Multibody Simulation Model of the Roller Test Rig

Multibody simulation model of the roller test rig is presented in this work. The roller test rig consists of a paper machine’s tube roll supported with a hard bearing type balancing machine. The simulation model includes non-idealities that are measured from the physical structure. These non-idealities are the shell thickness variation of the roll and roundness errors of the shafts of the roll. These kinds of non-idealities are harmful since they can cause subharmonic resonances of the rotor system. In this case, the natural vibration mode of the rotor is excited when the rotation speed is a fraction of the natural frequency of the system. With the simulation model, the half critical resonance is studied in detail and a sensitivity analysis is performed by simulating several analyses with slightly different input parameters. The model is verified by comparing the simulation results with those obtained by measuring the real structure. Comparison shows that good accuracy is achieved, since equivalent responses are achieved within the error limit of the input parameters.

Containment Measures in Adolescent Psychiatric Care - Focus on Mechanical Restrain

Rajoitetoimet, erityisesti sitominen, nuorisopsykiatrisessa hoitotyössä Tutkimuksen tavoitteena oli kuvata ja syventää tietoa rajoitetoimien, erityisesti sitomisen, käytöstä nuorisopsykiatrisessa vastentahtoisessa osastohoidossa. Tutkimuksen tavoitteena oli kuvata hoitajien, lääkäreiden ja potilaiden asenteita eri rajoittamiskeinoja kohtaan nuorisopsykiatrisessa osastohoidossa, kerätä tietoa yhden vuoden aikana tapahtuneiden sitomisten määrästä ja luonteesta sekä kuvata potilaiden kokemuksia sitomisesta nuorisopsykiatrisen osastohoidon aikana. Tutkimus tuottaa arvokasta tietoa korkeatasoisten sitomiskäytäntöjen kehittämiseen nuorisopsykiatrisessa osastohoidossa, sekä sitomisten määrää vähentämällä että sitomistapoja kehittämällä. Tavoitteena on parantaa sidottujen potilaiden kliinistä hoitoa. Tutkimusaineisto kerättiin suomalaisilla, pääkaupunkiseudulle sijoittuvilla, nuorisopsykiatrisilla osastoilla neljässä vaiheessa lokakuun 2009 ja huhtikuun 2012 välisenä aikana. Helsingin ja Uudenmaan sairaanhoitopiirin (HUS) nuorisopsykiatrian erikoisalan seitsemän suljetun osaston hoitohenkilökunta sekä lääkärit suhtautuivat myönteisesti rajoittamistoimenpiteisiin. Nuorisopsykiatriset potilaat suhtautuivat rajoittamistoimenpiteisiin kriittisemmin kuin henkilökunta. Nuoret suhtautuivat myönteisimmin tarvittaessa annettavaan lääkitykseen, ajoittaiseen tarkkailuun ja kulun rajoittamiseen. Vähiten hyväksytty menetelmä oli verkkosänky. Nuoret arvioivat sitomisen kolmen vähiten hyväksytyn menetelmän joukkoon. Sitomisen esiintyvyys ja pitkien sitomisten määrä olivat korkeita tutkimukseen valituissa yksiköissä. Useimmat sidotut nuoret tiesivät syyn sitomiseensa, suhtautuivat siihen ambivalentisti nähden siinä sekä hyötyä että haittaa, pitäen sitä kuitenkin rangaistuksena. Huolimatta tästä, suurin osa haastatelluista nuorista koki, että joissain tilanteissa sitomista tarvitaan nuorisopsykiatrisessa osastohoidossa. Nuorilla oli monia ehdotuksia, kuinka parantaa sitomista käytännön osastohoidossa. Tämä väitöskirja tuottaa uutta tietoa eri rajoittamistoimenpiteiden ja sitomisen toteuttamisesta nuorisopsykiatrisessa osastohoidossa. Käytännön hoitotyön parantamiseksi nuorisopsykiatrisilla osastoilla tarvitaan laaja-alaista ja syvälle luotaavaa koulutusta, jotta rajoittamis-toimenpiteiden määrää voidaan vähentää. Myös kriisitilanteiden hallintaan tarvitaan uusia keinoja. Tietoa, kuvausta toimenpiteistä ja tilanteiden käsittelyä jälkikäteen tulee tarjota ala-ikäiselle potilaalle hänen kehitystasonsa huomioiden. Sitomisten määrää tulee vähentää ja niiden kestoa lyhentää. Nuorten tulee olla aktiivisesti mukana kehittämässä aggression hallintamenetelmiä suomalaisessa nuorisopsykiatrisessa osastohoidossa.

