A Basic Analysis Of Aging Aircraft, Region Of The World, And Accidents

Differences in aviation safety records around the world should be minimal or nonexistent considering the global nature of aviation. However, significant differences exist and the reasons for those require the attention of governments, regulatory agencies, aircraft manufacturers, airlines and the flying public. One concern is that aircraft are increasingly used beyond their designed economic life. This study focuses on the relationship between aging aircraft and the country where the aircraft was registered. Findings support the idea that in general, the frequency of accidents increases with the age of an aircraft. The study also revealed that there is a correlation between the number of accidents, their severity and aircraft manufacturers. The aircraft’s phase of flight was also related to the number of accidents, with the Approach/Landing phase having the greatest number of accidents. The FAA and JAA have been influential in the development and dissemination of safety programs around the world. However, their efforts have not yet resulted in a world-wide standardization of safety and maintenance programs. This may be an indication that while an aircraft may be a global product, the aviation industry lags behind in becoming a global industry

Distribution of individual wave overtopping volumes on mound breakwaters

[EN] Conventional mound breakwaters are usually designed to withstand low mean wave overtopping discharges and a low proportion of overtopping waves (P-ow). Existing formulas to estimate P-ow, and maximum individual wave overtopping volume are usually based on tests with high P-ow; this study is focused on mound breakwaters subjected to P-ow, < 0.2. The performance of the 2-parameter Weibull and Exponential distributions is examined in order to describe individual wave overtopping volumes of mound breakwaters in non-breaking wave conditions. A new methodology is applied to 164 small-scale 2D physical tests to identify the number of overtopping waves, and the corresponding individual wave overtopping volumes. Utility functions are used to consider the relative relevance of the observed data: in this study, a quadratic utility function depending on all the individual wave overtopping volumes and step utility functions with 10%, 30% and 50% of the highest volumes are used to fit the Weibull and Exponential distributions. In this study, a new estimator of P-ow is proposed to improve the predictions required to estimate the maximum individual wave overtopping volume. Existing estimators of P-ow, underpredict the largest values of P-ow, measured in the physical tests. The parameters fitted to the Weibull and Exponential distributions using the quadratic utility function provide estimations of the dimensionless maximum individual wave overtopping volume with relative mean squared errors rMSE = 10.4% and 10.6%, respectively. When CLASH Neural Network-estimated mean overtopping rates are used to predict the maximum individual wave overtopping with the quadratic utility function, the 2-parameter Weibull and Exponential distributions provide rMSE = 31.6% and rMSE = 33.3%, respectively. The new estimators proposed in this study improve the predictions of P-ow and maximum individual wave overtopping volumes on conventional mound breakwaters designed for low wave overtopping rates.The authors are grateful for financial support from European FEDER and Spanish Ministerio de Economia y Competitividad (Grants BIA2012-33967 and BIA2015-70435-R), SATO (OHL Group), Universitat Politecnica de Valencia (Grant SP20180111, Primeros Proyectos de Investigacion (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia) and CDTI (Centro para el Desarrollo Tecnologico e Industrial). The authors also thank Debra Westall for revising the manuscript.Molines, J.; Herrera, MP.; Gómez-Martín, ME.; Medina, JR. (2019). Distribution of individual wave overtopping volumes on mound breakwaters. Coastal Engineering. 149:15-27. https://doi.org/10.1016/j.coastaleng.2019.03.006S152714

General Relativistic Radiant Shock Waves in the Post-Quasistatic Approximation

An evolution of radiant shock wave front is considered in the framework of a recently presented method to study self-gravitating relativistic spheres, whose rationale becomes intelligible and finds full justification within the context of a suitable definition of the post-quasistatic approximation. The spherical matter configuration is divided into two regions by the shock and each side of the interface having a different equation of state and anisotropic phase. In order to simulate dissipation effects due to the transfer of photons and/or neutrinos within the matter configuration, we introduce the flux factor, the variable Eddington factor and a closure relation between them. As we expected the strength of the shock increases the speed of the fluid to relativistic values and for some critical ones is larger than light speed. In addition, we find that energy conditions are very sensible to the anisotropy, specially the strong one. As a special feature of the model, we find that the contribution of the matter and radiation to the radial pressure are the same order of magnitude as in the mant as in the core, moreover, in the core radiation pressure is larger than matter pressure.Comment: To appear in Journal of Physics:Conference Series:"XXIX Spanish Relativity Meeting (ERE 2006): Einstein's Legacy: From the Theoretical Paradise to Astrophysical Observations

Nonannual tree rings in a climate-sensitive Prioria copaifera chronology in the Atrato River, Colombia

In temperate climates, tree growth dormancy usually ensures the annual nature of tree rings, but in tropical environments, determination of annual periodicity can be more complex. The purposes of the work are as follows: (1) to generate a reliable tree‐ring width chronology for Prioria copaifera Griseb. (Leguminoceae), a tropical tree species dwelling in the Atrato River floodplains, Colombia; (2) to assess the climate signal recorded by the tree‐ring records; and (3) to validate the annual periodicity of the tree rings using independent methods. We used standard dendrochronological procedures to generate the P. copaifera tree‐ring chronology. We used Pearson correlations to evaluate the relationship of the chronology with the meteorological records, climate regional indices, and gridded precipitation/sea surface temperature products. We also evaluated 24 high‐precision 14C measurements spread over a range of preselected tree rings, with assigned calendar years by dendrochronological techniques, before and after the bomb spike in order to validate the annual nature of the tree rings. The tree‐ring width chronology was statistically reliable, and it correlated significantly with local records of annual and October–December (OND) streamflow and precipitation across the upper river watershed (positive), and OND temperature (negative). It was also significantly related to the Oceanic Niño Index, Pacific Decadal Oscillation, and the Southern Oscillation Index, as well as sea surface temperatures over the Caribbean and the Pacific region. However, 14C high‐precision measurements over the tree rings demonstrated offsets of up to 40 years that indicate that P. copaifera can produce more than one ring in certain years. Results derived from the strongest climate–growth relationship during the most recent years of the record suggest that the climatic signal reported may be due to the presence of annual rings in some of those trees in recent years. Our study alerts about the risk of applying dendrochronology in species with challenging anatomical features defining tree rings, commonly found in the tropics, without an independent validation of annual periodicity of tree rings. High‐precision 14C measurements in multiple trees are a useful method to validate the identification of annual tree rings

