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Showing papers by "Helsinki University of Technology published in 2011"


Journal ArticleDOI
TL;DR: While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.
Abstract: Development of durable non-wetting surfaces is hindered by the fragility of the microscopic roughness features that are necessary for superhydrophobicity. Mechanical wear on superhydrophobic surfaces usually shows as increased sticking of water, leading to loss of non-wettability. Increased wear resistance has been demonstrated by exploiting hierarchical roughness where nanoscale roughness is protected to some degree by large scale features, and avoiding the use of hydrophilic bulk materials is shown to help prevent the formation of hydrophilic defects as a result of wear. Additionally, self-healing hydrophobic layers and roughness patterns have been suggested and demonstrated. Nevertheless, mechanical contact not only causes damage to roughness patterns but also surface contamination, which shortens the lifetime of superhydrophobic surfaces in spite of the self-cleaning effect. The use of photocatalytic effect and reduced electric resistance have been suggested to prevent the accumulation of surface contaminants. Resistance to organic contaminants is more challenging, however, oleophobic surface patterns which are non-wetting to organic liquids have been demonstrated. While the fragility of superhydrophobic surfaces currently limits their applicability, development of mechanically durable surfaces will enable a wide range of new applications in the future.

915 citations


Journal ArticleDOI
TL;DR: The different scaffolds that are used as stabilizer for silver nanoclusters (e.g. polymers, dendrimers, DNA oligomers, cryogenic noble gas matrixes, inorganic glasses, zeolites and nanoparticles) are overviewed.
Abstract: Silver nanoclusters are a class of fluorophores with attractive features, including brightness, photostability and subnanometer size. In this review we overview the different scaffolds that are used as stabilizer for silver nanoclusters (e.g. polymers, dendrimers, DNA oligomers, cryogenic noble gas matrixes, inorganic glasses, zeolites and nanoparticles), and we briefly discuss the recent advances.

747 citations


Journal ArticleDOI
TL;DR: High-porosity TEMPO-oxidized NFC nanopaper prepared by critical point drying has a specific surface area as high as 482 m(2) g(-1), which is better than for many thermoplastics, but at a significantly lower density.

427 citations


Journal ArticleDOI
TL;DR: Clay nanopaper extends the property range of cellulose nanopaper and is of interest in self-extinguishing composites and in oxygen barrier layers and in fire retardance and oxygen permeability characteristics were measured.

380 citations


Journal ArticleDOI
TL;DR: In this paper, the development of children's mobility in Denmark, Finland, Great Britain and Norway is compared to examine differences and similarities in these countries, and the trends are the same in these four countries, an increase in car use and decrease in bicycling and walking.

296 citations


Journal ArticleDOI
19 Jan 2011-Langmuir
TL;DR: It is demonstrated that superHydrophobic and superoleophobic nanocellulose aerogels, consisting of fibrillar networks and aggregates with structures at different length scales, support considerable load on a water surface and also on oils as inspired by floatation of insects on water due to their superhydrophobic legs.
Abstract: We demonstrate that superhydrophobic and superoleophobic nanocellulose aerogels, consisting of fibrillar networks and aggregates with structures at different length scales, support considerable load on a water surface and also on oils as inspired by floatation of insects on water due to their superhydrophobic legs. The aerogel is capable of supporting a weight nearly 3 orders of magnitude larger than the weight of the aerogel itself. The load support is achieved by surface tension acting at different length scales: at the macroscopic scale along the perimeter of the carrier, and at the microscopic scale along the cellulose nanofibers by preventing soaking of the aerogel thus ensuring buoyancy. Furthermore, we demonstrate high-adhesive pinning of water and oil droplets, gas permeability, light reflection at the plastron in water and oil, and viscous drag reduction of the fluorinated aerogel in contact with oil. We foresee applications including buoyant, gas permeable, dirt-repellent coatings for miniature sensors and other devices floating on generic liquid surfaces.

