scholarly journals Indicators of the critical state of the ship’s stability

2021 ◽  
Vol 2131 (5) ◽  
pp. 052057
Author(s):  
Yu Kochnev ◽  
E Ronnov ◽  
I Gulyaev
Keyword(s):  
Three Dimensional ◽  
Stability Margin ◽  
Static Stability ◽  
Stability Diagram ◽  
International Standards ◽  
Main Criterion ◽  
Value Determination ◽  
Factor Form ◽  
The Stability ◽  
Vessel Stability

Abstract According to the main criterion, the vessel stability according to the main criterion is standardized by the Rules of the Russian Register by the assumption that the units of the stability margin are practically equal, which is the ratio of listing and restoring moments characterizing the equality of their work. That is, the current domestic and international standards allow the achievement of a shipborne borderline hazardous state, after which it will either capsize, or an uncontrolled inflow of water into the hull and emergency flooding will begin. The characteristics of the vessel that affect stability during its assessment, both at the design stages and during operation, are determined with some error. It is caused by the assumptions of the Rules to the displacement value determination and the coordinates of the gravity center, incomplete compliance with the predicted cruise conditions, due to the ship falling into possible more severe conditions, the construction of a static stability diagram, which is the dependence of the reduced restoring moment on the inclination angle, with a flat waterline, while it is three-dimensional, and other factors related to the vessel’s type and purpose, which are not taken into account when calculating stability. In this paper, we consider a group of such factors, in relation to ships of inland and mixed (river-sea) navigation, the features and reasons for their occurrence, taking into account in verification calculations. A mathematical stability safety factor form, reflecting the expected increments of permissible values, which will improve the safety of the ship, is proposed.

Walking Stability Analysis of Multi-Legged Crablike Robot over Slope

2013 ◽  
Vol 572 ◽  
pp. 636-639
Author(s):  
Xi Chen ◽  
Gang Wang
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Stability Criterion ◽  
Stability Margin ◽  
Static Stability ◽  
Matlab Simulation ◽  
And Performance ◽  
The Stability ◽  
The Mathematical Model ◽  
The Relationship

This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.

A Design Study of a Supersonic Air Intake Device in a Wide Range of Main Flow Parameters

2020 ◽  
pp. 44-53
Author(s):  
E.S. Studennikov ◽  
R.S. Ayupov
Keyword(s):  
Boundary Layer ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Stability Margin ◽  
Aircraft Design ◽  
Software Systems ◽  
Flow Parameters ◽  
Wide Range ◽  
Air Intake ◽  
The Stability

This paper examines operation modes of a mixed compression air intake with a rectangular cross-section at Mach number 2.0. The perfect gas model was used for the calculation. Calculations were performed for three values of Mach numbers: 1.8, 2.0 and 3.0. k–ε turbulence model was chosen for describing flows with large adverse pressure gradients. Two-dimensional and three-dimensional configurations of the air intake device were examined. Versions of geometry with and without the boundary layer drain system were considered. The influence of the boundary layer drain system on the flow in the air intake and its characteristics was established. Throttle characteristic curves were formed for all the considered modes with regard to the averaged flow parameters. A comparison of the calculation and experimental data showed a good agreement of the results. The obtained results can serve as a basis for further optimization and improvement of the efficiency of the aircraft design layout, increase in the stability margin of air intakes, as well as development of software systems for regulating supersonic input devices.

