Wheel–rail contact: experimental study of the creep forces–creepage relationships

The wheel–rail contact problem plays an important role in the simulation methods used to solve railway dynamics problems. As a consequence, many different mathematical models have been developed to calculate wheel–rail contact forces. However, most of them tackle this problem purely from a theoretical point of view and need to be experimentally validated. Such validation could also reveal the influence of certain parameters not taken into account in the mathematical developments. This paper presents the steps followed in building a scaled test-bench to experimentally characterise the wheel–rail contact problem. The results of the longitudinal contact force as a function of the longitudinal creepage are obtained and the divergences with respect to Kalker's simplified theory are analysed. The influence of lateral creepage, angular velocity and certain contaminants such as cutting fluid or high positive friction modifier is also discussed

Hydrodynamics of Ebrié lagoon as revealed by a chemical and isotopic study

To determine the origin and the circulation of waters in the different areas of the Ebrié lagoon (Ivory Coast), ionic concentrations (K+, Cl-) and isotopic ... measurements were performed. Sixty stations were sampled. Chemical and isotopic analyses were made thrice during a hydrological cycle : in may 1986, at the end of the great dry season; in October 1986, during the maximum of rainfall, in december 1987, after the Comoe river peak flow. From a hydrodynamical point of view, the results reported in this work indicate that the lagoon comprises four distinctive areas. The first is filled with freshwater all the year round and is characterized by an weak isotopic enrichment (these waters are of continental origin and annually renewed); the second corresponds to oligohaline waters ... (waters essentially of continental origin and poorly renewed); the third area is constituted of a mixure of waters of continental and oceanic origins. The latter group can be separated into two subgroups : a group completely renewed by oceanic water during the dry season and another group totally renewed by freshwater during the rainy and flood seasons. (D'après résumé d'auteur

La Hipótesis de la Profecia Autocumplida en la Evaluación de la Evidencia en el Contexto de la Gestión Continuada

Este estudio analiza si el valor otorgado a la evidencia a favor y en contra de la hipótesis de gestión continuada, se ve afectada por las percepciones que los auditores tienen sobre la validez de la hipótesis de la profecía autocumplida. Hemos realizado un experimento en el que una muestra de auditores debe someter a estudio la continuidad de una hipotética empresa, basándose tanto en información financiera como en determinada evidencia tanto a favor como en contra de la continuidad de ésta. Los resultados obtenidos sugieren que los auditores que muestran una fuerte creencia en la validez de la hipótesis de la profecía autocumplida otorgan mayor valor probatorio a la evidencia a favor de la hipótesis de continuidad. Por el contrario, los auditores que no muestran una fuerte creencia en la hipótesis de la profecía autocumplida otorgan un mayor valor probatorio a la evidencia en contra de la continuidad.This paper analyzes whether auditors are affected by the so called “self-fulfilling prophecy effect” (in terms of perceptions) when evaluating clients’ going concern status. We designed a laboratory experiment to examine auditors’ attitude to both negative and positive evidence in the case of a fictitious financially distressed client. Our results show that those auditors more sensitive to the self-fulfilling prophecy effect offered a higher tendency to rely on the negative factors. On the other hand, those auditors less worried about the self-fulfilling prophecy effect showed a higher tendency to rely on the positive factors

Osteopoiquilosis.: a propósito de tres casos

Los autores presentan el estudio genealógico, clínico y radiológico de una familia con osteopoiquilosis, haciendo hincapié en el diagnóstico diferencial así como en la importancia de la biopsia en el caso de sospecha de una tumoración ósea.The authors show a genealogic, clinic and radiologic study of one family affected by osteopoikilosis. They emphasiz e the differential diagnosis as well as the importance of biopsy suspecting a bone tumor

A case–control study to assess the effectiveness of pertussis vaccination during pregnancy on newborns, Valencian community, Spain, 1 March 2015 to 29 February 2016

In the Valencian Community (Spain), the programme of maternal pertussis vaccination during pregnancy started in January 2015. The objective of this study was to estimate in this region the vaccine effectiveness (VE) in protecting newborns against laboratory-confirmed pertussis infection. A matched case–control study was undertaken in the period between 1 March 2015 and 29 February 2016. Twenty-two cases and 66 controls (+/− 15 days of age difference) were included in the study. Cases were non-vaccinated infants < 3 months of age at disease onset testing positive for pertussis by real-time PCR. For every case three unvaccinated controls were selected. Odds ratios (OR) were calculated by multiple conditional logistic regression for association between maternal vaccination and infant pertussis. Other children in the household, as well as mother- and environmental covariates were taken into account. The VE was calculated as 1 − OR. Mothers of five cases (23%) and of 41 controls (62%) were vaccinated during pregnancy. The adjusted VE was 90.9% (95% confidence interval (CI): 56.6 to 98.1). The only covariate in the final model was breastfeeding (protective effect). Our study provides evidence in favour of pertussis vaccination programmes for pregnant women in order to prevent whooping cough in infants aged less than 3 months

