Showing papers by "Helsinki University of Technology published in 2013"

First result from the Alpha Magnetic Spectrometer on the International Space Station: precision measurement of the positron fraction in primary cosmic rays of 0.5-350 GeV.

Abstract: A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

The Effect of Customers' Social Media Participation on Customer Visit Frequency and Profitability: An Empirical Investigation

Abstract: In this study we examine the effect of customers' participation in a firm's social media efforts on the intensity of the relationship between the firm and its customers as captured by customers' visit frequency. We further hypothesize and test for the moderating roles of social media activity and customer characteristics on the link between social media participation and the intensity of customer-firm relationship. Importantly, we also quantify the impact of social media participation on customer profitability. We assemble a novel data set that combines customers' social media participation data with individual customer level transaction data. To account for endogeneity that could arise because of customer self-selection, we utilize the propensity score matching technique in combination with difference in differences analysis. Our results suggest that customer participation in a firm's social media efforts leads to an increase in the frequency of customer visits. We find that this participation effect is ...

Switchable Static and Dynamic Self-Assembly of Magnetic Droplets on Superhydrophobic Surfaces

Abstract: Self-assembly is a process in which interacting bodies are autonomously driven into ordered structures. Static structures such as crystals often form through simple energy minimization, whereas dynamic ones require continuous energy input to grow and sustain. Dynamic systems are ubiquitous in nature and biology but have proven challenging to understand and engineer. Here, we bridge the gap from static to dynamic self-assembly by introducing a model system based on ferrofluid droplets on superhydrophobic surfaces. The droplets self-assemble under a static external magnetic field into simple patterns that can be switched to complicated dynamic dissipative structures by applying a time-varying magnetic field. The transition between the static and dynamic patterns involves kinetic trapping and shows complexity that can be directly visualized.

Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity

Abstract: Knowing how moving droplets dissipate energy is important for designing superhydrophobic surfaces, but measuring such small energy losses is challenging. Timonen et al. develop a technique to do this, which monitors freely decaying and resonant oscillations of moving magnetic droplets.

“What language does global business speak?” - The concept and development of BELF

Abstract: This paper focuses on the development of the concept of BELF, which originally stood for �Business English as Lingua Franca�, but later we have used the abbreviation to refer to �English as Business Lingua Franca�. With this change we want to emphasize the domain of use rather than the type of English. The concept of BELF originates from two large research projects conducted at the Aalto University School of Business from 2000 to 2009. The projects were inspired by research into English as a Lingua Franca (ELF) and, from that perspective, they set on exploring the language and communication practices of internationally operating business professionals. The findings of the projects showed how the domain of business, and particularly its goal-oriented nature, was significant for BELF discourse and for the perceptions of BELF communication of the practitioners themselves. Overall, it can be argued that for BELF speakers, grammatical correctness is not nearly as important as the genre knowledge of their own specific field of expertise, involving a shared understanding of what, why, how and when to communicate. Thus, we argue that professional competence in today�s global business environment involves communication knowhow as an integral element of business knowhow. Further, in an international context, competence in BELF is a necessity.

Random subset feature selection in automatic recognition of developmental disorders, affective states, and level of conflict from speech

Abstract: This work studies automatic recognition of paralinguistic properties of speech. The focus is on selection of the most useful acoustic features for three classification tasks: 1) recognition of autism spectrum developmental disorders from child speech, 2) classification of speech into different affective categories, and 3) recognizing the level of social conflict from speech. The feature selection is performed using a new variant of random subset sampling methods with k-nearest neighbors (kNN) as a classifier. The experiments show that the proposed system is able to learn a set of important features for each recognition task, clearly exceeding the performance of the same classifier using the original full feature set. However, some effects of overfitting the feature sets to finite data are also observed and discussed.

Efficient Evolutionary Algorithm for Single-Objective Bilevel Optimization

Abstract: Bilevel optimization problems are a class of challenging optimization problems, which contain two levels of optimization tasks. In these problems, the optimal solutions to the lower level problem become possible feasible candidates to the upper level problem. Such a requirement makes the optimization problem difficult to solve, and has kept the researchers busy towards devising methodologies, which can efficiently handle the problem. Despite the efforts, there hardly exists any effective methodology, which is capable of handling a complex bilevel problem. In this paper, we introduce bilevel evolutionary algorithm based on quadratic approximations (BLEAQ) of optimal lower level variables with respect to the upper level variables. The approach is capable of handling bilevel problems with different kinds of complexities in relatively smaller number of function evaluations. Ideas from classical optimization have been hybridized with evolutionary methods to generate an efficient optimization algorithm for generic bilevel problems. The efficacy of the algorithm has been shown on two sets of test problems. The first set is a recently proposed SMD test set, which contains problems with controllable complexities, and the second set contains standard test problems collected from the literature. The proposed method has been evaluated against two benchmarks, and the performance gain is observed to be significant.

