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.

Answer set optimization

Abstract: We investigate the combination of answer set programming and qualitative optimization techniques. Answer set optimization programs (ASO programs) have two parts. The generating program Pgen produces answer sets representing possible solutions. The preference program Ppref expresses user preferences. It induces a preference relation on the answer sets of Pgen based on the degree to which rules are satisfied. We discuss possible applications of ASO programming, give complexity results and propose implementation techniques. We also analyze the relationship between ASO programs and CP-networks.

Incremental instant radiosity for real-time indirect illumination

Abstract: We present a method for rendering single-bounce indirect illumination in real time on currently available graphics hardware. The method is based on the instant radiosity algorithm, where virtual point lights (VPLs) are generated by casting rays from the primary light source. Hardware shadow maps are then employed for determining the indirect illumination from the VPLs. Our main contribution is an algorithm for reusing the VPLs and incrementally maintaining their good distribution. As a result, only a few shadow maps need to be rendered per frame as long as the motion of the primary light source is reasonably smooth. This yields real-time frame rates even when hundreds of VPLs are used.

Reduced-order flux observers with stator-resistance adaptation for speed-sensorless induction motor drives

Abstract: This paper deals with reduced-order flux observers with stator-resistance adaptation for speed-sensorless induction motor drives. A general analytical solution for the stabilizing observer gain is given. The gain has two free positive parameters (which may depend on the operating point), whose selection significantly affects the damping, convergence rate, robustness, and other properties of the observer. The general stability conditions for the stator-resistance adaptation are derived. An observer design is proposed that yields a robust and well-damped system and requires a minimal amount of tuning work. The proposed observer design is experimentally tested using a 45-kW induction motor drive; stable operation at very low speeds under different loading conditions is demonstrated.

Mekong Delta at the Crossroads: More Control or Adaptation?

Abstract: Development in the Mekong Delta of Vietnam has been very dynamic in the recent past, and currently it stands at an interesting crossroads. On one hand, agricultural production has developed successfully, and economic growth has been very rapid, but on the other hand, intensifying agriculture and large-scale water-control structures have challenged the environmental sustainability and social equity. The development plans have included a strong belief in the human mastery over the nature and waters of the Mekong Delta. In many cases, water resources planners have underestimated the complexity and integrated nature of the ecology and livelihoods of the Mekong Delta. This article examines cases where development efforts, while successful in some dimensions, have also contributed to create new risks for, especially, the poorest groups. The current situation calls for a more sustainable future route that would require examination of more adaptive measures in relation to the changing water flows of the Mekong River.