Using passive techniques for vibration damping in mechanical systems

This paper examines two passive techniques for vibration reduction in mechanical systems: the first one is based on dynamic vibration absorbers (DVAs) and the second uses resonant circuit shunted (RCS) piezoceramics. Genetic algorithms are used to determine the optimal design parameters with respect to performance indexes, which are associated with the dynamical behavior of the system over selected frequency bands. The calculation of the frequency response functions (FRFs) of the composite structure (primary system + DVAs) is performed through a substructure coupling technique. A modal technique is used to determine the frequency response function of the structure containing shunted piezoceramics which are bonded to the primary structure. The use of both techniques simultaneously on the same structure is investigated. The methodology developed is illustrated by numerical applications in which the primary structure is represented by simple Euler-Bernoulli beams. However, the design aspects of vibration control devices presented in this paper can be extended to more complex structures.

Is there correlation between the turbulent eddies size and mechanical hemolysis ?

Hemolytic profile of an artificial device chronically implanted in the cardiovascular system may represent the difference between the success and failure in its long-term performance. Last decades have witnessed efforts on the development of methods capable of predicting red blood cell damage in artificial organs. However, all of them have had limited success to predict hemolysis. The primary cause of this problem is that such models do not take into consideration structures of turbulent flow. The present paper demonstrates that microscopic measurable occurrences of the turbulent flow may be linked to red blood cell trauma. This study suggests that if the smallest turbulent eddies dimension is under 10 m m hemolysis is not dependent on the exposure time and the red blood cells damage depends only on the dissipation of the turbulent energy in the erythrocyte membrane. The analysis reported here opens the possibility of mapping the flow field in artificial assist devices based on the smallest eddy length scales. This is a promising new trend and should be considered in the designing requirements of the next generations of artificial organs.

Effect of particle morphology on the mechanical and thermo-mechanical behavior of polymer composites

Fiber reinforced polymer composites have been used in many applications, such as in automobile, aerospace and naval industries, due basically to their high strength-to-weight and modulus-to-weight, among other properties. Even though particles are usually not able to lead to the level of reinforcement of fibers, particle reinforced polymer composites have been proposed for many new applications due to their low cost, easy fabrication and isotropic properties. In this work, polymer composites were prepared by incorporating glass particles of different morphologies on poly(aryl sulfones) matrices. Particles with aspect ratios equal to 1, 2.5 and 10 were used. The prepared composites were characterized using electron microscopy and thermal analysis. Mechanical properties of the composites were evaluated using a four-point bending test. The thermo-mechanical behavior of the obtained composites was also investigated. The results showed that the morphology of the particles alter significantly the mechanical properties of composites. Particles with larger values of aspect ratio led to large elastic modulus but low levels of strain at failure. This result was explained by modeling the thermo-mechanical behavior of the composites using a viscoelastic model. Parameters of the model, obtained from a Cole-Cole type of plot, demonstrated that interactions at the polymer-reinforcing agent interface were higher for composites with large aspect ratio particles. Higher levels of interactions at interfaces can lead to higher degrees of stress transfer and, consequently, to composites with large elastic modulus, as experimentally observed.

Surface Tension Implementation for Gensmac2d

In the present work we describe a method which allows the incorporation of surface tension into the GENSMAC2D code. This is achieved on two scales. First on the scale of a cell, the surface tension effects are incorporated into the free surface boundary conditions through the computation of the capillary pressure. The required curvature is estimated by fitting a least square circle to the free surface using the tracking particles in the cell and in its close neighbors. On a sub-cell scale, short wavelength perturbations are filtered out using a local 4-point stencil which is mass conservative. An efficient implementation is obtained through a dual representation of the cell data, using both a matrix representation, for ease at identifying neighbouring cells, and also a tree data structure, which permits the representation of specific groups of cells with additional information pertaining to that group. The resulting code is shown to be robust, and to produce accurate results when compared with exact solutions of selected fluid dynamic problems involving surface tension.

An Inspection System to Identify Fatigue Damage on Steel-Bridge Structures

Crack formation and growth in steel bridge structural elements may be due to loading oscillations. The welded elements are liable to internal discontinuities along welded joints and sensible to stress variations. The evaluation of the remaining life of a bridge is needed to make cost-effective decisions regarding inspection, repair, rehabilitation, and replacement. A steel beam model has been proposed to simulate crack openings due to cyclic loads. Two possible alternatives have been considered to model crack propagation, which the initial phase is based on the linear fracture mechanics. Then, the model is extended to take into account the elastoplastic fracture mechanic concepts. The natural frequency changes are directly related to moment of inertia variation and consequently to a reduction in the flexural stiffness of a steel beam. Thus, it is possible to adopt a nondestructive technique during steel bridge inspection to quantify the structure eigenvalue variation that will be used to localize the grown fracture. A damage detection algorithm is developed for the proposed model and the numerical results are compared with the solutions achieved by using another well know computer code.

