Abstract:

Lunar construction （LC） is one of the important future directions of human exploration， utilization， and development of the Moon. This paper reviews the research progress of LC and in-situ resource utilization （ISRU）， focusing on the key basic science issues including what materials to use and how to build. First， the main supporting technologies for ISRU on the lunar surface are summarized， including lunar soil property analysis， lunar soil simulant preparation， and lunar soil in-situ additive manufacturing technologies. Second， the progress of the intelligent construction of the lunar base is introduced， including the development of the lunar base construction scheme， the comparison of in-situ construction technology， and the analysis of the lunar base construction environment. Finally， the key scientific challenges of LC and ISRU are discussed， including resource exploration， scientific site selection， lunar base bearing safety， lunar soil melting and sintering， and space construction schemes.

Abstract:

To select the regions with both high engineering safety and scientific interest for International Lunar Research Station （ILRS） ， this study conducted a thorough analysis using intelligent site selection，evaluation of typical elements， and assessments of rover accessibility across the selected regions. By leveraging the 1D-CNN site selection model，4 candidate landing sites were pinpointed and outlined in the southwestern region of Scott M. Additionally，environmental elements such as real-time illumination，radiation levels，physical temperature variations and presence of water ice were remotely detected and meticulously examined in these selected zones. Furthermore，a traverse planning model with a consideration of the energy consumption was employed to assess the accessibility to water ice from the central points of the candidate landing zones. The results indicate that the candidate landing zones are optimized for both terrain safety and energy supply. The comprehensive approach can also serve as a valuable framework for analyzing the typical environmental patterns in other potential site selection regions，providing a useful reference for ILRS landing site selection and scientific detection.

Abstract:

Lunar water ice is an important target for the International Lunar Research Station (ILRS). Infrared remote sensing serves as a crucial tool for detecting lunar water ice, yet its direct application in the permanently shadowed region (PSR) poses challenges due to the absence of direct sunlight. In this study, we propose a spectral correction method for the PSR based on the sunlight scattering model. Additionally, we have developed a water ice detection methodology based on spectral absorption characteristics.The method was applied to two typical craters, Shackleton and Nobili, situated in the lunar south polar area, successfully unveiling water ice indications in both locations. The outcomes of our investigation are anticipated to offer valuable insights for the forthcoming site selection and establishment of the ILRS.

Abstract:

The morphological characteristics of lunar regolith particles have a significant impact on in-situ excavation， transportation， 3D printing， and other processes on the Moon. The samples obtained independently by China’s Chang’e-5 mission can provide key parameter information for the construction of the lunar research station. This paper focuses on the morphological characteristics of lunar regolith particles that are of concern in the process of in-situ resource utilization on the Moon. Optical microscopy was used to obtain images of the Chang’e-5 lunar regolith particle samples approved by Tongji University， a set of image processing and particle recognition methods were constructed， and a directional difference index was proposed to characterize the roughness of the particle surface. The automatic extraction of particle edges and the calculation of their size and morphological indicators were achieved. The results show that the particle size range of the studied Chang’e-5 samples is 4.36~792.30 μm， with an average aspect ratio of 0.66， an average circularity of 0.806， and an average directional difference index of 0.111. Small particles make up a large proportion， with particles below 10 μm accounting for 44.19%. The directional difference index of the particles is approximately normally distributed， indicating that a large number of particles have similar surface roughness， with a small number of particles having smoother or rougher surfaces. There is a negative correlation between the size and aspect ratio， circularity of small particles， and little correlation with surface roughness. There is no correlation between the size and morphology of large particles. The study also found that the circularity of the particles in the Chang’e -5 samples is smaller and the morphology is more irregular in comparison with the Apollo 11 and Apollo 15 samples.

Abstract:

Lunar is a near-Earth celestial body with great scientific and strategic value. Implementation of manned lunar exploration with the first Chinese landing on an extraterrestrial body will be the significant milestone in building a strong aerospace country. In manned lunar exploration engineering， the special conditions and resources of Lunar can be fully utilized to carry out a series of scientific activities with manned participation， which can contribute to new achievements in lunar science， lunar-based science and utilization of lunar resources. In this paper， the lunar exploration engineering such as Apollo program， Artemis Program and Chang ’e Engineering are analyzed， especially the mission implementation and key achievements with regard to scientific research domain， and the development tendency of scientific mission in manned lunar exploration is summarized. Furthermore， the preliminary implementation suggestions of scientific research in manned lunar exploration are put forward， which involves the lunar samples collection， the scientific exploration of lunar， and the in-situ resources utilization on lunar surface. The analyze of development tendency and the implementation suggestions of scientific research in manned lunar exploration can provide design reference of future missions.