Balanced and optimal bianisotropic particles: maximizing power extracted from electromagnetic fields

Abstract: Here we introduce the concept of 'optimal particles' for strong interactions with electromagnetic fields. We assume that a particle occupies a given electrically small volume in space and study the required optimal relations between the particle polarizabilities. In these optimal particles, the inclusion shape and material are chosen so that the particles extract the maximum possible power from given incident fields. It appears that for different excitation scenarios the optimal particles are bianisotropic chiral, omega, moving and Tellegen particles. The optimal dimensions of resonant canonical chiral and omega particles are found analytically. Such optimal particles have extreme properties in scattering (e.g., zero backscattering or invisibility). Planar arrays of optimal particles possess extreme properties in reflection and transmission (e.g. total absorption or magnetic-wall response), and volumetric composites of optimal particles realize, for example, such extreme materials as the chiral nihility medium.

Success factors of innovation ecosystems - Initial insights from a literature review

Abstract: The aim of this paper is to review research on innovation ecosystems to derive success factors supporting the implementation of them. The reviewed studies highlight different factors for the successful implementation of innovation ecosystems which can be assigned to the areas of resources, governance, strategy and leadership, organizational culture, human resources management, people, partners, technology and clustering. Based on the findings a number of future research directions are proposed which may stimulate more research in this new field of study.

Supervised Morphological Segmentation in a Low-Resource Learning Setting using Conditional Random Fields

Abstract: We discuss data-driven morphological segmentation, in which word forms are segmented into morphs, the surface forms of morphemes. Our focus is on a lowresource learning setting, in which only a small amount of annotated word forms are available for model training, while unannotated word forms are available in abundance. The current state-of-art methods 1) exploit both the annotated and unannotated data in a semi-supervised manner, and 2) learn morph lexicons and subsequently uncover segmentations by generating the most likely morph sequences. In contrast, we discuss 1) employing only the annotated data in a supervised manner, while entirely ignoring the unannotated data, and 2) directly learning to predict morph boundaries given their local sub-string contexts instead of learning the morph lexicons. Specifically, we employ conditional random fields, a popular discriminative log-linear model for segmentation. We present experiments on two data sets comprising five diverse languages. We show that the fully supervised boundary prediction approach outperforms the state-of-art semi-supervised morph lexicon approaches on all languages when using the same annotated data sets.

Co-Evolutionary Mechanisms of Emotional Bursts in Online Social Dynamics and Networks

Abstract: Collective emotional behavior of users is frequently observed on various Web portals; however, its complexity and the role of emotions in the acting mechanisms are still not thoroughly understood. In this work, using the empirical data and agent-based modeling, a parallel analysis is performed of two archetypal systems—Blogs and Internet-Relayed-Chats—both of which maintain self-organized dynamics but not the same communication rules and time scales. The emphasis is on quantifying the collective emotions by means of fractal analysis of the underlying processes as well as topology of social networks, which arise and co-evolve in these stochastic processes. The results reveal that two distinct mechanisms, which are based on different use of emotions (an emotion is characterized by two components, arousal and valence), are intrinsically associated with two classes of emergent social graphs. Their hallmarks are the evolution of communities in accordance with the excess of the negative emotions on popular Blogs, on one side, and smooth spreading of the Bot’s emotional impact over the entire hierarchical network of chats, on the other. Another emphasis of this work is on the understanding of nonextensivity of the emotion dynamics; it was found that, in its own way, each mechanism leads to a reduced phase space of the emotion components when the collective dynamics takes place. That a non-additive entropy describes emotion dynamics, is further confirmed by computing the q-generalized Kolmogorov-Sinai entropy rate in the empirical data of chats as well as in the simulations of interacting emotional agents and Bots.