Escape in a nonideal electro-mechanical system

In this work a particular system is investigated consisting of a pendulum whose point of support is vibrated along a horizontal guide by a two bar linkage driven from a DC motor, considered as a limited power source. This system is nonideal since the oscillatory motion of the pendulum influences the speed of the motor and vice-versa, reflecting in a more complicated dynamical process. This work comprises the investigation of the phenomena that appear when the frequency of the pendulum draws near a secondary resonance region, due to the existing nonlinear interactions in the system. Also in this domain due to the power limitation of the motor, the frequency of the pendulum can be captured at resonance modifying completely the final response of the system. This behavior is known as Sommerfeld effect and it will be studied here for a nonlinear system.

Indoor Localization Solutions for a Marine Industry Augmented Reality Tool

In this report are described means for indoor localization in special, challenging circum-stances in marine industry. The work has been carried out in MARIN project, where a tool based on mobile augmented reality technologies for marine industry is developed. The tool can be used for various inspection and documentation tasks and it is aimed for improving the efficiency in design and construction work by offering the possibility to visualize the newest 3D-CAD model in real environment. Indoor localization is needed to support the system in initialization of the accurate camera pose calculation and auto-matically finding the right location in the 3D-CAD model. The suitability of each indoor localization method to the specific environment and circumstances is evaluated.

Magnesium hydroxide-based peroxide bleaching of high-brightness mechanical pulps

A high final brightness is desired in most paper and board products. This requires bleaching processes that are able to produce high-brightness pulps. Mechanical pulps are widely bleached for high brightness using alkaline hydrogen peroxide with traditional sodium hydroxide and sodium silicate as additives. With high doses however, peroxide bleaching causes high organic loads in the mill effluent and anionic trash carry-over to papermaking. To alleviate the problems that arise from the use of sodium-based additives in peroxide bleaching, interest in the use of alternative magnesium-based chemicals has increased. In this study, a new, technical high-purity magnesium hydroxide-based bleaching additive was evaluated on laboratory-scale, pilot-scale and mill-scale experiments and trials for its ability to produce a high brightness in peroxide bleaching without the known problems of sodium-based chemicals. The key findings of this study include: a high brightening potential of peroxide bleaching using the Mg(OH)2-based additive, significant reductions (40-70%) in all categories of environmental load, and cationic demand lowered by 60-70% in bleached pulp with no loss in strength properties or in sheet bulk. When used in TMP refiner bleaching, the Mg(OH)2-based additive resulted in savings in specific energy consumption and provided a good bleaching response.

Communication Solutions for LVDC Island Networks

Production and generation of electrical power is evolving to more environmental friendly technologies and schemes. Pushed by the increasing cost of fossil fuels, the operational costs of producing electrical power with fossil fuels and the effect in the environment, like pollution and global warming, renewable energy sources gain con-stant impulse into the global energy economy. In consequence, the introduction of distributed energy sources has brought a new complexity to the electrical networks. In the new concept of smart grids and decen-tralized power generation; control, protection and measurement are also distributed and requiring, among other things, a new scheme of communication to operate with each other in balance and improve performance. In this research, an analysis of different communication technologies (power line communication, Ethernet over unshielded twisted pair (UTP), optic fiber, Wi-Fi, Wi-MAX, and Long Term Evolution) and their respective characteristics will be carried out. With the objective of pointing out strengths and weaknesses from different points of view (technical, economical, deployment, etc.) to establish a richer context on which a decision for communication approach can be done depending on the specific application scenario of a new smart grid deployment. As a result, a description of possible optimal deployment solutions for communication will be shown considering different options for technologies, and a mention of different important considerations to be taken into account will be made for some of the possible network implementation scenarios.

Applying Nordic Energy Efficiency and Renewable Energy Solutions in Kaliningrad Oblast, Russia

RENSOL (Regional Energy Solutions) project deals with the use of energy efficiency and renewable energy solutions in Kaliningrad Oblast to tackle climate change. Overall objective of the RENSOL work package 1 is to build awareness and knowledge on solutions for energy efficient buildings and street lightning applications. The project report describes available solutions to improve housing energy efficiency.