285 citations


Journal ArticleDOI
TL;DR: In this article, a new elastic viscoplastic model, extended from the overstress theory of Perzyna, is developed to account for inherent and induced anisotropy, interparticle bonds and bond degradation, and viscosity.
Abstract: The paper focuses on investigating the destructuration process during time-dependent stress-strain evolution. For this purpose, various oedometer tests and triaxial tests on intact and reconstituted samples of soft sensitive Vanttila clay were carried out. Based on experimental observations, a new elastic viscoplastic model, extended from the overstress theory of Perzyna, is developed. The proposed model accounts for inherent and induced anisotropy, interparticle bonds and bond degradation, and viscosity. The determination of model parameters is discussed, demonstrating how all model parameters can be determined in a straightforward way and no additional test is needed for the proposed model compared to the modified Cam clay model. The model is implemented into a finite-element code, which enables coupled consolidation analyses. The model is used to simulate various strain-rate and creep tests under one-dimensional and triaxial conditions on the intact samples of Vanttila clay. The comparisons between experimental results and simulations show that the model has good predictive ability on the time-dependent behavior of a soft sensitive clay.

227 citations


Proceedings Article
14 Sep 2011
TL;DR: A framework for evaluating and designing game design patterns commonly called as “achievements” is presented, based on empirical studies of a variety of popular achievement systems.
Abstract: This paper presents a framework for evaluating and designing game design patterns commonly called as “achievements”. The results are based on empirical studies of a variety of popular achievement systems. The results, along with the framework for analyzing and designing achievements, present two definitions of game achievements. From the perspective of the achievement system, an achievement appears as a challenge consisting of a signifying element, rewards and completion logics whose fulfilment conditions are defined through events in other systems (usually games). From the perspective of a single game, an achievement appears as an optional challenge provided by a meta-game that is independent of a single game session and yields possible

214 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examine the interpretation processes through which project management teams come to know their external stakeholder environment and identify distinctive interpretation modes of external stake-holder environments in four international projects.

208 citations


Journal ArticleDOI
TL;DR: A simple yet effi cient approach for droplet transport is demonstrated, in which the droplet is moving on a superhydrophobic surface, using gravity or electrostatic forces as the driving force for droplets transportation and using tracks with vertical walls as gravitational potential barriers to design trajectories.
Abstract: anti-fogging, [ 6 ] anti-icing, [ 7 ] buoyancy [ 8 ] and drag reduction. [ 9 ] By defi nition, a surface is superhydrophobic if the contact angle between a water drop and the surface at the solid/liquid/air interface is larger than 150 ° , and the contact angle hysteresis is small, i.e., drops readily slide or roll off when the surface is tilted slightly. [ 10–12 ] Here we explore the feasibility of using superhydrophobicity for guided transport of water droplets. We demonstrate a simple yet effi cient approach for droplet transport, in which the droplet is moving on a superhydrophobic surface, using gravity or electrostatic forces as the driving force for droplet transportation and using tracks with vertical walls as gravitational potential barriers to design trajectories. Although the slope of the platform is as small as a few degrees, the drops move at a considerable speed up to 14 cm s − 1 , even in highly curved trajectories. We further demonstrate splitting of a droplet using a superhydrophobic knife and drop-size selection using superhydrophobic tracks. These concepts may fi nd applications in droplet microfl uidics and lab-on-a-chip systems where single droplets with potential analytes are manipulated. [ 13–16 ]

203 citations


Proceedings Article
01 Jan 2011
TL;DR: This paper proposes an alternative PLS marker variable approach for analyzing data contaminated with method variance and provides simulation evidence for the validity of this new approach.
Abstract: Partial least squares (PLS) path modeling has been adopted as part of the statistical toolbox of many information systems (IS) scholars, particularly when dealing with survey data. Since these data are susceptible to common method variance, several statistical approaches for diagnosing and controlling for this undesirable feature have been developed. While most of these statistical techniques are only applicable to structural equation modeling (SEM), Liang, Saraf, Hu, and Xue (2007) proposed how one of these techniques can be used with PLS analysis. Since this was the first time that a method for controlling common method variance had been made available for PLS users, the method of Liang et al. quickly gained popularity in IS journals. However, recent analysis on the Liang et all approach shows that the method does neither detect nor control for common method variance. In this paper, we propose an alternative PLS marker variable approach for analyzing data contaminated with method variance and provide simulation evidence for the validity of this new approach.

