Aims In this study we have considered the three dimensional corrective forces for correction of scoliosis by using a patient specific finite element model. Materials and Methods An objective function of corrective forces in three-dimensional space was defined. Computed tomography images were used to reconstruct three dimensional model of scoliotic trunk. Computer aided engineering software Abaqus was used to establish finite element model of deformed spine and its biomechanical characteristics were analyzed. By adjusting magnitude and position of corrective forces, objective function was minimized to achieve best orthopedic effect. The proposed corrective conditions were divided into three groups: (1) thoracic deformity; (2) lumbar deformity; (3) both thoracic and lumbar deformities were considered. Results In all three cases, the objective function was reduced by 58, 52, and 63%, respectively. The best correction forces point was located on convex side of maximum displacement of vertebral body. Conclusion Using minimum objective function method, spinal deformity in three-dimensional space can be sufficiently reduced. This study provides scientific basis for design of a new corrective brace for treatment of scoliosis.

This paper investigates the vibration patterns, i.e. rigid motions of shaft and elastic deformation of support structures, of fan rotor system in aero-engine, which differs from traditional flexible rotor systems, and together with its shaft transverse motions due to unbalanced mass. The fan rotor system commonly is composed of one rigid shaft and two flexible support structures (such as squirrel cages), which is effective to decrease the critical speeds avoiding serious shaft vibration due to unbalance. Scaled test rig for realistic fan rotor system is set up according to similarity principles, governing differential equations of which are deduced by means of Lagrangian approach with four degrees of freedom. In contrast to modeling a traditional flexible rotor system, the system stiffness is not determined by the shaft but the two flexible support structures. The rigid shaft only contributes to the inertial items of the governing equations. Parameter values of dynamic model are identified from measurements on the scaled test rig, the modal shapes and the modal energy distributions are calculated. These modal characteristics of the fan rotor system are quite different from those of a traditional flexible rotor system whose stiffness mainly contributed by its elastic shaft even the system values are consistent. The obtained modal characteristics are compared and confirmed by using the simulation results of a corresponding finite element model, in which shaft is built by rotating beam elements and its flexible structures are built by equivalent spring elements. Campbell diagrams of the fan rotor system are used to illustrate the gyroscopic effect with the increasing speeds. And then the unbalance responses are calculated through the deduced analytical formula rapidly and comparisons, including the response spectrum and orbits, the amplitude and phase frequency response curves, and operating deflection shapes, are carried out in the sub- and super-critical range.

To study how to design different grades of individualized wheelchairs according to users' needs, a personalized wheelchair design method based on AHP and Kano model is proposed. The AHP model determines the relative importance of characteristics of customers' demands. The subfunctions of manual wheelchairs and their attributes are given. The weight coefficients are calculated. 20 experts (10 are the members of the research team, 5 are doctors, and 5 are wheelchair designers) are involved in the above two parts of the work. Kano model represents the types of user requirements. 30 participants' (wheelchair users) needs are divided into 5 categories: M, O, E, I, and R. According to the types of user needs and the weight of each subfunction, three manual wheelchair models are built. Traditional design method usually cannot satisfy the requirements of users and product structure, so this paper makes a contribution to solve this problem. The method can be used to design individualized wheelchairs which may improve the product quality and customers' satisfaction. Meanwhile it also can reduce the design time, thereby reducing the design cost.

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In order to improve the surface bioactivity of titanium implants, CaCO₃ and CaHPO₄·2H₂O powder was used to fabricate a calcium phosphate (CaP) coating using laser rapid forming (LRF) technology. The surface characterization showed that a porous and beta-tricalcium phosphate (beta-TCP) layer with small amount of alpha-TCP was formed on commercial pure titanium (Ti). The bonding strength between the coating and the Ti substrate was above 40.17 MPa measured by the means of pull-off test. The elastic modulus and the average microhardness of the coating were 117.61 GPa and 431.2 HV₀.₁, respectively. Through the static immersion test, it was proved that the coating could not only prevent the corrosion of Ti but also promote the redeposition of beta-TCP in artificial saliva. Osteoblasts possessed good attachment performance and strong proliferation ability on the surface of LRF coating (p < 0.05) in our cell experiments. This result demonstrated that the LRF coating could improve the surface cytocompatibility of titanium. Using scanning electron microscopy observation, it was found that osteoblasts grown on LRF coating formed multiple layers in pours. The result of reverse transcription PCR analysis demonstrated that the expressions of ITGβ1 and BMP-2 were significantly (p < 0.05) upregulated on the LRF coating in a time-dependent manner, compared with uncoated Ti. These findings suggested that the LRF technology might be a promising potential treatment for fabricating CaP coatings on titanium implants.