438 research outputs found
Comparative Study of Vibration Response in Steel and Braided-Carbon-Fiber Bicycle Handlebars: A Numerical-Experimental Approach with Various Sensors
\ua9 2024 by the authors. The comfort and safety of a cyclist are directly influenced by the vibrational behavior of the handlebar. Hence, the objective of this article is to comparatively assess the vibrational characteristics of two bicycle handlebars: one made of steel and the other made of braided composite material. The transmissibility function represents the relationship between the excitation applied to both handlebars through their stems and the corresponding response in the handle area, which was experimentally obtained by applying a random vibrating signal (constant amplitude of 0.01 g2/Hz) using a shaker. This signal was applied in a frequency range between 100 Hz and 1200 Hz, and the response was measured at one of the two cantilevered ends of the handlebar. Different sensors, including a laser vibrometer and a control accelerometer in the shaker, were utilized. The transmissibility, natural frequencies and damping functions were obtained. Subsequently, another experimental analysis was carried out with the instrumented handlebars mounted on a bicycle, placing three accelerometers and a GPS meter and traveling through a real test circuit, with a rough surface, speed bumps and areas with shaped warning bands. Power Spectral Density (PSD) curves were obtained for the steel and carbon-fiber-composite handlebars in order to quantify the signal intensity. Finally, a fatigue analysis was carried out in order to evaluate the expected life of both handlebars under the experimentally applied load, which is considered the reference cycle. This study offers a comparative analysis of the vibration behavior exhibited by steel and carbon-fiber-composite bicycle handlebars under experimentally applied load. In conclusion, data on natural frequencies, damping functions and fatigue life expectancy for both handlebar materials were obtained. Our study provides valuable insights into the vibrational behavior and performance characteristics of steel and carbon-fiber-composite bicycle handlebars, contributing to the understanding of their comfort and safety implications for cyclists
Assessment of hygienic conditions of ground pepper (Piper nigrum L.) on the market in SĂŁo Paulo city, by means of two methodologies for detecting the light filth
Pepper should to be collected, processed, and packed under optimum conditions to avoid the presence of foreign matter. The hygienic conditions of ground pepper marketted in São Paulo city were assessed in determining the presence of foreign matter by means of two extraction methodologies. This study was carried out during a six-month time period from May to September 2006. The occurrence of light impurities was determined either by the flotation technique following the methodology recommended by AOAC or by enzyme – linked immunosorbent assay (ELISA). It was observed that 100% of the examined samples contained insect fragments, and many samples were housing more than one type of foreign matter. Twentytwo percent of samples were unqualified for consumption owing to the occurrence of rodent hairs. For the calibration of ELISA test for quantification of insect contamination level in pepper samples, a range of standard-infested samples was prepared in adding 1, 2, 4, 8 and 10 insects in a control sample to estimate the number of insects in the analyzed samples by measuring optical densities (OD) values with a spectrophotometer. Among the 22 samples, 36.4% of samples presented OD values close to that corresponding to the standard infested with eight insects, 40.9% of samples were comparable to OD of the standard infested with four insects, 18.2% comparable to standard with 10 insects, and 4.5% to the standard with two insects. According to the results observed in the present study, the technique described in AOAC official methods manual was found more suitable for detecting not only the insects but also the additional impurities in analyzed samples, while ELISA is specific to detect myosin from the insect muscle, which undergoes serious degradation with time. Keywords: Pepper, ELISA test , Light filth, AOAC official method
Providing care for older adults in the Emergency Department: expert clinical recommendations from the European Task Force on Geriatric Emergency Medicine
Cures agudes; Medicina d'urgències; GeriatriaCuidados agudos; Medicina de urgencias; GeriatrĂaAcute care; Emergency medicine; GeriatricsPurpose: Despite the rapidly expanding knowledge in the field of Geriatric Emergency Medicine in Europe, widespread implementation of change is still lacking. Many opportunities in everyday clinical care are missed to improve care for this susceptible and growing patient group. The aim was to develop expert clinical recommendations on Geriatric Emergency Medicine to be disseminated across Europe.