Detection of Pathologic Changes Following Traumatic Brain Injury Using Magnetic Resonance Imaging

Background: Approximately two percent of Finns have sequels after traumatic brain injury (TBI), and many TBI patients are young or middle-aged. The high rate of unemployment after TBI has major economic consequences for society, and traumatic brain injury often has remarkable personal consequences, as well. Structural imaging is often needed to support the clinical TBI diagnosis. Accurate early diagnosis is essential for successful rehabilition and, thus, may also influence the patient’s outcome. Traumatic axonal injury and cortical contusions constitute the majority of traumatic brain lesions. Several studies have shown magnetic resonance imaging (MRI) to be superior to computed tomography (CT) in the detection of these lesions. However, traumatic brain injury often leads to persistent symptoms even in cases with few or no findings in conventional MRI. Aims and methods: The aim of this prospective study was to clarify the role of conventional MRI in the imaging of traumatic brain injury, and to investigate how to improve the radiologic diagnostics of TBI by using more modern diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) techniques. We estimated, in a longitudinal study, the visibility of the contusions and other intraparenchymal lesions in conventional MRI at one week and one year after TBI. We used DWI-based measurements to look for changes in the diffusivity of the normal-appearing brain in a case-control study. DTI-based tractography was used in a case-control study to evaluate changes in the volume, diffusivity, and anisotropy of the long association tracts in symptomatic TBI patients with no visible signs of intracranial or intraparenchymal abnormalities on routine MRI. We further studied the reproducibility of different tools to identify and measure white-matter tracts by using a DTI sequence suitable for clinical protocols. Results: Both the number and extent of visible traumatic lesions on conventional MRI diminished significantly with time. Slightly increased diffusion in the normal-appearing brain was a common finding at one week after TBI, but it was not significantly associated with the injury severity. Fractional anisotropy values, that represent the integrity of the white-matter tracts, were significantly diminished in several tracts in TBI patients compared to the control subjects. Compared to the cross-sectional ROI method, the tract-based analyses had better reproducibility to identify and measure white-matter tracts of interest by means of DTI tractography. Conclusions: As conventional MRI is still applied in clinical practice, it should be carried out soon after the injury, at least in symptomatic patients with negative CT scan. DWI-related brain diffusivity measurements may be used to improve the documenting of TBI. DTI tractography can be used to improve radiologic diagnostics in a symptomatic TBI sub-population with no findings on conventional MRI. Reproducibility of different tools to quantify fibre tracts vary considerably, which should be taken into consideration in the clinical DTI applications.

Microstructural and environmental effects on the mechanical properties of porous particle-polymer composites

Papper kan anses vara ett av de mest använda materialen i det dagliga livet. Tidskrifter, tidningar, böcker och diverse förpackningar är några exempel på pappersbaserade produkter. Papperets egenskaper måste anpassas till användningsändamålet. En tidskrift kräver t.ex. hög ljushet, opacitet och en slät yta hos papperet, medan dessa egenskaper är mindre viktiga för en dagstidning. Allt tryckpapper behöver vissa mekaniska egenskaper för att tåla vidarebearbetning såsom kalandrering, tryckning och vikning. Man kan bestryka papper för att förbättra dess optiska egenskaper och tryckbarhetsegenskaper. Vid bestrykning appliceras en dispersion av mineralpigment och polymerbindemedel som ett tunt lager på papperets yta. Bestrykningsskiktet kan ses som ett komplext, poröst kompositmaterial som även bidrar till papperets mekaniska egenskaper och dess processerbarhet i diverse konverteringsoperationer. Kravet på framställning av förmånligt papper med tillräckliga styrkeegenskaper ställer allt högre krav på optimeringen av pappersbestrykningsskiktets egenskaper och produktionskostnader. Målet med detta arbete var att förstå sambandet mellan pigmentbestrykningsskiktets mikrostruktur och dess makroskopiska, mekaniska egenskaper. Resultaten visar att adhesionen i gränsytan mellan pigment och bindemedel är kritisk för bestrykningsskiktets förmåga att bära mekanisk belastning. Polära vätskor är vanliga i tryckfärger och kan, eftersom de påverkar syra/bas-interaktionerna mellan pigment och latexbindemedel, försvaga denna adhesion. Resultaten tyder på att ytstyrkan hos bestruket papper kan höjas genom användning av bifunktionella dispergeringsmedel för mineralpigment. Detta medför inbesparingar i pappersproduktionen eftersom mängden bindemedel, den dyraste komponenten i bestrykningsskiktet, kan minskas.

Vibration analysis for Bearing outer race condition diagnostics

This paper investigates defect detection methodologies for rolling element bearings through vibration analysis. Specifically, the utility of a new signal processing scheme combining the High Frequency Resonance Technique (HFRT) and Adaptive Line Enhancer (ALE) is investigated. The accelerometer is used to acquire data for this analysis, and experimental results have been obtained for outer race defects. Results show the potential effectiveness of the signal processing technique to determine both the severity and location of a defect. The HFRT utilizes the fact that much of the energy resulting from a defect impact manifests itself in the higher resonant frequencies of a system. Demodulation of these frequency bands through use of the envelope technique is then employed to gain further insight into the nature of the defect while further increasing the signal to noise ratio. If periodic, the defect frequency is then present in the spectra of the enveloped signal. The ALE is used to enhance the envelope spectrum by reducing the broadband noise. It provides an enhanced envelope spectrum with clear peaks at the harmonics of a characteristic defect frequency. It is implemented by using a delayed version of the signal and the signal itself to decorrelate the wideband noise. This noise is then rejected by the adaptive filter that is based upon the periodic information in the signal. Results have been obtained for outer race defects. They show the effectiveness of the methodology to determine both the severity and location of a defect. In two instances, a linear relationship between signal characteristics and defect size is indicated.

