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101.
102.
The Discrete Basis Problem 总被引:2,自引:0,他引:2
Miettinen Pauli Mielik inen Taneli Gionis Aristides Das Gautam Mannila Heikki 《Knowledge and Data Engineering, IEEE Transactions on》2008,20(10):1348-1362
Matrix decomposition methods represent a data matrix as a product of two factor matrices: one containing basis vectors that represent meaningful concepts in the data, and another describing how the observed data can be expressed as combinations of the basis vectors. Decomposition methods have been studied extensively, but many methods return real-valued matrices. Interpreting real-valued factor matrices is hard if the original data is Boolean. In this paper, we describe a matrix decomposition formulation for Boolean data, the Discrete Basis Problem. The problem seeks for a Boolean decomposition of a binary matrix, thus allowing the user to easily interpret the basis vectors. We also describe a variation of the problem, the Discrete Basis Partitioning Problem. We show that both problems are NP-hard. For the Discrete Basis Problem, we give a simple greedy algorithm for solving it; for the Discrete Basis Partitioning Problem we show how it can be solved using existing methods. We present experimental results for the greedy algorithm and compare it against other, well known methods. Our algorithm gives intuitive basis vectors, but its reconstruction error is usually larger than with the real-valued methods. We discuss about the reasons for this behavior. 相似文献
103.
Anger and aggression among drivers in three European countries 总被引:3,自引:0,他引:3
Recent reports of 'road rage' in the British media give the impression that driver aggression is escalating. In order to understand this phenomenon we need to know what it is about driving that provokes motorists to feel anger and then to go on to express that anger in the form of aggression. A postal questionnaire survey of more than 2500 drivers was carried out in three European countries: Britain, Finland and the Netherlands. The study had three main aims: (a) to discover how angry, if at all, a range of situations on the road make drivers, (b) to find out how many drivers are likely to react aggressively to those situations, and (c) to investigate individual and/or cultural differences in terms of anger and/or aggressive responses among motorists. Results indicate that the same types of behaviour provoke anger and aggression in all three countries, and that traffic density may play a role. 相似文献
104.
Teemu Suutari Tiina Silen Didem S˛en Karaman Heikki Saari Diti Desai Erja Kerkelä Saara Laitinen Martina Hanzlikova Jessica M. Rosenholm Marjo Yliperttula Tapani Viitala 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(45):6289-6300
The surface plasmon resonance technique in combination with whole cell sensing is used for the first time for real‐time label‐free monitoring of nanoparticle cell uptake. The uptake kinetics of several types of nanoparticles relevant to drug delivery applications into HeLa cells is determined. The cell uptake of the nanoparticles is confirmed by confocal microscopy. The cell uptake of silica nanoparticles and polyethylenimine–plasmid DNA polyplexes is studied as a function of temperature, and the uptake energies are determined by Arrhenius plots. The phase transition temperature of the HeLa cell membrane is detected when monitoring cell uptake of silica nanoparticles at different temperatures. The HeLa cell uptake of the mesoporous silica nanoparticles is energy‐independent at temperatures slightly higher than the phase transition temperature of the HeLa cell membrane, while the uptake of polyethylenimine–DNA polyplexes is energy‐dependent and linear as a function of temperature with an activation energy of Ea = 62 ± 7 kJ mol?1 = 15 ± 2 kcal mol?1. The HeLa cell uptake of red blood cell derived extracellular vesicles is also studied as a function of the extracellular vesicle concentration. The results show a concentration dependent behavior reaching a saturation level of the extracellular vesicle uptake by HeLa cells. 相似文献
105.
Visual measurement and tracking in laser hybrid welding 总被引:1,自引:0,他引:1
Henri Fennander Ville Kyrki Anna Fellman Antti Salminen Heikki Kälviäinen 《Machine Vision and Applications》2009,20(2):103-118
This paper presents a novel system for the automatic analysis of a hybrid welding process. High-speed imaging and laser illumination
are used to measure the regularity of electric arc frequency and flight directions of filler metal droplets. A fuzzy c-means
clustering method is used to detect arcs and segment the video sequences. The droplets are localized by combining principal
component analysis and a support vector machine classifier. The flight of a droplet is tracked using Kalman filtering. Experiments
indicate that the system is able to track the flights of droplets and to determine the regularity of the arc frequency with
a high accuracy if the imaging conditions are stable.
相似文献
Ville KyrkiEmail: |
106.
Miah Muhammed Das Gautam Hristidis Vagelis Mannila Heikki 《Knowledge and Data Engineering, IEEE Transactions on》2009,21(7):959-973
In recent years, there has been significant interest in the development of ranking functions and efficient top-k retrieval algorithms to help users in ad hoc search and retrieval in databases (e.g., buyers searching for products in a catalog). We introduce a complementary problem: How to guide a seller in selecting the best attributes of a new tuple (e.g., a new product) to highlight so that it stands out in the crowd of existing competitive products and is widely visible to the pool of potential buyers. We develop several formulations of this problem. Although the problems are NP-complete, we give several exact and approximation algorithms that work well in practice. One type of exact algorithms is based on Integer Programming (IP) formulations of the problems. Another class of exact methods is based on maximal frequent item set mining algorithms. The approximation algorithms are based on greedy heuristics. A detailed performance study illustrates the benefits of our methods on real and synthetic data. 相似文献
107.
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109.
Pure N-isopropyl acrylamide (NIPA) polymer gel and NIPA copolymers containing 2-acrylamido-2-methylpropane sulfonic acid (AMPS), 2-acetamidoacrylic acid (AAA), and acrylic acid (AA) were prepared and evaluated with respect to their capability for taking up zinc, nickel, and chromium ions from solutions. AAA-containing NIPA gels were found to take up these metal ions most efficiently. Titration of these gels verified the strong acidic nature of the AMPS–NIPA gel and the weakly acidic nature of the AA–NIPA and AAA–NIPA gels. The ion-exchange capacities, derived from the titration curves, were, however, rather low in all cases. NIPA gels are known to collapse at temperatures about 32°C. This, however, was found to have no effect on the ion-exchange behavior of the gels. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:355–362, 1998 相似文献
110.
Katja Tiitinen Marjatta Vahvaselkä Mari Hakala Simo Laakso Heikki Kallio 《European Food Research and Technology》2006,222(5-6):686-691
Malolactic fermentation (MLF) traditionally used in winemaking was applied to sea buckthorn to reduce the high sourness of
the berry juice. Chemical and microbiological aspects, as well as sensory properties of the juice during MLF were studied
in order to develop an optimal process. In 1:1 water diluted juice with malic acid content of 15 g/l and pH 2.8, efficient
conversion of l-malic acid to l-lactic acid was achieved with direct inoculation of unadapted Oenococcus oeni at a cell density of 109 CFU/ml. The rapid malic acid degradation was performed by non-growing bacterial cells without loss of sugars, vitamin C,
or pulp oil. More than 50% of the initial malic acid was metabolized to lactic acid and CO2 already in 12 h of fermentation and a significant decrease in sourness and astringency was noticed. In 24 h fermentation,
pH value was increased to 3.1 and only 3 g/l malic acid remained in the juice. Prolonged fermentation had only minor effect
on malolactic reaction, but off-flavor of the juice began to increase. 相似文献