Numerical Investigation on the Effects of Circumferential Coverage of Injection in a Transonic Compressor With Discrete Tip Injection

2014 ◽  
Author(s):  
Wei Wang ◽  
Wuli Chu ◽  
Haoguang Zhang ◽  
Yanhui Wu
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Time Lag ◽  
Three Dimensional ◽  
Stability Margin ◽  
Transonic Compressor ◽  
Blade Tip ◽  
Tip Injection ◽  
The Stability ◽  
Total Pressure Ratio

Discrete tip injection upstream of the rotor tip is an effective technique to extend stability margin for a compressor system in an aeroengine. The current study investigates the effects of injectors’ circumferential coverage on compressor performance and stability using time-accurate three-dimensional numerical simulations for multi passages in a transonic compressor. The percentage of circumferential coverage for all the six injectors ranges from 6% to 87% for the five investigated configurations. Results indicate that circumferential coverage of tip injection can greatly affect compressor stability and total pressure ratio, but has little influence on adiabatic efficiency. The improvement of compressor total pressure ratio is linearly related with the increasing circumferential coverage. The unsteady flow fields show that there exists a non-ignorable time lag of the injection effects between the passage inlet and outlet, and blade tip loading will not decline until the injected flow reaches the passage outlet. Stability improves sharply with the increasing circumferential coverage when the coverage is less than 27%, but increases flatly for the rest. It is proven that the injection efficiency which is a measurement of averaged blockage decrement in the injected region is an effective guideline to predict the stability improvement.

scholarly journals Investigation of the Causes of Malfunctions of Special Electrical Equipment of Pumping Stations

2021 ◽  
Vol 12 (5) ◽  
pp. 1905-1910
Author(s):  
AyubjonVokhidov, Et. al.
Keyword(s):  
Voltage Drop ◽  
Stability Margin ◽  
Electrical Equipment ◽  
Static Stability ◽  
Technical Parameters ◽  
Operating Modes ◽  
Pumping Stations ◽  
Special Power ◽  
The Stability ◽  
Pumping Units

The task of this work was to consider the main technical parameters of pumping stations that affect the operating modes and the overall reliability of a special power supply system. Also, the technological processes of the irrigation pumping station were investigated and the analysis of mechanical and parametric characteristics, the causes of the asynchronous operation of mechanisms and the failure of the pumping units themselves was carried out. As a result of the work, a method for calculating the voltage drop was proposed, a new independent algorithm for calculating the static stability and the stability margin for the active power of special electrical equipment was developed.

scholarly journals Determination of the drag coefficient of lattice structures under wind load using porous media approach

2021 ◽  
pp. 233-233
Author(s):  
Milada Pezo ◽  
Nikola Mirkov ◽  
Vukman Bakic
Keyword(s):  
Drag Coefficient ◽  
Lattice Structure ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
International Standards ◽  
Lattice Structures ◽  
Three Dimensional Model ◽  
Aerodynamic Forces ◽  
Wind Velocities ◽  
The Stability

The power transmitters, guyed masts and other lattice structures are exposed to wind action. The aerodynamic forces acting on tall tower constructions have crucial importance on the stability of the structure. The lattice structure drag coefficient determination is the subject of the international standards ESDU 81027 and 81028 and Eurocode 3 Part 3.1, but it can also be determined by numerical methods. For that purpose modeling using Computational Fluid Dynamics (CFD) proved to be both accurate and reliable. In this study the fluid flow around the segment of a power transmitter was simulated by a three-dimensional model, where the geometry of the segment is approximated with a porous structure having the appropriate factor of porosity, in order to simplify the geometry. We have used three representative models of turbulence, standard k-? model, RNG k-? model and Reynolds Stress Model. Drag coefficient values are extracted from the flow field and compared for all studied cases and with available experimental results from the wind tunnel. Simulations were performed for four wind velocities between 10 m/s and 30 m/s. The results are supplemented by the ones obtained by Artificial Neural Network. The aim of this study is to show how the simple turbulence model coupled with approximated geometry can be used in the analysis of the aerodynamic forces acting on the lattice structure.

scholarly journals A Large Goaf Group Treatment by means of Mine Backfill Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hanwen Jia ◽  
Baoxu Yan ◽  
Erol Yilmaz
Keyword(s):  
Group Treatment ◽  
Laser Scanning ◽  
Large Scale ◽  
Mechanical Characteristics ◽  
Three Dimensional ◽  
Stability Diagram ◽  
Surrounding Rock ◽  
Mine Backfill ◽  
Treatment Scheme ◽  
The Stability