Critical aspects on the behavior of material from the mechanical tool-workpiece interaction in single point diamond turning

Some material aspects such as grain size, purity and anisotropy exert an important influence on surface quality, especially in single point diamond turning. The aim of this paper is to present and discuss some critical factors that can limit the accuracy of ultraprecision machining of non-ferrous metals and to identify the effects of them on the cutting mechanism with single point diamond tools. This will be carried out through observations of machined surfaces and chips produced using optical and scanning electron microscopy. Solutions to reduce the influence of some of these limiting factors related with the mechanism of generation of mirror-like surfaces will be discussed.

Non-linear analysis of laminated metal matrix composites by an integrated micro/macro-mechanical model

The present paper describes an integrated micro/macro mechanical study of the elastic-viscoplastic behavior of unidirectional metal matrix composites (MMC). The micromechanical analysis of the elastic moduli is based on the Composites Cylinder Assemblage model (CCA) with comparisons also draw with a Representative Unit Cell (RUC) technique. These "homogenization" techniques are later incorporated into the Vanishing Fiber Diameter (VFD) model and a new formulation is proposed. The concept of a smeared element procedure is employed in conjunction with two different versions of the Bodner and Partom elastic-viscoplastic constitutive model for the associated macroscopic analysis. The formulations developed are also compared against experimental and analytical results available in the literature.

Multiple scales analysis of nonlinear oscillations of a portal frame foundation for several machines

An analytical study of the nonlinear vibrations of a multiple machines portal frame foundation is presented. Two unbalanced rotating machines are considered, none of them resonant with the lower natural frequencies of the supporting structure. Their combined frequencies is set in such a way as to excite, due to nonlinear behavior of the frame, either the first anti-symmetrical mode (sway) or the first symmetrical mode. The physical and geometrical characteristics of the frame are chosen to tune the natural frequencies of these two modes into a 1:2 internal resonance. The problem is reduced to a two degrees of freedom model and its nonlinear equations of motions are derived via a Lagrangian approach. Asymptotic perturbation solutions of these equations are obtained via the Multiple Scales Method.

Modelling of mechanical properties of CRFC composites under flexure loading

Carbon Fibre Reinforced Carbon (CFRC) Composites are increasing their applications due to their high strength and Young’s Modulus at high temperatures in inert atmosphere. Although much work has been done on processing and structure and properties relationship, few studies have addressed the modelling of mechanical properties. This work is divided in two parts. In the first part, a modelling of mechanical properties was carried out for two bi-directional composites using a model based on the Bernoulli-Euler theory for symmetric laminated beams. In the second part, acoustic emission (AE) was used as an auxiliary technique for monitoring the failure process of the composites. Differences in fracture behaviour are reflected in patterns of AE.

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.

On non-ideal and non-linear portal frame dynamics analysis using bogoliubov averaging method

We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.

Homogeneous assay technologies in drug screening: Quenching Resonance Energy Transfer (QRET) technique

Information gained from the human genome project and improvements in compound synthesizing have increased the number of both therapeutic targets and potential lead compounds. This has evolved a need for better screening techniques to have a capacity to screen number of compound libraries against increasing amount of targets. Radioactivity based assays have been traditionally used in drug screening but the fluorescence based assays have become more popular in high throughput screening (HTS) as they avoid safety and waste problems confronted with radioactivity. In comparison to conventional fluorescence more sensitive detection is obtained with time-resolved luminescence which has increased the popularity of time-resolved fluorescence resonance energy transfer (TR-FRET) based assays. To simplify the current TR-FRET based assay concept the luminometric homogeneous single-label utilizing assay technique, Quenching Resonance Energy Transfer (QRET), was developed. The technique utilizes soluble quencher to quench non-specifically the signal of unbound fraction of lanthanide labeled ligand. One labeling procedure and fewer manipulation steps in the assay concept are saving resources. The QRET technique is suitable for both biochemical and cell-based assays as indicated in four studies:1) ligand screening study of β2 -adrenergic receptor (cell-based), 2) activation study of Gs-/Gi-protein coupled receptors by measuring intracellular concentration of cyclic adenosine monophosphate (cell-based), 3) activation study of G-protein coupled receptors by observing the binding of guanosine-5’-triphosphate (cell membranes), and 4) activation study of small GTP binding protein Ras (biochemical). Signal-to-background ratios were between 2.4 to 10 and coefficient of variation varied from 0.5 to 17% indicating their suitability to HTS use.