109 research outputs found
Threading holder based on axial metal cylinder pins to reduce tap risk during reversion instant
Internal thread profiles are used widely in manufacturing processes with the aim of assembling/disassembling different components during maintenance activities from the aeronautics sector until common industrial parts. The threading process is one of the last operations carried out to obtain those components, and consequently, it is an operation of high added value. Threading is a complex operation that must carefully synchronize the rotation with the feed movements to avoid tool breakage during the instant of tapping reversion stage. In order to avoid this risk, several toolholders were developed present in the literature but deficiencies in terms of stability and productivity. Therefore, in this work, a new toolholder is proposed in which the common springs used to mitigate the lack of perfect synchronization between rotation and feed movements are replaced by elastic metal pins achieving a torsional compliance toolholder. The results show that the use of the proposed toolholder implies not only a productivity increase but also a surface integrity improvement as well as a stress reduction that the cutting tap is subjected and thus, achieving a substantial improvement in the current tapping processes. In particular, the use of the proposed toolholder implied a 75% reduction of the maximum stress achieved in the reversal instant, improving 20% tool life with an increase of 30% cutting speed. Therefore, the use of the proposed toolholder implies a substantial improvement in the current tapping processes
FREE-FORM TOOLS DESIGN AND FABRICATION FOR FLANK SUPER ABRASIVE MACHINING (FSAM) NON DEVELOPABLE SURFACES
Manufacturing improvements are becoming a real need in industry. In order to satisfy these industrial requirements,
they should be targeted in two different directions: new manufacturing processes and surface optimization through
algorithms. On the one hand, Super Abrasive Machining (SAM) is presented as a new manufacturing process
combining benefits from milling and grinding technologies. On the other hand, there is a tendency to manufacture
non developable surfaces by flank milling and to achieve final dimensional and roughness requirements, by
calculating mathematically-optimized tool trajectories. This work presents a design and manufacturing of a free
form tool to be used for the manufacturing of a complex surface through Flank SAM (FSAM). Based on the tool
requirements, it will cover the following stages: tool geometry design, tool core manufacturing, and electroplating
for final abrasive tool generation
Estimation of biomass of horse mackerel (Trachurus trachurus L.) in northern-Spain ( Nortbern IXa and VIIIc ) using the daily egg production method.
In order to estimate the spawning stock biomass of horse mackerel
in the North Atlantic Spanish waters, a series of egg and adult
cruises were carried out by lEO (Instituto Español de OceanografÃa)
and AZTI -SIO (Instituto de Investigación y TecnologÃa para la
OceanografÃa, Pesca y Alimentación) .
The survey was carried out from 23 April to 25 May 1992. A total
of 627 plankton samples and 37 adults samples were collected.
A total daily egg production of 3.3 X 1012 egg (SE = 7.26 X 1011
,
CV = 0.22) was estimated for the whole area sarnpled (ICES Division
Vlllc and subdivision northern IXa north). The estirnate of horse
mackerel spawning biornass ranged from 486,549 tons (CV = 0.34, when
using adult pararneter estirnates exclusively frorn the Spanish
survey, down to 368,814 tn (C = 0.32), when alternatively using an
estimate of relative batch fecundity from the southern region of
horse rnackerel western stock
Effects of laser-textured on rake face in turning PCD tools for Ti6Al4V
The demand inherent to the aeronautical industry in terms of productivity and quality requirements leads to develop new cutting tools. Hence, PCD tools meet the requirements in productivity while machining low machinability aeronautical alloys such as Ti6Al4V. Tool chipbreakers play a considerable role in terms of tool life. However, due to the extreme conditions (temperature and pressure) required to manufacture PCD tools, any complex geometry on tool rake faces is not viable, so chipbreakers are not possible, except for those external to inserts.
This work proposes a groove-type laser engraved chipbreaker design and a manufacturing methodology, with experimental validation on turning a Ti6Al4V workpiece. The so-manufactured chipbreakers achieve titanium alloy chip fragmentation, making easy chip removal from the cutting zone.
