Jet Engine Health Signal Denoising Using Optimally Weighted Recursive Median Filters

The removal of noise and outliers from health signals is an important problem in jet engine health monitoring. Typically, health signals are time series of damage indicators, which can be sensor measurements or features derived from such measurements. Sharp or sudden changes in health signals can represent abrupt faults and long term deterioration in the system is typical of gradual faults. Simple linear filters tend to smooth out the sharp trend shifts in jet engine signals and are also not good for outlier removal. We propose new optimally designed nonlinear weighted recursive median filters for noise removal from typical health signals of jet engines. Signals for abrupt and gradual faults and with transient data are considered. Numerical results are obtained for a jet engine and show that preprocessing of health signals using the proposed filter significantly removes Gaussian noise and outliers and could therefore greatly improve the accuracy of diagnostic systems. [DOI: 10.1115/1.3200907].

Uuden median murros Alma Mediassa, Sanoma Oy:ssä ja Yleisradiossa 1994-2004

This is a qualitative and multimethodological comparative study, which consists of two main parts: examining the development of new media and analysing and comparing the new media strategies of the three companies studied (Alma Media, Sanoma and the Finnish Broadcasting Company Yleisradio). The study includes the first large-scale review in Finnish of the development of new media, paying attention to the birth of the Internet as well as to mobile media, web TV and any other element of new media. It also concentrates on the function of electronic distribution channels before the age of the Internet, e.g. cable text and videotext. Answers about how the three traditional Finnish media houses began spreading their content to the Internet and wireless applications in 1994–2004 are also given. In researching the new media strategies the study pays special attention to the attitudes that the three media companies adopted towards the Internet and other forms of new media in their strategies during the years in question. By analysing and comparing, e.g., the companies’ strategies and their investments, the study ascertains whether the companies had a joint functional model in adopting new media or acted totally on their own without taking too much notice of the media field overall. The study makes extensive use of previously published material. The researcher has also interviewed almost twenty people who were involved in getting the companies’ new media functions under way. The methods for the interviews were dialogue and snowball sampling. The researcher has created a classification in which he divides the business strategies into four different categories: active strategy, careful strategy, permissive strategy, and passive strategy. In comparing and analysing the companies the researcher has used the classification devised by Allan Afuah & Christopher L. Tucci. The seven element classification consists of dominant managerial logic, competency trap, fear of cannibalisation and loss of revenue, channel conflict, political power, co-opetitor power and emotional attachment. In analysing the company strategies the researcher has also noted the classifications of convergence made by Everette E. Dennis and Graham Murdock as well as the aspects formulated by Sylvia Chan-Olmsted and Louisa Ha concerning the success of the companies in adopting the Internet into their functions. Based on all these classifications and by further developing them the researcher analyses and compares the success of the new media strategies of the three Finnish companies. The outcome of the study is a conclusion as to what kind of strategies the companies have carried out their new media functions and how they have succeeded in it.

Coding for Two-User Gaussian MAC with PSK and PAM Signal Sets

Constellation Constrained (CC) capacity regions of a two-user Gaussian Multiple Access Channel(GMAC) have been recently reported. For such a channel, code pairs based on trellis coded modulation are proposed in this paper with MPSK and M-PAM alphabet pairs, for arbitrary values of M,toachieve sum rates close to the CC sum capacity of the GMAC. In particular, the structure of the sum alphabets of M-PSK and M-PAMmalphabet pairs are exploited to prove that, for certain angles of rotation between the alphabets, Ungerboeck labelling on the trellis of each user maximizes the guaranteed squared Euclidean distance of the sum trellis. Hence, such a labelling scheme can be used systematically,to construct trellis code pairs to achieve sum rates close to the CC sum capacity. More importantly, it is shown for the first time that ML decoding complexity at the destination is significantly reduced when M-PAM alphabet pairs are employed with almost no loss in the sum capacity.

Comparative measurements of HV impulses to evaluate different sets of response parameters

Results are reported of comparative measurements made in 14 HV (high-voltage) laboratories in ten different countries. The theory of the proposed methods of characterizing the dynamic behavior is given, and the parameters to be used are discussed. Comparative measurements made using 95 systems based on 53 dividers are analyzed. This analysis shows that many of the system now in use, even though they fulfil the basic response requirements of the standards, do not meet the accuracy requirements. Because no transfer measurements were made between laboratories, there is no way to detect similar errors in both the system under test and the reference system. Hence, the situation may be worse than reported. This has led to the recommendation that comparative measurements should be the main route for quantifying industrial impulse measuring systems

