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Carbide-free bainitic steels with the bainitic ferrite (BF) as matrix constituent have been widely used and manufactured. The mixed microstructure of pre-formed martensite (M), BF, and retained austenite (RA) was obtained by quenching for a short time below the martensitic transformation temperature followed by austempering. A similar amount of fresh martensite was obtained by interrupted austempering at the same temperature. Results show that the carbon distribution among these constituents in the mixed microstructure plays a major role in controlling mechanical properties. The carbon content of M and BF in the M-BF-RA microstructure is lower than that of BF-M-RA microstructure, while that of RA was reversed. Mechanical properties of the M-BF-RA microstructure exhibit higher toughness, higher product of strength and elongation as well as higher yield ratio, rather than strength, compared to that of the BF-M-RA microstructure. It can be attributed to toughened pre-formed martensite with low carbon content and mechanical stable RA with high carbon content. In addition, the pre-formed martensite decreases the block size, leading to the increase of high angle grain boundaries, which further improves toughness. The high carbon fresh martensite BF increased the strength of the BF-M-RA microstructure, but sharply decreases ductility and toughness.

Background Vascular graft infection with anastomotic dehiscence requires immediate surgical intervention to preserve life and limb. We present our experience of using the Omniflow® II biosynthetic vascular prosthesis (LeMaitre Vascular) in the emergency repair of vascular graft dehiscence at the femoral anastomosis. Methods A retrospective review of consecutive patients presenting with femoral anastomotic dehiscence in a single centre was conducted. All patients were revascularized using an in situ Omniflow II graft. Patient demographics, affected graft type, microbiology, and antibiotic regimes were documented. Primary outcome measures were limb salvage, patency rates, and mortality. Results Five patients presented with acute femoral false aneurysm and four of five with significant hemorrhage. Infected grafts included one aortobifemoral, two femoral crossover, one axillobifemoral, and one infrainguinal reversed vein graft. All were revascularized with an in situ Omniflow II graft following the excision of the infected graft material. The median followup was 50 months. Limb salvage was achieved in 8 of 9 threatened limbs, and none required further intervention for re-infection. One graft occluded at 5 months. Two of five patients died during followup (one at 12 months, one at 50 months). Conclusions Omniflow II provides a useful “off-the-shelf” conduit for the urgent revascularization of infected femoral dehiscence.

In recent years, more and more attention has been paid to isogeometric methods, in which shape functions are used to accurately describe CAD models and approximate unknown fields. The isogeometric boundary element method (IGABEM) realizes the integration on the exact boundary of the region, which means there is no geometric discretization error. In this paper, a more general interface integral formula for elastic energy increment of heterogeneous materials is extended from previous work (Dong, 2018), in which the only unknown variable is the displacement located on the interface between matrix and inclusion. This feature makes it more compatible with boundary element method (BEM) because of none of volume parametrization. However, the geometry discontinuity on the boundary called ‘corner point problem’ increases the difficulty and decreases the accuracy when solving complex numerical examples when heterogeneous structures are considered. The discontinuous element method combined with IGABEM is presented and applied to deal with ‘corner point problem’. In the numerical examples, the interface between matrix and inclusion is discretized by quadratic isogeometric elements. Compared with the analytical solution, the numerical results show that the method has higher accuracy and efficiency.

The damage of a Hadfield steel crossing in a railway turnout due to wheel rolling impact passages is investigated numerically. A three dimensional elastic–plastic finite element model has been developed by taking into account non-linear material properties, dynamic wheel impact and wheel–crossing contact. The effects of wheel velocity on the damage and deformation of the crossing is analysed. In the present study, four rolling velocities of the wheel, i.e., 50 km/h, 100 km/h, 150 km/h, and 200 km/h were chosen. The wheel exhibits elastic material behaviour, whereas the crossing exhibits elastic–plastic material behaviour. To represent the damage and deformation behaviours of the crossing, non-linear dynamic work hardening is further included in the calculation. Dynamic stress and strain in the crossing were obtained by the explicit finite element method, including the maximum von Mises stress, the maximum strain, the maximum horizontal stress, perpendicular stress and parallel stress. The snake-like motion of the wheel rolling on the crossing was verified by the simulation; in the meantime, there is a significant impact load on the nose rail, which caused a big von Mises stress in the nose rail. The big von Mises stress is the main reason for the nose rail fatigue spalling. The maximum von Mises stress and maximum strain in the nose rail increase with the train speed increasing. The study provides a method for the further research on the fatigue and the wear behaviours of railway crossings.

Highway construction has been played an important role in Chinese economic development. A good design was a key factor to a successful project, and at the same time, the geometric parameters and mechanical parameters of asphalt pavement both were of great weight. In this paper, a model of semi-rigid base and asphalt pavement was established, and load response was calculated with BISAR on base of three-layer system, comparison of impact of different parameters on the response was carried out to get the discipline, and this will help the designers to optimize design.

The existing multimedia classroom vision environment is researched in this paper with the study, the analysis and the research, and the question with the multimedia classroom vision environment is proposed by present situation investigation. By the human work efficiency study, the principle and the method with the visual environment, the multimedia classroom existences not the analogy energy region to illuminance questions to different demand are solved creativity by this paper. The visual environments with pleasant and highly effective are realized in this paper.

Susceptibility analysis is important in any study of debris flows. This paper presents a model for debris flow susceptibility analysis using a combination weighting and an improved fuzzy C-means algorithm. Twelve factors of influence were acquired by 3S technologies. Analytic hierarchy process (AHP) and entropy method were performed to obtain subjective and objective weighting of the factors, respectively. Game theory was carried out to determine the combination weighting since it provides analytical tools to model interactions among factors. An improved fuzzy C-means clustering analysis was applied to determine the susceptibility level of debris flows. This method is based on a particle swarm optimization algorithm, which is an evolutionary algorithm that can achieve global optimization, and is not sensitive to the initial cluster centers. Results showed that the susceptibility levels for one of the debris flow catchments was high, four were moderate, and five were low. Our quantitative assessments based on these nonlinear methods were consistent with field investigations.

An open-ended dielectric resonator method and experimental apparatus for measuring microwave surface resistance of the high Tc superconducting thin films are reported. Making use of two sapphire rods the quality factor related to the losses of the resonator except its superconducting part can be evaluated. The Rs value of an individual superconducting thin film can be determined without any assistance of other superconducting films or calibrators. This measurement provides a convenient and absolute approach for Rs-measurement of high Tc superconducting thin films. Also the error in the Rs-measurement with the method was discussed.

This paper uses the technical of the VPD (Virtual Product Design) with the parallel coordination design, and the problem with the tradition design like in some link has been solved. It is possibly interrupt or brings disaster to the insufficiency which directly the entire design will carry on normally, and it proposed that the hypothesized product development design (VPD) the architecture key technologies, through the hypothesized product development design cycle analysis, confirms the VPD technology sophistication fully.

There could be considerable benefits in designing supply chains structures taking into account the design of the product and the design of the manufacturing processes. The revised structures involve delaying product differentiation until later production stages. We develop models representing possible implementations of the delayed product differentiation structures and compare their performance in total supply chain costs involving the cost of expected customer waiting times. Some numerical experiments were designed to investigate how different factors affect the performance of structures. We also offer guidance to managers using reasonable structure for a balance between customization and responsiveness.