Abstract:

The Mars sample return mission of China will be the Category V “Restricted Earth return” mission， requiring stringent planetary protection measures to prevent cross-contamination between Earth and Mars and to facilitate groundbreaking scientific discoveries. Based on the planetary protection design specification of the TW-3 mission and considering unique characteristics of the mission， this paper introduces systems engineering methodologies to conduct research and requirement analysis of the standardization of planetary protection for the mission. The top-level design of the planetary protection standards system has been carried out， and a framework for the planetary protection standards system of the mission is constructed from both vertical and horizontal dimensions. Additionally， a detailed list of planetary protection standards is formulated. The work supported the systematic construction of the standardization of planetary protection for the mission. The achievements and experience presented in this paper have significant both referential and practical value for enhancing the standardization level of planetary protection for deep space exploration in China.

Abstract:

Joints are the weak parts of segmental precast Bridges. To ensure the positioning and force transmission between segments， steel shear keyed joints are designed. To fully grasp the local shear performance of steel shear keyed joint， the shear mechanism and calculation method of steel shear keyed joint were deeply studied based on the existing experimental research results and theoretical analysis. The results showed that the steel shear keyed joint transmits the shear force between the joint by means of the contact pressure between the steel key and the concrete under the action of confining pressure， and the joint had high shear capacity and good ductility. Combined with the force transfer mechanism of steel shear keyed joint， a mechanical model was constructed， and the shear mechanism and failure mode of steel tenon joint were revealed， including shear failure of steel key、partial compression failure of concrete、tearing failure of concrete. Finally， the paper suggests that the shear failure of steel key should be used as the basis for the resistance design of steel shear keyed joints， and the strength of concrete around the steel key should be checked.

Abstract:

Aiming at increasing engineering practice of compressed-air-assisted method， based on the numerical calculation model of air-water-solid coupling established by Geostudio Air/w， the influence of different shield tunnel top buried depth， thickness of overlying airtightness layer， stratum property and pressure chamber height on the seepage volume of excavation face was discussed. The results show that： The application case of compressed-air-assisted method in a section of Guangzhou Metro Line 21 is analyzed. The seepage gas volume is controlled within 1.2 m³·min^-1. A stable support pressure is established on the excavation surface to ensure that the shield tunneling reaches the micro-disturbance control level. When the earth pressure shield tunneling in silty clay and clay stratum with high airtightness ability， appropriate compressed air can be injected into the pressure chamber to better maintain the stability of the support pressure of the excavation face； To ensure the seepage volume is less than the gas production. When it is difficult to carry out full-cabin excavation in sandy cobble ， upper soft and lower hard stratum with large permeability coefficient and unequal geological distribution， the appropriate empty chamber height can be selected according to the buried depth and the thickness of the overlying airtightness layer. When the earth pressure shield crossing permeable stratum and the thickness of the overlying airtightness layer exceeding 10.0m， or the buried depth exceeding 28.0m， compressed air escape amount is less， and it is not easy to occer roof fall under compressed air.

Abstract:

Based on flume experiment and numerical simulation， wave transformation and wave-induced current characteristics over a series of periodic distribution of single row perforated reef-type breakwater group with different disposal spaces were studied under short period regular incident wave condition. Wave surface and wave height of reef-type breakwaters without disposal space were measured in a short period incident wave. Wave height is significantly reduced due to the wave energy dissipation caused by wave shoaling effect， but the wave still maintains a quasi-symmetrical sinusoidal wave and propagates for-ward due to the large submergence on the breakwaters. Further， a non-reflected numerical wave model was developed using smoothed particle hydrodynamic （SPH） method and verified by experimental data， which was served to simulate the regular wave propagation over reef-type breakwaters with disposal spacing ratio of 0.5~3.0. The results show that reflection coefficients of all scenarios are above 0.75， indicating that disposal spacing between reef-type breakwaters has a large impact on wave reflection. Transmission coefficients generally decrease with disposal spacing between reef-type breakwaters increasing. It is noticeable that when the spacing ratio is 2.5， the wave reaches the same frequency as breakwaters， triggering the Bragg resonance reflection effect and resulting in the wave height on breakwater-top rising sharply， which causes almost the strongest wave reflection and transmission， and the largest upwelling zone with strong turbulence on the first seaward breakwater.