Kuluttajien kokemukset lastenvaatteiden ja -tarvikkeiden verkkokaupan palvelun laadusta sosiaalisen median keskusteluissa

Tämän pro gradu- tutkielman tavoitteena oli löytää kuluttajien palvelukokemukseen vaikuttavat tekijät lastenvaatteiden- ja tarvikkeiden -verkkokaupassa. Empiirinen tutkimus lähestyi aihetta netnografian avulla. Aineistoksi tähän tutkielmaan valittiin sosiaalisen median keskustelut. Tutkimuksen teoreettinen osa muodostui kolmesta aiheesta: verkko-ostamisesta ja palvelun laadusta, sosiaalisesta mediasta sekä word-of-mouth-viestinnästä. Verkko-ostamisessa käsiteltiin ostamisen eri vaiheet, kuluttajien motivaatiot verkosta ostamiseen, sekä siihen liittyvät riskit ja tarkasteltiin sähköisen palvelun laatua. Sosiaalinen media-luku kertoi sosiaalisen median käytöstä sekä eri medioista. Word-of-mouth-viestintä esitteli perinteisen word-of-mouth-viestinnän lisäksi sähköisen WOM-viestinnän ulottuvuudet. Empiirinen tutkimus oli laadullinen ja se toteutettiin netnografisesti. Netnografia on etnografiaan perustuva menetelmä, jota käytetään internet-aineistoissa. Aineiston analysoinnissa käytettiin teemoittelua. Aihetta lähestyttiin faktanäkökulmasta, eli tutkimuksessa oltiin kiinnostuneita niistä tosiasioista joita keskustelijat kertoivat. Aineisto kerättiin perhe-aiheisten lehtien keskustelupalstoilta sekä blogeista Google-haun avulla. Sosiaalisen median keskustelut valittiin aineistoksi, koska niistä uskottiin saatavan kaikkein totuudenmukaisinta tietoa, johon tutkijan kysymyksen asettelu ei vaikuta. Spontaanit keskustelut antavat erilaista tietoa kuin suoran kysymyksen vastaukset. Tutkimuksen tuloksena löytyi seitsemän teemaa, joita keskusteluissa käsiteltiin. Nämä ovat toimitus, palvelu, palautus ja normalisointi, ulkoasu ja toimivuus, hinta, maksaminen sekä tuotteet ja valikoima. Sen sijaan teorian pohjalta odotettavissa olleet turvallisuus ja yksityisyys eivät tulleet aineistosta lainkaan esiin. Erityisen huonona palveluna asiakkaat pitivät varastosaldojen paikkansapitämättömyyttä, hitaita toimituksia sekä epäystävällistä palvelua. Hyvää palvelua olivat nopeat toimitukset sekä yksilöllinen palvelu ja reklamaatioiden hyvä hoito.

Playing Games on Sets and Models

The most prominent objective of the thesis is the development of the generalized descriptive set theory, as we call it. There, we study the space of all functions from a fixed uncountable cardinal to itself, or to a finite set of size two. These correspond to generalized notions of the universal Baire space (functions from natural numbers to themselves with the product topology) and the Cantor space (functions from natural numbers to the {0,1}-set) respectively. We generalize the notion of Borel sets in three different ways and study the corresponding Borel structures with the aims of generalizing classical theorems of descriptive set theory or providing counter examples. In particular we are interested in equivalence relations on these spaces and their Borel reducibility to each other. The last chapter shows, using game-theoretic techniques, that the order of Borel equivalence relations under Borel reduciblity has very high complexity. The techniques in the above described set theoretical side of the thesis include forcing, general topological notions such as meager sets and combinatorial games of infinite length. By coding uncountable models to functions, we are able to apply the understanding of the generalized descriptive set theory to the model theory of uncountable models. The links between the theorems of model theory (including Shelah's classification theory) and the theorems in pure set theory are provided using game theoretic techniques from Ehrenfeucht-Fraïssé games in model theory to cub-games in set theory. The bottom line of the research declairs that the descriptive (set theoretic) complexity of an isomorphism relation of a first-order definable model class goes in synch with the stability theoretical complexity of the corresponding first-order theory. The first chapter of the thesis has slightly different focus and is purely concerned with a certain modification of the well known Ehrenfeucht-Fraïssé games. There we (me and my supervisor Tapani Hyttinen) answer some natural questions about that game mainly concerning determinacy and its relation to the standard EF-game

Distributed algorithms for edge dominating sets

An edge dominating set for a graph G is a set D of edges such that each edge of G is in D or adjacent to at least one edge in D. This work studies deterministic distributed approximation algorithms for finding minimum-size edge dominating sets. The focus is on anonymous port-numbered networks: there are no unique identifiers, but a node of degree d can refer to its neighbours by integers 1, 2, ..., d. The present work shows that in the port-numbering model, edge dominating sets can be approximated as follows: in d-regular graphs, to within 4 − 6/(d + 1) for an odd d and to within 4 − 2/d for an even d; and in graphs with maximum degree Δ, to within 4 − 2/(Δ − 1) for an odd Δ and to within 4 − 2/Δ for an even Δ. These approximation ratios are tight for all values of d and Δ: there are matching lower bounds.