01 Jan 2011
TL;DR: This paper presents a documentation for an optimal filtering toolbox for the mathematical software package Matlab, which features many filtering methods for discrete-time state space models, including the well-known linear Kalman filter and several non-linear extensions to it.
Abstract: In this paper we present a documentation for an optimal filtering toolbox for the mathematical software package Matlab. The toolbox features many filtering methods for discrete-time state space models, including the well-known linear Kalman filter and several non-linear extensions to it. These non-linear methods are the extended Kalman filter, the unscented Kalman filter, the Gauss-Hermite Kalman filter and the third-order symmetric cubature Kalman filter. Algorithms for multiple model systems are provided in the form of an Interacting Multiple Model (IMM) filter and it’s non-linear extensions, which are based on banks of extended and unscented Kalman filters. Also included in the toolbox are the Rauch-TungStriebel and two-filter smoother counter-parts for the filters, which can be used to smooth the previous state estimates, after obtaining new measurements. The usage and function of each method is illustrated with eight demonstration problems.

Journal ArticleDOI
TL;DR: In this paper, the formation energies of various intrinsic defects and defect complexes in ZnO have been calculated using a density-functional-theory-based pseudopotential all-electron method.
Abstract: Formation energies of various intrinsic defects and defect complexes in ZnO have been calculated using a density-functional-theory-based pseudopotential all-electron method. The various defects considered are oxygen vacancy (${\mathrm{V}}_{\mathrm{O}}$), zinc vacancy (${\mathrm{V}}_{\mathrm{Zn}}$), oxygen at an interstitial site (${\mathrm{O}}_{i}$), Zn at an interstitial site (${\mathrm{Zn}}_{i}$), Zn at ${\mathrm{V}}_{\mathrm{O}}$ (${\mathrm{Zn}}_{\mathrm{O}}$), O at ${\mathrm{V}}_{\mathrm{Zn}}$(${\mathrm{O}}_{\mathrm{Zn}}$), and an antisite pair (combination of the preceding two defects). In addition, defect complexes like (${\mathrm{V}}_{\mathrm{O}}+{\mathrm{Zn}}_{i}$) and Zn-vacancy clusters are studied. The Schokkty pair (${\mathrm{V}}_{\mathrm{O}}+{\mathrm{V}}_{\mathrm{Zn}}$) and Frenkel pairs [(${\mathrm{V}}_{\mathrm{O}}+{\mathrm{O}}_{i}$) and (${\mathrm{V}}_{\mathrm{Zn}}+{\mathrm{Zn}}_{i}$)] are considered theoretically for the first time. Upon comparing the formation energies of these defects, we find that ${\mathrm{V}}_{\mathrm{O}}$ would be the dominant intrinsic defect under both Zn-rich and O-rich conditions and it is a deep double donor. Both ${\mathrm{Zn}}_{\mathrm{O}}$ and ${\mathrm{Zn}}_{i}$ are found to be shallow donors. The low formation energy of donor-type intrinsic defects could lead to difficulty in achieving $p$-type conductivity in ZnO. Defect complexes have charge transitions deep inside the band gap. The red, yellow, and green photoluminescence peaks of undoped samples can be assigned to some of the defect complexes considered. It is believed that the red luminescence originates from an electronic transition in ${\mathrm{V}}_{\mathrm{O}}$, but we find that it can originate from the antisite ${\mathrm{Zn}}_{\mathrm{O}}$ defect. Charge density and electron-localization function analyses have been used to understand the effect of these defects on the ZnO lattice. The electronic structure of ZnO with intrinsic defects has been studied using density-of-states and electronic band structure plots. The acceptor levels introduced by ${\mathrm{V}}_{\mathrm{Zn}}$ are relatively localized, making it difficult to achieve $p$-type conductivity with sufficient hole mobility.

