An information-based rough set approach to critical engineering factor identification

In order to analyze the main critical engineering factors, an information-based rough set approach that considers conditional information entropy as a measurement of information has been developed. An algorithm for continuous attribute discretization based on conditional information entropy and an algorithm for rule extraction considering the supports of rules are proposed. The initial decision system is established by collecting enough monitoring data. Then, the continuous attributes are discretized, and the condition attributes are reduced. Finally, the rules that indicate the action law of the main factors are extracted and the results are explained. By applying this approach to a crack in an arch gravity dam, it can be concluded that the water level and the temperature are the main factors affecting the crack opening, and there is a negative correlation between the crack opening and the temperature. This conclusion corresponds with the observation that cracks in most concrete dams are influenced mainly by water level and temperature, and the influence of temperature is more evident.

Engineering critical assessment on welding flaws of the X65 UOE girth weld based on CRACKWISE

Focused on the girth weld of a φ762 x 28.6 mm （X65） offshore UOE pipe, the fracture toughness properties at different weld joint positions were tested. Meanwhile,the largest size of different cracks under service condition was calculated by using CRACKWISE. The service life of the UOE pipe with postulated crack-like flaws was calculated by considering various fatigue factors, such as vibrations caused by ocean current and fluctuations of inner pressure. The assessment process and results can be used to direct the repair of weld flaws laid in pipes or to assess the reliability of in-serving pipes.

Selection of Fe as a barrier for manufacturing low-cost MgB2 multifilament wires-Advanced microscopy study between Fe and B reaction

The high cost of using the niobium(Nb)barrier for manufacturing magnesium diboride(MgB2)mono-and multi-filamentary wires for large-scale applications has become one of the barriers to replacing current commercial niobium-titanium superconductors.The potential of replacing the Nb barrier with a low-cost iron(Fe)barrier for multifilament MgB2 superconducting wires is investigated in this manuscript.Therefore,MgB2 wires with Fe barrier sintered with different temperatures are studied(from 650°C to 900°C for 1 h)to investigate the non-superconducting reaction phase of Fe-B.Their superconducting performance including engineering critical current density(Je)and n-value are tested at 4.2 K in various external magnetic fields.The best sample sintered at 650°C for 1 h has achieved a Je value of 3.64×10^(4) A cm^(−2) and an n-value of 61 in 2 T magnetic field due to the reduced formation of Fe2B,better grain connectivity and homogenous microstructure.For microstructural analysis,the focused ion beam(FIB)is utilised for the first time to acquire three-dimensional microstructures and elemental mappings of the interface between the Fe barrier and MgB2 core of different wires.The results have shown that if the sintering temperature can be controlled properly,the Je and n-value of the wire are still acceptable for magnet applications.The formation of Fe2B is identified along the edge of MgB2,as the temperature increases,the content of Fe2B also increases which causes the degradation in the performance of wires.

Research status of corrosion environment failure and safety assessment of pipeline welded joint

Pipeline transportation is an economical, safe, and efficient transportation method for transporting oil, natural gas, mineral slurry, and other fluids.Welding is the most critical construction process in pipeline engineering and is crucial in the safe operation and service of an entire pipeline system.Theoretically, the girth welded joint is the weakest link in a pipeline system.The unevenness of the structure and performance of the joint caused by welding frequently results in the failure of the welded joint before the failure of the base material of the pipe body, causing the pipeline to leak or even break.For steel pipes used in an acidic corrosive medium environment, the integration of the corrosive medium and mechanical load will accelerate the failure of the welded joint.This article reviews the failure modes of pipeline welded joints in acidic corrosive media, including stress corrosion cracking, hydrogen-induced cracking, and corrosion fracture, and corrosion fatigue considering the diffusion and accumulation of H;at the crack tip.It also reviews service pipelines in acidic corrosive media.The general processing technology of pipe joint engineering critical assessment(ECA) is investigated to provide a reference for the future development of technology in this field.