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.

Life cycle costing: a review of published case studies

Abstract: Purpose – Despite existing life cycle costing (LCC) method descriptions and practicable suggestions for conducting LCC analyses, no systematic analyses on actual implementations of LCC methods exist. This paper aims to review reports on LCC applications to provide an overview of LCC uses and implementation feasibility.Design/methodology/approach – A review of LCC cases reported in academic and practitioner literature. Case reports were compared against one another and against the defining articles in the field.Findings – Most of the reported LCC applications were far from ideal. Compared to the methods suggested in the literature many of the case study applications: covered fewer parts of the whole life cycle, estimated the costs on a lower level of detail, used cost estimation methods based on expert opinion rather than statistical methods, and were content with deterministic estimates of life cycle costs instead of using sensitivity analyses.Research limitations/implications – This review is limited to ...

Convergence of supercell calculations for point defects in semiconductors: Vacancy in silicon

Abstract: The convergence of first-principles supercell calculations for defects in semiconductors is studied with the vacancy in bulk Si as a test case. The ionic relaxations, defect formation energies, and ionization levels are calculated for supercell sizes of up to 216 atomic sites using several k-point meshes in the Brillouin-zone integrations. The energy dispersion, inherent for the deep defect states in the supercell approximation, and the long range of the ionic relaxations are shown to postpone the convergence so that conclusive results for the physical properties cannot be obtained before the supercell size is of the order of 128--216 atomic sites.

A new algorithm for the maximum-weight clique problem

Abstract: Given a graph, in the maximum clique problem one wants to find the largest number of vertices, any two of which are adjacent. In the maximum-weight clique problem, the vertices have positive, integer weights, and one wants to find a clique with maximum weight. A recent algorithm for the maximum clique problem is here used as a basis for developing an algorithm for the weighted case. Computational experiments with random graphs show that this new algorithm is faster than earlier algorithms in many cases. A set of weighted graphs obtained from the problem of constructing good constant weight error-correcting codes are proposed as test cases for maximum-weight clique algorithms; in fact, one of these leads to a new record-breaking code.

Identifying the success factors in e‐grocery home delivery

Abstract: Efforts in the electronic grocery shopping, i.e. e‐grocery business, focus especially on the physical distribution of the goods. For example, in the USA there are several e‐grocery service providers with various operating concepts and offering various service levels. The home delivery concept of Streamline is based on a reception box at the customer’s garage or home yard enabling unmanned reception. In contrast, WebVan has launched a home delivery concept where the customer can select a convenient half an hour delivery time window. Various service concepts have been implemented and offered, but has anyone really analysed the differences in cost structures of these two and of other concepts in between the two extremes? Investigates existing home delivery service concepts from different angles and presents concrete simulation results of various parameters representing several home delivery service levels. Eventually, identifying the parameters will give guidelines for the future development of the e‐grocery home delivery services.