Measurements of the Dynamic Forced Response of an O-Rings Sealed Squeeze Film Damper Supplied with a Low Supply Pressure

Modern SFD designs are short in axial length to limit weight and part count and supplied with a low lubricant feed pressure to reduce operating costs related to lubricant storage and pumping power. O-rings (ORs) reduce lubricant side leakage, increasing the viscous damping within a constrained physical space and provide a modest centering support stiffness to the rotor. Continuing a long-term project characterizing SFDs for air breathing engines, the thesis details comprehensive measurements of the forced performance of an OR sealed damper (OR-SFD), with a film land length L=25.4 mm, 127 mm in diameter (D), and a radial clearance c=0.279 mm. The damper, with a slenderness ratio L/D = 0.2. undergoes centered whirl motions with amplitudes r=0.05c to 0.45c, over ω = 10 Hz to 130 Hz (max. squeeze film velocity vs=rω=102.5 mm/s). Lubricant ISO VG 2 supplied at 0.69 bar(g) fills an upstream oil plenum and flows through a single orifice with a check valve midway of the damper length (1/2L). Measurements of dynamic loads, along with the ensuing displacements and accelerations identify the parameters of the test structure, ORs and SFD. This research effort is the first to identify ORs force coefficients over a range of orbit amplitudes and assess its effects on the dynamic performance of the OR-SFD. The ORs force coefficients remain nearly invariant within the identification frequency range; however, they showcase significant orbit amplitude dependence. At r/c = 0.05 the OR centering stiffness (KOR) doubles the static stiffness (KOR,static), and as r/c→ 0.45, KOR approaches ½KOR,static, likely due to the extensive elastic deformation and slow recovery in the rings’ polymeric structure bonds. At r=0.05c and 0.10c, the ORs viscous damping coefficient (COR) contributes to ~10% of the total in the lubricated system (CL), while for r/c > 0.25, it contributes to just 3% of CL. For small orbit amplitudes (r ≤ 0.25c), the experimental SFD added mass (MSFD) and viscous damping (CSFD) coefficients are nearly equivalent to theoretical magnitudes for a fully sealed damper (no side leakage). However, as the orbit size grows to r → 0.45c, MSFD drops nearly 75% and COR decreases by ~40%. The reduction in force coefficients is due to the onset of both lubricant cavitation and air ingestion occurring for vs ≥ 24.5 mm/s. A prediction model delivers squeeze film added mass and viscous damping coefficients which are on average, 10% larger than those derived experimentally. Measured film dynamic pressures evidence both oil vapor cavitation and air ingestion, and video recordings depict a bubbly mixture in the lubricant return line and through the damper top end. Peak-peak film pressures for operation at vs ≥ 34 mm/s show the gas content prevents the generation of peak pressures proportional to vs. Moreover, pk-pk pressures inside the journal oil delivery plenum follow the same trend as those in the film land, showing the mechanical check valve installed in the journal allows for lubricant backflow. A novel approach enables the estimation of the gas volume fraction (GVF), which rapidly increases with vs. The simple procedure draws into a deflated balloon the material contents in the film, weighs the sample and identifies its volume to produce an estimation of the GVF. The research findings reveal more details on the effect of ORs to the forced performance of a damper and their limited ability to prevent air ingestion when operating at large squeeze velocities and a low lubricant feed pressure

Factores que influyen en la vacunación contra el virus del papiloma humano en padres de escolares: Revisión documental

A nivel mundial el cáncer de cuello uterino representa una de las neoplasias de mayor morbilidad y mortalidad en las mujeres, sin embargo no deja de ser una enfermedad prevenible, gracias a las estrategias sanitarias que se han implementado a lo largo del tiempo, la inmunización resulta ser una de las más efectivas para reducir la incidencia de este tipo de neoplasia, sin embargo las coberturas no son las ideales, dejando a miles de adolescentes susceptibles de padecer esta enfermedad en algún momento de su vida. La presente investigación identifica la evidencia que existe sobre los factores que influyen en la vacunación contra el Virus del Papiloma Humano en padres de escolares. Realiza una revisión documental en bases de datos: Science Direct, Scielo, Dialnet, PubMet, Repositorio UNMSM, Repositorio UNAC, utilizando para la búsqueda palabras claves, descriptores en Ciencias de la Salud, encontrándose 15 artículos en idiomas de español, inglés, y francés, tras aplicar criterios de selección. Concluye que los factores que influyen en la vacunación contra el VPH en padres de escolares son; factor demográfico, sociocultural, cognitivo, institucional, y psicológico.Perú. Universidad Nacional Mayor de San Marcos. Vicerrectorado de Investigación y Posgrado. Programa de Promoción de Trabajo de Investigación para optar el Grado de Bachiller. A20010610