A set of experiments involving various laser parameters to characterize the PCD depth and surface integrity and experimental validation for those chipbreakers designs were carried out in finishing cutting conditions. The optimum parameters for the engraving of PCD were found, obtaining satisfactory breakage of titanium chips. Chip length was always below 17.29 mm.Authors are grateful to Basque government group IT IT1337- 19, the Ministry of Mineco REF DPI2016-74845-R and PID2019- 109340RB-I00, and the UPV/EHU itself for the financial aid for the pre-doctoral grants PIF 19/96
Evolution of innovation policy in Emilia-Romagna and Valencia: Similar reality, similar results?
This is an author's accepted manuscript of an article published in:
“European Planning Studies"; Volume 22, Issue 11, 2014; copyright Taylor & Francis; available online at: http://dx.doi.org/10.1080/09654313.2013.831398[EN] This paper examines the evolution of regional innovation policy in Emilia-Romagna and
Valencia, two regions with similar economic features that implemented close innovation policies in
the 1970s and 1980s. We investigate whether their similarities have led to parallel targets, policy
tools and governance developments. We show that innovation policy in both regions suffered
from the effects of privatization, budget constraints and changes to manufacturing during the
1990s and we highlight the consequences. Although Emilia-Romagna experienced deeper changes
to its innovation policy, privatizations and/or the replacement of public funds promoted
commercial approaches and induced market failures in both regions. The worst effects of these
policies were the implementation of less-risky innovation projects, the shift towards extraregional
projects and markets, and the favouring of large firms.López Estornell, M.; Barberá Tomás, JD.; Garcia Reche, A.; Mas Verdú, F. (2013). Evolution of innovation policy in Emilia-Romagna and Valencia: Similar reality, similar results?. European Planning Studies. 22(11):2287-2304. doi:10.1080/09654313.2013.831398S22872304221
Metabolomics Reveals Metabolic Biomarkers of Crohn's Disease
The causes and etiology of Crohn's disease (CD) are currently unknown although both host genetics and environmental factors play a role. Here we used non-targeted metabolic profiling to determine the contribution of metabolites produced by the gut microbiota towards disease status of the host. Ion Cyclotron Resonance Fourier Transform Mass Spectrometry (ICR-FT/MS) was used to discern the masses of thousands of metabolites in fecal samples collected from 17 identical twin pairs, including healthy individuals and those with CD. Pathways with differentiating metabolites included those involved in the metabolism and or synthesis of amino acids, fatty acids, bile acids and arachidonic acid. Several metabolites were positively or negatively correlated to the disease phenotype and to specific microbes previously characterized in the same samples. Our data reveal novel differentiating metabolites for CD that may provide diagnostic biomarkers and/or monitoring tools as well as insight into potential targets for disease therapy and prevention
International lower limb collaborative (INTELLECT) study: a multicentre, international retrospective audit of lower extremity open fractures
Trauma remains a major cause of mortality and disability across the world1, with a higher burden in developing nations2. Open lower extremity injuries are devastating events from a physical3, mental health4, and socioeconomic5 standpoint. The potential sequelae, including risk of chronic infection and amputation, can lead to delayed recovery and major disability6. This international study aimed to describe global disparities, timely intervention, guideline-directed care, and economic aspects of open lower limb injuries
VERY HIGH ENERGY γ-RAYS from the UNIVERSE'S MIDDLE AGE: DETECTION of the z = 0.940 BLAZAR PKS 1441+25 with MAGIC
The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 (z = 0.944), PKS 1441+25 is the most distant very high energy (VHE) blazar detected to date. The observations were triggered by an outburst in 2015 April seen at GeV energies with the Large Area Telescope on board Fermi. Multi-wavelength observations suggest a subdivision of the high state into two distinct flux states. In the band covered by MAGIC, the variability timescale is estimated to be 6.4 ±1.9 days. Modeling the broadband spectral energy distribution with an external Compton model, the location of the emitting region is understood as originating in the jet outside the broad-line region (BLR) during the period of high activity, while being partially within the BLR during the period of low (typical) activity. The observed VHE spectrum during the highest activity is used to probe the extragalactic background light at an unprecedented distance scale for ground-based gamma-ray astronomy
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