Hydration and dynamic state of nanoconfined polymer layers govern toughness in nacre-mimetic nanocomposites

Abstract: Funded by: Graduate School for Materials Physics, Emil Aaltonen Foundation, and Academy of Finland.

The Rise and Fall of Crowdsourcing

Abstract: Crowdsourcing has been discussed both in academic and managerial articles in recent years. Despite some critical voices, the overall attitude towards crowdsourcing has been quite positive in extant literature. In this paper we want to address potential drawbacks and issue that create shadows on top of crowdsourcing. The overall purpose of this paper is to discuss the reasons why crowdsourcing initiatives may not always live up to the expectations placed upon them. Despite some seemingly successful case examples, not every crowdsourcing initiative has taken off. While some of the barriers are case or industry specific, there are also certain overall reasons hindering crowdsourcing from reaching de facto modus operandi, especially in the innovation creation context. This paper is intentionally written through a critical lens by design and hopefully provides a constructive balance for those with an overly positive approach towards crowdsourcing.

Open Data Services: Research Agenda

Abstract: Open data promises an increased availability of previously private, mostly , governmental datasets for service development. However, research on the topic is only starting to surface. In this article we propose a research agenda for open data service research. We review earlier relevant literature to extrapolate open data as a phenomenon from the perspective of the information systems field. Based on a classification of research challenges, we build a research agenda, and outline a set of research questions. We contribute to the discussion on future avenues for research on open data in IS.

Data Processing and Quality Evaluation of a Boat-Based Mobile Laser Scanning System

Abstract: Mobile mapping systems (MMSs) are used for mapping topographic and urban features which are difficult and time consuming to measure with other instruments. The benefits of MMSs include efficient data collection and versatile usability. This paper investigates the data processing steps and quality of a boat-based mobile mapping system (BoMMS) data for generating terrain and vegetation points in a river environment. Our aim in data processing was to filter noise points, detect shorelines as well as points below water surface and conduct ground point classification. Previous studies of BoMMS have investigated elevation accuracies and usability in detection of fluvial erosion and deposition areas. The new findings concerning BoMMS data are that the improved data processing approach allows for identification of multipath reflections and shoreline delineation. We demonstrate the possibility to measure bathymetry data in shallow (0–1 m) and clear water. Furthermore, we evaluate for the first time the accuracy of the BoMMS ground points classification compared to manually classified data. We also demonstrate the spatial variations of the ground point density and assess elevation and vertical accuracies of the BoMMS data.

Using group delay functions from all-pole models for speaker recognition

Abstract: Popular features for speech processing, such as mel-frequency cepstral coefficients (MFCCs), are derived from the short-term magnitude spectrum, whereas the phase spectrum remains unused. While the common argument to use only the magnitude spectrum is that the human ear is phase-deaf, phase-based features have remained less explored due to additional signal processing difficulties they introduce. A useful representation of the phase is the group delay function, but its robust computation remains difficult. This paper advocates the use of group delay functions derived from parametric all-pole models instead of their direct computation from the discrete Fourier transform. Using a subset of the vocal effort data in the NIST 2010 speaker recognition evaluation (SRE) corpus, we show that group delay features derived via parametric all-pole models improve recognition accuracy, especially under high vocal effort. Additionally, the group delay features provide comparable or improved accuracy over conventional magnitude-based MFCC features. Thus, the use of group delay functions derived from all-pole models provide an effective way to utilize information from the phase spectrum of speech signals. Index Terms: speaker verification, group delay functions, high vocal effort

Success Factors of Open Innovation - A Literature Review

Abstract: This paper reviews the research on the open innovation process in order to identify critical success factors. The study consists of a systematic review of 29 referred empirical articles on the open innovation process. The studies reviewed highlight different success factors for the open innovation process. These factors are grouped into nine themes: 1) relational aspects, 2) the people involved in the process, 3) governance, 4) facilitators, 5) provision of resources, 6) strategy, 7) process management, 8) leadership and 9) culture. Based upon the findings, the study proposes a number of future research directions that may stimulate more intensive investigation of this field.

