On the axial bearing capability of construction steel tube considering the uniform corrosion effect

168-178To study the law of corrosion on the mechanical properties of the components used in spatial steel structures and obtain the load-carrying capability of circular steel tubes under varying degrees of corrosion, experiments on a periodic spray have been designed to study the accelerated corrosion and axial loading of tubes without a protective layer. The experiment results show that the yield and ultimate load-carrying capacities of the components are heavily influenced by the corrosion, the latter being more sensitive to corrosion, and that a good functional relationship exists between the weight loss ratio and the load-carrying capability of the corrosive components. In addition, a finite element model of a circular steel tube experiencing corrosion has been established using ANSYS with an equivalent cross-section reduction method to simulate of the experiment results. The simulation results agree well with the experiment results, which effectively indicates that the corrosion of the steel tube components obeys the uniform corrosion law. And the equivalent cross-section reduction method also possesses good reliability. The results of the study provide a technical reference for research on the mechanical properties of larger building components such as circular steel tubes experiencing corrosion

On the axial bearing capability of construction steel tube considering the uniform corrosion effect

To study the law of corrosion on the mechanical properties of the components used in spatial steel structures and obtain the load-carrying capability of circular steel tubes under varying degrees of corrosion, experiments on a periodic spray have been designed to study the accelerated corrosion and axial loading of tubes without a protective layer. The experiment results show that the yield and ultimate load-carrying capacities of the components are heavily influenced by the corrosion, the latter being more sensitive to corrosion, and that a good functional relationship exists between the weight loss ratio and the load-carrying capability of the corrosive components. In addition, a finite element model of a circular steel tube experiencing corrosion has been established using ANSYS with an equivalent cross-section reduction method to simulate of the experiment results. The simulation results agree well with the experiment results, which effectively indicates that the corrosion of the steel tube components obeys the uniform corrosion law. And the equivalent cross-section reduction method also possesses good reliability. The results of the study provide a technical reference for research on the mechanical properties of larger building components such as circular steel tubes experiencing corrosion

New Insights into the Organization, Recombination, Expression and Functional Mechanism of Low Molecular Weight Glutenin Subunit Genes in Bread Wheat

The bread-making quality of wheat is strongly influenced by multiple low molecular weight glutenin subunit (LMW-GS) proteins expressed in the seeds. However, the organization, recombination and expression of LMW-GS genes and their functional mechanism in bread-making are not well understood. Here we report a systematic molecular analysis of LMW-GS genes located at the orthologous Glu-3 loci (Glu-A3, B3 and D3) of bread wheat using complementary approaches (genome wide characterization of gene members, expression profiling, proteomic analysis). Fourteen unique LMW-GS genes were identified for Xiaoyan 54 (with superior bread-making quality). Molecular mapping and recombination analyses revealed that the three Glu-3 loci of Xiaoyan 54 harbored dissimilar numbers of LMW-GS genes and covered different genetic distances. The number of expressed LMW-GS in the seeds was higher in Xiaoyan 54 than in Jing 411 (with relatively poor bread-making quality). This correlated with the finding of higher numbers of active LMW-GS genes at the A3 and D3 loci in Xiaoyan 54. Association analysis using recombinant inbred lines suggested that positive interactions, conferred by genetic combinations of the Glu-3 locus alleles with more numerous active LMW-GS genes, were generally important for the recombinant progenies to attain high Zeleny sedimentation value (ZSV), an important indicator of bread-making quality. A higher number of active LMW-GS genes tended to lead to a more elevated ZSV, although this tendency was influenced by genetic background. This work provides substantial new insights into the genomic organization and expression of LMW-GS genes, and molecular genetic evidence suggesting that these genes contribute quantitatively to bread-making quality in hexaploid wheat. Our analysis also indicates that selection for high numbers of active LMW-GS genes can be used for improvement of bread-making quality in wheat breeding

Comparative analysis and applicability of corrosion test methods for construction steel components

In this paper, a systematic study of different methods of manufacturing corroded components and their post-corrosion morphology has been carried out to verify the effectiveness of different accelerated corrosion testing methods. Corrosion tests were performed on specimens of construction steel Q345 by three corrosion methods, i.e., atmospheric exposure corrosion, salt spray accelerated corrosion, and accelerated electrochemical corrosion. The surface morphology of the specimens after corrosion was measured, the characteristics of the corrosion morphology development of the various corrosion methods of the components were analyzed, and the corresponding probability model of the corrosion morphology distribution was developed. Accordingly, a random corrosion surface modeling technique was developed based on the fast Fourier transform and two-dimensional digital filtering techniques, and the mechanical analysis of axially pressed components with different corrosion surfaces was carried out. The results indicate a clear difference in the undulation and variation pattern of the corroded surface under different corrosion methods. However, the disparity in the axial compression load capacity of the specimens under different surface conditions were minimal, was less than 1%. Therefore, the axial compression performance of corroded steel members can be studied using electrochemical corrosion and smooth corrosion surface simulation in the future study

