Creation and analysis of a flight attendant platform

Flight simulators have been used for a long time to train pilots of any type of aircraft. This type of training is more economical. The flight simulator improves control skills in extreme situations with minimal risks for the future pilot. Training on a flight simulator makes it possible to reproduce adverse weather conditions at any time. The pilot is on the ground in a special cockpit, which is mounted on a movable platform. This system is needed to ensure flight conditions as close to real as possible. The subject of the research in the article is an aviation simulator on the Stewart platform. The aim is to create and analyze an flight simulator platform using software. The paper presents the already existing flight simulator and its characteristics. Taking into account its dimensions and weight, the platform is modeled in SolidWorks. The kinematic diagram of the type design (6-6) is selected and presented. The basic equation of dynamics for calculating platform motion law for given values of the control forces is given. Also using this equation it is possible to find the controlling forces knowing the law of motion. The developed 3D model consists of two platforms, a movable and a stationary one. The legs with automatically variable length are attached to the platform using hinges. Selected material aluminum alloy type 2024 from which the platform is created. Selected material aluminum alloy type 2024 from which the platform is created. Static analysis of the loaded platform was performed. By loaded platform is meant that in the places where the simulator and the pi-lot's seat are installed, loads equal in weight to the simulator and the maximum weight of the seat with the pilot are applied. The anal-ysis includes such epurfaces: loads to assess whether the structure can support a given weight, displacement, deformation, safety margins and a Design Insight plot to evaluate design details. Identification of elements that are most likely to start collapsing under the weight of the simulator. The research was performed using SolidWorks Simulation software. Based on the data obtained from the plot, conclusions were made about the performance and safety of the developed platform.

Seismic control of damaged structure by pole assignment and intermittent wavelet-based identification

Calculation of the control forces by control algorithms, such as the pole assignment, proportional-integral-derivative, and linear quadratic regulator, is usually based on initial dynamic characteristics of the intact and undamaged structure, which is considered to be in the ideal conditions. However, because of the effect of natural loads and damage due to aging, these features can change during the structure’s life span, eventually leading to incorrect control forces. In this research, to overcome this problem and to get closer to the actual dynamic characteristics and on the other hand, in order to elude the adverse effects of real-time identification, such as elapsed time of detection, induced to the controller, the intermitted wavelet-based identification technique besides the pole assignment control is introduced. Performance of the proposed controller on three- and five-story with different cases of stiffness and two failure scenarios, under far and near-field earthquakes, are examined and compared by non-updated wavelet-based pole assignment, proportional-integral-derivative and linear quadratic regulator controllers. Results show that damaged structure response controlled by the suggested adapted pole assignment method is significantly reduced compared to ones controlled by other control methods.

Vibration control of a linear flexible beam structure excited by multiple harmonics

This paper deals with designing a control force to create nodal point(s) having zero displacement and/or zero slope at selected locations in a vibrating beam structure excited by multiple harmonic forces. It is shown that the steady state vibrations at desired points can be eliminated using applied control forces. The control forces design method is implemented using dynamic Green’s functions that transform the equations of motion from differential to algebraic equations, in which the resulting solution is analytic and exact. The control problem is greatly simplified by utilizing the superposition principle that leads to calculating the control forces to create node(s) for each excitation frequency independently. The calculated control forces can be realized using passive elements such as masses and springs connected to the beam having reaction forces equal to the calculated control forces. The effectiveness of the proposed method is demonstrated on various cases using numerical examples. Through examples, it was shown that creating node(s) with zero deflection, as well as zero slope, not only results in isolated stationary points, but also suppresses the vibrations along a wide region of the beam.

A trim problem formulation for maximum control authority using the Attainable Moment Set geometry

This paper presents a generic trim problem formulation, in the form of a constrained optimization problem, which employs forces and moments due to the aircraft control surfaces as decision variables. The geometry of the Attainable Moment Set (AMS), i.e. the set of all control forces and moments attainable by the control surfaces, is used to define linear equality and inequality constraints for the control forces decision variables. Trim control forces and moments are mapped to control surface deflections at every solver iteration through a linear programming formulation of the direct Control Allocation algorithm. The methodology is applied to an innovative box-wing aircraft configuration with redundant control surfaces, which can partially decouple lift and pitch control, and allow direct lift control. Novel trim applications are presented to maximize control authority about the lift and pitch axes, and a “balanced” control authority. The latter can be intended as equivalent to the classic concept of minimum control effort. Control authority is defined on the basis of control forces and moments, and interpreted geometrically as a distance within the AMS. Results show that the method is able to capitalize on the angle of attack or the throttle setting to obtain the control surfaces deflections which maximize control authority in the assigned direction. More conventional trim applications for minimum total drag and for assigned angle of elevation are also explored.

