[en] The Primary System (PS), the Residual Heat Removal System (RHRS) and the Boron Injection System (BIS) of 200 MW nuclear heating reactor have no driving equipment, therefore fluid circulation depends on natural circulation (in PS and RHRS) or gravity (in BIS). The design and inherent safety of these systems are described

[en] Nuclear safety-related storage battery must keep its function under earthquake. The seismic properties of the battery are justified by experiment. The seismic properties of the supporting shelf of the battery are proved by calculate. However, accurate seismic analysis is very difficult because the battery is very heavy and has no rigid connection with the supporting shelf, seismic calculate can not accurate carried out. The author introduces the method for the seismic calculation of the supporting shelf of 10 MW high temperature gas cooled reactor. In order to keep ample for abundance of seismic design of the storage battery supporting shelf of the storage battery, finite element method is used to calculate the natural frequency and then equivalent static method is used to calculate the stresses

[en] The hydraulic pressure test of 10 MW High Temperature Gas-cooled Reactor (HTR-10) pressure vessel was successfully performed according to the requirement of the section NB-6200, ASME III code. The test requirement, the test results and the test evaluations are described in detail. The test tension was effectively and rationally done through an hydraulic tensioner, which was developed at institute of nuclear energy technology of Tsinghua University. The strain and deformation of the HTR-10 pressure vessel were also measured

[en] Three types of bolt tensioner are designed and successfully used for the installation and dismantling of the pressure vessels of 10 MW high temperature reactor (HTR-10) instead of using the expensive tools from abroad. The structure characteristics, the parameters and the test results of the bolt tensioner are presented, and the calculation method of the main bolt pre-tightening force is given

No abstract available

[en] The differences between tri-axial vibration signals are often considered to be too small to affect the accuracy of gearbox fault diagnosis. Thus, the traditional approach of vibration signal processing based on one particular single axis is often used, which is often chosen by the accelerometer’s orientation relative to the fault location (vertical or horizontal) or the signal’s sensitivity to fault characteristics. This can cause some uncertainty and incompleteness in accurate diagnosis. To tackle this problem, we proposed a novel tri-axial signal information fusion model. In this model, measured vibration signals on three axes were analyzed at three levels to show their differences, and the visualized results were illustrated with histograms. Based on the comparison of the differences, the fusion model was used to analyze differences between the three different axes quantitatively based on the cross-approximate entropy, and such quantitative differences were utilized as adaptive weight coefficients to fuse three orthogonal axial signals. Through this process, the proposed model could transfer differences between different axial signals as adaptive fusion weights. To verify the superiority of the proposed strategy, a classical fuzzy C-means method was used to classify the fused signals from the model. With the measured gear fault signals under variable working conditions from the test bench, the reliability and superiority of the information fusion model proposed were proven through a comparison to fault diagnosis based on traditional signal axis selection. (paper)

[en] Highlights: • The process parameters of stainless steel CX fabricated by SLM were optimized. • Effects of various heat treatments on phase transformation and microstructure evolution were discussed. • Excellent mechanical properties of the SLMed stainless steel CX were achieved using the solution aging treatment. -- Abstract: The present work envisages the effects of three heat treatment processes, i.e. solution treatment (ST), aging treatment (AT) and solution aging treatment (ST+AT) on the microstructure and mechanical properties of a new type of martensitic stainless steel CX (SS-CX) alloy formed by selective laser melting (SLM) with Cr and Ni as the main components. The results revealed that the densest parts with a few tiny pores were fabricated at optimized laser process parameters (laser power 340 W, scanning speed 850 mm/s, hatch spacing 0.1 mm). The SS-CX that underwent the SLM process was mainly composed of the martensite and retained austenite, and has a tensile strength of 1058 MPa and an impact toughness of 57.7 J. After ST at 900 °C for 1 h, the micro-segregation disappeared, the retained austenite of the as-built transformed into martensite, Ni and Al dissolved in the matrix to form supersaturated solid solution, and a reduction of the mechanical properties of the SS-CX was observed. When the SS-CX was aged at 530 °C for 3 h (AT), part of the martensite in the as-built recovered to austenite, and the precipitated particles with the mechanical properties strengthened. When the SS-CX was solution-aged at 900 °C for 1 h and then 530 °C for 3 h (ST+AT), the retained austenite of the as-built transformed completely into martensite, and the dissolved elements in the solution treatment precipitated again, forming the precipitation particles composed of β-NiAl. The precipitated particles increased rapidly the tensile strength and the surface hardness of the SS-CX with values of 1683 MPa and 50.4 HRC, respectively, thereby indicating that the SS-CX exhibited a good comprehensive property.

