Biomechanical analysis of pedalling for rehabilition purposes: experimental results on two pathological subjects and comparison with non-pathological findings

In this paper the experimental results obtained by means of a prototype measuring device dedicated to the evaluation of the rehabilitation level of the lower limb are presented. The analysis of the experimental data collected on non-pathological subjects allows the identification of the characteristic meaning of the most significant parameters typical of healthy subjects. These data have been employed for a systematic comparison with the same parameters measured on two pathological subjects, in order to define quantitative indicators of the rehabilitation degree of the lower limbs and indicators of the “quality” of the movement

Identification of Rub and Unbalance in a 320MW Turbogenerators

The paper presents two experiences of application of a model based fault identification method on real machines. The first case presented is an unbalance identification on a 320MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but of a different manufacturer, the LP turbine was affected by a rub in the sealings. This time, the fault is modeled by local bows. The identification of the faults is performed by means of a model based identification technique in frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations are presented also about the best choice of the rotating speed set of the run-down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings

Use of Modal Representation for the Supporting Structure in Model Based Fault Identification of Large Rotating Machinery: Part 2: Application to a Real Machine

Model-based techniques are often employed in diagnostics of rotating machines to locate and to evaluate the severity of a malfunction. The use of a reliable model can increase the accuracy of identification. Rigid supports or lumped mass pedestals are not always enough to account for foundation dynamics; a modal representation of the supports can improve the identification results. The method, discussed in the first part, is here validated using experimental data of a 320 MW steam turbogenerator. To the authors’ knowledge, this is the first case of fault identification on real data from a large machine, where the supporting structure is accounted for by means of a modal model

Use of Modal Representation for the Supporting Structure in Model Based Fault Identification of Large Rotating Machinery: Part 1 – Theoretical Remarks

Fault identification by means of model-based techniques, both in frequency and time domain, is often employed in diagnostics of rotating machines, when the main task is to locate and to evaluate the severity of the malfunction. The model of the fully assembled machine is composed by the submodels of the rotor, of the bearings and of the foundation, while the effect of the faults is modelled by means of equivalent force systems. Some identification techniques, such as the least squares identification in frequency domain, proposed by the authors, have proven to be quite robust even if the submodels are not fine-tuned. Anyhow, the use of a reliable model can increase the accuracy of the identification. Normally a supporting structure is represented by means of rigid foundation or by pedestals, i.e. 2 d.o.f. mass–spring–damper systems, but these kind of models are often not able to reproduce correctly the influence of the dynamical behaviour of the supporting structure on the shaft, especially in large machines where coupled modes are present. Therefore, peculiar aspect of this paper is the use of a modal foundation to model the supporting structure of the machine and the method is discussed in detail in this first part. The modal representation of the foundation is then introduced in the least squares identification technique in frequency domain

Glutathione infusion before primary percutaneous coronary intervention: A randomised controlled pilot study

Objective: In the setting of reperfused ST-elevation myocardial infarction (STEMI), increased production of reactive oxygen species (ROS) contributes to reperfusion injury. Among ROS, hydrogen peroxide (H2O2) showed toxic effects on human cardiomyocytes and may induce microcirculatory impairment. Glutathione (GSH) is a water-soluble tripeptide with a potent oxidant scavenging activity. We hypothesised that the infusion of GSH before acute reoxygenation might counteract the deleterious effects of increased H2O2 generation on myocardium. Methods: Fifty consecutive patients with STEMI, scheduled to undergo primary angioplasty, were randomly assigned, before intervention, to receive an infusion of GSH (2500 mg/25 mL over 10 min), followed by drug administration at the same doses at 24, 48 and 72 hours elapsing time or placebo. Peripheral blood samples were obtained before and at the end of the procedure, as well as after 5 days. H2O2 production, 8-iso-prostaglandin F2α (PGF2α) formation, H2O2 breakdown activity (HBA) and nitric oxide (NO) bioavailability were determined. Serum cardiactroponin T (cTpT) was measured at admission and up to 5 days. Results: Following acute reperfusion, a significant reduction of H2O2 production (p=0.0015) and 8-iso-PGF2α levels (p=0.0003), as well as a significant increase in HBA (p<0.0001)and NO bioavailability (p=0.035), was found in the GSH group as compared with placebo. In treated patients, attenuated production of H2O2 persisted up to 5 days from the index procedure (p=0.009) and these changes was linked to those of the cTpT levels (r=0.41, p=0.023). Conclusion: The prophylactic and prolonged infusion of GSH seems to determine a rapid onset and persistent blunting of H2O2 generation improving myocardial cell survival. Nevertheless, a larger trial, adequately powered for evaluation of clinical endpoints, is ongoing to confirm the current finding

Noble metal nanoparticles networks stabilized by rod-like organometallic bifunctional thiols

Rod-like organometallic dithiol containing square-planar Pt(II) centers, i. e., trans,trans-[(H3COCS)Pt(PBu3)(2)(C equivalent to C-C6H4-C6H4-C equivalent to C)(PBu3)(2)Pt(SCOCH3)] was used as bifunctional stabilizing agent for the synthesis of Pd-, Au-, and AgNPs (MNPs). All the MNPs showed diameters of about 4 nm, which can be controlled by carefully modulating the synthesis parameters. Covalent MNPs stabilization occurred through a single S bridge between Pt(II) and the noble metal nanocluster surfaces, leading to a network of regularly spaced NPs with the formation of dyads, as supported by SR-XPS data and by TEM imaging analysis. The chemical nature of NPs systems was also confirmed by EDS and NMR. Comparison between SR-XPS data of MNPs and self-assembled monolayers and multilayers of pristine rod-like dithiols deposited onto polycrystalline gold surfaces revealed an electronic interaction between Pt(II) centers and biphenyl moieties of adjacent ligands, stabilizing the organic structure of the network. The possibility to obtain networks of regularly spaced MNPs opens outstanding perspectives in optoelectronics

Conhecendo o IAF do cafeeiro arábica através do índice de vegetação por diferença normalizada

O objetivo deste trabalho foi relacionar a série temporal do Índice de Área Foliar (IAF) estimado pelo método proposto por Barbosa et al. (2012) ao índice de vegetação por diferença normalizada (NDVI) adequando um modelo de determinação do IAF através de dados de NDVI coletados em um cafezal na região de Lavras, sul de Minas Gerais. Para isso foi realizado o estudo em cafezal no campus da Universidade Federal de Lavras (UFLA) no período de fevereiro de 2014 a fevereiro de 2015 onde trinta plantas de Coffea arabica L, cv Catuaí IAC 144 foram avaliadas mensalmente com medições de altura do ramo ortotrópico e comprimento de plagiotrópicos em 5 posições na copa para estimativa do IAF, enquanto as avaliações de NDVI foram realizadas semanalmente em três posições distintas da planta. Dados mensais de precipitação (mm- Prec) e temperatura média do ar (°C- Tm) também foram coletados. Os valores de cada variável foram submetidos à análise de correlação (r). A série temporal demonstra que o IAF varia em função da temperatura e precipitação. O modelo de regressão exponencial foi o mais adequado para determinar os valores de IAF em função do NDVI. As correlações do IAF com o NDVI variam em função da posição da medida de NDVI da planta. A série temporal do IAF é uma variável útil nas práticas de manejo, enquanto NDVI pode ser utilizado para determinar o IAF em plantas de café