Recurrent ANN-based modelling of the dynamic evolution of the surface roughness in grinding

Grinding is critical in modern manufacturing due to its capacity for producing high surface quality and high-precision parts. One of the most important parameters that indicate the grinding quality is the surface roughness (R _a). Analytical models developed to predict surface finish are not easy to apply in the industry. Therefore, many researchers have made use of artificial neural networks. However, all the approaches provide a particular solution for a wheel–workpiece pair, not generalizing to new grinding wheels. Besides, these solutions do not give surface roughness values related to the grinding wheel status. Therefore, in this work the modelling of the dynamic evolution of the surface roughness (R _a) based on recurrent neural networks is presented with the capability to generalize to new grinding wheels and conditions taking into account the wheel wear. Results show excellent prediction of the surface finish dynamic evolution. The absolute maximum error is below 0.49 µm, being the average error around 0.32 µm. Besides, the analysis of the relative importance of the inputs shows that the grinding conditions have higher influence than the wheel characteristics over the prediction of the surface roughness confirming experimental knowledge of grinding technology users.

     

Ni-doped carbon xerogels for H2 storage

Activated carbon xerogels, with selected characteristics, were doped with Ni, using different methods, and tested for hydrogen storage. The results obtained show that the amount of nickel incorporated, the Ni-carbon interaction and the nickel particle size distribution depend more on the doping method used than on the textural properties of the carbon support. The amount of nickel incorporated by strong electrostatic adsorption is lower than that incorporated by dry impregnation. However, the strong electrostatic adsorption method produces Ni-doped carbon xerogels with a high Ni-carbon interaction and a narrower Ni particle size distribution. The influence of Ni on H₂ storage capacity depends on the operating conditions and the doping conditions used. Thus, at −196 °C and 40 bar, storage capacity seems to be mainly influenced by the textural properties of carbon support while, at 25 °C and 200 bar, the spillover effect plays a significant role, being the interaction between the support and Ni particles key factor in the storage process. The best Ni-doped carbon xerogels obtained in this work exhibit hydrogen storage capacities of 6 wt.% and 31.8 g l⁻¹ at −196 °C and 40 bar.     

Psychological treatment of chronic posttraumatic stress disorder in victims of sexual aggression

The aim of this research was to test the comparative effectiveness of two therapeutic modalities in the treatment of chronic posttraumatic stress disorder in victims of sexual aggression: (a) self-exposure and cognitive restructuring and (b) progressive relaxation training. The sample consisted of 20 patients (victims of rape in adulthood or adult victims of childhood sexual abuse) selected according to DSM-III-R criteria. A multigroup experimental design with repeated measures (pretreatment, posttreatment, and 1-, 3-, 6-, and 12-month follow-up) was used. Most treated patients improved, but the success rate was higher in all measures in the exposure and cognitive restructuring group immediately on posttreatment and at follow-up. Implications of this study for clinical practice and future research in this field are commented on.     

CHOP vs. ProMACE-CytaBOM in the treatment of aggressive non-Hodgkin's lymphomas: long-term results of a multicenter randomized trial.(PETHEMA: Spanish Cooperative Group for the Study of Hematological Malignancies Treatment, Spanish Society of Hematology)

From May 1985 to May 1989, 175 patients with previously untreated aggressive non-Hodgkin's lymphoma were randomized to receive CHOP or ProMACE-CytaBOM. Eligibility criteria included follicular large-cell diffuse small cleaved-cell, diffuse mixed, diffuse large-cell and immunoblastic lymphoma with an Ann Arbor stage II, III or IV. One hundred and forty-eight patients were evaluable. There were no significant differences between the 2 treatments in response rate (83.5% [57.5% CR] for CHOP vs. 88% [62% CR] for ProMACE-CytaBOM), time to treatment failure (29% vs. 31% at 5 yr), or overall survival (42% in both groups at 5 yr). Furthermore, there were no significant differences between the 2 regimens when response rates and outcome were analyzed for different prognostic subgroups. Toxicity was not significantly different between the 2 regimens, although only 1 patient died as result of treatment-related toxicity in the CHOP arm compared to 6 patient in the ProMACE-CytaBOM group (p = 0.126). In conclusion, in this study ProMACE-CytaBOM has not proved to be superior to CHOP in aggressive lymphomas. This trial gives support to the notion that CHOP still is the standard chemotherapy for aggressive lymphomas, and that new treatment approaches for these lymphomas should be compared to CHOP.     