Transformer-based Atmospheric Density Forecasting

As the peak of the solar cycle approaches in 2025 and the ability of a single geomagnetic storm to significantly alter the orbit of Resident Space Objects (RSOs), techniques for atmospheric density forecasting are vital for space situational awareness. While linear data-driven methods, such as dynamic mode decomposition with control (DMDc), have been used previously for forecasting atmospheric density, deep learning-based forecasting has the ability to capture nonlinearities in data. By learning multiple layer weights from historical atmospheric density data, long-term dependencies in the dataset are captured in the mapping between the current atmospheric density state and control input to the atmospheric density state at the next timestep. This work improves upon previous linear propagation methods for atmospheric density forecasting, by developing a nonlinear transformer-based architecture for atmospheric density forecasting. Empirical NRLMSISE-00 and JB2008, as well as physics-based TIEGCM atmospheric density models are compared for forecasting with DMDc and with the transformer-based propagator.Comment: Conference: 24th Advanced Maui Optical and Space Surveillance Technologies At: Maui, Hawaii, United State

Key soft skills in the orientation process and level of employability

We understand soft skills as an integrated set of knowledge, skills and values that facilitate the effective, affective and efficient development of a skill or activity. The objective of this study was to identify the soft skills that are most often used in the orientation process and those that improve employability, according to Spanish counselors. A qualitative methodology was used. The participants (n = 57) were orientation professionals. A total of 273 interviews were conducted over five years. The results and conclusions show that communication and decision-making are the most important competencies in the orientation process and at the level of employability, followed by intrapersonal skills, skills in interpersonal relationships, teamwork, problem solving, adaptation to new situations, creativity and leadership

El Mundo de los galgos

Treball presentat a l'assignatura de Deontologia i Veterinària Legal (21223

Real-time moving object segmentation in H.264 compressed domain based on approximate reasoning

AbstractThis paper presents a real-time segmentation algorithm to obtain moving objects from the H.264 compressed domain. The proposed segmentation works with very little information and is based on two features of the H.264 compressed video: motion vectors associated to the macroblocks and decision modes. The algorithm uses fuzzy logic and allows to describe position, velocity and size of the detected regions in a comprehensive way, so the proposed approach works with low level information but manages highly comprehensive linguistic concepts. The performance of the algorithm is improved using dynamic design of fuzzy sets that avoids merge and split problems. Experimental results for several traffic scenes demonstrate the real-time performance and the encouraging results in diverse situations

XMM-Newton Finds That SAX J1750.8-2900 May Harbor the Hottest, Most Luminous Known Neutron Star

We have performed the first sensitive X-ray observation of the low-mass X-ray binary SAX J1750.8-2900 in quiescence with XMM-Newton. The spectrum was fit to both a classical black body model, and a non-magnetized, pure hydrogen neutron star atmosphere model. A power law component was added to these models, but we found that it was not required by the fits. The distance to SAX J1750.8-2900 is known to be D = 6.79 kpc from a previous analysis of photospheric radius expansion bursts. This distance implies a bolometric luminosity (as given by the NS atmosphere model) of (1.05 +/- 0.12) x 10^34 (D/6.79 kpc)^2 erg s^-1, which is the highest known luminosity for a NS LMXB in quiescence. One simple explanation for this surprising result could be that the crust and core of the NS were not in thermal equilibrium during the observation. We argue that this was likely not the case, and that the core temperature of the NS in SAX J1750.8-2900 is unusually high

“Nivel de conocimiento en relación a las practicas de bioseguridad de las enfermeras en el centro quirúrgico de la Clínica Vesalio San Borja, 2018”

La presente investigación tuvo como objetivo determinar la relación del nivel de conocimiento y las prácticas de bioseguridad de las enfermeras de centro quirúrgico, de la Clínica Vesalio san Borja, 2018. Material y método; presente estudio de investigación es tipo cuantitativo, descriptivo de corte transversal, ya que permitió de la realidad para presentar los hechos tal como se obtuvieron en un tiempo y espacio determinado. Para la recolección de los datos el instrumento usado fue el cuestionario la técnica fue la observación mediante una lista de cotejo. Resultados; Del 100% de los profesionales de enfermería conocen sobre las medidas de bioseguridad, el 56% tiene nivel de conocimiento alto sobre lavado de manos, el 25% medio y sólo el 19% bajo; en el manejo de manejo de biocontaminados el 66% tiene nivel alto, el 25% medio y el 9% bajo; de los cuales al aplicar las prácticas de bioseguridad en lavado de manos estas no se cumplen en su totalidad, ya que un alto porcentaje no se lava las manos antes de ingresar al servicio, durante el tiempo correcto, antes y después del contacto con el paciente, fluidos corporales y procedimientos; ni en manejo de residuos ya que estos no se manipulan con barreras protectoras. Conclusiones; se determinó que la relación del nivel de conocimiento y las prácticas de bioseguridad de las enfermeras de centro quirúrgico en la clínica Vesalio, la mayoría de los profesionales conocen sobre las normas, medidas de bioseguridad, sin embargo algunas de ellas no lo ponen en práctica ni la utiliza de manera adecuada; esto se confirmó durante las observaciones realizadas.Tesis de segunda especialida