Tampere University of Technology

About: Tampere University of Technology is a based out in . It is known for research contribution in the topics: Laser & Context (language use). The organization has 6802 authors who have published 19787 publications receiving 431793 citations. The organization is also known as: Tampereen teknillinen yliopisto.

Contact Micromanipulation—Survey of Strategies

Abstract: This paper surveys contact micromanipulation strategies that are developed to tackle the microscale-related phenomena in microassembly. Strategies are divided according to how they take account of adhesion forces. Micromanipulation refers to handling of objects that have dimensions below hundreds of micrometers with handling accuracy down to submicrometers. The line between micro- and nanomanipulation is not definite but typically the object size in nanomanipulation is considered to reach from atomic and molecular scale to hundreds of nanometers. In contact micromanipulation, the tool physically touches the manipulated objects during handling. Scaling-effect-induced adhesion forces severely complicate micromanipulation when compared to conventional macromanipulation. At microscale, the most important adhesive forces are van der Waals force, electrostatic force, and capillary force. Adhesion forces are also the reason behind the fairly low level of automation in microassembly systems. Improved success rate of micromanipulation operations requires that the special features of microscale phenomena be taken into consideration.

D-bar method for electrical impedance tomography with discontinuous conductivities

Abstract: The effects of truncating the (approximate) scattering transform in the D‐bar reconstruction method for two‐dimensional electrical impedance tomography are studied. The method is based on the uniqueness proof of Nachman [Ann. of Math. (2), 143 (1996), pp. 71–96] that applies to twice differentiable conductivities. However, the reconstruction algorithm has been successfully applied to experimental data, which can be characterized as piecewise smooth conductivities. The truncation is shown to stabilize the method against measurement noise and to have a smoothing effect on the reconstructed conductivity. Thus the truncation can be interpreted as regularization of the D‐bar method. Numerical reconstructions are presented demonstrating that features of discontinuous high contrast conductivities can be recovered using the D‐bar method. Further, a new connection between Calderon’s linearization method and the D‐bar method is established, and the two methods are compared numerically and analytically.

OpenCL-based design methodology for application-specific processors

Abstract: OpenCL is a programming language standard which enables the programmer to express the application by structuring its computation as kernels. The OpenCL compiler is given the explicit freedom to parallelize the execution of kernel instances at all the levels of parallelism. In comparison to the traditional C programming language which is sequential in nature, OpenCL enables higher utilization of parallelism naturally available in hardware constructs while still having a feasible learning curve for engineers familiar with the C language. This paper describes methodology and compiler techniques involved in applying OpenCL as an input language for a design flow of application-specific processors. At the core of the methodology is a whole program optimizing compiler that links together the host and kernel codes of the input OpenCL program and parallelizes the result on a customized statically scheduled processor. The OpenCL vendor extension mechanism is used to provide clean access to custom operations. The methodology is studied with a design case to verify the scalability of the implementation at the instruction level and to exemplify the use of custom operations. The case shows that the use of OpenCL allows producing scalable application-specific processor designs and makes it possible to gradually reach the performance of hand-tailored RTL designs by exploiting the OpenCL extension mechanism to access custom hardware operations of varying complexity.

Boundary element method for surface nonlinear optics of nanoparticles

Abstract: We present the frequency-domain boundary element formulation for solving surface second-harmonic generation from nanoparticles of virtually arbitrary shape and material. We use the Rao-Wilton-Glisson basis functions and Galerkin’s testing, which leads to very accurate solutions for both near and far fields. This is verified by a comparison to a solution obtained via multipole expansion for the case of a spherical particle. The frequency-domain formulation allows the use of experimentally measured linear and nonlinear material parameters or the use of parameters obtained using ab-initio principles. As an example, the method is applied to a non-centrosymmetric L-shaped gold nanoparticle to illustrate the formation of surface nonlinear polarization and the second-harmonic radiation properties of the particle. This method provides a theoretically well-founded approach for modelling nonlinear optical phenomena in nanoparticles.