Sosiaalisen median odotuksia ja käyttötarpeita osana asiantuntijaorganisaation viestintää

Tarkastelen pro gradu -tutkielmassani työyhteisön viestintätapojen muutosta ja sosiaalisen mediai roolia muutoksessa. Tutkimukseni tavoitteena on jäsentää ja ymmärtää sosiaalisen median roolia työyhteisön viestinnässä ja tarkastella miten sosiaalinen media taipuu tietoperustaisen asiantuntiorganisaation tarpeisiin. Tutkimuksen teoreettisessa osuudessa selvitän sitä, miten työn tekemisessä tapahtuneet muutokset ovat muuttaneet työyhteisön tapaa ja tarvetta viestiä. Työn tekemisen uusia muotoja ja verkostoitumista jäsennän tutkimuskirjallisuuden Alvesson (2000), Gruber & Palonen (2007), Kasvio & Tjäder (2007), Sennett (2007) kautta. Työn uusia muotoja voidaan kuvata käsitteillä asiantuntijakeskeisyys, tietointensiivisyys ja tietoperustainen työ. Kuva tutkimuksessani myös sosiaalisen median käsitettä sekä sen tunnusomaisuuksia. Tarkastelen tietoperustaisen asiantuntijaorganisaation odotuksia ja käyttötarpeita sosiaaliselle medialle Elisa Juholinin (2008) määrittelemän työyhteisöviestinnän uuden agendan (agendamalli) viitekehykses Tutkimukseni empiirisessä osuudessa tarkastelen aihetta yhden tietoperustaisen asiantuntijaorganisaation jäsenten kautta. Tavoitteeni on selvittää 1) millaisia odotuksia asiantuntijaorganisaatiossa työskentelevillä on sosiaalisen median käytöstä osana työyhteisön viestintää sekä 2) millaisia käyttötarpeita asiantuntijaorganisaatiossa työskentelevillä on sosiaalis* median käytöstä osana työyhteisön viestintää. Tutkimusotteeni on laadullinen, ja aineiston keruur menetelmänä käytän fokusryhmäkeskustelua sekä teemahaastattelua. Analysoin aineiston teemoittelemalla. Aineiston koodauksessa käytin Atlas.ti -ohjelmaa. Tutkimukseni perusteella voidaan todeta, että tärkeimpänä sosiaalisen median odotuksiin ja käyttötarpeisiin liittyi ajatus käyttäjälähtöisyydestä ja vuorovaikutuksesta. Käyttäjälähtöisyys ja vuorovaikutus näkyivät erityisesti odotuksena viestinnän rutiinien, tiedon ja osaamisen jakamisena entistä avoimempaan ; vuorovaikutteisempaan suuntaan. Tutkimus antaa viitteitä siitä, että sosiaalisen median sovelluksilla on mahdollista tukea vuorovaikutusta juuri niissä työyhteisöviestinnän tehtävissä, joissa vuorovaikutus jää helposti vähäiseksi. Sosiaalisen median sovelluksia tarvitaan myös tietoperustaisen asiantuntijaorganisaation osaamisen ja ns. hiljaisen tiedonjakamiseen. Tutkimuksen perusteella sosiaalinen media osana työyhteisön viestintää taipuu tiedontarpeen tyydyttäjänä, tarjoaa vaihtoehdon viestintäkanaville ja viestinnän toimintamalleille, mahdollistaa osallistumaan ja vaikuttamaan työyhteisön asioihin sekä tarjoaa tavan koota työyhteisössä olevaa osaamista ja hiljaista tietoa.

Minimal sets of generators for the relation ideals of certain monomial curves

Let O be a monomial curve in the affine algebraic e-space over a field K and P be the relation ideal of O. If O is defined by a sequence of e positive integers some e - 1 of which form an arithmetic sequence then we construct a minimal set of generators for P and write an explicit formula for mu(P).

