Notice of RetractionOn solving the min-max problem of the stress of the structural elements in the structural topology optimization
In this paper, we deal with the min-max problem of the stress of the structural elements in the structural topology optimization. A generalized KS function is presented which transforms the local stress to global strain energy of structure through Von Mises Criterion. The ICM method is employed for solving the topology optimization problem. Some classic numerical examples are presented which provide quality solutions and the minimum stress design to obtain the final design.
SYSTEMATIC CONTROL DESIGN BY OPTIMIZING A VECTOR PERFORMANCE INDEX
Abstract An iterative procedure for control design is presented. By optimizing a vector performance index, the components of which rate different design specifications, free controller coefficients in a given control structure are determined in such a way that a systematic improvement of the result in each iteration step is guaranteed, even if a great many of design specifications have to be considered. Opposite to previous works, handling design specifications as constraints within the meaning of nonlinear programming the described procedure excels by high systematic policy for choosing free design parameters and by requiring only unconstrained minimization which can be realized comparatively simple.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.