Journal ArticleDOI
TL;DR: This work shows the feasibility of genetically engineered proteins having two well-defined binding blocks, denoted as diblock proteins, that bind and assemble the structural components for biomimetic composites.
Abstract: Nature has materials with extraordinary stiffness, strength, and toughness that is based on aligned, tailored self-assemblies. They have inspired biomimetic nanocomposites with drastically better properties than synthetic composites. Herein we show a new approach to making biomimetic nanocomposites based on the exfoliation of graphite into a matrix of genetically engineered proteins and native nanofibrillated cellulose. The protein was genetically engineered to incorporate a hydrophobin block, which binds to graphene, and a cellulose-binding block, which binds to nanofibrillated cellulose, thereby bringing about both the self-assembly and adhesion between the nanoscale components. The aligned co-assembly leads to remarkably good mechanical properties (modulus: 20.2 GPa, strength: 278 MPa, strain-to-failure: 3.1 %, and work-of-fracture 57.9 kJ m ). The bifunctional protein was crucial for the excellent mechanical properties. This concept shows how high-performance biomimetic composites can be built through the binding and self-assembly of advanced biomolecules that have been genetically tailored. Biology shows numerous composite materials wherein aligned hard and soft self-assembled components are bound together to result in excellent mechanical properties such as the combination of toughness, strength, and stiffness. Such materials are, for example, nacre, plant tissue, bone, silk, and tendon. Factors contributing to their advantageous properties include the chemical nature of the hard-reinforcing and soft-dissipating components, their molecular interactions, their mechanical interlocking, dimensions, and alignment, which contributes to the mechanics of crack propagation. The soft matrix is especially interesting as it acts as glue that keeps the hard components together and allows dissipation of fracture energy. Still, very little is known about, for example, how the matrix proteins of nacre function. A rational route towards a controlled interconnectivity between the self-assembled domains in biomimetic composites is suggested by the design principles of block copolymers, which are used in materials science, for example, to interface two different polymers in mixtures or to stabilize colloidal systems, even for responses or functions. In this work we show the feasibility of genetically engineered proteins having two well-defined binding blocks, denoted as diblock proteins, that bind and assemble the structural components for biomimetic composites. Previously we have shown that the adhesive surfactantlike proteins, hydrophobins, allow exfoliation of graphite to give singleor few-layer flakes of graphene in aqueous solutions. Here, the same route to disperse singleor fewlayer flakes of graphene using proteins in a cellulose matrix was employed to form biomimetic nanocomposite materials. The dispersions of the singleor few-layer flakes of graphene are referred to herein simply as graphene dispersions, although there may be a range of flake thicknesses present. A genetically modified hydrophobin was used to combine graphene and native nanofibrillated cellulose (NFC), also called nanocellulose or microfibrillated cellulose. The structure of the resulting composite resembles that of nacre where self-assembled, aligned platelet-like aragonite reinforcements are embedded in a protein matrix containing nanofibrillar chitin. By using engineered molecules that contain unusual combinations of binding abilities, it is possible to build composites from components that do not occur in natural materials. This technique allowed us to combine flakes of graphene, one of the strongest materials presently known, and nanofibrillated cellulose having a modulus approaching the one of steel 16] in a nanocomposite material. The protein was genetically engineered to connect graphene and NFC, so that it self-assembles at the interfaces, thus leading to cohesion and alignment (Figure 1 a). Binding to graphene was achieved by a hydrophobin, more specifically the class II hydrophobin HFBI, which self-assembles on various interfaces and surfaces, including graphene. Binding to cellulose was achieved by using a protein denoted as a cellulose-binding domain (CBD) found in cellulose[*] Dr. P. Laaksonen, J.-M. Malho, Prof. M. B. Linder Nanobiomaterials, VTT Technical Research Centre of Finland P.O. Box 1000, 02044 VTT (Finland) E-mail: paivi.laaksonen@vtt.fi Homepage: http://www.vtt.fi/research/technology/nanobiotechnology.jsp

Journal ArticleDOI
TL;DR: Native cellulose nanofibers are functionalized using luminescent metal nanoclusters to form a novel type of functional nanocellulose/nanocluster composite, leading to composites with fluorescence and antibacterial activity.
Abstract: Native cellulose nanofibers are functionalized using luminescent metal nanoclusters to form a novel type of functional nanocellulose/nanocluster composite. Previously, various types of cellulose fibers have been functionalized with large, non-luminescent metal nanoparticles. Here, mechanically strong native cellulose nanofibers, also called nanofibrillatedcellulose (NFC), microfibrillatedcellulose (MFC) ornanocellulose, disintegrated from macroscopic cellulose pulp fibers are used as support for small and fluorescent silver nanoclusters. The functionalization occurs in a supramolecular manner, mediated by poly(methacrylic acid) that protects nanoclusters while it allows hydrogen bonding with cellulose, leading to composites with fluorescence and antibacterial activity.

