scholarly journals Five-mode quasilinear model of nonlinear dynamics of extended system

2021 ◽  
Vol 38 (2) ◽  
pp. 104-120
Author(s):  
Oleksii G. Lebid
Keyword(s):  
Gas Flow ◽  
Initial Conditions ◽  
Technical Condition ◽  
Point Of View ◽  
Great Length ◽  
Inhomogeneous Field ◽  
Near Earth Space ◽  
Concrete Piles ◽  
Reinforced Concrete Piles ◽  
Wave Models

Distributed systems are widely used in practice. These are cosmic ligaments in the near-Earth space with a length of tens of kilometers. They approximate reinforced concrete piles in the soil when calculating the stress-strain state and assessing the technical condition; pipelines both in air and in liquid, underwater towed systems. Known underwater airlift systems of great length for the extraction of minerals (nodules) from the ocean floor with a length of 5-10 km. To solve the problems of the dynamics of such systems in various environments, the well-known mathematical models are not quite correct from the point of view of taking into account the variety of wave processes. It determines the need to build refined wave models. A new quasilinear mathematical model, which describes the nonlinear four-mode dynamics of the distributed system in the spatially inhomogeneous field of mass and surface forces, has been obtained. It is described by a nonlinear system of twelve first-order partial differential equations. For it, the principles of ultimate and hyperbolicity are fulfilled. Together with the boundary and initial conditions, it can be used to describe dynamics and statics of geometrically and physically nonlinear rod elements, piles in the ground, crane equipment ropes, mine lifts, aerial cableways, towed systems in liquid and gas flow, etc. For two-mode spatial reduction of the model, the theorem about correctness of Cauchy problem has been considered. As a result of the calculations, the earlier assumptions about the movement of the cable along its initial configuration were changed as the length of the cable changed. It has been found out that this assumption is only true for the initial transition participant. It is also established that at a given tachogram in the configuration of the towed line, there is a point of inflection, which shifts from top to bottom when lifting it. It can be a factor in the looping, contributing to the breakage of the cable system during towing.

scholarly journals On Kaufmann's theory of the impact of the pianoforte hammer

1920 ◽  
Vol 97 (682) ◽  
pp. 99-110 ◽  
Keyword(s):  
Initial Conditions ◽  
Practical Importance ◽  
Prima Facie ◽  
Point Of View ◽  
Infinite Length ◽  
Modes Of Vibration ◽  
Rigorous Treatment ◽  
The Subject ◽  
Set Up ◽  
The Impact

The theory of the vibrations of the pianoforte string put forward by Kaufmann in a well-known paper has figured prominently in recent discussions on the acoustics of this instrument. It proceeds on lines radically different from those adopted by Helmholtz in his classical treatment of the subject. While recognising that the elasticity of the pianoforte hammer is not a negligible factor, Kaufmann set out to simplify the mathematical analysis by ignoring its effect altogether, and treating the hammer as a particle possessing only inertia without spring. The motion of the string following the impact of the hammer is found from the initial conditions and from the functional solutions of the equation of wave-propagation on the string. On this basis he gave a rigorous treatment of two cases: (1) a particle impinging on a stretched string of infinite length, and (2) a particle impinging on the centre of a finite string, neither of which cases is of much interest from an acoustical point of view. The case of practical importance treated by him is that in which a particle impinges on the string near one end. For this case, he gave only an approximate theory from which the duration of contact, the motion of the point struck, and the form of the vibration-curves for various points of the string could be found. There can be no doubt of the importance of Kaufmann’s work, and it naturally becomes necessary to extend and revise his theory in various directions. In several respects, the theory awaits fuller development, especially as regards the harmonic analysis of the modes of vibration set up by impact, and the detailed discussion of the influence of the elasticity of the hammer and of varying velocities of impact. Apart from these points, the question arises whether the approximate method used by Kaufmann is sufficiently accurate for practical purposes, and whether it may be regarded as applicable when, as in the pianoforte, the point struck is distant one-eighth or one-ninth of the length of the string from one end. Kaufmann’s treatment is practically based on the assumption that the part of the string between the end and the point struck remains straight as long as the hammer and string remain in contact. Primâ facie , it is clear that this assumption would introduce error when the part of the string under reference is an appreciable fraction of the whole. For the effect of the impact would obviously be to excite the vibrations of this portion of the string, which continue so long as the hammer is in contact, and would also influence the mode of vibration of the string as a whole when the hammer loses contact. A mathematical theory which is not subject to this error, and which is applicable for any position of the striking point, thus seems called for.

