Vertical shift of submerged body moving near the free surface

Object and purpose of research. The object of the research is model tests of the submerged body motions near the free surface in test basin. The purpose of the study is to determine how the magnitude of the relative vertical shift of the submerged body depends on its speed. Materials and methods. The material for research is the modeling technique, technology and the results of model experiments in the test basin. Numerical modeling was performed using the ANSYS software package. Main results. Model tests and numerical experiments were carried out to determine the magnitude of the vertical displacement of the submerged body moving near the free surface and the forces acting on it. Conclusion. The results obtained are useful for horizontal stabilization of submerged body moving near free surface at different speeds.

ANÁLISE DE ESTABILIDADE GLOBAL EM EDIFÍCIOS ALTOS

RESUMO: O projeto de edifícios esbeltos em concreto armado normalmente tem como principal desafio a busca por uma solução estrutural que viabilize sua estabilização horizontal, sem comprometer a segurança, nem os aspectos arquitetônicos ou a economia. Para formar o sistema de contraventamento desses edifícios, normalmente têm-se disponíveis a associação de vigas e pilares formando pórticos, ou a adoção de núcleos rígidos quando a estrutura de tais edifícios exige grande rigidez frente a ações horizontais. Neste trabalho é apresentado o estudo da estabilidade de uma edificação em concreto armado composta por laje nervurada, com ordem de esbeltez de um para quatro para três tipologias de sistemas de contraventamento: pórticos, núcleos rígidos em formato (“U” e pilar-parede). Em cada sistema, foram considerados dois diferentes tipos de ligações (rígidas e semi-rígidas) para avaliar não só a participação das vigas no contraventamento da estrutura como também, a influência de tais modelos e critérios nos deslocamentos laterais e na estabilidade global da edificação, a partir do parâmetro de instabilidade z previsto na norma brasileira NBR 6118 (ABNT, 2014). Para as modelagens foi utilizado o programa comercial Altoqi Eberick V9, que considera as premissas e as prescrições de dimensionamento de estruturas de concreto previstas nas normas brasileiras. Os valores encontrados pelo Software foram analisados e reforçam a importância da utilização de Pilar -Parede ou núcleos rígidos em formato “U” para edifícios altos em concreto armado. ABSTRACT: The Project of slender buildings in reinforced concret, normally has as main challenge the search for a lasting solution that allow its horizontal stabilization, without compromising the safety, neither the architectural aspects or the economy. To form the bracing system of these buildings, normally has been available the association of beams and pillars forming the frameworks, or the adoption of rigid cores when the structure of these buildings requires great rigidity against horizontal actions. In this research aimed to study the overall stability of a building in reinforced concrete consisting of waffle slab, with slenderness approximately one to four, for three types of bracing systems, frameworks and rigid core into two types of format ("U" and pillars in which the lengths are signifi cantly larger than their widths). In each system were considered two different types of connections ( rigid and semi-rigid ) to evaluate not only the participation of the beams in the bracing structure, even as the influence of such models and criteria in the lateral displacement and the overall stability of the building, using instability parameter z fixed on Brazilian standard NBR 6118 (ABNT, 2014). For the modeling, was used the commercial software Altoqi Eberick V9, which considers the assumptions and the sizing requirements of concrete structures described in Brazilian standards. The values that were found by the software, they were analysed, and reinforce the importance of using pillars in which the lengths are signifi cantly larger than their widths or rigid core "U" for tall buildings in reinforced concrete.

INVESTIGATION OF THE CHARACTERISTICS OF THE SENSOR UNIT OF THE PA-2 HORIZONTAL STABILISATION SYSTEM

For tasks such as radiation and environmental monitoring using an unmanned air vehicle, it is necessary to maintain stable flight level. The authors used a PA-2 horizontal stabilization system, manufactured by Futaba Inc., to maintain the orientation of an unmanned aircraft during flight. This work represents the investigation of the characteristics of a PA-2 sensor unit in the laboratory. The authors obtained the optical and output characteristics of the sensor unit, operating angles, and dependence of output characteristics on UAV orientation.

Design and Realization of Two-Axis Horizontal Stabilized Platform Based on Self-Correction Control Method

To enhance the accuracy of stabilization, this paper presents a design of two-axis horizontal stabilization platform system, which is based on the combination of gyroscope and inclinometer sensors. The self-correction control method is put forward to solve the system error caused by gyroscope zero drift in traditional gyro stabilized platform, which works in the way of revising the gyroscope zero coefficient, according to the real-time attitude information feed backed by inclinometer sensors fixed in objective platform.