Dual-steel portal frame design to withstand a fire exposure of 45 minutes

This paper presents the design of industrial portal frames with plain carbon steel (S275) and micro-alloyed Fire Resistant (FR) steel, coated with intumescent paint as fire protection for the structure. The coating improves the overall heat resistance of the metallic structure. The portal frames with different spans were calculated to observe their fire behavior. The structure was dimensioned by estimating the stresses to which each particular structural section was subjected and by selecting the most economic combination. The process was then repeated with the new dimensions to reach an optimal structural design. The key variables analyzed in this study are: five different spans, seven intumescent paint thicknesses, and eleven price ratios between the FR and the S275 steels, considering a fire exposure time of 45 minutes in all of the scenarios under study. The main conclusion was that the use of FR combined with S275 and the intumescent paint system was the most profitable option. In many cases, the better performance of this combination offered the most technically feasible option for the design of portal frame steel structures.     

An energy efficient intelligent torque vectoring approach based on fuzzy logic controller and neural network tire forces estimator

Neural Computing and Applications - In electric vehicles (EVs) with multiple motors, torque vectoring (TV) control can effectively enhance the cornering response and safety. Moreover, TV systems...     

Studying chemical activation in carbon xerogels

Chemical activation of carbon xerogels synthesized with different resorcinol/sodium carbonate molar ratios (R/C) was performed using alkaline hydroxides (KOH and NaOH). The effect of R/C and the type and amount of alkaline hydroxide on the final properties of the activated carbon xerogels were evaluated. It was found that, in general, both hydroxides produce an increase in microporosity regardless of the R/C value chosen, without altering the meso/macroporosity developed during the synthesis. KOH develops the microporosity of micro-mesoporous carbon xerogels more efficiently than NaOH, and for samples of large pore size (micro-macroporous samples), a similar textural development was observed for both hydroxides. However, when NaOH is used as activating agent, it is more difficult to eliminate residual Na from the activated carbon xerogels.     

Recent changes in emergency room visits and hospitalization for asthma in childhood

OBJECTIVE: The purpose of this study was to investigate recent changes in the emergency room visits and hospital admission rates between 1993 and 1997 in our hospital. PATIENTS AND METHODS: From January 1, 1993 until December 31, 1997, the 12,848 patients between 0 and 14 years of age whose discharge diagnosis was coded as asthma (ICD9) and who were managed in the emergency room of our hospital were included in the study. RESULTS: During the study period, the number of emergency room visits for asthma (EA) remained unchanged. However, in children between 0 and 5 years of age the number of EA showed a significant increase from 1305 in 1993 (53.5% of all EA) to 1849 in 1997 (68.9% of EA), with an increase of the repeat visits in this age group from 46 (35.8% of all EA in this age group) in 1993 to 791 (42.8%) in 1997 (p < 0.01). In the same period of time, the admission rates for asthma decrease from 7.2% to 2.9% (p < 0.01). There was a trend towards more intense treatment of asthma in the emergency observation unit. CONCLUSIONS: There has been an upward trend in the number of acute asthma episodes between 1993 and 1997 in children between 0 and 5 years of age. It was associated with an increase in the number of repeat visits per patient. The use of a more intense treatment in the emergency observation unit was associated with a reduction in the hospitalization rate for asthma.     

Spanish energy roadmap to 2020: Socioeconomic implications of renewable targets

The European Union has established challenging targets for the share of renewable energies to be achieved by 2020; for Spain, 20% of the final energy consumption must be from renewable sources at such time. The aim of this paper is the analysis of the consequences for the electricity sector (in terms of excess cost of electricity, investment requirements, land occupation, CO₂ emissions and overcapacity of conventional power) of several possibilities to comply with the desired targets. Scenarios are created from different hypotheses for energy demand, biofuel share in final energy in transport, contribution of renewables for heating and cooling, renewable electricity generation (generation mix, deployment rate, learning curves, land availability) and conventional power generation (lifetime of current installations, committed deployment, fossil fuel costs and CO₂ emissions cost). A key input in the estimations presented is the technical potential and the cost of electricity from renewable sources, which have been estimated in previous, detailed studies by the present authors using a methodology based on a GIS (Geographical Information System) and high resolution meteorological data. Depending on the scenario, the attainment of the targets will lead to an increase in the cost of electricity from 19% to 37% with respect to 2007.