3D Modeling of Coarse Fluvial Sediments Based on Mobile Laser Scanning Data

Abstract: High quality sedimentary measurements are required for studying fluvial geomorphology and hydrological processes e.g., flood and river dynamics. Mobile laser scanning (MLS) currently provides the opportunity to achieve high precision measurements of coarse fluvial sediments in a large survey area. Our study aims to investigate the capability of single-track MLS data for individual particle-based sediment modeling. Individual particles are firstly detected and delineated from a digital surface model (DSM) that is generated from the MLS data. 3D MLS points of each detected individual particle are then extracted from the point cloud. The grain size and the sphericity as well as the orientation of each individual particle are estimated based on the extracted MLS points. According to the evaluations conduced in the paper, it is possible to detect and to model sediment particles above 63 mm from a single-track MLS point cloud with a high reliability. The paper further discusses the strength and the challenges of individual particle-based approach for sedimentary measurement.

New Levels of Climate Adaptation Policy: Analyzing the Institutional Interplay in the Baltic Sea Region

Abstract: International policy development and expected climate change impacts such as flooding, landslides, and the extinction of sensitive species have forced countries around the Baltic Sea to begin working on national climate adaptation policies. Simultaneously, the EU is building both a central and a macro-regional Baltic Sea-wide adaptation strategy to support national policy developments. However, it yet remains unclear how these EU strategies will complement each other or national policies. This article analyzes the constraints and opportunities presented by this new institutional interplay and discusses the potential of the forthcoming EU strategies to support national policy. It does so by mapping how adaptation is institutionalized in two case countries, Sweden and Finland, and is organized in the two EU approaches. The vertical institutional interplay between scales is analyzed in terms of three factors: competence, capacity, and compatibility. Results indicate institutional constraints related to: risks of policy complexity for sub-national actors, an unclear relationship between the two EU approaches, an overly general approach to targeting contextualized climate change vulnerabilities, and a general lack of strategies to steer adaptation. However, there are also opportunities linked to an anticipated increased commitment to the national management of adaptation, especially related to biodiversity issues.

Pressure oxidation of pyrite-arsenopyrite refractory gold concentrate

Abstract: Refractory gold ores have poor gold recoveries with direct cyanide leaching. Typically the refractoriness is due to encapsulation of the gold particles inside the host mineral. To liberate gold for leaching the host mineral must be broken by mechanical or chemical means. The aim of this study was to study the effect of temperature, oxygen partial pressure and slurry density on pressure oxidation of pyrite- arsenopyrite gold concentrate. Batch oxidation tests in an autoclave were done using a factorial design. Different responses were measured and analysed to study effect of the three factors and oxidation kinet- ics. Generally, high slurry density required high temperature and oxygen partial pressure to reach com- plete oxidation. Oxidation kinetics at 225°C temperature, with 1050 kPa oxygen partial pressure and 15% slurry density was found to be fastest resulting in complete conversion of sulfides in 30 minutes. At 195°C, 700 kPa oxygen partial pressure and 10% slurry density, the oxidation kinetics for complete sul- fide conversion was about 60 minutes. Slurry densities above 10% had an adverse effect on the oxidation rate, when the temperature was below 225°C and oxygen partial pressure below 1050 kPa.

HTML 5 in Mobile Devices -- Drivers and Restraints

Abstract: Application stores have played a crucial role in the proliferation of applications for smart phones and other mobile devices. However, web-based mobile applications are challenging the application store model by allowing developers to directly reach the end users. These web-based applications are enhanced by the HTML5 standard, which provides additional capabilities for the use of developers and brings the performance of mobile web applications closer to that of native applications. In this paper, we analyze the potential of HTML5 and identify drivers and restraints that affect the future of the technology.

Ionically interacting nanoclay and nanofibrillated cellulose lead to tough bulk nanocomposites in compression by forced self-assembly

Abstract: Several approaches have recently been shown for self-assembled biomimetic composite films, aiming at combinations of high toughness, strength, and stiffness. However, it remains challenging to achieve high toughness using simple processes especially for bulk materials. We demonstrate that ionically interacting cationic native nanofibrillated cellulose (C-NFC) and anionic nanoclay, i.e. montmorillonite (MTM), allow local self-assemblies by a simple centrifugation process to achieve 3D bulk materials. The composite with MTM/C-NFC of 63/37 w/w has a high compressive strain to failure of 37% with distinct plastic deformation behaviour, a high work to fracture of 23.1 MJ m−3, and a relatively high compression strength of 76 MPa. Unlike the conventionally used sequential deposition methods to achieve well-defined layers for the oppositely charged units as limited to films, the present one-step method allows quick formation of bulk materials and leads to local self-assemblies, however, having a considerable amount of nanovoids and defects between them. We suggest that the nanovoids and defects promote the plastic deformation and toughness. Considering the simple preparation method and bio-based origin of NFC, we expect that the present tough bulk nanocomposites in compression have potential in applications for sustainable and environmentally friendly materials in construction and transportation.