[en] Photobiomodulation therapy (PBMT) can enhance the mesenchymal stem cell (MSC) proliferation, differentiation, and tissue repair and can therefore be used in regenerative medicine. The objective of this study is to investigate the effects of photobiomodulation on the directional neural differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) and provide a theoretical basis for neurogenesis. hUC-MSCs were divided into control, inducer, laser, and lasers combined with inducer groups. A 635-nm laser and an 808-nm laser delivering energy densities from 0 to 10 J/cm² were used in the study. Normal cerebrospinal fluid (CSF) and injured cerebrospinal fluid (iCSF) were used as inducers. The groups were continuously induced for 3 days. Cellular proliferation was evaluated using MTT. The marker proteins nestin (marker protein of the neural precursor cells), NeuN (marker protein of neuron), and GFAP (glial fibrillary acidic protein, marker proteins of glial cells) were detected by immunofluorescence and western blot. We found that irradiation with 635-nm laser increased cell proliferation, and that with 808 nm laser by itself and combined with cerebrospinal fluid treatment generated significant neuron-like morphological changes in the cells at 72 h. Nestin showed high positive expression at 24 h in the 808 nm group. The expression of GFAP increased in the 808-nm combined inducer group at 24 h but decreased at 72 h. The expression of neuN protein increased only at 72 h in both the 808-nm combined inducer group and inducer group. We concluded that 808 nm laser irradiation could help CSF to induce neuronal differentiation of hUC-MSCs in early stage and tend to change to neuron rather than glial cells.

[en] A good adhesion between a polymer coating and a metal or metal alloy substrate such as Al 2024-T3 plays a critical role in corrosion protection of metal substrates. In our study, a self-assembled monolayer film of 3-aminopropyltrimethoxysilane was formed on Al 2024-T3 substrate by covalent bonding. The adhesion property of a self-priming polyurethane coating was evaluated by pull-off adhesion test, wet tape test and thermal cycling test. All the testing results indicate that both dry and wet adhesion properties of the polyurethane coating were improved significantly after APS treatment of Al 2024-T3 in polar solvents such as methanol and acetone. In nonpolar solvents such as hexane, the APS treatment led to inconsistent improvement or sometime decreased adhesion of polyurethane coating. X-ray photoelectron spectroscopic study revealed that while a monolayer film was formed on the aluminum alloy surface after treating the substrate with APS in methanol and acetone, a multilayer film was formed on the substrate surface when the treatment was conducted in hexane. The APS monolayer film served as a covalent bond linkage between polymer coating and aluminum alloy substrates, which led to the increased adhesion property of polymer coating and corrosion resistance of the metal alloy substrate

[en] We herein report the dispersion of multi-walled carbon nanotubes (MWCNTs) using trifluoroacetic acid (TFA) as a co-solvent. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents. Our study demonstrates that MWCNTs can be effectively purified and readily dispersed in a range of organic solvents including dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloromethane when mixed with 10 vol.% trifluoroacetic acid (TFA). X-ray photoelectron spectroscopic analysis revealed that the chemical structure of the TFA-treated MWCNTs remained intact without oxidation. The dispersed carbon nanotubes in TFA/THF solution were mixed with poly(methyl methacrylate) (PMMA) to fabricate polymer nanocomposites. A good dispersion of nanotubes in solution and in polymer matrices was observed and confirmed by SEM, optical microscopy, and light transmittance study. Low percolation thresholds of electrical conductivity were observed from the fabricated MWCNT/PMMA composite films. Further enhancement in the dispersion of MWCNTs was achieved by adding a conjugated conducting polymer, poly(3-hexylthiophene) (P3HT), to the dispersion, wherein TFA also serves as a doping agent to the conducting polymer. The ternary nanocomposite MWCNT/P3HT/PMMA exhibited an extremely low percolation threshold of less than 0.006 wt% of MWCNT content. This low percolation threshold is attributed to a good dispersion of MWCNTs and enhanced conductivity of the nanocomposites by conjugated conducting polymer