Journal Article
TL;DR: This paper illustrates the situations where standard EP fails to converge and review different modifications and alternative algorithms for improving the convergence and demonstrates that convergence problems may occur during the type-II maximum a posteriori (MAP) estimation of the hyperparameters.
Abstract: This paper considers the robust and efficient implementation of Gaussian process regression with a Student-t observation model, which has a non-log-concave likelihood. The challenge with the Student-t model is the analytically intractable inference which is why several approximative methods have been proposed. Expectation propagation (EP) has been found to be a very accurate method in many empirical studies but the convergence of EP is known to be problematic with models containing non-log-concave site functions. In this paper we illustrate the situations where standard EP fails to converge and review different modifications and alternative algorithms for improving the convergence. We demonstrate that convergence problems may occur during the type-II maximum a posteriori (MAP) estimation of the hyperparameters and show that standard EP may not converge in the MAP values with some difficult data sets. We present a robust implementation which relies primarily on parallel EP updates and uses a moment-matching-based double-loop algorithm with adaptively selected step size in difficult cases. The predictive performance of EP is compared with Laplace, variational Bayes, and Markov chain Monte Carlo approximations.

Journal ArticleDOI
TL;DR: In this article, the authors classified the rating curves on the basis of the synchronous nature of the suspended sediment concentration (SSC) and the water discharge among the adjacent stations (e.g. Chiang Saen, Luang Prabang, Nong Khai, Mukdahan and Khong Chiam).
Abstract: Although sediment issues have critical implications for aquatic ecology, agriculture, water supply and river navigation, studies regarding the sediment production, deposition and transportation in the Lower Mekong River are relatively sparse. With the construction and operation of dams in the Upper Mekong River, this issue has attracted more attention in recent years. The estimation of sediment loads has been hindered by the serious lack of sediment measurements in the Lower Mekong River. This study aimed to investigate the possibility of estimating the sediment loads for the years without good quality SSC measurements in the Lower Mekong River. To make this estimate, this study classified the rating curves on the basis of the synchronous nature of the suspended sediment concentration (SSC) and the water discharge among the adjacent stations (e.g. Chiang Saen, Luang Prabang, Nong Khai, Mukdahan and Khong Chiam). Together with other methods, it was possible to estimate the yearly sediment loads for the period of 1962–2003 at the five mainstream Lower Mekong River stations. Consequently, the spatial and temporal variations in the sediment loads and water discharge in the Lower Mekong River were examined. In addition, the possible impacts of Chinese dams as well as the annual sediment load of the Mekong River into the sea were also investigated. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the maximum power limits for high-speed permanent-magnet (PM) electrical machines for air compressor applications are determined in the speed range 20000-100000 r/min.
Abstract: The maximum-power limits for high-speed permanent-magnet (PM) electrical machines for air compressor applications are determined in the speed range 20000-100000 r/min. For this purpose, five PM machines are designed and the electromagnetic, thermal, and mechanical designs of each machine are simultaneously performed. The critical values of the thermal and mechanical constraints are considered in order to obtain the maximum powers of the electrical machines. The electromagnetic losses generated in the machine are the output parameters of the electromagnetic design and input parameters for the thermal design. The thermal design is performed using a multiphysics method, which couples computational-fluid-dynamics equations with heat-transfer equations. The mechanical design considers the retention of the rotor elements against the huge centrifugal forces that arise during the high-speed operation and also the rotor dynamics properties of the rotor. The reliability of these design techniques is experimentally validated in the paper. The obtained maximum-power limit defines the speed-power region, in which the high-speed PM electrical machines intended for compressor applications can have a safe operation.

