gravity of the earth and try to reduce or eliminate the influence of gravity. In this paper, the method of counteracting gravity by air-floating platform is used to simulate the space microgravity environment, and to do the unfolding experiments for single deployable antenna. After the deployment of the single antenna, the connection structure of single antenna is tested by modal experiment. The microgravity simulation experiment shows that the shape memory hinge can normally satisfy the folding and unfolding of a single antenna. The whole unfolding process is smooth and there is no obvious vibration. The first six modes and natural frequencies are obtained and compared with the simulation results. The comparison shows that the experimental results are in agreement with the simulation results.

A novel space target-tracking method based on generalized Gaussian distribution for on-orbit maintenance robot in Tiangong-2 space laboratory

Accurate target tracking based on visual images is the key for intelligent robots to assist or replace astronauts to work in space station. However, the special space environment such as non-uniform illumination and high-energy particle radiation is a huge challenge, which may lead to complex noise coupling in vision image. This paper proposes a novel method for accurate target tracking, the essence of which is the Retinex image enhancement algorithm in CIELAB color space (LAB-GRetinex) and the generalized maximum correntropy Kalman filter (GMCKF) which are all based on generalized Gaussian distribution. The LAB-GRetinex algorithm chooses the CIELAB color space, which is closer to the human vision, as the processing color space, and the generalized Gaussian distribution can estimate the light image accurately, so the influence of non-uniform illumination can be reduced effectively. Meanwhile, the GMCKF algorithm adopts the generalized correntropy criterion based on the generalized Gaussian distribution to replace the minimum mean square error (MMSE) criterion to realize the optimal filtering effect under the complex non-Gaussian noise, which can improve the target tracking accuracy. Sufficient ground simulation experiments and application experiments in the Tiangong-2 space laboratory verify the effectiveness of the proposed algorithm which can track the target accurately in the special space environment and provide the precise pose information for on-orbit robot maintenance verification. This research lays a technical foundation for the application of intelligent robot in the construction and operation on space station in the future.

Simulations on the electron dynamics in excitation of whistler mode waves with Dipole Research EXperiment (DREX) parameters

Chorus waves are widely investigated in space physics due to their significant role played in the radiation belts. Multiple structures of chorus frequency chirping elements, such as rising-tone structure, falling-tone structure, and hook-like structure, are observed in both space plasmas and the ground simulation experiments. In this paper, the numerical simulation on the generation of descending elements of chorus waves with parameters of a launching device, Dipole Research EXperiment, is conducted by a hybrid code named DAWN. The descending element of chorus waves is self-consistently generated without additional requirements except for a hot electron component as the free energy source. A case of ascending element under the magnetosphere parameters is also carried out to verify our simulations. Phase space distributions of electrons for the two chirping structures are analyzed, and the simulation results are consistent with previous theoretical predictions. It is obtained from the simulation results that the ascending element of chorus is observed together with an electron phase space hole (a depleted distribution function), while the descending elemet is observed together with an electron phase space clump.

Phase characteristic and information transmission of laser signals through plasma in shock tube

Laser communication is a promising way of achieving effective communication during reentry. This paper focuses on the phase characteristics and information transmission of laser signals in plasma sheaths. First, propagation of the laser signals through the sheaths is analyzed theoretically. Next, phase characteristics of the periodic laser signals are studied by ground simulation experiments in shock tube. Further, experiments of the pseudorandom amplitude and phase modulated signals are conducted. Finally, information transmission is tested. This paper is the basic research of laser transmission characteristics in plasma sheaths and has experimentally realized successful information transmission in the plasma generated by shock tube. The results could provide reference for the future ground and flight experiments.

GF-5 VIMI On-Orbit Calibration Instrument and Performance

The Visible and Infrared Multispectral Imager (VIMI) is one of the main payloads of the GF-5 satellite. It has 12 spectral bands covering the wavelength from visible light to thermal infrared. The imager designed life is 8 years. In order to monitor and correct the radiometric performance of the imager for a long time and meet the user’s demand for the quantitative remote sensing application, the expandable diffuser used for calibration in full FOV and full optical path method is designed. The solar diffuser is installed on the front side of the optical system and does not affect the normal imaging of VIMI. When VIMI need calibration, the diffuser is expand to the front of optical system via the driving mechanism. According to the characteristics of the GF-5 satellite orbit, the requirement of the calibration energy and the installation matrix of the imager relative to the satellite, the expansion angle of the diffuser is 39 degrees. The 430 mm × 430 mm large-size PTEE diffuser is manufactured to ensure full FOV and full optical path calibration. The diffuser’s directional hemispherical reflectance is higher than 95% from 420 nm to 2400 nm and variation of BRDF in the direction of imager observation is better than 2.5%. The diffuser stability monitoring radiometer is designed to monitor the on-orbit attenuation performance of the diffuser. Results of ground simulation experiments and preliminary on-board calibration experiments were introduced.