Adaptive control of damaged structures by using smart tunable liquid column gas damper considering dynamic soil–structure interaction

Liquid column dampers are adjusted based on the characteristics of the host structure and the type of external forces. It is assumed in most studies that the structure is rigidly connected to the ground, and the characteristics of the structure are invariant during external excitations. The performance of passive dampers may lose, or structural displacements may be increased by changing these conditions. This study presented a new method to find the optimal control forces for structures equipped with smart tuned liquid column gas damper (TLCGDs), considering variable characteristics of the structure and the soil–structure interaction. The proposed method calculates the gas pressure inside the columns by regularly adjusting and updating the frequency and damping of the TLCGD. The unknown or changed soil–structure characteristics are estimated by a system identification method, and damper parameters are determined through an optimization algorithm. The method was tested on 3- 9- and 10-story shear buildings under harmonic and earthquake excitation. According to the results, the smart damper more effectively reduced the structural displacement.

Closed-form time derivatives of the equations of motion of rigid body systems

Derivatives of equations of motion (EOM) describing the dynamics of rigid body systems are becoming increasingly relevant for the robotics community and find many applications in design and control of robotic systems. Controlling robots, and multibody systems comprising elastic components in particular, not only requires smooth trajectories but also the time derivatives of the control forces/torques, hence of the EOM. This paper presents the time derivatives of the EOM in closed form up to second-order as an alternative formulation to the existing recursive algorithms for this purpose, which provides a direct insight into the structure of the derivatives. The Lie group formulation for rigid body systems is used giving rise to very compact and easily parameterized equations.

Modeling the dynamic evolution of the Universe under the action of the entropic force associated with the modified Sharma-Mittal entropy

Using the Verlind formalism, the paper considers several scenarios of the evolution of the Friedman-Robertson-Walker Universe, which arise in the framework of entropic cosmology based on the formulated new modification of the Sharma-Mittal entropy. The research, carried out in the framework of non-Gaussian statistical theory, uses several entropies associated with the surface of the horizon of the Universe due to the holographic information stored there. A set of new generalized Friedmann equations is obtained, in which, instead of the cosmological constant, control forces appear based on the Bekenstein-Hawking, Tsallis-Chirto and Barrow entropies, as well as modified Sharma-Mittal and Renyi entropies containing additional nonextensity parameters. The proposed approach, associated with the use of probabilistic nonextensive aspects of the Hubble horizon of the surface of the Universe, meets all the basic requirements for thermodynamic modeling of the dynamic behavior of outer space without involving the concept of dark energy.

„Slovník“ aneb Vídeňský učitel v roli pašeráka exilové literatury

The arrival of the occupying armies in August 1968 and the subsequent normalisation purges resulted in an unusually large wave of emigration. The regime responded to this by closing state borders in October 1969. The great number of refugees brought new stimuli to activities in exile, such as establishment of new exile periodicals and publishing houses, which contributed to preserving independent Czech literature. Some of the books produced by publishing houses in exile were always intended for readers in Czechoslovakia, where they were transported using various smuggling routes. A new smuggling channel was created in 1983 – the so-called Austrian route – by agreement between Jiří Pelikán and Vilém Prečan. They used the code word “dictionary” for this route when communicating with each other. The “dictionary” was a large passenger car, which Jiří Pelikán authorised Adolf Müller to purchase and which was modified by experts from the American secret service who created a secret compartment for transporting books and periodicals in the luggage space. Vilém Prečan and Josef Jelínek then came up with a way to fill the compartment. Young teacher Helmut Bachmann, took receipt of the car from V. Prečan in Vienna. He was talked into collaborating by Jana Stárková. Bachmann drove the car to Czechoslovakia as a tourist roughly once every three months and Jiřina Šiklová organised receipt of the consignments in Prague. The compartment was created so cleverly that the Czechoslovak border control forces were unable to find it, even after thoroughly inspecting the car for forty minutes, something that occurred in March 1984. This transport channel, financed by Jiří Pelikán, was used from the summer of 1983 until the end of 1987, when the car was taken out of operation.