A Ten-microRNA Expression Signature Predicts Survival in Glioblastoma

Glioblastoma (GBM) is the most common and aggressive primary brain tumor with very poor patient median survival. To identify a microRNA (miRNA) expression signature that can predict GBM patient survival, we analyzed the miRNA expression data of GBM patients (n = 222) derived from The Cancer Genome Atlas (TCGA) dataset. We divided the patients randomly into training and testing sets with equal number in each group. We identified 10 significant miRNAs using Cox regression analysis on the training set and formulated a risk score based on the expression signature of these miRNAs that segregated the patients into high and low risk groups with significantly different survival times (hazard ratio HR] = 2.4; 95% CI = 1.4-3.8; p < 0.0001). Of these 10 miRNAs, 7 were found to be risky miRNAs and 3 were found to be protective. This signature was independently validated in the testing set (HR = 1.7; 95% CI = 1.1-2.8; p = 0.002). GBM patients with high risk scores had overall poor survival compared to the patients with low risk scores. Overall survival among the entire patient set was 35.0% at 2 years, 21.5% at 3 years, 18.5% at 4 years and 11.8% at 5 years in the low risk group, versus 11.0%, 5.5%, 0.0 and 0.0% respectively in the high risk group (HR = 2.0; 95% CI = 1.4-2.8; p < 0.0001). Cox multivariate analysis with patient age as a covariate on the entire patient set identified risk score based on the 10 miRNA expression signature to be an independent predictor of patient survival (HR = 1.120; 95% CI = 1.04-1.20; p = 0.003). Thus we have identified a miRNA expression signature that can predict GBM patient survival. These findings may have implications in the understanding of gliomagenesis, development of targeted therapy and selection of high risk cancer patients for adjuvant therapy.

Three- and Seven-Point Optimally Weighted Recursive Median Filters for Gas Turbine Diagnostics

Measured health signals incorporate significant details about any malfunction in a gas turbine. The attenuation of noise and removal of outliers from these health signals while preserving important features is an important problem in gas turbine diagnostics. The measured health signals are a time series of sensor measurements such as the low rotor speed, high rotor speed, fuel flow, and exhaust gas temperature in a gas turbine. In this article, a comparative study is done by varying the window length of acausal and unsymmetrical weighted recursive median filters and numerical results for error minimization are obtained. It is found that optimal filters exist, which can be used for engines where data are available slowly (three-point filter) and rapidly (seven-point filter). These smoothing filters are proposed as preprocessors of measurement delta signals before subjecting them to fault detection and isolation algorithms.

Noise and outlier removal from jet engine health signals using weighted FIR median hybrid filters

The removal of noise and outliers from measurement signals is a major problem in jet engine health monitoring. Topical measurement signals found in most jet engines include low rotor speed, high rotor speed. fuel flow and exhaust gas temperature. Deviations in these measurements from a baseline 'good' engine are often called measurement deltas and the health signals used for fault detection, isolation, trending and data mining. Linear filters such as the FIR moving average filter and IIR exponential average filter are used in the industry to remove noise and outliers from the jet engine measurement deltas. However, the use of linear filters can lead to loss of critical features in the signal that can contain information about maintenance and repair events that could be used by fault isolation algorithms to determine engine condition or by data mining algorithms to learn valuable patterns in the data, Non-linear filters such as the median and weighted median hybrid filters offer the opportunity to remove noise and gross outliers from signals while preserving features. In this study. a comparison of traditional linear filters popular in the jet engine industry is made with the median filter and the subfilter weighted FIR median hybrid (SWFMH) filter. Results using simulated data with implanted faults shows that the SWFMH filter results in a noise reduction of over 60 per cent compared to only 20 per cent for FIR filters and 30 per cent for IIR filters. Preprocessing jet engine health signals using the SWFMH filter would greatly improve the accuracy of diagnostic systems. (C) 2002 Published by Elsevier Science Ltd.

Tree structure for efficient data mining using rough sets

In data mining, an important goal is to generate an abstraction of the data. Such an abstraction helps in reducing the space and search time requirements of the overall decision making process. Further, it is important that the abstraction is generated from the data with a small number of disk scans. We propose a novel data structure, pattern count tree (PC-tree), that can be built by scanning the database only once. PC-tree is a minimal size complete representation of the data and it can be used to represent dynamic databases with the help of knowledge that is either static or changing. We show that further compactness can be achieved by constructing the PC-tree on segmented patterns. We exploit the flexibility offered by rough sets to realize a rough PC-tree and use it for efficient and effective rough classification. To be consistent with the sizes of the branches of the PC-tree, we use upper and lower approximations of feature sets in a manner different from the conventional rough set theory. We conducted experiments using the proposed classification scheme on a large-scale hand-written digit data set. We use the experimental results to establish the efficacy of the proposed approach. (C) 2002 Elsevier Science B.V. All rights reserved.