High velocity impact characteristics of MWNT added CFRP at LEO space environment

In this paper, multi-wall carbon nanotube (MWNT) added carbon fiber reinforced plastics (CFRP) composites are suggested as solutions to improve the impact energy absorbing capability of CFRP for spacecraft application because it was proven that the resistance against LEO environment and the quasi-static material properties of CFRP can be improved by adding MWNT in previous papers. To verify the effect of MWNT on the impact energy absorbing capability of composite materials, normal CFRP and MWNT-reinforced CFRP were prepared and tested by using a two-stage light gas gun that can accelerate an aluminum ball of a diameter of 5.56 mm to 1 km/s. And the applicability of MWNT against hypervelocity impact of space debris was studied. In addition, accelerated ground simulation experiments were performed for each material model to simulate the aging of composite materials to verify the effect of LEO environmental aging on impact absorbing capability of composites. For the aging experiment, the impact specimens were simultaneously exposed to high vacuum, atomic oxygen, ultra violet light, and thermal cycling. After being exposed to simulated LEO environment, high velocity impact tests were performed for each material. As a result, MWNT did not have a significant improvement on the impact energy absorbing capability of CFRP under high velocity impact, even though the quasi static material properties are improved by adding MWNT. This is caused by the early generation of fiber breakages on the impact surface before enough generation of progressive failure which is one of the impact energy absorbing mechanism. Similarly, MWNT has less effect on the impact energy absorbing capability of CFRP under LEO environment.

Shifts in metabolism and its regulation under the effect of spaceflight factors

The review deals with the results of studying the adaptive changes in metabolism and its neuroendocrine regulation in humans and animals under the effect of spaceflight factors and ground-based simulation of the gravitational unloading. The majority of the investigations were concerned with the water-electrolyte and mineral turnover, as well as protein, lipid and carbohydrates metabolism. Biochemical measurements of the body liquids (blood, urine and saliva) before, in and after space flight or in ground simulation experiments were used as indictors of the status of sympathoadrenal, hypothalamo-pituitary-adrenal and other systems involved in systemic regulation of metabolism, and also strength of stress-reaction to adversities. The authors generalized data on the interrelation and interaction of the neuroendocrine and psychophysiological status both in the real and simulated conditions of space flight.

基于大气实时修正的飞机辐射特性测量

The measuring method for dynamic radiation characteristics of a flying airplane is researched. As traditional atmospheric correction method by calculating the atmospheric transmittance and path radiation with software has poor correction precision, this paper proposes a new radiation measurement method to measure the atmoshperic transmittance in real time. The method uses a blackbody carried by the target airplane to measure the atmoshperic transmittance in real time and takes the real-time measured data to correct the target airplane radiation and to improve the radiation measurement precision. Ground simulation experiments for an airplane infrared radiation measurement are performed by means of a midwave (MW) infrared camera, a longwave (LW) infrared camera, two extended-area blackbodies, and a piece of ZnSe. The MODTRAN calculated, CART calculated, and the real-time measured atmospheric transmittances are used to correct the inverted blackbody target radiation. The obtained results show that the target radiation measurement precision by the proposed real-time measured atmospheric transmittance has improved by above 100% as compared with those of MODTRAN and CART calculated.

What can we learn from the toughest animals of the Earth? Water bears (tardigrades) as multicellular model organisms in order to perform scientific preparations for lunar exploration

Space missions of long duration required a series of preliminary experiments on living organisms, validated by a substantial phase of ground simulation experiments, in the field of micro- and inter-mediate gravities, radiobiology, and, for planetary explorations, related to risks deriving from regolith and dust exposure. In this review, we present the tardigrades, whose characteristics that recommend them as an emerging model for space biology. They are microscopic animals but are characterized by a complex structural organization similar to that of larger animals; they can be cultured in lab in small facilities, having small size; they are able to produce clonal lineages by means of parthenogenesis; they can completely suspend their metabolism when entering in dormant states (anhydrobiosis induced by dehydration and cryobiosis induced by freezing); desiccated anhydrobiotic tardigrades are able to withstand chemical and physical extremes, but a large tolerance is showed also by active animals; they can be stored in dry state for many years without loss of viability. Tardigrades have already been exposed to space stressors on Low Earth Orbit several times. The relevance of ground-based and space studies on tardigrades rests on the presumption that results could suggest strategies to protect organisms, also humans, when exposed to the space and lunar environments.

