scholarly journals Development and Motion Testing of a Robotic Ray

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Jianhui He ◽  
Yonghua Zhang
Keyword(s):  
Aspect Ratio ◽  
Morphological Parameters ◽  
Kinematic Parameters ◽  
Motion Patterns ◽  
Pectoral Fins ◽  
Fin Ray ◽  
The Stability ◽  
And Control ◽  
Undulating Fin ◽  
Fin Shape

Biomimetics takes nature as a model for inspiration to immensely help abstract new principles and ideas to develop various devices for real applications. In order to improve the stability and maneuvering of biomimetic fish like underwater propulsors, we selected bluespotted ray that propel themselves by taking advantage of their pectoral fins as target. First, a biomimetic robotic undulating fin driven propulsor was built based on the simplified pectoral structure of living bluespotted ray. The mechanical structure and control circuit were then presented. The fin undulating motion patterns, fin ray angle, and fin shape to be investigated are briefly introduced. Later, the kinematic analysis of fin ray and the whole fin is discussed. The influence of various kinematic parameters and morphological parameters on the average propulsion velocity of the propulsor was analyzed. Finally, we conclude that the average propulsion velocity generally increases with the increase of kinematic parameters such as frequency, amplitude, and wavelength, respectively. Moreover, it also has a certain relationship with fin undulating motion patterns, fin ray angle, fin shape, and fin aspect ratio.

scholarly journals DEFINITION THE STABILITY AND CONTROL DERIVATIVES IN THE LONGITUDINAL CHANNEL OF SMALL SUBSONIC UAV

2013 ◽  
pp. 55-68
Author(s):  
О. В. Збруцький ◽  
Р. В. Карнаушенко ◽  
О. П. Мариношенко
Keyword(s):  
Angular Velocity ◽  
Speed Of Sound ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Kinematic Parameters ◽  
Stability And Control ◽  
Control Derivatives ◽  
The Stability ◽  
And Control ◽  
Longitudinal Channel

The problems of determining the stability and control derivatives of small subsonic UAV in the longitudinal channel are solved.An approach to the stability and control derivatives determination based on the analysis results of wind tunnel investigation and analyzes conducted .To the longitudinal movement usually referred traffic aircraft where it is in the plane of symmetry of one and the same vertical plane. Thus the aerodynamic lateral force, rolling moment and yaw angles of heel and slip and angular velocity of roll and glide zero. To investigate the longitudinal motion of the aircraft (movement in the longitudinal channel) important issue is to determine the components of the aerodynamic forces and moments as a function of the kinematic parameters of the flight, the so-called aerodynamic derivatives.Given that the object is a lightweight UAV that has subsonic range of operating speeds, significantly less than the speed of sound, it should be noted that the derivative of the coefficient of lift coefficient and drag coefficient for longitudinal moment of flight speed can be taken to be zero at subsonic speed range. This is due to the fact that these values are almost constant with airspeed , lower the speed of sound . Change the value of these parameters with growth rate appears only when approaching the speed of sound, due to changes in the position of the center of pressure and the additional impedance. Also, when calculating stability derivatives are generally neglected by changing the drag because the drag value of derivatives are small and commensurate with the error of the calculation methods.Derivatives of lift coefficient by the following kinematic parameters: angle of attack, the angular velocity of rotation around the transverse axis , rate of change of angle of attack and angle of elevator deflection are defined.Obtained results make it possible to analyze the movement of the UAV in the longitudinal channel and determinate the coefficients of a mathematical model of the UAV. Also possible  to determinate the stability and controllability of the UAV during automatic control systems design.

