Helsinki University of Technology

About: Helsinki University of Technology is a based out in . It is known for research contribution in the topics: Artificial neural network & Finite element method. The organization has 8962 authors who have published 20136 publications receiving 723787 citations. The organization is also known as: TKK & Teknillinen korkeakoulu.

The Odin satellite - I. Radiometer design and test

Abstract: The Sub-millimetre and Millimetre Radiometer (SMR) is the main instrument on the Swedish, Canadian, Finnish and French spacecraft Odin. It consists of a 1.1 metre diameter telescope with four tuneable heterodyne receivers covering the ranges 486-504 GHz and 541-581 GHz, and one fixed at 118.75 GHz together with backends that provide spectral resolution from 150 kHz to 1 MHz. This Letter describes the Odin radiometer, its operation and performance with the data processing and calibration described in Paper II.

Calculation of solidification-related thermophysical properties for steels

Abstract: Special algorithms have been developed to calculate important solidification-related thermophysical properties: enthalpy and enthalpy-related data (i.e., specific and latent heat), density, and thermal conductivity for low-alloyed and stainless steels. The algorithms are heavily based on the use of earlier developed phase transformation models, an interdendritic solidification model (IDS), and an austenite decomposition model (ADC), which solve, as a function of temperature, the phase fractions and compositions needed in these calculations. As a result, the thermophysical properties can be calculated at any temperature, from 1600 °C to 25 °C, taking into account the discontinuities caused by special phase transformations (i.e., ferritic, austenitic and peritectic solidification, ferrite/austenite transformation, and austenite decomposition to various structures) influenced by the steel grade and the cooling conditions.

Eigenmode method for electromagnetic synthesis of diffractive elements with three-dimensional profiles

Abstract: We extend the rigorous eigenmode theory of binary surface-relief gratings to accommodate three-dimensional-modulation profiles, to formulate a synthesis problem for doubly periodic resonance-domain diffractive elements, and to demonstrate some of the problem’s symmetry properties. Several solutions for multiple beam splitters with ~90% transmission-mode diffraction efficiency are obtained by nonlinear parametric optimization. The polarization sensitivity and the required fabrication accuracy are analyzed for some solutions.