Journal ArticleDOI
TL;DR: Voxel-based morphometry showed that increased AQ scores were associated with decreased white matter volume in the posterior superior temporal sulcus, a region important in processing socially relevant stimuli and associated with structural and functional impairments in ASD.
Abstract: Autism spectrum disorders (ASDs) are typically characterized by impaired social interaction and communication, narrow interests, and repetitive behaviors. The heterogeneity in the severity of these characteristics across individuals with ASD has led some researchers to suggest that these disorders form a continuum which extends into the general, or “typical,” population, and there is growing evidence that the extent to which typical adults display autistic traits, as measured using the autism-spectrum quotient (AQ), predicts performance on behavioral tasks that are impaired in ASD. Here, we show that variation in autism spectrum traits is related to cortical structure and function within the typical population. Voxel-based morphometry showed that increased AQ scores were associated with decreased white matter volume in the posterior superior temporal sulcus (pSTS), a region important in processing socially relevant stimuli and associated with structural and functional impairments in ASD. In addition, AQ was correlated with the extent of cortical deactivation of an adjacent area of pSTS during a Stroop task relative to rest, reflecting variation in resting state function. The results provide evidence that autism spectrum characteristics are reflected in neural structure and function across the typical (non-ASD) population.

Journal ArticleDOI
14 Apr 2011-Langmuir
TL;DR: This study analyzes Langmuir-Blodgett films of asphaltenes and related model compounds with sum frequency generation (SFG) vibrational spectroscopy to demonstrate robust determination of functional group orientations.
Abstract: Asphaltenes are an important class of compounds in crude oil whose surface activity is important for establishing reservoir rock wettability which impacts reservoir drainage. While many phenomenological interfacial studies with crude oils and asphaltenes have been reported, there is very little known about the molecular level interactions between asphaltenes and mineral surfaces. In this study, we analyze Langmuir-Blodgett films of asphaltenes and related model compounds with sum frequency generation (SFG) vibrational spectroscopy. In SFG, the polarization of the input (vis, IR) and output (SFG) beams can be varied, which allows the orientation of different functional groups at the interface to be determined. SFG clearly indicates that asphaltene polycyclic aromatic hydrocarbons (PAHs) are highly oriented in the plane of the interface and that the peripheral alkanes are transverse to the interface. In contrast, model compounds with oxygen functionality have PAHs oriented transverse to the interface. Computational quantum chemistry is used to support corresponding band assignments, enabling robust determination of functional group orientations.

Journal ArticleDOI
TL;DR: The capability of MLS in erosion change mapping on a test site located in a 58 km-long tributary of the River Tenojoki (Tana) in the sub-arctic is demonstrated.
Abstract: Laser measurements have been used in a fluvial context since 1984, but the change detection possibilities of mobile laser scanning (MLS) for riverine topography have been lacking. This paper demonstrates the capability of MLS in erosion change mapping on a test site located in a 58 km-long tributary of the River Tenojoki (Tana) in the sub-arctic. We used point bars and river banks as example cases, which were measured with the mobile laser scanner ROAMER mounted on a boat and on a cart. Static terrestrial laser scanner data were used as reference and we exploited a difference elevation model technique for describing erosion and deposition areas. The measurements were based on data acquisitions during the late summer in 2008 and 2009. The coefficient of determination (R2) of 0.93 and a standard deviation of error 3.4 cm were obtained as metrics for change mapping based on MLS. The root mean square error (RMSE) of MLS‑based digital elevation models (DEM) for non-vegetated point bars ranged between 2.3 and 7.6 cm after correction of the systematic error. For densely vegetated bank areas, the ground point determination was more difficult resulting in an RMSE between 15.7 and 28.4 cm.

Journal ArticleDOI
TL;DR: In this paper, the key issues for research and development that are common to current state-of-the-art MCFC and SOFC technologies are discussed by analyzing overlapping aspects regarding materials, operating conditions and applications of the two types of high-temperature fuel cell (HTFC).

Journal ArticleDOI
TL;DR: In this article, the authors discuss the potential of biomass as a renewable, low-CO2, and increasingly cost competitive alternative to traditional fossil fuels for heat and/or electric power generation.
Abstract: Biomass continues to attract much interest as a renewable, low-CO2, and increasingly cost competitive alternative to traditional fossil fuels for heat and/or electric power generation. At the same ...