There are few studies on the management methods of large-scale goaf groups per the specific surrounding rock mass conditions of each goaf. This paper evaluates comprehensively the stability of the multistage large-scale goaf group in a Pb-Zn mine in Inner Mongolia, China, via the modified Mathews stability diagram technique. The volume of each goaf to be backfilled was quantitatively analyzed in the combination of theoretical analysis and three-dimensional laser scanning technology. The corresponding mechanical characteristics of the filling were determined by laboratory testing while formulating the treatment scheme of the large goaf group using the backfill method. The applicability of the treatment scheme using the backfill was verified by the combination of the numerical results of the distribution of the surrounding rock failure zone and the monitored data of the surface subsidence. The research results and treatment scheme using the backfill can provide a reference for similar conditions of mines worldwide.

scholarly journals Estimation of the stability of a fishing vessel during purse seining

2021 ◽  
Vol 937 (3) ◽  
pp. 032057
Author(s):  
A V Ivanovskaya ◽  
E V Bogatyreva
Keyword(s):  
Three Dimensional ◽  
Static Stability ◽  
Tension Force ◽  
Geometrical Parameters ◽  
Dimensional Representation ◽  
Fishing Vessel ◽  
Three Dimensional Representation ◽  
The Stability ◽  
Improve Stability ◽  
Purse Seining

Abstract One of the reasons for the emergency of a fishing vessel, as well as for the failure of fishing equipment, is the sudden tension of the purse rope, which occurs when the fishing equipment is pulled. As a result of the loss of stability the vessel may enter the encircled seine area and even capsize. There are a number of measures to improve stability during the operation of the vessel. However, when designing fishing equipment, it is necessary to know forces acting on the vessel from the seine side. The article presents a method for assessing the static stability of a vessel with a static application of the tension force of the purse rope. As a result of the study, an expression for determining the static heel angle using a three-dimensional representation of the vessel is given. During simulation the geometrical parameters of the purse rope in the process of purse seine were taken into account. The tension force of the purse rope is also presented as a variable.

scholarly journals Analysis of the ship's stability reserve for inland and mixed (river-sea) navigation

2020 ◽  
pp. 56-60
Author(s):  
Е.П. Роннов ◽  
Ю.А. Кочнев ◽  
И.А. Гуляев
Keyword(s):  
Stability Margin ◽  
Emergency Situation ◽  
The Other ◽  
Main Criterion ◽  
Worst Case ◽  
The Stability ◽  
The One ◽  
Russian River ◽  
A Minor ◽  
Weather Criterion

При проверке остойчивости по основному критерию или критерию погоды, кренящий и восстанавливающий момент мо гут быть равны между собой. С одной стороны этого достаточно, что бы судно было признано остойчивым при действии динамического ветра, с другой стороны, минимальные отклонения различных элементов и характеристик судна от расчётных значений, могут вызвать рост кренящего и снижение восстанавливающего моментов, который при низком уровне самой остойчивости судна может привести к чрезвычайной ситуации, и в худшем случае потере судна. В настоящей работе представлен общий подход к определению фактически необходимого коэффициента запаса остойчивости, проанализированы факторы влияющие на изменение действующих на судно моментов при его наклонении на конечные углы. Авторами так же рассмотрены минимальные приращения данных факторов, которые допускаются действующими Правилами Российского Речного Регистра и фактически приводят, к незначительной ошибке. В качестве примера рассчитан фактический коэффициент запаса остойчивости, для сухогрузного судна смешанного (река-море) плавания. When checking the stability of the main criterion or the weather criterion, the heeling and restoring moment can be equal to each other. On the one hand, this is sufficient for the ship to be considered stable under the influence of dynamic wind, on the other hand, the minimum deviations of various elements and characteristics of the vessel from the calculated values can cause an increase in the heeling and reducing the restoring moments, which, if the ship's stability is low, can lead to an emergency situation, and in the worst case, the loss of the vessel. This paper presents a General approach to determining the actual required coefficient of stability margin, and analyzes the factors that affect the change in the moments acting on the ship when it tilts to the final angles. The authors also consider the minimum increments of these factors, which are confirmed by the current Rules of the Russian River Register and actually lead to a minor error. As an example, the actual coefficient of responsiveness is calculated for a dry cargo ship of mixed (river-sea) navigation.

