Residual stresses develop due to intrinsic and extrinsic strains that form during the processing. Extrinsic strains can be determined using coefficient of thermal expansion, material properties, and processing conditions. An “Equivalent Reference Temperature (ERT)” technique is described and used to model and evaluate the intrinsic strains. piezoelectric microelectromechanical systems (P-MEMS) are considered in this work. Laminate theory with three-dimensional state of stress and strain is used to evaluate residual stresses using the ERT model. In finite element analysis (FEA), the residual stresses and strains of multi-layer P-MEMS structures deposited layer-by-layer during processing, are simulated using the “element birth-and-death” approach. The evaluated residual stresses for a simplified geometry using ANSYS three-dimensional FEA and analytical analysis employing three-dimensional laminate theory are presented along with their corresponding experimental results. A user-friendly software based on the 3-D laminate theory is developed and installed on the Internet. The “equivalent reference temperature” as well as residual stresses and strains can be determined using this software. The level of residual stresses and strains of P-MEMS depend upon various factors such as geometrical design, material selection, and process conditions.
Ischemic stroke (IS) is the leading cause of disability. Researchers have
demonstrated that IS is more a multifactorial disorder than a single-factor
disease. At present, no consistent conclusions have been reached on
susceptibility loci for IS on chromosome 9p21. We conducted this meta-analysis
to verify whether genetic loci on chromosome 9p21 reported domestically and
abroad could be responsible for IS in Chinese populations. We analyzed data from
eight studies that covered a total of 9756 individuals with Chinese ancestry
comprising 4254 cases and 5502 controls. Each of the four reported
susceptibility loci (rs2383206, rs2383207, rs10757274, and rs10757278) was
analyzed separately. The odds ratios (ORs) of rs2383206 and rs10757274 were 1.09
(95% confidence interval (CI): 1.02–1.06,
P
= 0.01) and 1.09
(95% CI: 1.01–1.17,
P
= 0.03), respectively. For rs2383207, OR
value was 0.91 (95% CI: 0.84–0.98,
P
= 0.01). No statistical
association was identified for rs10757278. We have verified previous
associations for IS in Chinese populations on chromosome 9p21. Loci rs2383206
and rs10757274 may increase susceptibility to IS. Mutation at locus rs2383207
may be beneficial. However, we are unable to identify any association between
rs10757278 and IS.
The paper proposes an identification method of the dynamic stiffness matrix of a bearing joint region on the basis of theoretical analysis and experiments. The author deduces an identification model of the dynamic stiffness matrix from the synthetic substructure method. The dynamic stiffness matrix of the bearing joint region can be identified by measuring the matrix of frequency response function (FRFs) of the substructure (axle) and whole structure (assembly of the axle, bearing, and bearing housing) in different positions. Considering difficulty in measuring angular displacement, applying moment, and directly measuring relevant FRFs of rotational degree of freedom, the author employs an accurately calibrated finite element model of the unconstrained structure for indirect estimation. With experiments and simulation analysis, FRFs related with translational degree of freedom, which is estimated through the finite element model, agrees with experimental results, and there is very high reliability in the identified dynamic stiffness matrix of the bearing joint region.
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