Two-Loop Acceleration Autopilot Design and Analysis Based on TD3 Strategy

A two-loop acceleration autopilot is designed using the twin-delayed deep deterministic policy gradient (TD3) strategy to avoid the tedious design process of conventional tactical missile acceleration autopilots and the difficulty of meeting the performance requirements of the full flight envelope. First, a deep reinforcement learning model for the two-loop autopilot is developed. The flight state information serves as the state, the to-be-designed autopilot control parameters serve as the action, and a reward mechanism based on the stability margin index is designed. The TD3 strategy is subsequently used to offline learn the control parameters for the entire flight envelope. An autopilot control parameter fitting model that can be directly applied to the guidance loop is obtained. Finally, the obtained fitting model is combined with the impact angle constraint in the guidance system and verified online. The simulation results demonstrate that the autopilot based on the TD3 strategy can self-adjust the control parameters online based on the real-time flight state, ensuring system stability and achieving accurate acceleration command tracking

Angular Displacement Control for Timoshenko Beam by Optimized Traveling Wave Method

The vibration of flexible structures in spacecraft, such as large space deployable reflectors, solar panels and large antenna structure, has a great impact on the normal operation of spacecraft. Accurate vibration control is necessary, and the control of angular displacement is a difficulty of accurate control. In the traditional control method, the mode space control has a good effect on suppressing low-order modes, but there is control overflow. The effect of traveling wave control on low-order modes is worse than the former, but it has the characteristics of broadband control. It can better control high-order modes and reduce control overflow. In view of the advantages and disadvantages of the two control methods, based on Timoshenko beam theory, this paper uses vector mode function to analyze the modal of spacecraft cantilever beam structure, establishes the system dynamic equation, and puts forward an optimized traveling wave control method. As a numerical example, three strategies of independent mode space control, traditional traveling wave control and optimized traveling wave control are used to control the active vibration of beam angle. By comparing the numerical results of the three methods, it can be seen that the optimal control method proposed in this paper not only effectively suppresses the vibration, but also improves the robustness of the system, reflecting good control performance. An innovation of this paper is that the Timoshenko beam model is adopted, which considers the influence of transverse shear deformation and moment of inertia on displacement and improves the accuracy of calculation, which is important for spacecraft accessory structures with high requirements for angle control. Another innovation is that the optimized traveling wave control method is exquisite in mathematical processing and has good results in global and local vibration control, which is not available in other methods

Designed Diblock Oligonucleotide for the Synthesis of Spatially Isolated and Highly Hybridizable Functionalization of DNA–Gold Nanoparticle Nanoconjugates

Conjugates of DNA and gold nanoparticles (AuNPs) typically exploit the strong Au–S chemistry to self-assemble thiolated oligonucleotides at AuNPs. However, it remains challenging to precisely control the orientation and conformation of surface-tethered oligonucleotides and finely tune the hybridization ability. We herein report a novel strategy for spatially controlled functionalization of AuNPs with designed diblock oligonucleotides that are free of modifications. We have demonstrated that poly adenine (polyA) can serve as an effective anchoring block for preferential binding with the AuNP surface, and the appended recognition block adopts an upright conformation that favors DNA hybridization. The lateral spacing and surface density of DNA on AuNPs can also be systematically modulated by adjusting the length of the polyA block. Significantly, this diblock oligonucleotide strategy results in DNA–AuNPs nanoconjugates with high and tunable hybridization ability, which form the basis of a rapid plasmonic DNA sensor

Anchoring Single Copper Atoms to Microporous Carbon Spheres as High-Performance Electrocatalyst for Oxygen Reduction Reaction

Although the carbon-supported single-atom (SA) electrocatalysts (SAECs) have emerged as a new form of highly efficient oxygen reduction reaction (ORR) electrocatalysts, the preferable sites of carbon support for anchoring SAs are somewhat elusive. Here, a KOH activation approach is reported to create abundant defects/vacancies on the porous graphitic carbon nanosphere (CNS) with selective adsorption capability toward transition-metal (TM) ions and innovatively utilize the created defects/vacancies to controllably anchor TM–SAs on the activated CNS via TM-Nx coordination bonds. The synthesized TM-based SAECs (TM-SAs@N-CNS, TM: Cu, Fe, Co, and Ni) possess superior ORR electrocatalytic activities. The Cu-SAs@N-CNS demonstrates excellent ORR and oxygen evolution reaction (OER) bifunctional electrocatalytic activities and is successfully applied as a highly efficient air cathode material for the Zn–air battery. Importantly, it is proposed and validated that the N-terminated vacancies on graphitic carbons are the preferable sites to anchor Cu-SAs via a Cu-(N-C2)3(N-C) coordination configuration with an excellent promotional effect toward ORR. This synthetic approach exemplifies the expediency of suitable defects/vacancies creation for the fabrication of high-performance TM-based SAECs, which can be implemented for the synthesis of other carbon-supported SAECs.</p