Optimal turning gait of a six-legged robot using a GA-fuzzy approach

2000 ◽  
Vol 14 (3) ◽  
pp. 207-219 ◽  
Author(s):  
DILIP KUMAR PRATIHAR ◽  
KALYANMOY DEB ◽  
AMITABHA GHOSH
Keyword(s):  
Stability Margin ◽  
Static Stability ◽  
Legged Robot ◽  
Fuzzy Approach ◽  
Traditional Methods ◽  
Gait Generation ◽  
Minimum Number ◽  
Stable Gait ◽  
Multilegged Robot ◽  
The Stability

This paper describes a new method for generating the turning-gait of a six-legged robot using a combined genetic algorithm (GA)-Fuzzy approach. The main drawback of the traditional methods of gait generation is their high computational load. Thus, there is still a need for the development of a computationally tractable algorithm that can be implemented online to generate stable gait of a multilegged robot. In the proposed genetic-fuzzy system, the fuzzy logic controllers (FLCs) are used to generate the stable gait of a hexapod and a GA is used to improve the performance of the FLCs. The effectiveness of the proposed algorithm is tested on a number of turning-gait generation problems of a hexapod that involve translation as well as rotation of the vehicle. The hexapod will have to take a sharp circular turn (either clockwise or counter-clockwise) with minimum number of ground legs having the maximum average kinematic margin. Moreover, the stability margin should lie within a certain range to ensure static stability of the vehicle. Each leg of a six-legged robot is controlled by a separate FLC and the performance of the controllers is improved by using a GA. It is to be noted that the actual optimization is done off-line and the hexapod can use these optimized FLCs to navigate in real-world scenarios. As an FLC is computationally less expensive, the proposed algorithm will be faster compared with the traditional methods of gait-generation, which include both graphical as well as analytical methods. The GA-tuned FLCs are found to perform better than the author-defined FLCs.

The assembly of ionic currents in a thalamic neuron I. The three-dimensional model

1989 ◽  
Vol 237 (1288) ◽  
pp. 267-288 ◽  
Keyword(s):  
Three Dimensional ◽  
State Diagram ◽  
Ionic Currents ◽  
Stability Diagram ◽  
Repetitive Firing ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Two Dimensional Model ◽  
The Stability

We have previously discussed qualitative models for bursting and thalamic neurons that were obtained by modifying a simple two-dimensional model for repetitive firing. In this paper we report the results of making a similar sequence of modifications to a more elaborate six-dimensional model of repetitive firing which is based on the Hodgkin–Huxley equations. To do this we first reduce the six-dimensional model to a two-dimensional model that resembles our original two-dimensional qualitative model. This is achieved by defining a new variable, which we call q . We then add a subthreshold inward current and a subthreshold outward current having a variable, z , that changes slowly. This gives a three-dimensional ( v, q, z ) model of the Hodgkin–Huxley type, which we refer to as the z -model. Depending on the choice of parameter values this model resembles our previous models of bursting and thalamic neurons. At each stage in the development of these models we return to the corresponding seven-dimensional model to confirm that we can obtain similar solutions by using the complete system of equations. The analysis of the three-dimensional model involves a state diagram and a stability diagram. The state diagram shows the projection of the phase path from v, q, z space into the v, z plane, together with the projections of the curves ż = 0 and v̇ = q̇ = 0. The stability of the points on the curve v̇ = q̇ = 0, which we call the v, q nullcurve, is determined by the stability diagram. Taken together the state and stability diagrams show how to assemble the ionic currents to produce a given firing pattern.

Sign in / Sign up

Export Citation Format

Share Document