This paper establishes a coherent framework for delineating the nexus between the digital economy and the subjective efficacy of labor resource allocation. It elucidates the theoretical underpinnings ...of the digital economy's impact and its channel effects on the efficiency of labor allocation. Within the digital economy landscape, the phenomena of survivorship bias, digital divide, and algorithmic hegemony wield substantial sway over the efficiency of labor market allocation. Empirical analysis, conducted through a cross-sectional data model, validates the theoretical framework. The findings demonstrate that the digital economy markedly diminishes the subjective efficiency of labor allocation. Notably, this inhibitory effect is more pronounced among female workers, households with multiple residences, the non-unmarried demographic, and individuals over the age of 40, with the most pronounced effect observed among those aged over 60. In the examination of the causative mechanisms, it is discerned that the digital economy attenuates the subjective efficiency of labor allocation by workers through three conduits: alterations in social and economic status, shifts in living standards, and modifications in workplace comfort.
This paper considers the problem of relative motion control for spacecraft formation flying (SFF). Using terminal sliding mode technique, a relative position/velocity tracking control based on the ...nonlinear model is developed. The presented controller enables rapid formation reconfiguration with feasible fuel cost and strong robustness in the presence of uncertain but bounded disturbances. A nonlinear model with J 2 disturbance and bounded uncertainties is used for dynamic simulation.
•The thermal behavior of AlSi10Mg molten pool was analyzed.•The SLM-processed sample with a relatively low surface roughness was obtained.•Effects of parameters on surface topography of scan track ...were investigated.•Effects of parameters on microstructure of parts were investigated.•Optimum processing parameters for AlSi10Mg SLM was obtained.
This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.
In this work, kaolin/steel slag particle electrodes (KSPEs) were synthesized using a calcination method, and they were used to degrade norfloxacin (NOR) wastewater in three-dimensional (3D) reactor. ...Characterization methods used by KSPEs included SEM, XRF, XRD and BET. The effects of cell voltage, initial pH, KSPEs dosage and initial NOR concentration on NOR degradation were studied in the optimization experiment of operating parameters. The NOR degradation rate and COD removal rate can reach 96.02% and 93.45% under the optimal parameters within 30 min, and energy consumption is 0.99 kWh m−3. As a result, KSPEs shows excellent catalytic performance and cycling, and still has high electrocatalytic activity after 10 cycles. Finally, the degradation mechanism and degradation pathways of KSPEs to treat NOR are proposed.
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•Optimized kaolin/steel slag particle electrode was prepared for norfloxacin removal.•The reactor exhibited excellent catalytic activity and economical efficiency.•The corresponding mechanism and pathway were proposed.
Copper mine tailings are causing great environmental concern nowadays due to their high contents of heavy metals. These hazards may release to air, water, and soil, posing great threat to the living ...organisms in the surroundings. In the present work, we profiled the heavy metal contents, microbiome and resistome of a mine tailing in Dexing Copper Mine, which is the largest open-pit copper mine in China. A total of 39.75 Gb clean data was generated by metagenomics sequencing and taxonomy analysis revealed Actinobacteria, Proteobacteria, Acidobacteria, Euryarchaeota, and Nitrospirae as the most abundant phylum in this tailing. In general, 76 heavy metal resistance genes (HMRGs) and 194 antimicrobial resistance genes (ARGs) were identified with merA and rpoB2 as the most abundant HMRG and ARG, respectively. We also compared the differences of heavy metal concentrations among the six sampling sites in the same tailing and found that significant differences exited in copper and zinc. Hierarchical cluster analysis showed that the samples from the six sampling sites were clustering in two groups based on heavy metal concentrations. Accordingly, clustering based on microbial composition and relative abundances of resistance genes exhibited the same clustering pattern, indicating a possible shaping influence of heavy metals on the microbiome and resistome in this tailing. Our work presented heavy metal contents, microbial composition and resistance genes in a copper mine tailing of the largest copper mine in China, and these data will of great use in the surveillance, maintenance, and remediation of this tailing.
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•Presented the metagenomics data of a tailing in the biggest copper mine in China.•Concentrations of heavy metals in the tailing were generally high.•Heavy metal properties have impact on the microbiome and resistome in the tailing.
Heavy metals are of high concentrations in the tailing of the largest copper mine in China and these metals are shaping the microbiome and resistome in this tailing.
Although the robustness of indirect methods is enhanced by the homotopic approach and switching detection technique when applied to fuel-optimal low-thrust trajectory optimization, the bottleneck in ...adjoint initialization still needs further investigation. This paper overcomes this bottleneck by the adjoint mapping between the Lagrange multipliers of direct methods to the adjoint variables. The nonconvex optimization problem deduced from direct methods is converted into a convex one by lossless convexification and successive convex programming. By combining these techniques, a framework is built to effectively solve the fuel-optimal low-thrust trajectory optimization problem.
Solidification is the most widely applied treatment method for radioactive waste, and cement is the most commonly used material for the immobilization of radionuclides, due to its advantages, such as ...high mechanical strength of the solidified waste form, easy operation and low cost. In the past decades, great efforts have been made to improve the cementation technology for enhancing the performance of the solidified waste, including mechanical properties and durability, and for reducing the leaching of radionuclides. Particularly, special cements have been developed based on Portland cement for solidifying radioactive waste. In this review article, various types of cements were briefly introduced, including Portland cement, alkali-activated cement, geopolymer, calcium aluminate cement, and sulphoaluminate cement; the main parameters used to characterize the performance of the solidified waste forms were summarized, such as package capacity, compressive strength, tensile strength, and leaching resistance, and the measures taken to improve these performances were analyzed; the mechanisms for the immobilization of radionuclides in cements were discussed, mainly involving two ways: chemically fixing them in an insoluble form, and physically adsorbing and trapping them in a rigid, durable matrix. This review will deepen the understanding of the principle and application of the solidification of radioactive wastes by various cement-based materials.
•The solidification of radioactive wastes by various cement-based materials was reviewed.•Various cements used for solidification of radioactive waste were briefly introduced.•Measures taken to improve the performances of the solidified waste forms were summarized.•Chemical fixation and physical adsorption/inclusion are main mechanism for solidification.
•A new soft robotic gripper with variable stiffness was designed. Its uniqueness lies in the structural decoupling of the deformation actuator for bending and the variable stiffness mechanism of the ...soft robotic gripper.•Based on the Cosserat theory, a grasping force model is built for the proposed soft robotic gripper with variable stiffness.•A series of experimental tests and simulations on the grasping force of the soft robotic gripper are investigated to discuss the modeling properties.
The purpose of this research is to present a grasping force model for a soft robotic gripper with variable stiffness. The soft robotic gripper was made of shape memory alloys (SMAs) with contraction and variable stiffness properties. A variable stiffness mechanism with embedded sets of SMA fibers was developed; however, the response characteristics of its backbone did not comply with the constant-curvature model when it was subjected to complex forces/torques, such as gravity, grasping forces and driving torques. In this case, the Cosserat theory was used to implement real-time computations of the grasping force of the soft robotic gripper that was subjected to complex forces. Finally, a series of tests were conducted on the grasping force of the soft finger and the gripper. The elicited results showed that the grasping force is related to the stiffness and to the object's offset and friction coefficient. Moreover, experimental results showed that the grasping force of the soft robotic gripper increased by 48.7% when the Young's modulus of the SMA-2 wires increased from 25 GPa to 48 GPa.
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