Influence of aluminium doping on thermoelectric performance of atomic layer deposited ZnO thin films

Abstract: We study the effect of Al doping on thermoelectric power factor of ZnO films grown using atomic layer deposition method. The overall doping level is tuned by either varying the precursor pulsing sequence or by varying the number of precursor pulses while keeping the sequence unchanged. We observe that commonly utilized doping approach when periodic dopant layers are densely packed results in reduced power factor. At the same time, we find that thermoelectric performance can be improved by clustering the dopants. In addition, the clustering was found to tune the preferred crystal orientation of the polycrystalline film.

HMM-based synthesis of creaky voice

Abstract: Creaky voice, also referred to as vocal fry, is a voice quality frequently produced in many languages, in both read and conversational speech. To enhance the naturalness of speech synthesis, these latter should be able to generate speech in all its expressive diversity, including creaky voice. The present study looks to exploit our recent developments, including creaky voice detection, prediction of creaky voice from context, and rendering of creaky excitation, into a fully functioning and automatic HMMbased synthesis system. HMM-based synthetic creaky voices are built and evaluated in subjective listening tests, which show that the best synthetic creaky voices are rated more natural and more creaky compared to a conventional voice. A non-creaky voice is also successfully transformed to use creak by modifying the F0 contour and excitation of the predicted creaky parts. The transformed voice is rated equal in terms of naturalness and clearly more creaky compared to the original voice. Index Terms: speech synthesis, creaky voice, contextual factors, F0 estimation, excitation modeling

Reduction of Internal Reflections in Integrated Lens Antennas for Beam-Steering

Abstract: The conventional integrated lens antennas (ILAs) for beam steering sufier from internal re∞ections that deteriorate the scanning properties. The internal re∞ections are known to afiect side lobes, cross-polarisation level, input impedance of the feed, and mutual coupling. In this paper, ILAs are designed to exhibit very low re∞ection loss, i.e., to minimize the internal re∞ections. Wide ranges of realistic relative permittivities of the lens and of the feed element directivities are considered. It is shown that with any permittivity and with any feed directivity it is possible to design the lens shape in such a way that the re∞ection loss is low, for moderate beam-steering angles, without resorting to a complicated matching layer. The gain, directivity, beam-width, and the resulting distance between the feed elements are compared for all the designed lenses.

Analysis and synthesis of shouted speech

Abstract: In this study, the acoustic properties of shouted speech are analyzed in relation to normal speech, and various synthesis techniques for shouting are investigated. The analysis shows large differences between the two styles, which induces difficulties in synthesis. Analysis-synthesis experiments show that the use of spectral estimation methods that are not biased by the sparse harmonics of shouted speech is beneficial. The synthesis of shouting is performed through adaptation and voice conversion. Subjective evaluation of synthesis reveals that, despite quality degradation, the impression of shouting and use of vocal effort is fairly well preserved. In addition, the use of specific spectral estimation methods is found to be beneficial also in adaptation. Index Terms: shouting, speech analysis, speech synthesis

Towards an improved understanding of stakeholder dynamics during the project front-end: the case of nuclear waste repository projects

Abstract: The importance of project stakeholder management and dynamics is emphasized in nuclear power field where stakeholders’ negative attitude towards a project can severely endanger the achievement of project’s objectives. The aim of this paper is to enrich our understanding of stakeholder dynamics during the project’s front-end stage – a research area which clearly merits from further empirical research. The study focuses on the examination of stakeholder dynamics of two pioneering nuclear repository projects, Onkalo in Finland and Yucca Mountain in USA during the project front-end stage. In order to systematically analyze changes in stakeholders’ importance and position, a salience-position matrix is developed in the study. This framework is believed to be of practical use for project managers when analyzing the needs and concerns of different stakeholders during the early feasibility and conceptual design stages of projects. Furthermore, the results of the study are valuable for project stakeholder research, since prior stakeholder literature has rarely conceptualized stakeholder dynamics and the elements of stakeholder dynamism in a systematic manner.