Magnetic field-based arc stability sensor for electric arc furnaces

During the last decades the strategy to define the optimal Electric Arc Furnaces (EAF) electrical operational parameters has been constantly evolving. Foaming slag practice is currently used to allow high power factors that ensures higher energy efficiency. However, this performance depends on strict electric arc stability control. Control strategies for these are normally defined for alternating current furnaces (AC EAF) and are based on intrusive and highly expensive systems. In this work we analyze the variation of the magnetic field vector around the direct current EAF (DC EAF) and its relationship with arc stability. We propose a cheap stability control system with no installation or integration requirements and thus, easily implementable to both AC and DC EAFs. To this end we have built a non-intrusive and low-cost 3-axis Hall-effect sensor that can be mounted neighboring the furnace’s electrical bars. The sensor allows acquiring the magnetic field magnitude and orientation that provides a newly defined arc stability factor metric. This proposed Arc Stability Index has been compared with three different alternative well established and more expensive measurement methodologies obtaining with similar results. The proposed index serves as a closed loop signal to the electrical regulation for controlling the arc voltage, ensuring the most convenient arc length that guaranties non-instabilities. The new system was developed and industrially validated at two different DC EAF’s in ArcelorMittal demonstrating an improvement of 6.7 kWh per Liquid steel ton during the evaluated period and a time reduction of 1.1 min per heat over the current standard procedure. Additional validation tests were also carried out also in ArcelorMittal AC EAF proving the capability of this technology for both AC and DC of furnaces.Partial financial support of this work by the Basque Govern-ment (Hazitek AURRERAB ZE-2017/00009 and FASIN ZE-2016/0016 Projects) is gratefully acknowledged

Multidisciplinary, evidence-based consensus guidelines for human papillomavirus (HPV) vaccination in high-risk populations, Spain, 2016

High-risk populations; Human papillomavirus infection; VaccinesPoblacions d'alt risc; Virus del papil·loma humà; VacunesPoblaciones de alto riesgo; Virus del papiloma humano; VacunasINTRODUCTION: Although human papillomavirus (HPV) routine vaccination programmes have been implemented around the world and recommendations have been expanded to include other high-risk individuals, current recommendations often differ between countries in Europe, as well as worldwide. AIM: To find and summarise the best available evidence of HPV vaccination in high-risk patients aiding clinicians and public health workers in the day-to-day vaccine decisions relating to HPV in Spain. METHODS: We conducted a systematic review of the immunogenicity, safety and efficacy/effectiveness of HPV vaccination in high-risk populations between January 2006 and June 2016. HPV vaccination recommendations were established with levels of evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. RESULTS: A strong recommendation about HPV vaccination was made in the following groups: HIV infected patients aged 9-26 years; men who have sex with men aged 9-26 years; women with precancerous cervical lesions; patients with congenital bone marrow failure syndrome; women who have received a solid organ transplant or hematopoietic stem cell transplantation aged 9-26 years; and patients diagnosed with recurrent respiratory papillomatosis. CONCLUSIONS: Data concerning non-routine HPV vaccination in populations with a high risk of HPV infection and associated lesions were scarce. We have developed a document to evaluate and establish evidence-based guidelines on HPV vaccination in high-risk populations in Spain, based on best available scientific evidence

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.

OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

Long-Term Evolution of the Electrical Stimulation Levels for Cochlear Implant Patients

ObjectivesThe stimulation levels programmed in cochlear implant systems are affected by an evolution since the first switch-on of the processor. This study was designed to evaluate the changes in stimulation levels over time and the relationship between post-implantation physiological changes and with the hearing experience provided by the continuous use of the cochlear implant.MethodsSixty-two patients, ranging in age from 4 to 68 years at the moment of implantation participated in this study. All subjects were implanted with the 12 channels COMBI 40+ cochlear implant at San Cecilio University Hospital, Granada, Spain. Hearing loss etiology and progression characteristics varied across subjects.ResultsThe analyzed programming maps show that the stimulation levels suffer a fast evolution during the first weeks after the first switch-on of the processor. Then, the evolution becomes slower and the programming parameters tend to be stable at about 6 months after the first switch-on. The evolution of the stimulation levels implies an increment of the electrical dynamic range, which is increased from 15.4 to 20.7 dB and improves the intensity resolution. A significant increment of the sensitivity to acoustic stimuli is also observed. For some patients, we have also observed transitory changes in the electrode impedances associated to secretory otitis media, which cause important changes in the programming maps.ConclusionWe have studied the long-term evolution of the stimulation levels in cochlear implant patients. Our results show the importance of systematic measurements of the electrode impedances before the revision of the programming map. This report also highlights that the evolution of the programming maps is an important factor to be considered in order to determine an adequate calendar fitting of the cochlear implant processor

Influence of Partial and Total Replacement of Used Foundry Sand in Self-Compacting Concrete

In this work, the feasibility of partially and totally replacing natural sand with used foundry sand in self-compacting concrete was studied. Natural sand was replaced in 50% and 100% vol. by used foundry sand. The fresh state properties parameters analyzed in this study were slump flow, t500, V-funnel, Japanese ring and L-box following EFNARC guidelines. Results indicated an improvement in the fresh state properties when used foundry sand was utilized for partial and total replacement. The mechanical properties compressive strength and splitting tensile strength were obtained and analyzed at 7 and 28 days. Regarding the compressive strength, used foundry sand enhanced compressive strength by up to 67% compared to control concrete. For splitting tensile strength, the self-compacting concrete with 50% vol. of used foundry sand displayed a slight decrease (2.8%) compared with the control concrete. SEM images showed that the concretes with used foundry sand had a less porous and more compacted matrix than the control concrete. It was concluded that the incorporation of used foundry sand in large volumes can be utilized as a sustainable alternative natural fine aggregate

On-Line Stator Winding Fault Diagnosis in Induction Generators for Renewable Generation

Electrotechnical Conference, 2004. MELECON 2004. Proceedings of the 12th IEEE MediterraneanRenewable generation systems are increasing its presence in electrical power systems. For this reason, it is more important than ever to count with reliable and secure generation systems. In this way, the use of on-line diagnostic techniques in the maintenance schemes can be useful. This paper is about on-line condition monitoring in induction generators for small hydro stations and wind farms. In particular, stator winding fault diagnosis is analyzed. Currently, there are diagnostic techniques that are used in induction motors, but they could be used in generators as well. This paper analyzes the induction generator characteristics and describes the appropriate diagnostic techniques. These techniques depend on the machine voltage. As most of the induction generators are low voltage machines, the diagnosis of stator winding faults will be based on the detection of inter-turn short circuits. Most of the inter-turn short circuit diagnostic techniques are non-invasive as they are based on voltage and line current monitoring

DFT Performance in the IQA Energy Partition of Small Water Clusters

In this contribution, we assess performance of a large set of exchange-correlation functionals in the description of hydrogen bonding within the Interacting Quantum Atoms (IQA) energy partition. Apart from LDA-like approximations, all the considered families of exchange-correlation functionals (GGA, meta-GGA, and hybrid) reproduce the trends associated with hydrogen-bond non-additive effects computed with reference Møller-Plesset and coupled cluster wave functions. This might be further exploited in the examination of larger hydrogen-bonded complexes