Journal ArticleDOI
TL;DR: In this article, the contribution of the DMC to the total received power can vary as much as between 10% and 95%, being generally higher in non-line-of-sight (LOS) than in LOS scenarios.
Abstract: The dense multipath components (DMC) represent the part of the radio channel that cannot be characterized by using the specular components (SC). In this paper, the propagation characteristics of the DMC are analyzed in indoor environments based on extensive channel measurements. The results show that the contribution of the DMC to the total received power can vary as much as between 10% and 95%, being generally higher in non-line-of-sight than in line-of-sight scenarios. However, it was found that the DMC have a well distinguishable structure in the angular domain in all the investigated scenarios and, furthermore, the propagation mechanisms of the SC and DMC have large similarities. In addition, the effect of shadowing objects on the SC and DMC has been investigated.

Journal ArticleDOI
TL;DR: In this article, a consumption-based life cycle assessment of carbon emissions was performed in four different urban structure related lifestyles in Finland and the results showed that substantially more carbon emissions seem to be caused on a per capita level in cities than in suburban and rural areas.
Abstract: Sustainable consumption has been addressed from different perspectives in numerous studies. Recently, urban structure-related lifestyle issues have gained more emphasis in the research as cities search for effective strategies to reduce their 80% share of the global carbon emissions. However, the prevailing belief often seen is that cities would be more sustainable in nature compared to surrounding suburban and rural areas. This paper will illustrate, by studying four different urban structure related lifestyles in Finland, that the situation might be reversed. Actually, substantially more carbon emissions seem to be caused on a per capita level in cities than in suburban and rural areas. This is mainly due to the higher income level in larger urban centers, but even housing-related emissions seem to favor less urbanized areas. The method of the study is a consumption-based life cycle assessment of carbon emissions. In more detail, a hybrid life cycle assessment (LCA) model, that is comprehensive in providing a full inventory and can accommodate process data, is utilized.

Journal ArticleDOI
TL;DR: In this paper, the adsorption of different polysaccharides and cellulose derivatives on cellulose nanofibril films was compared using Quartz Crystal Microbalance with Dissipation (QCM-D).
Abstract: The objective of this work was to compare the adsorption of different polysaccharides and cellulose derivatives on cellulose nanofibril films. Cellulose films having the native cellulose I structure were prepared from hardwood kraft pulp by extensive mechanical disintegration. Further fractionation enabled the preparation of reproducible, nanometer-scale thickness films. Systematic comparison by Quartz Crystal Microbalance with Dissipation (QCM-D) showed that various industrially available galactomannans have almost as good affinity to cellulose surface as xyloglucan and that most of the polysaccharides attach irreversibly to cellulose nanofibrils at low pH (4.5) and intermediate ionic strength (10 mM). SPR results support the QCM-D findings. Atomic Force Microscopy (AFM) imaging and Digital Pulsed Force Mode (DPFM) measurements further confirmed that a uniform non-aggregated layer of polysaccharides was formed that changed the properties of the NFC film.

Journal ArticleDOI
TL;DR: A stage serves as an apt metaphor to explore the ways in which these ubiquitous screens can transform passive viewing into an involved performance.
Abstract: Framed digital displays will soon give way to walls and facades that creatively motivate individual and group interaction. A stage serves as an apt metaphor to explore the ways in which these ubiquitous screens can transform passive viewing into an involved performance.