Trusting/distrusting auditors' opinion

Trust relations are essential for effective interchanges in the financial markets. Investors 9 (trustors), as well as other market participants, can only trust financial markets if they trust their 10 auditors (trustees). Especially, auditors' assessment on the client's financial condition and its 11 ability to continue as a going concern is paramount to improving social capital and maintaining 12 sustainable financial markets. Research shows that a going concern opinion may have immediate 13 consequences for both the auditing profession and financial statement users. We utilize the 14 Throughput Model to illustrate how different trust positions are aligned with a particular 15 auditor's decision-making pathway to enhance trust, distrust or no trust from the point of view of 16 investors' and creditors'

La hipótesis de la profecía autocumplida en la evaluación de la evidencia en el contexto de la gestión continuada: The role played by the self fulfilling prophecy effect in the going concern evaluation process

This paper analyzes whether auditors are affected by the so called “self-fulfilling prophecy effect” (in terms of perceptions) when evaluating clients’ going concern status. We designed a laboratory experiment to examine auditors’ attitude to both negative and positive evidence in the case of a fictitious financially distressed client. Our results show that those auditors more sensitive to the self-fulfilling prophecy effect offered a higher tendency to rely on the negative factors. On the other hand, those auditors less worried about the self-fulfilling prophecy effect showed a higher tendency to rely on the positive factors.Este estudio analiza si el valor otorgado a la evidencia a favor y en contra de la hipótesis de gestión continuada, se ve afectada por las percepciones que los auditores tienen sobre la validez de la hipótesis de la profecía autocumplida. Hemos realizado un experimento en el que una muestra de auditores debe someter a estudio la continuidad de una hipotética empresa, basándose tanto en información financiera como en determinada evidencia tanto a favor como en contra de la continuidad de ésta. Los resultados obtenidos sugieren que los auditores que muestran una fuerte creencia en la validez de la hipótesis de la profecía autocumplida otorgan mayor valor probatorio a la evidencia a favor de la hipótesis de continuidad. Por el contrario, los auditores que no muestran una fuerte creencia en la hipótesis de la profecía autocumplida otorgan un mayor valor probatorio a la evidencia en contra de la continuidad.PALABRAS CLAVE: Gestión Continuada, Auditoría, Evaluación de la Evidencia, Profecía Autocumplid

Towards an engineering model for curve squeal

Curve squeal is a strong tonal noise that may arise when a railway vehicle negotiates a curve. The wheel/rail contact model is the central part of prediction models, describing the frictional instability occurring in the contact during squeal. A previously developed time-domain squeal model considers the wheel and rail dynamics, and the wheel/rail contact is solved using Kalker’s nonlinear transient CONTACT algorithm with Coulomb friction. In this paper, contact models with different degree of simplification are compared to CONTACT within the previously developed squeal model in order to determine a suitable contact algorithm for an engineering curve squeal model. Kalker’s steady-state FASTSIM is evaluated, and, without further modification, shows unsatisfying results. An alternative transient single-point contact algorithm named SPOINT is formulated with the friction model derived from CONTACT. Comparing with the original model results, the SPOINT implementation results are promising and similar to results from CONTACT

La prótesis Bicontact resultados a 11 años de seguimiento

Peer Reviewe

Misión Arqueológica española en Pompeya. Informe de los trabajos realizados durante las campañas de 1989-1990 en la casa/caupona (1.8.8-9) de L. Vetutius Placidus

The works carried out during the 1989/1990 Campaings have tried to achieve: the thorough documentation of the building using the diaries of the dig: the study of the architecture, paintign, pavements and material culture as well as a diagnosis of how well-preserved the aforementioned remains are. The Home/Caupona (I.8.8-9) belonging to L. Vetutius Placidu, in its initial stages, dates back to the 2nd Century B.C., and three stages have been detected in gradual progression between that date and the year 79 A.D. These reforms can also be seen in the pictorial decoration from the II, III and IV styles and in the opus signinum and «cocciopesto» pavements that have been conserved. The material culture, represented by ceramics (t.s.i, amphoras, dolia, and lamps), metals and objects made out of bone, make up the furnishings of a middle-class home in Pompeii. Finally, the state of conservation of the materials under study has been diagnosed and posible repairs have been suggested.Los trabajos llevados a cabo durante las Campañas de 1989-1990 han pretendido: la documentación exhaustiva del edilicio a través de los diarios de excavación; el estudio de la arquitectura, pintura, pavimento y cultura material y el diagnóstico del estado de conservación de los restos mencionados. La Casa/Caupona (I. 8.8-9) de L. Vetutius Placidus, en su etapa inicial, se remonta al s/II a.C., detectándose tres fases que se escalonan desde esa fecha hasta el año 79 d.C. Estas reformas se aprecian igualmente en las decoracciones pictóricas del II, III y IV estilos y en los pavimentos de opus signinum y «cocciopesto> conservados. La cultura material representada por cerámicas (t.s.i., ánforas, dolia y lucernas), metales y objetos de hueso resume el ajuar de una casa de tipo medio en Pompeya. Por último, se realiza un diagnóstico del estado de conservación de los materiales estudiados, sugiriendo posibles intervenciones