Inverse method based on 3D nonlinear physically constrained minimisation in the framework of traction force microscopy

Traction force microscopy is a methodology that enables to estimate cellular forces from the measurement of the displacement field of an extracellular matrix (ECM)-mimicking hydrogel that a cell is mechanically interacting with. In this paper, a new inverse and physically-consistent methodology is developed and implemented in the context of 3D nonlinear elasticity. The proposed method searches for a displacement field that approximates the measured one, through the imposition of fulfillment of equilibrium with real and known forces acting in the hydrogel. The overall mathematical formulation leads to a constrained optimisation problem that is treated through a Lagrange operator and that is solved numerically by means of a nonlinear finite element framework. In order to illustrate the potential and enhanced accuracy of the proposed inverse method, it is applied to a total of 5 different real cases of cells cultured in a 3D hydrogel that is considered to behave as a nonlinear elastic material. Different error indicators are defined in order to compare ground truth simulated displacements and tractions to the ones recovered by the new inverse as well as by the forward method. Results indicate that the evaluation of displacement gradients leads to errors, in terms of recovered tractions, that are more than three times lower (on average) for the inverse method compared to the forward method. They highlight the enhanced accuracy of the developed methodology and the importance of appropriate inverse methods that impose physical constraints to traction and stress recovery in the context of traction force microscopyMinisterio de Economía y Competitividad (MINECO). PGC2018-097257-B-C31Consejo Europeo de Resucitación 308223Consejo Europeo de Resucitación G087018NMinisterio de Educación, Cultura y Deporte (MECD). España CAS17/00096Hércules G0H6316NFonds Wetenschappelijk Onderzoek (FWO) 12ZR120NFonds Wetenschappelijk Onderzoek (FWO) V413019

Lightning Impulse Current Tests on Conductive Fabrics

Submitted to "Journal of Industrial Textiles"The large amount of electric current associated to lightning discharges is hazardous for living beings, equipment, structures and buildings. To protect those targets against lightning are used Lightning Protection Systems (LPS). However, there are some temporary outdoor activities and backcountry places where an adequate LPS cannot be set up mainly due to the large dimensions of its components and its heavy weight. On the search of light weight lightning protection materials that can be used as part of special LPS, we research some types of electroconductive fabrics by applying high lightning impulse currents in laboratory. The fabric samples checked were pieces of 10 cm x 10 cm: two rip-stop type, a plain-weave, a non-woven and a carbon-impregnated polymeric, all of them obtained commercially. Under laboratory conditions, these samples were subject to subsequent lightning impulse currents registering the voltage and current signals. Optical and scanning electron microscope inspections were performed after tests. Despite some changes visualized as marks left on the fabric surface, the results show that investigated conductive textiles can endure ground currents produced by atmospheric lightning since they withstand the several applied laboratory lightning impulse currents. The outcomes suggest that the weave pattern of the conductive fabric influences the lightning current tolerance, enabling some conductive fabrics to be used in heavy-current applications and as part of personal LPS for outdoor, backcountry and mobile shelters, particularly when lightweight and portability are mandatory

Enfermedad por depósito de cristales de pirofosfato de calcio como ejemplo de forma de manifestación de la enfermedad en el adulto mayor

Indexación: Web of Science; Scielo.Illness presentation in the elderly may be entirely non-specific, with fatigue, loss of function or the presence of geriatric syndromes. We report a 90 years old male consulting in the emergency room for delirium that persisted throughout hospitalization without finding a cause. During the course of hospitalization mild fever appeared and a left knee swelling became apparent. A synovial fluid aspiration showed a leukocyte count of 360 per field with 60% polymorphonuclear cells. The culture was negative. With a presumptive diagnosis of pseudogout, cochicine and celecoxib were started with remission of the confusional state. The patient was discharged 13 days after admission in good conditions. Key words: Aged; Chondrocalcinosis; Delirium; Fever

Adaptive Bone Remodeling With New Design of the ABG Stem. Densitometric Study

To establish the pattern of bone remodeling caused by a cementless, anatomic implant, we intend to evaluate the changes in bone mineral density observed after surgery in the Gruen zones. A controlled, prospective study was carried out, in which a group of 37 patients with primary coxarthrosis were densitrometrically analyzed over the 1 year period following the implant of an ANATO stem (Stryker). The patient's healthy hip was taken as the control. Any differences in the remodeling pattern were compared according to age, body mass index, and implant size. Decreases in bone mineral density were observed after 3 months in all of the zones studied. However, this bone mineral density loss was recovered in all zones by the end of the study, except in zone 7 where a decrease of 7.2% in bone mass was observed. In zones 2 and 6, where more loads are transmitted, bone mass preservation, in accordance with Wolff's law, can be seen. No differences were found in the remodeling pattern in relation to age and body mass index. There were also no differences related to stem size except in zones 1 and 7. The ANATO stem achieves an efficient transmission of loads between the stem and the proximal femur, providing enough mechanical loads for bone preservation. It is only in zone 7 where significant bone atrophy can be observed, attributable to the damage that this area suffers during the surgical process and the subsequent stress-shielding caused by the implant design