Journal ArticleDOI
TL;DR: In this article, a consumption-based tiered hybrid life cycle assessment (LCA) approach is employed in order to produce a comprehensive assessment, free of territorial boundaries and system cutoffs typical of traditional LCAs.
Abstract: Hindering urban sprawl is one of the main goals for contemporary urban planning Urban density is considered crucial in climate change mitigation since it reduces automobile dependence and decreases unit sizes, for example This letter analyzes the effect of density in a city context In the study the Finnish capital Helsinki is divided into two areas of different urban densities: the high density downtown area and the more scarcely populated suburbs The study is a continuation of a recently published study on the implications of urban structure on carbon emissions, and analyzes further the main finding of the first study—that higher urban density might have negligible or even reverse effect on the per capita carbon emissions Similarly to the previous study, a consumption based tiered hybrid life cycle assessment (LCA) approach is employed in order to produce a comprehensive assessment, free of territorial boundaries and system cutoffs typical of traditional LCAs Based on the findings of the previous study, it is hypothesized that when assessing city level carbon dioxide emissions from a wider, consumer oriented LCA perspective, increased urban density may not necessarily reduce carbon emissions Surprisingly, the study finds that carbon dioxide equivalent (CO2e) emissions are substantially higher in the dense downtown area than in the surrounding suburbs, which is suggested to imply that the increased consumption due to the higher standard of living increases emissions more than the higher density is able to reduce them The results demonstrate that, while increasing urban density can be justified from a number of ecological, social and economic viewpoints, density is not necessarily a key parameter in the particular case of climate change In cities like Helsinki, where wealth is concentrated in the downtown area, climate policies should give higher priority to the energy consumption of buildings, to alternative energy production and distribution modes, as well as to low carbon consumption within the city

Journal ArticleDOI
TL;DR: In this article, the authors presented a generalized formulation for determining the optimal operating strategy and cost optimization scheme as well as reducing the emissions of a microgrid (MG) multiobjective optimization based on modified game theory is applied to the environmental economic problem of the MG.
Abstract: This paper presents a generalized formulation for determining the optimal operating strategy and cost optimization scheme as well as reducing the emissions of a microgrid (MG) Multiobjective (MO) optimization based on modified game theory is applied to the environmental economic problem of the MG The proposed problem is formulated as a nonlinear constrained MO optimization problem The proposed problem considers the operation and maintenance costs as well as the emissions reduction of NOx, SO2, and CO2 The MG considered in this paper consists of a wind turbine, a micro turbine, a diesel generator, a photovoltaic array, a fuel cell, and a battery storage The MO formulation is employed to minimize the cost function of the system while constraining it to meet the customer demand and safety of the system Three typical scenarios of MG operation are investigated A comparison is made with Multiobjective Sequential Quadratic Programming (MOSQP), Multiobjective Genetic Algorithms (MOGA) and Multiobjective Mesh Adaptive Direct Search (MOMADS) The results demonstrate the efficiency of the proposed approach to satisfy the load and to reduce the cost and the emissions Copyright © 2010 John Wiley & Sons, Ltd

Journal ArticleDOI
TL;DR: In this paper, the concept of multifunctional alkaline pulping has been proposed to produce high-purity and high-yield dissolving pulps, where the selective removal of hemicelluloses was achieved by either water autohydrolysis (PH) or alkaline extraction (E) both applied as pre-treatments prior to cooking.
Abstract: In this study, the concept of multifunctional alkaline pulping has been approved to produce high-purity and high-yield dissolving pulps. The selective removal of hemicelluloses was achieved by either water autohydrolysis (PH) or alkaline extraction (E) both applied as pre-treatments prior to cooking. Alternatively, hemicelluloses were isolated after oxygen delignification in a process step denoted as cold caustic extraction (CCE). Eucalyptus globulus wood chips were used as the raw material for kraft and soda-AQ pulping. In all process modifications sulfur was successfully replaced by anthraquinone. By these modifications purified dissolving pulps were subjected to TCF bleaching and comprehensive viscose and lyocell application tests. All pulps met the specifications for dissolving pulps. Further more, CCE-pulps showed a significantly higher yield after final bleaching. Morphological changes such as ultrastructure of the preserved outer cell wall layers, specific surface area and lateral fibril aggregate dimension correlated with the reduced reactivity towards regular viscose processing. The residual xylan after alkali purification depicted a lower content of functional groups and a higher molecular weight and was obviously entrapped in the cellulose fibril aggregates which render the hemicelluloses more resistant to steeping in the standard viscose process. Simultaneously, the supramolecular structure of the cellulose is partly converted from cellulose I to cellulose II by the alkaline purification step which did not influence the pulps reactivity significantly. Nevertheless, these differences in pulp parameters did not affect the lyocell process due to the outstanding solubility of the pulps in NMMO. Laboratory spinning revealed good fiber strength for both, regular viscose and lyocell fibers. The high molecular weight xylan of the CCE-treated pulps even took part in fiber forming.