Making the impact on research and society: a case study - open repository and crowdsourcing solutions developed for the Finno-Ugric Digitization Pilot Project at the National Library of Finland

Jussi-Pekka Hakkaraisen esitys 24. Kansainvälisessä tieteen-, teknologian ja lääketieteen historian kongressissa (24th International Congress of History of Science, Technology and Medicine) Manchesterissa 26.7.2013

Viilunkuivaajan tuotantotehokkuuden kehittäminen

Mekaanisen metsäteollisuuden tuotteiden kiristyvä globaali kilpailu ja jatkuva kustannusten kasvaminen kiristyvillä markkinoilla aiheuttavat jatkuvaa tuotannon tehostamisen tarvetta. Käyntiaikojen maksimoinnilla ja tuotantokoneiden käyttöasteen nostamisella haetaan hintaetua sekä toimituskapasiteetin maksimointia kilpailussa asiakkaista myös tulevaisuutta silmälläpitäen. Vanerin tuotantoprosessiin osaprosessina kuuluva viilun kuivaus on tehtaan tuotannon pullonkaula. Kuivauskoneen tuotannollisten häiriöiden syiden selvittämisillä ja käyntiajan lisäämisellä on suora tuotannollinen vaikutus. Tutkimuksessa löydettiin mahdollisia parannuskohteita tuotantolaitteisiin. Käsiteltävän aiheen ollessa aiemmin kirjallisuudessa käsittelemätön, jouduttiin kehitys- ja parannustoimenpiteissä tekemään suoraviivaisia syy- ja seuraussuhteisiin perustuvia ratkaisuja. Vaihtoehdoista etsittiin toiminnaltaan mahdollisimman yksinkertaisia sekä hankinta- ja käyttökustannuksiltaan kustannustehokkaita ratkaisuja.

Developing Bioimage Informatics – from Microscopy to Software Solutions – with alpha2beta1 Integrin as a Case Study

Biokuvainformatiikan kehittäminen – mikroskopiasta ohjelmistoratkaisuihin – sovellusesimerkkinä α2β1-integriini Kun ihmisen genomi saatiin sekvensoitua vuonna 2003, biotieteiden päätehtäväksi tuli selvittää eri geenien tehtävät, ja erilaisista biokuvantamistekniikoista tuli keskeisiä tutkimusmenetelmiä. Teknologiset kehitysaskeleet johtivat erityisesti fluoresenssipohjaisten valomikroskopiatekniikoiden suosion räjähdysmäiseen kasvuun, mutta mikroskopian tuli muuntua kvalitatiivisesta tieteestä kvantitatiiviseksi. Tämä muutos synnytti uuden tieteenalan, biokuvainformatiikan, jonka on sanottu mahdollisesti mullistavan biotieteet. Tämä väitöskirja esittelee laajan, poikkitieteellisen työkokonaisuuden biokuvainformatiikan alalta. Väitöskirjan ensimmäinen tavoite oli kehittää protokollia elävien solujen neliulotteiseen konfokaalimikroskopiaan, joka oli yksi nopeimmin kasvavista biokuvantamismenetelmistä. Ihmisen kollageenireseptori α2β1-integriini, joka on tärkeä molekyyli monissa fysiologisissa ja patologisissa prosesseissa, oli sovellusesimerkkinä. Työssä saavutettiin selkeitä visualisointeja integriinien liikkeistä, yhteenkeräytymisestä ja solun sisään siirtymisestä, mutta työkaluja kuvainformaation kvantitatiiviseen analysointiin ei ollut. Väitöskirjan toiseksi tavoitteeksi tulikin tällaiseen analysointiin soveltuvan tietokoneohjelmiston kehittäminen. Samaan aikaan syntyi biokuvainformatiikka, ja kipeimmin uudella alalla kaivattiin erikoistuneita tietokoneohjelmistoja. Tämän väitöskirjatyön tärkeimmäksi tulokseksi muodostui näin ollen BioImageXD, uudenlainen avoimen lähdekoodin ohjelmisto moniulotteisten biokuvien visualisointiin, prosessointiin ja analysointiin. BioImageXD kasvoi yhdeksi alansa suurimmista ja monipuolisimmista. Se julkaistiin Nature Methods -lehden biokuvainformatiikkaa käsittelevässä erikoisnumerossa, ja siitä tuli tunnettu ja laajalti käytetty. Väitöskirjan kolmas tavoite oli soveltaa kehitettyjä menetelmiä johonkin käytännönläheisempään. Tehtiin keinotekoisia piidioksidinanopartikkeleita, joissa oli "osoitelappuina" α2β1-integriinin tunnistavia vasta-aineita. BioImageXD:n avulla osoitettiin, että nanopartikkeleilla on potentiaalia lääkkeiden täsmäohjaussovelluksissa. Tämän väitöskirjatyön yksi perimmäinen tavoite oli edistää uutta ja tuntematonta biokuvainformatiikan tieteenalaa, ja tämä tavoite saavutettiin erityisesti BioImageXD:n ja sen lukuisten julkaistujen sovellusten kautta. Väitöskirjatyöllä on merkittävää potentiaalia tulevaisuudessa, mutta biokuvainformatiikalla on vakavia haasteita. Ala on liian monimutkainen keskimääräisen biolääketieteen tutkijan hallittavaksi, ja alan keskeisin elementti, avoimen lähdekoodin ohjelmistokehitystyö, on aliarvostettu. Näihin seikkoihin tarvitaan useita parannuksia,