Design of the Undulating Fin Propulsor with Rajiform Swimming Mode

2013 ◽  
Vol 579-580 ◽  
pp. 451-459
Author(s):  
Yang Wei Wang ◽  
Jin Bo Tan ◽  
Bao Tong Gu ◽  
Dong Biao Zhao
Keyword(s):  
Control Method ◽  
Harmonic Wave ◽  
Kinematic Model ◽  
Underwater Robots ◽  
Pectoral Fins ◽  
Swimming Mode ◽  
And Control ◽  
Unique Species ◽  
Prototype Design ◽  
Undulating Fin

Fishes have evolved remarkable swimming abilities after years of evolution which inspire scientists and engineers to develop new underwater robots that mimic different kinds of fishes. Stingray is a unique species among median and/or paired fin (MPF) mode fishes which undulates the enlarged pectoral fins while swimming. In this paper, a biomimetic prototype design and a developed undulating fin propulsor that mimics stingrays are presented. Kinematic model of the undulating fin is built. The flexibility of the curved surface is checked by the fitting results. Detailed mechanism structure and control system design of the bionic prototype are illustrated. The simulation experiments of the propulsor were conducted on the ground and the results show that an approximated harmonic wave can be generated on each side fin. The feasibility of the motion control method is verified.

scholarly journals Scythes, sickles and other blades: defining the diversity of pectoral fin morphotypes in Pachycormiformes

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7675
Author(s):  
Jeff J. Liston ◽  
Anthony E. Maltese ◽  
Paul H. Lambers ◽  
Dominique Delsate ◽  
William E.H. Harcourt-Smith ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Suspension Feeder ◽  
Ratio Analysis ◽  
Pectoral Fin ◽  
Landmark Analysis ◽  
Pectoral Fins ◽  
Fin Shape

The traditional terminology of ‘scythe’ or ‘sickle’ shaped is observed to be flawed as an effective descriptor for pectoral fin shape in pachycormids. The diversity of pachycormid pectoral fin shapes is assessed across the 14 recognised genera that preserve complete pectoral fins, and improved terms are defined to more effectively describe their form, supported by anatomical observation and aspect ratio analysis of individual fins, and corroborated by landmark analysis. Three clear and distinct pectoral fin structural morphotypes emerge (falceform, gladiform, falcataform), reflecting a diversity of pachycormid lifestyles throughout the Mesozoic, from agile pursuit predator to slow-cruising suspension feeder.

β-Ga2O3 lateral transistors with high aspect ratio fin-shape channels

2020 ◽  
Vol 60 (1) ◽  
pp. 014001
Author(s):  
Yuewei Zhang ◽  
Akhil Mauze ◽  
Fikadu Alema ◽  
Andrei Osinsky ◽  
Takeki Itoh ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Fin Shape

scholarly journals Data-Driven Stability Assessment of Multilayer Long Short-Term Memory Networks

2021 ◽  
Vol 11 (4) ◽  
pp. 1829
Author(s):  
Davide Grande ◽  
Catherine A. Harris ◽  
Giles Thomas ◽  
Enrico Anderlini
Keyword(s):  
Neural Network ◽  
Network Architecture ◽  
Short Term Memory ◽  
Moving Average ◽  
Machine Learning Algorithms ◽  
Physical Models ◽  
Data Driven ◽  
The Stability ◽  
And Control ◽  
Nonlinear Autoregressive

Recurrent Neural Networks (RNNs) are increasingly being used for model identification, forecasting and control. When identifying physical models with unknown mathematical knowledge of the system, Nonlinear AutoRegressive models with eXogenous inputs (NARX) or Nonlinear AutoRegressive Moving-Average models with eXogenous inputs (NARMAX) methods are typically used. In the context of data-driven control, machine learning algorithms are proven to have comparable performances to advanced control techniques, but lack the properties of the traditional stability theory. This paper illustrates a method to prove a posteriori the stability of a generic neural network, showing its application to the state-of-the-art RNN architecture. The presented method relies on identifying the poles associated with the network designed starting from the input/output data. Providing a framework to guarantee the stability of any neural network architecture combined with the generalisability properties and applicability to different fields can significantly broaden their use in dynamic systems modelling and control.