Methods: A group of multi-disciplinary experts in the field of Geriatric Emergency Medicine in Europe was assembled. Using a modified Delphi procedure, a prioritized list of topics related to Geriatric Emergency Medicine was created. Next, a multi-disciplinary group of nurses, geriatricians and emergency physicians performed a review of recent guidelines and literature to create recommendations. These recommendations were voted upon by a group of experts and placed on visually attractive posters. The expert group identified the following eight subject areas to develop expert recommendations on: Comprehensive Geriatric Assessment in the Emergency Department (ED), age/frailty adjusted risk stratification, delirium and cognitive impairment, medication reviews in the ED for older adults, family involvement, ED environment, silver trauma, end of life care in the acute setting.
Results: Eight posters with expert clinical recommendations on the most important topics in Geriatric Emergency Medicine are now available through https://posters.geriemeurope.eu/ .
Conclusion: Expert clinical recommendations for Geriatric Emergency Medicine may help to improve care for older patients in the Emergency Department and are ready for dissemination across Europe
Lie symmetries for equations in conformal geometries
We seek exact solutions to the Einstein field equations which arise when two
spacetime geometries are conformally related. Whilst this is a simple method to
generate new solutions to the field equations, very few such examples have been
found in practice. We use the method of Lie analysis of differential equations
to obtain new group invariant solutions to conformally related Petrov type D
spacetimes. Four cases arise depending on the nature of the Lie symmetry
generator. In three cases we are in a position to solve the master field
equation in terms of elementary functions. In the fourth case special solutions
in terms of Bessel functions are obtained. These solutions contain known models
as special cases.Comment: 19 pages, To appear in J. Phys.
Targeting of NLRP3 Inflammasome With a Novel Selective Inhibitor as a Suitable Strategy for the Pharmacological Treatment of Bowel Inflammation
Kinematic Self-Similarity
Self-similarity in general relativity is briefly reviewed and the differences
between self-similarity of the first kind and generalized self-similarity are
discussed. The covariant notion of a kinematic self-similarity in the context
of relativistic fluid mechanics is defined. Various mathematical and physical
properties of spacetimes admitting a kinematic self-similarity are discussed.
The governing equations for perfect fluid cosmological models are introduced
and a set of integrability conditions for the existence of a proper kinematic
self-similarity in these models is derived. Exact solutions of the irrotational
perfect fluid Einstein field equations admitting a kinematic self-similarity
are then sought in a number of special cases, and it is found that; (1) in the
geodesic case the 3-spaces orthogonal to the fluid velocity vector are
necessarily Ricci-flat and (ii) in the further specialisation to dust the
differential equation governing the expansion can be completely integrated and
the asymptotic properties of these solutions can be determined, (iii) the
solutions in the case of zero-expansion consist of a class of shear-free and
static models and a class of stiff perfect fluid (and non-static) models, and
(iv) solutions in which the kinematic self-similar vector is parallel to the
fluid velocity vector are necessarily Friedmann-Robertson-Walker (FRW) models.Comment: 29 pages, AmsTe
Segmentação DistribuĂda de Imagem de Sensoriamento Remoto a partir de Banco de Dados PostgreSQL/InterIMAGE.
A abordagem de classificação baseada em objetos representa um novo paradigma no processamento de imagens de altas resoluções espaciais, espectrais e temporais, e a construção de objetos baseia-se na segmentação das imagens. A análise de imagens baseada em objetos (GEOBIA - Geographic Object-Based Image Analysis) apresenta mĂ©todos capazes de explorar, alĂ©m de atributos espectrais, elementos como textura, forma ou contexto. Existem aplicações que buscam melhorar o desempenho computacional com soluções sequenciais e distribuĂdas, ou programas como TerraView que abordam o uso de sistemas gerenciadores de banco de dados. Este trabalho propõe explorar especificações de aplicações para integrar o Sistema Gerenciador de Banco de Dados (SGBD) PostgreSQL/PostGIS e o classificador Object-Based Image Analysis (OBIA) do InterIMAGE Desktop para processamento de grandes imagens orbitais. O mĂ©todo apresentado Ă© expansĂvel no uso da biblioteca TerraLib 5, com linguagem de programação C++. Os experimentos realizados com as representações matriciais (raster) indicaram a viabilidade das aplicações e podem se consolidar sob a forma de processos de armazenamento e processamento da segmentação no SGBD
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