Stability analysis of a free falling pararotor

The pararotor is a decelerator device based on the autorotation of a rotating wing. When it is dropped, it generates an aerodynamic force parallel to the main motion direction, acting as a decelerating force. In this paper, the rotational motion equations are shown for the vertical flight without any lateral wind component and some simplifying assumptions are introduced to obtain analytic solutions of the motion. First, the equilibrium state is obtained as a function of the main parameters. Then the equilibrium stability is analyzed. The motion stability depends on two nondimensional parameters, which contain geometric, inertia, and aerodynamic characteristics of the device. Based on these two parameters a stability diagram can be defined. Some stability regions with different types of stability trajectories (nodes, spirals, focuses) can be identified for spinning motion around axes close to the major, minor, and intermediate principal axes. It is found that the blades contribute to stability in a case of spin around the intermediate principal inertia axis, which is otherwise unstable. Subsequently, the equations for determining the angles of nutation and spin of the body are obtained, thus defining the orientation of the body for a stationary motion and the parameters on which that position depends

Selection, characterisation and analytical application of dna aptamer against the anaphylactic toxic allergen, b-conglutin, lup an 1

Lupin has recently been added to the list of allergens requiring mandatory advisory labelling on foodstuffs sold in the European Union, and since December 2008 all products containing even trace amounts of lupin must be labelled correctly. Lupin globulins consist of two major globulins called α-conglutin (11S and “legumin-like”) and β-conglutin (7S and “vicilin-like”), and another additional two globulins, γ-conglutin and δ-conglutin, which are present in lower amounts. β-conglutin is the only conglutin currently included in the list of the International Union of Immunological Societies (IUIS), designated as Lup an 1. The overall objective of these PhD is the selection of aptamers that can detect this allergen. Nucleic acid aptamers are synthetic ligands selected from vast combinatorial libraries through a process referred to as SELEX – Systematic Evolution of Ligand By Exponential Enrichment. Aptamers possess unique chemical and biochemical characteristics, such as: well known chemistry and remarkable stability, moreover, aptamers can be selected against virtually any target and in non-physiological conditions. In order to achieve the overall objective, a set of subobjectives will be achieved. The first of these involves the elucidation of protocols for the selective extraction of each of the lupin α, β, γ, and δ subunits, resulting in (i) protocols that can be used for selective extraction and isolation of the lupin α, β, γ, and δ proteins from food for subsequent analysis; (ii) standards that can be used in analytical assays and tools; and (iii) target that can be used for the selection of aptamers specific to the β-conglutin subunit. The core of the work is the selection of aptamers against the allergen Lup an 1 using a SELEX procedure, as well the preparation of protocols that can be used to monitor the evolution of aptamer selection. The functionality of the aptamer is demonstratedby exploiting it in an enzyme linked oligonucleotide assay as well as apta-PCR. Finally the resulting aptamer candidates that exhibit high affinity are fully characterised, truncated, and the structure of the final truncated aptamer is elucidate

Ensayos Experimentales del Efecto Magnus sobre diferentes cuerpos cilíndricos

La presente publicación presenta el desarrollo de diferentes ensayos experimentales con el fin de poder determinar las características aerodinámicas asociadas al Efecto Magnus en cuerpos no cilíndricos circulares. Se realiza la descripción del banco y los equipos utilizados para los ensayos, los modelos, la metodología y los resultados de los ensayos realizados. Se presentan la sustentación y resistencia aerodinámica de los modelos para diferentes velocidades de rotación y de la corriente de aire

Pararotor dynamics: center of mass displacement from the blade plane—analytical approach

The pararotor is a biology-inspired decelerator device based on the autorotation of a rotary wing whose main purpose is to guide a load descent into a certain atmosphere. This paper focuses on a practical approach to the general dynamic stability of a pararotor whose center of mass is displaced from the blade plane. The analytical study departs from the motion equations of pararotor flight, considering the center of mass displacement from the blade plane, studied over a number of simplifying hypotheses that allows determining the most important influences to flight behavior near equilibrium. Two practical indexes are developed to characterize the stability of a pararotor in terms of geometry, inertia, and the aerodynamic characteristics of the device. Based on these two parameters, a stability diagram can be defined upon which stability regions can be identified. It was concluded that the ability to reach stability conditions depends mainly on a limited number of parameters associated with the pararotor configuration: the relationship between moments of inertia, the position of the blades, the planform shape (associated with the blade aerodynamic coefficients and blade area), and the vertical distance between the center of mass and the blade plane. These parameters can be evaluated by computing practical indexes to determine stability behavior

