738 research outputs found
Continuous improvement in maintenance: a case study in the automotive industry involving Lean tools
Maintenance function assumes a key role in today’s industry. The automotive industry is not an exception and there are strict rules to comply with. Indeed, the IATF 16949:2016 imposes the implementation of key performance indicator as a mean to control the overall manufacturing performance. This work presents a case study carried out in a multinational company related with the production of parts for the automotive industry where it was necessary to implement key performance indicators to comply with the IATF 16949: 2016 standard and a model was also created for the management of spare parts linked to the maintenance of existing equipment. The introduction of these changes forced the application of some Lean tools, with a view to improving procedures and information flows. The work was completed successfully, and key performance indicators were implemented, whose support data, which is now collected and calculated automatically on a routine basis, and the spare-parts management was validated with a view to optimization of warehouse space and at a conveniently low inventory level in this type of parts, without endangering critical equipment in production. The SMED methodology was applied, which allowed the setup time to be reduced by 11%, and the Lean 5S tool was used to organize the mould exchange activities. An OEE of more than 90% has been achieved.info:eu-repo/semantics/publishedVersio
Comparação cinemática e neuromuscular de um exercício de abdominais no solo e na fitball
O objectivo deste estudo foi comparar a cinemática e a actividade neuromuscular em
exercícios de abdominais no solo e na Fitball. Quinze jovens mulheres participaram voluntariamente
neste estudo. Cada sujeito efectuou duas vezes, três séries de dez abdominais com um intervalo mínimo
de 60 segundos entre cada série. O exercício foi efectuado uma vez no solo e outra na Fitball. Os dados
cinemáticos e neuromusculares foram recolhidos ao longo de todo o protocolo. Foi avaliada a
actividades neuromuscular do recto femoral, do recto abdominal superior, do recto abdominal inferior e
do oblíquo externo. Um electrogoniómetro foi colocado entre a sexta costela e a crista ilíaca (coluna) e
outro entre a crista ilíaca e a zona trocantérica (anca) para avaliação cinemática. O período do
exercício entre as condições em estudo não foi significativo. O ângulo mínimo da anca e da coluna
lombar foram significativamente inferiores durante a execução do exercício no solo do que na Fitball. A
actividade neuromuscular foi significativamente superior quando o exercício foi realizado na Fitball do
que no solo em todos os grupos musculares. Como conclusão, actividade neuromuscular é superior
aquando da exercitação na Fitball do que no solo
Inter-relation of sylvatic and domestic transmission of Trypanosoma cruzi in areas with and without domestic vectorial transmission in Minas Gerais, Brazil
During the period 1980-1986, we captured triatomine bugs and mammalian
reservoir hosts from sylvatic and domestic situations in different
municipalities of the State of Minas Gerais. Trypanosoma cruzi was
isolated from captured bugs, mammals and patients. After cultivation in
LIT medium, the electrophoretic enzyme profiles were determined. We
obtained a total of 32 parasite isolates from regions with active
domestic transmission, and 24 isolates from areas under control. For
the first areas the results suggest introduction of T. cruzi from
sylvatic habitats, through incursion of infected opossums and/or
sylvatic T. sordida, which appears to have given rise to at least one
acute human infection. Of particular interest is the finding of
sylvatic opossums and a T. sordida nymph infected with ZB, that could
indicate return of parasites from chronic human infections to sylvatic
transmission cycles. For the areas under control we also interpret the
results as interaction between sylvatic and domestic cycles of
transmission, here through the invasion of houses by bugs carrying the
Z1 zymodeme from the sylvatic environment. The Multivariate
Correspondence Analysis gives a spatial description between the
different parasite isolates and confirms the existence of a bridge in
the opposite direction in the region with active vectorial transmission
including the exporting of Z2 through the peridomestic environment into
the sylvatic cycle. For the other areas this bridge corresponds
especially to Panstrongylus megistus, importing Z1 into the domestic
environment
Stereoselective reduction of imines with trichlorosilane using solid-supported chiral picolinamides
The stereoselective reduction of imines with trichlorosilane catalyzed by chiral Lewis bases is a well-established procedure for the synthesis of enantio-enriched amines. Five supported cinchona-based picolinamides have been prepared and their activity tested in a model reaction. The comparison of different supporting materials revealed that polystyrene gave better results than silica in terms of stereoselectivity. The applicability of the solid-supported catalyst of choice to the reduction of different imines was also demonstrated. Additionally, for the first time, a catalytic reactor containing a polymer-immobilized chiral picolinamide has been employed for the stereoselective reduction of imines with trichlorosilane under continuous flow conditions
Varying numbers of players in small-sided soccer games modifies action opportunities during training
This study examined the effects of the numbers of players involved in small-sided team games (underloading and overloading) on opportunities for maintaining ball possession, shooting at goal and passing to teammates during training. These practice constraint manipulations were assumed to alter values of key performance variables identified in previous research, such as interpersonal distances between players and time to intercept shots and passes. Fifteen male soccer players (age: 19.60±1.99 years) were grouped into three teams and played against each other in different versions of small-sided soccer games, in which the number of players was manipulated in three different conditions: 5 vs. 5, 5 vs. 4 and 5 vs. 3. Dependent variables were the values of interpersonal distance between an outfield attacker and nearest defender (ID), and the relative distance of a defender needed to intercept the trajectory of a shot (RDishot) or pass (RDipass). Statistical analyses revealed that mean ID values were significantly lower in 5 vs. 5 than in 5 vs. 4 and 5 vs. 3 conditions, and significantly lower in 5 vs. 4 than 5 vs. 3. They also revealed that mean values of RDishot were significantly higher in 5 vs. 3 than in 5 vs. 5 conditions. Finally, results showed that the mean values of RDipass were significantly higher in 5 vs. 3 than in 5 vs. 5. Findings revealed how task constraints in SSGs can be manipulated to vary values of key spatial and temporal performance variables (interpersonal distance and time to intercept) to influence the nature of interpersonal interactions between competing players during practice. We observed that these manipulations tended to decrease opportunities for maintaining ball possession during training when equal numbers of attackers and defenders existed in SSGs, and led to more shots and passes emerging when the number of defenders was decreased relative to attackers
Study of thermal degradation of PLGA, PLGA nanospheres and PLGA/Maghemite superparamagnetic nanospheres
Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (Eα) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Is the meiofauna a good indicator for climate change and anthropogenic impacts?
Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research
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