Abstract:

To study the trends and reduction pathways of carbon emissions in the construction industry of the Yangtze River Delta region， this paper establishes a carbon emission model combining random forest and regression analysis. Baseline and emission reduction scenarios for the Yangtze River Delta region are analyzed. The results show that the overall construction industry in the Yangtze River Delta will reach its carbon peak by 2035. Shanghai and Zhejiang can achieve their carbon peak in the construction industry by 2030 without taking additional mitigation measures. By 2060， conventional reduction measures can reduce carbon emissions by 47.84% to 60.99%， with the most significant reduction achieved through "reducing new construction and replacing demolition with renovation，" which can reduce emissions by 13.54% to 18.65%. Integrated policies can further reduce carbon emissions by an additional 2.71% to 18.34% on top of conventional reductions. Under the ideal implementation of various mitigation measures， the construction industry in different areas of the Yangtze River Delta will need to rely on external measures （such as green social electricity） to further reduce emissions by 13.26% to 17.12%， achieving carbon neutrality by 2060. The findings from this study can provide research ideas and a basis for low-carbon development in the construction industry of other integrated regions.

Abstract:

Ramp scenarios with gradual curves challenge the autonomous vehicles because of their irregular curvatures， diverse planar layouts， and multidimensional vehicle conflicts. This paper presents an algorithm based on the coupled "vehicle-road" risk to increase the safety of lane-changing on ramps with gradual curves. The quintic polynomial is adopted to construct a set of candidate lane-changing trajectories. The cost function is developed by risk， efficiency， and comfort indicators. Simulation tests under parallel continue curved and tapered continue curved ramps show that the proposed model improved safety performance by 13.9 % and 12.6 % under the two ramp configurations compared to earlier lane-changing algorithms based on collision detection and rule-based risk evaluation. These results showed the proposed algorithm can be applied to complicated driving scenarios to increase the trajectory safety of autonomous vehicles.

Abstract:

The electromagnetic damping of the superconducting electrodynamic maglev train is low during the operation. With the assistance of the propulsion control of the linear synchronous motor， a levitation stability control system is designed for a technical guarantee for the levitation stability of the train. Taking the superconducting electrodynamic maglev train of the MLX01 as the research object， combined with the field-circuit-motion coupling numerical model composed of a single bogie and ground coils， the levitation characteristics of the superconducting electrodynamic maglev train were revealed. The relationship between superconducting magnetic field strength， levitation displacement， running speed and standard air gap were studied. Analysis was made of the variation law of the electromagnetic spring coefficient in the levitation direction of a single bogie under different superconducting magnetic field strength and standard air gaps. The vector control strategy was adapted to analyze the linear synchronous motor of the superconducting electrodynamic maglev train to realize the decoupling of the components of the direct axis and the quadrature axis， and the numerical expression between the direct axis current and the levitation force was also established. A levitation stability control system was designed， and state feedback is used to realize the pole configuration of the levitation system. The balance displacement response of bogie applied before and after the levitation stability control system were compared， which proved the effectiveness of the levitation control structure. The research results show that the levitation stability control system can effectively resist external disturbances， maintain the levitation stability of the train， and further improve the ride comfort of the train.

Abstract:

Among the various forms of antimony（Sb）， Sb（III） and Sb（V） have higher toxicity and a higher proportion in the composition of antimony in urban soil. This research investigated the effects of factors including extraction instrument， extractants， extraction conditions， and chromatographic separation mobile phase conditions on the extraction and determination， and established a novel extraction-determination method for Sb（III） and Sb（V） in the soil. The highest extracting efficiency was obtained by soaking and oscillating soil samples in citric acid solution at 70℃ first， then separated with dipotassium edetate and phthalic acid as mobile phase by liquid chromatography， and finally measured by inductively coupled plasma mass spectrometry. With the proposed method， low detection limits， good accuracies and precisions for both of Sb（III） and Sb（V） were obtained. It was highly recommended for the effective extraction and determination of antimony speciation in real soil samples.