Cisto periapical inflamatório de grande proporção : um desafio diagnóstico

Os cistos periapicais inflamatórios e os cistos residuais são as lesões císticas mais frequentes na odontologia. Clinicamente não há sintomatologia, apenas em casos nos quais ocorre agudização do processo inflamatório, ou em se tratando de cistos de grandes proporções. Radiograficamente, apresentam área radiolúcida, circular ou oval, bem delimitada e sem reabsorção de outras estruturas. Os cistos periapicais são caracterizados por uma cápsula de tecido conjuntivo fibroso revestida por epitélio, com um lúmen contendo líquido e restos celulares. Quando um processo patológico destrói os tecidos periapicais, pode-se estabelecer a relação direta da raiz dentária com a mucosa do seio maxilar, desencadeando sintomatologia que pode simular uma sinusopatia de evolução atípica. O presente estudo relata o caso de um paciente com sintomatologia de sinusite e epistaxe, que ao exame tomográfico apresentou uma lesão de caráter expansivo no seio maxilar direito, diagnosticado como cisto periapical inflamatório residual. A lesão, normalmente de diagnóstico simples, teve sua identificação prejudicada devido à grande extensão atingida, à invasão do seio maxilar e à história de trauma do paciente. O cisto foi enucleado e removido cirurgicamente no Hospital de Clínicas de Porto Alegre (HCPA).Inflammatory periapical cysts and residual cysts are the most frequent cystic lesions in dentistry. Clinically there is no symptomatology, except in cases when the inflammatory process worsens or in large proporsion cysts. Radiographically, they have a radiolucent, circular or oval area. Periapical cysts are characterized by a fibrous connective tissue capsule coated with epithelium, with a lumen containing fluid and cellular debris. When a pathological process destroys the periapical tissues, a direct relation can be established between the dental root and the maxillary sinus mucosa, triggering symptomatology that can simulate atypical evolution sinusopathy. The present study reports the case of a patient with sinusitis and epistaxis symptoms, who at the tomographic exam presented an expansive lesion in the right maxillary sinus, diagnosed as a residual periapical inflammatory cyst. The lesion, normally easy to diagnose, had it’s identification impaired by the big extension achieved, the maxillary sinus invasion and the patient’s history of trauma. The cyst was enucleated and surgically removed at the Hospital de Clínicas de Porto Alegre (HCPA)

Model of the aerodynamic behavior of a pararotor

Asimple semi-empirical model for the aerodynamic behavior of a low-aspect ratio pararotor in autorotation at low Reynolds numbers is presented. The paper is split into three sections: Sec. II deals with the theoretical model derivation, Sec. III deals with the wind-tunnel measurements needed for tuning the theoretical model, and Sec. IV deals with the tuning between the theoretical model and the experimental data. The study is focused on the effect of both the blade pitch angle and the blade roughness and also on the stream velocity, on the rotation velocity, and on the drag of a model. Flow pattern visualizations have also been performed. The value of the free aerodynamic parameters of the semi-empirical model that produces the best fit with the experimental results agrees with the expected ones for the blades at the test conditions. Finally, the model is able to describe the behavior of a pararotor in autorotation that rotates fixed to a shaft, validated for a range of blade pitch angles. The movement of the device is found to be governed by a reduced set of dimensionless parameters

Model of the aerodynamic behavior of a pararotor

Asimple semi-empirical model for the aerodynamic behavior of a low-aspect ratio pararotor in autorotation at low Reynolds numbers is presented. The paper is split into three sections: Sec. II deals with the theoretical model derivation, Sec. III deals with the wind-tunnel measurements needed for tuning the theoretical model, and Sec. IV deals with the tuning between the theoretical model and the experimental data. The study is focused on the effect of both the blade pitch angle and the blade roughness and also on the stream velocity, on the rotation velocity, and on the drag of a model. Flow pattern visualizations have also been performed. The value of the free aerodynamic parameters of the semi-empirical model that produces the best fit with the experimental results agrees with the expected ones for the blades at the test conditions. Finally, the model is able to describe the behavior of a pararotor in autorotation that rotates fixed to a shaft, validated for a range of blade pitch angles. The movement of the device is found to be governed by a reduced set of dimensionless parameters

A recovery-explicit error estimator in energy norm for linear elasticity

Significant research effort has been devoted to produce one-sided error estimates for Finite Element Analyses, in particular to provide upper bounds of the actual error. Typically, this has been achieved using residual-type estimates. One of the most popular and simpler (in terms of implementation) techniques used in commercial codes is the recovery-based error estimator. This technique produces accurate estimations of the exact error but is not designed to naturally produce upper bounds of the error in energy norm. Some attempts to remedy this situation provide bounds depending on unknown constants. Here, a new step towards obtaining error bounds from the recovery-based estimates is proposed. The idea is (1) to use a locally equilibrated recovery technique to obtain an accurate estimation of the exact error, (2) to add an explicit-type error bound of the lack of equilibrium of the recovered stresses in order to guarantee a bound of the actual error and (3) to efficiently and accurately evaluate the constants appearing in the bounding expressions, thus providing asymptotic bounds. The numerical tests with h-adaptive refinement process show that the bounding property holds even for coarse meshes, providing upper bounds in practical applications