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Institution

Helsinki University of Technology

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


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors compare several widely used Bayesian model selection methods in practical model selection problems, highlight their differences and give recommendations about the preferred approaches for variable subset selection for regression and classification.
Abstract: The goal of this paper is to compare several widely used Bayesian model selection methods in practical model selection problems, highlight their differences and give recommendations about the preferred approaches. We focus on the variable subset selection for regression and classification and perform several numerical experiments using both simulated and real world data. The results show that the optimization of a utility estimate such as the cross-validation (CV) score is liable to finding overfitted models due to relatively high variance in the utility estimates when the data is scarce. This can also lead to substantial selection induced bias and optimism in the performance evaluation for the selected model. From a predictive viewpoint, best results are obtained by accounting for model uncertainty by forming the full encompassing model, such as the Bayesian model averaging solution over the candidate models. If the encompassing model is too complex, it can be robustly simplified by the projection method, in which the information of the full model is projected onto the submodels. This approach is substantially less prone to overfitting than selection based on CV-score. Overall, the projection method appears to outperform also the maximum a posteriori model and the selection of the most probable variables. The study also demonstrates that the model selection can greatly benefit from using cross-validation outside the searching process both for guiding the model size selection and assessing the predictive performance of the finally selected model.

197 citations

Book ChapterDOI
11 Mar 2002
TL;DR: In this paper, the authors argue that threshold trust is not an option in most of the real-life electronic auctions, and propose two new cryptographic Vickrey auction schemes that involve, apart from the bidders and the seller S, an auction authority A so that unless S and A collude the outcome of auctions will be correct, and moreover, S will not get any information about the bids, while A will learn bid statistics.
Abstract: We argue that threshold trust is not an option in most of the real-life electronic auctions. We then propose two new cryptographic Vickrey auction schemes that involve, apart from the bidders and the seller S, an auction authority A so that unless S and A collude the outcome of auctions will be correct, and moreover, S will not get any information about the bids, while A will learn bid statistics. Further extensions make it possible to decrease damage that colluding S and A can do, and to construct (m + 1)st price auction schemes. The communication complexity between the S and A in medium-size auctions is at least one order of magnitude less than in the Naor-Pinkas-Sumner scheme.

197 citations

Journal ArticleDOI
TL;DR: In this paper, a multiblock simulation model was developed in order to allow the close examination of different regions of a stirred tank for drop size distribution calculations, and the model is tested in a parameter fitting procedure.

197 citations

Proceedings ArticleDOI
01 Aug 2000
TL;DR: This work considers user participation as a way to address part of the challenges of designing concepts for new mobile services and devices and develops two participatory techniques that help in facing the design challenges.
Abstract: Designing concepts for new mobile services and devices, poses several challenges to the design. We consider user participation as a way to address part of the challenges. We show how our effort relates to current and past research. In particular, PD (Participatory Design) has inspired us in developing two participatory techniques. The two techniques are organized around situations either staged or real where users and designers can envision and enact future scenarios: a role-playing game with toys, and SPES (Situated and Participative Enactment of Scenarios). They were developed in an industry-funded project that investigates services for the nomadic Internet user of the future. We then discuss how the techniques help in facing the design challenges.

197 citations

Book ChapterDOI
01 Apr 1998
TL;DR: In this article, the authors present an efficient, compact and easily searchable implementation of an IP routing table by using an LC-trie, a trie structure with combined path and level compression.
Abstract: We consider the problem of organizing address tables for internet routers to enable fast searching. Our proposal is to to build an efficient, compact and easily searchable implementation of an IP routing table by using an LC-trie, a trie structure with combined path and level compression. The depth of this structure increases very slowly as function of the number of entries in the table. A node can be coded in only four bytes and the size of the main search structure never exceeds 256 kB for the tables in the US core routers. We present a software implementation that can sustain approximately half a million lookups per second on a 133 MHz Pentium personal computer, and two million lookups per second on a more powerful SUN Sparc Ultra II workstation.

197 citations


Authors

Showing all 8962 results

NameH-indexPapersCitations
Ashok Kumar1515654164086
Hannu Kurki-Suonio13843399607
Nicolas Gisin12582764298
Anne Lähteenmäki11648581977
Riitta Hari11149143873
Andreas Richter11076948262
Mika Sillanpää96101944260
Markku Leskelä9487636881
Ullrich Scherf9273536972
Mikko Ritala9158429934
Axel H. E. Müller8956430283
Karl Henrik Johansson88108933751
T. Poutanen8612033158
Elina Lindfors8642023846
Günter Breithardt8555433165
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2021154
2020153
2019155
201851
201714
201630