Efficacy of oxygen-supplying capacity of Azolla in a controlled life support system

Azolla shows high growth and propagation rates, strong photosynthetic O 2-releasing ability and high nutritional value. It is suitable as a salad vegetable and can be cultured on a multi-layered wet bed. Hence, it possesses potential as a fresh vegetable, and to release O 2 and absorb CO 2 in a Controlled Ecological Life Support System in space. In this study, we investigated the O 2-providing characteristics of Azolla in a closed chamber under manned, controlled conditions to lay a foundation for use of Azolla as a biological component in ground simulation experiments for space applications. A closed test chamber, representing a Controlled Ecological Life Support System including an Azolla wet-culture device, was built to measure the changes in atmospheric O 2 and CO 2 concentrations inside the chamber in the presence of coexisting Azolla, fish and men. The amount of O 2 consumed by fish was 0.0805–0.0831 L kg −1 h −1 and the level of CO 2 emission was 0.0705–0.0736 L kg −1 h −1; O 2 consumption by the two trial volunteers was 19.71 L h −1 and the volume of respiration-released CO 2 was 18.90 L h −1. Under 7000–8000 Lx artificial light and Azolla wet-culture conditions, human and fish respiration and Azolla photosynthesis were complementary, thus the atmospheric O 2 and CO 2 concentrations inside chamber were maintained in equilibrium. The increase in atmospheric CO 2 concentration in the closed chamber enhanced the net photosynthesis efficiency of the Azolla colony. This study showed that Azolla has strong photosynthetic O 2-releasing ability, which equilibrates the O 2 and CO 2 concentrations inside the chamber in favor of human survival and verifies the potential of Azolla for space applications.

Improvement of tensile properties of CFRP composites under LEO space environment by applying MWNTs and thin-ply

Multi-wall carbon nanotube (MWNT) added carbon fiber reinforced plastics (CFRP) and thin-ply composites are suggested as solutions to improve resistance against low earth orbit (LEO) environment and mechanical properties. Accelerated ground simulation experiments were performed for CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP. The used ground simulation facility can simulate high vacuum, atomic oxygen, ultraviolet (UV) light and thermal cycling simultaneously. The aging experiment was performed for 20 h. After the aging experiment, total mass loss (TML) and tensile properties were measured. As a result, by applying thin-ply thickness and MWNT fillers, the tensile strength was improved at ground conditions. Under an LEO space environment, while thin-ply composites cannot relieve the degradation rate, the composites with MWNT can do so. Highly improved tensile strength was observed by simultaneously applying the thin-ply techniques and MWNT under both LEO aged and LEO non-aged conditions.

Assessing single-event-upsets in SRAM based on TCAD and Geant 4

基于Geant4和TCAD (Technology-Computer Aided-Design)建立了一套评估静态存储器(SRAM)单粒子效应的方法. 该方法利用TCAD软件模拟半导体存储单元对粒子能量沉积的响应, 获得SRAM的重离子单粒子翻转截面, 并应用蒙特卡罗工具包Geant 4计算质子与硅材料的核反应以及次级粒子在灵敏体积内的能量沉积, 进而获得质子的单粒子翻转率. 利用该方法, 计算了TSMC 0.18 μm未加固SRAM的重离子和质子翻转率, 通过与同工艺SRAM的重离子实验结果进行比较, 初步验证了该方法的有效性. 该方法不依赖于地面模拟实验, 可以用来评估处于设计阶段的抗辐射加固器件.

Damage effect of keV proton irradiation on aluminized Kapton film

Damage effects of proton irradiation on aluminized Kapton films were investigated through ground simulation experiments, in which the energy of protons was 90 keV and the flux was 5.0×10 11 cm −2 s −1. Changes in surface morphology, optical properties, microhardness and microstructure of Kapton/Al were analyzed. The experimental results show that proton irradiation results in the increase of surface roughness and microhardness, and the degradation of the reflective property in the 500–1200 nm range. Raman spectra and XPS analysis demonstrate that changes in chemical structure occurred during irradiation, including the bond breaking of the part of the carbonyl and aromatic ether, ring opening reaction of cyclic imide, and the formation of some new bonds and structure.

Radiation effect of keV protons on optical properties of aluminized Kapton film

Effects of proton radiation on aluminized Kapton films were investigated through ground simulation experiments, in which the energy of protons was 90 keV and the flux was 5.0×10 11 cm −2 s −1. Changes in optical properties and microstructure were analyzed by using UV/VIS and FTIR spectroscopic techniques. It is shown that proton radiation results in the degradation of the reflective property in the 500–1200 nm range due to the formation of new chromophores and auxochromes during irradiation. The optical energy gap E g of the irradiated Kapton film, which establishes the relationship between microstructure and optical property, was obtained from Tauc's plots.

Experimental studies of single-event effects induced by heavy ions

This paper presents the results of ground-based heavy ion test of single-event effect (SEE) vulnerability on microcircuits used in space. We observed the dependence of upset cross-sections on the incident angle of ions in Intel 8086 CPU. SEU cross-sections of various SRAMs did not depend on the stored pattern, but 0→1 and 1→0 transitions were completely different for different manufacturer products. Some SEE protection methods were verified in conditions of ground simulation experiments.