Abstract:

In order to reflect the rate dependence of mechanical behavior under dynamic loading， based on the elastoplastic damage theory framework， the dynamic damage evolution is expanded from the static model. The damage evolution is delayed due to the rate effect， which leads to the strengthening phenomena. Inspired by the viscoplastic theory， two types of dynamic visco-damage evolution models are established in the damage subspace： Perzyna model and Duvaut-Lions model. The constitutive theories and the numerical results of the two kinds of viscous damage evolution models are compared respectively. In terms of constitutive theory， the two models have different viscous variables. In the simulation results， concrete dynamic behaviors simulated by the linear visco-damage models with Perzyna format and Duvaut-Lions format are nearly consistent. In contrast， those calculated by the nonlinear visco-damage models with Perzyna format and Duvaut-Lions format differ. In addition， the improvement in dynamic strength predicted by both nonlinear models agrees well with test data， indicating that both can reflect the rate sensitivity of concrete material.

Abstract:

Multi-source and multi-ion coupling corrosion is widespread in cast-in-situ structures in sulphate saline soil area. By premixing Mg²⁺， Cl^- and SO₄^2- into mortar and placing it in different corrosive environments， the pore distribution， mass， size and sulfate concentration at different depths， as well as the evolution law of flexural and compressive strength of specimens were measured during corrosion period. The microstructure and mineral composition of specimens were observed by scanning electron microscope-energy dispersive spectroscopy analysis （SEM-EDS）， X-ray diffraction （XRD） and thermogravimetric analysis （TG-DTG）. Results show that internal corrosion increased the content of harmful pores and accelerated the corrosion process. Internal corrosion has a significant adverse effect on the development of flexural strength， the strength of the specimens are reduced by 50%~67% compared with that of the specimens without internal corrosion. Internal Mg²⁺ negatively affects the development of the flexural strength of the specimens in the sulfate environment， the flexural strength of the specimens are only 4.4% of that of the non-corrosive specimens. Mg²⁺ in the periphery of specimens alleviates the increasing trend of harmful pore content and has a certain protective effect on the internal structure.

Abstract:

Addressing the challenge of hydrogen flow control in the on-board proton exchange membrane fuel cell system under variable loads， a control system architecture and method for hydrogen flow load matching based on proportional pressure reducing valve and flow control valve were proposed. The comprehensive model from the hydrogen tank to the fuel cell stack was established. Control strategies for the proportional pressure reducing valve， flow control valve， and hydrogen circulation pump were designed and validated through simulations. The results show that the anode pressure of the stack can promptly track the set pressure with a response time of approximately 2~3 s. The hydrogen flow can adjust to load variations， with the transient overshoot correlating positively with the pressure response speed. In a stable state， the hydrogen utilization rate remains above 95%， the hydrogen excess ratio exceeds 1.27， and the nitrogen content in the supplied gas is below 5%， meeting the stack performance criteria.

Abstract:

The convergence rate of greedy Kaczmarz method can be improved by introducing right preconditioner through orthogonal triangularization of coefficient matrix. However， when the number of rows of the coefficient matrix is much larger than the number of columns， the cost of orthogonal triangularization is too high. By introducing Count Sketch transform， a preconditioning greedy Kaczmarz method based on Count Sketch is proposed to reduce the cost. Convergence analysis of the new algorithm is provided， and the theoretical analysis shows that the new method has better convergence rate than the existing method when the condition number of coefficient matrix is large. The numerical experiments verified the effectiveness.

Abstract:

Recently the central and local governments have strengthened policy efforts to actively cultivate the specialized fined peculiar and innovative mall and medium-sized enterprises （SMEs）and to enhance the competitiveness of small and medium-sized enterprises. Based on a review and analysis of domestic and foreign literature， the influence model of enterprise competitiveness was constructed， and the regression analysis was carried out on the basis of the panel data of 608 SMEs in Shanghai for 6 years. It is found that the R&D intensity of enterprises has a direct impact on the competitiveness of enterprises represented by gross profit margin， and enterprise patents and the government supports have mediating and moderating effects respectively. The moderating effect of the government support on enterprises in the new energy vehicle industry is more significant. Based on the analysis results， some policy suggestions are put forward to improve the competitiveness of SMEs.