The Application of the Amorphous Metal Transformers in Heavy Oil Electric Heating System

2014 ◽  
Vol 532 ◽  
pp. 191-195 ◽  
Author(s):  
Bao Jiang Sun ◽  
Lei Su ◽  
Chao Zhang
Keyword(s):  
Electric Heating ◽  
Heating System ◽  
Intermediate Frequency ◽  
Amorphous Metal ◽  
Technical Performance ◽  
Alloy Material ◽  
Working Principle ◽  
The Stability ◽  
And Control ◽  
Fast Rise

In order to solve the problem that the big loss of no-load and the fast rise of temperature when employ the conventional silicon steel metal transformer (SSMT) in the electric heating system, we choose the amorphous metal transformer (AMMT). In this paper, firstly, we give a brief introduction of the amorphous alloy material properties and compare the no-load characteristic of the AMMT with the SSMT. Secondly, the structure of intermediate frequency heating system working principle and control strategy are introduced. Finally, extensive experiments were conducted to validate the ideas. The experiments show that the AMMT not only improve the efficiency of transformer, solve the heating problem of transformer, but also improve the stability, security and other technical performance of the system, so it is worth recommending and promoting.

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

THE ROLE OF ACCOUNTING AND CONTROL IN THE MANAGEMENT OF ECONOMIC SECURITY OF AN ORGANIZATION

2021 ◽  
Vol 7 (2) ◽  
pp. 165-178
Author(s):  
Nicolay T. Labyntsev ◽  
Lyubov F. SHILOVA ◽  
Ocsana V. Chukhrova
Keyword(s):  
Economic Security ◽  
Accounting Profession ◽  
Economic Management ◽  
Economic Interests ◽  
Doing Business ◽  
The Subject ◽  
The Stability ◽  
High Level ◽  
And Control

This article revises the mission and the name of the accounting profession in the context of strengthening the economic security of enterprises under the conditions of digitalization of the economy. The authors note that in the contemporary conditions of economic management, enterprises should form and ensure the functioning of the economic security of the enterprise at the proper level. The necessity of in-depth research of economic security at microlevel was considered, the factors influencing the stability of the enterprise were highlighted. High level of economic security of the subject of management consists in guaranteeing him maximum effective and stable functioning now and in future. Subjects of economic security were individual enterprises, and objects — their economic interests. The main goals of ensuring economic security of the enterprise in the part of accounting were singled out, the tasks of accounting policy, aimed at ensuring economic security, were determined. The prospects of the accounting profession in the process of ensuring economic security and reliable safe presentation of the results of doing business in reporting are substantiated. The study contains proposals on the revision of requirements for the qualifications of accountants in order to emphasize their activities aimed at strengthening the economic security of the enterprise.

Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

Three-dimensional adaptive fixed-time guidance law against maneuvering targets with impact angle constraints and control input saturation

2021 ◽  
pp. 014233122110598
Author(s):  
Fei Ma ◽  
Yunjie Wu ◽  
Siqi Wang ◽  
Xiaofei Yang ◽  
Yueyang Hua
Keyword(s):  
Sliding Mode ◽  
Input Saturation ◽  
Three Dimensional ◽  
Fixed Time ◽  
Impact Angle ◽  
Guidance System ◽  
Control Input ◽  
Guidance Law ◽  
The Stability ◽  
And Control

This paper presents an adaptive fixed-time guidance law for the three-dimensional interception guidance problem with impact angle constraints and control input saturation against a maneuvering target. First, a coupled guidance model formulated by the relative motion equation is established. On this basis, a fixed-time disturbance observer is employed to estimate the lumped disturbances. With the help of this estimation technique, the adaptive fixed-time sliding mode guidance law is designed to accomplish accurate interception. The stability of the closed-loop guidance system is proven by the Lyapunov method. Simulation results of different scenarios are executed to validate the effectiveness and superiority of the proposed guidance law.

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