scholarly journals On some kinds of dense orbits in general nonautonomous dynamical systems

2020 ◽  
Vol 7 (1) ◽  
pp. 163-175
Author(s):  
Mehdi Pourbarat
Keyword(s):  
Dynamical Systems ◽  
Initial Conditions ◽  
Point Of View ◽  
Topological Conjugacy ◽  
Topological Transitivity ◽  
Nonautonomous Systems ◽  
Nonautonomous Dynamical Systems ◽  
Sensitive Dependence ◽  
Dense Orbits

AbstractWe study the theory of universality for the nonautonomous dynamical systems from topological point of view related to hypercyclicity. The conditions are provided in a way that Birkhoff transitivity theorem can be extended. In the context of generalized linear nonautonomous systems, we show that either one of the topological transitivity or hypercyclicity give sensitive dependence on initial conditions. Meanwhile, some examples are presented for topological transitivity, hypercyclicity and topological conjugacy.

Artificial Planning Experience by Means of a Heuristic Cell-Space Model: Simulating International Migration in the Urban Process

1995 ◽  
Vol 27 (10) ◽  
pp. 1647-1665 ◽  
Author(s):  
J Portugali ◽  
I Benenson
Keyword(s):  
Urban Policy ◽  
Initial Conditions ◽  
Point Of View ◽  
Town Planning ◽  
Space Model ◽  
Self Organized ◽  
A Cell ◽  
Policy And Planning ◽  
The City ◽  
Theory And Model

We suggest considering the city as a complex, open, and thus self-organized system, and describing it by means of a cell-space model. A central property of self-organizing systems is that they are not controllable—not by individuals, nor by economic, political, and planning institutions. The city, in this respect, is complex and untamable. Inability to recognize and accept this property is one of the reasons for the difficulties and problems of modernist town planning. The theory and model we present are built to describe the urban process as a historical one in which, given identical initial conditions, each simulation run is unique and never fully repeats itself. From the point of view of urban policy and planning, our heuristic model can guide decisionmakers by answering the following question: ‘given the initial conditions of an inflow of new immigrants (that is, from the ex-USSR), what possible urban scenarios can result, and what are their global structural properties?’.

BASIN CONFIGURATION OF A SIX-DIMENSIONAL MODEL OF AN ELECTRIC POWER SYSTEM

2002 ◽  
Vol 12 (06) ◽  
pp. 1333-1356 ◽  
Author(s):  
YOSHISUKE UEDA ◽  
HIROYUKI AMANO ◽  
RALPH H. ABRAHAM ◽  
H. BRUCE STEWART
Keyword(s):  
Power Systems ◽  
Power System ◽  
Initial Conditions ◽  
Electrical Power ◽  
Practical Importance ◽  
Intervention Strategy ◽  
Basins Of Attraction ◽  
Electric Power System ◽  
Point Of View ◽  
Electrical Power System

As part of an ongoing project on the stability of massively complex electrical power systems, we discuss the global geometric structure of contacts among the basins of attraction of a six-dimensional dynamical system. This system represents a simple model of an electrical power system involving three machines and an infinite bus. Apart from the possible occurrence of attractors representing pathological states, the contacts between the basins have a practical importance, from the point of view of the operation of a real electrical power system. With the aid of a global map of basins, one could hope to design an intervention strategy to boot the power system back into its normal state. Our method involves taking two-dimensional sections of the six-dimensional state space, and then determining the basins directly by numerical simulation from a dense grid of initial conditions. The relations among all the basins are given for a specific numerical example, that is, choosing particular values for the parameters in our model.

Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors

2013 ◽  
Author(s):  
Constanze Schilder ◽  
Harald Kohlhoff ◽  
Detlef Hofmann ◽  
Frank Basedau ◽  
Wolfgang R. Habel ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Strain Sensors ◽  
Fibre Optic ◽  
Concrete Piles ◽  
Reinforced Concrete Piles ◽  
Pile Testing

Application of fiber-optic measuring technology and phase-chronometric method for control and monitoring of technical condition of aircraft structures

2021 ◽  
pp. 49-56
Author(s):  
Stanislav S. Khabarov ◽  
Alexander S. Komshin
Keyword(s):  
Fatigue Life ◽  
Fiber Optic ◽  
Technical Condition ◽  
Point Of View ◽  
Flight Performance ◽  
Diagnostic Systems ◽  
Safe Operation ◽  
Excess Reserves ◽  
The Creation ◽  
Original Approach

Problems of ensuring the safe operation of an aircraft from the point of view of the fatigue life of its structure are considered. The relevance of the creation and implementation of diagnostic systems for monitoring the technical condition of structures of complex technical objects is shown on the example of a helicopter. An original approach to the creation and implementation of complex systems for diagnostics and monitoring of the technical condition of complex technical objects is presented, combining fiber-optic measuring technology and phase-chronometric method. It is shown that the use of monitoring and diagnostic systems ensures the transition to operation based on the actual technical condition. The proposed approach makes it possible to increase the time between overhaul intervals and reduce excess reserves in terms of the reliability factors of structures, which increases the flight performance of aircraft.

QUALITY MANAGEMENT IN THE PRODUCTION OF REINFORCED CONCRETE PRODUCTS FOR AGRICULTURAL FACILITIES

2020 ◽  
Author(s):  
E.A. Shlyakhova ◽  
◽  
I.A. Serebryanaya ◽  
A.V Serdyukova
Keyword(s):  
Reinforced Concrete ◽  
Quality Management ◽  
Business Process ◽  
Process Map ◽  
Concrete Piles ◽  
Reinforced Concrete Piles ◽  
Inputs And Outputs

The article provides an example of regulation of the main business process on the example of the process of "Production of reinforced concrete piles". A process map has been developed and the main inputs and outputs have been identified, and an example of drawing up a business process passport has been developed&

Сase-systems for development of multiagent system (MAS) in the system of diagnostics and maintenance of vehicles

2021 ◽  
Vol 13 (1) ◽  
pp. 87-93
Author(s):  
Viacheslav Pavlenko ◽  
◽  
Volodymyr Manuylov ◽  
Volodymyr Kuzhel ◽  
◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Technical Condition ◽  
Point Of View ◽  
Multi Agent Systems ◽  
Agent Systems ◽  
Software Products ◽  
Multi Agent ◽  
Software Code ◽  
Low Performance ◽  
Intelligent Methods

The article provides a comparative analysis of existing software products and libraries that allow the design of multi-agent systems for diagnostics and maintenance systems for modern cars. The authors substantiate two main shortcomings inherent in all products - analogues: the need for high qualification of the user as a software code developer, and low performance of intelligent methods in the structure of agents, which worsens their performance. Both manufacturers and car owners are objectively interested in the widespread use of telematics systems for monitoring the technical condition of cars. Predictive diagnostics gives them access to a huge amount of information about all the nuances of car operation, wherever they are, during the entire service life. The application of this approach using a multi-agent system (MAS) will allow taking the next step in this direction. Information from the connected vehicles goes to the main server. Systematization and analysis of data make it possible to establish the causes of malfunctions, identify patterns of their occurrence and make further predictions. Purpose of the work: to perform a comparative analysis of existing software products and libraries that allow the design of multi-agent systems. The topic of the work is disclosed on the example of the analysis of software tools for the development and design of MAS at the present stage. There are a number of systems and libraries on the market designed for the development of multi-agent systems. These Case - systems are suitable for the development of multi-agent systems of any direction, that is, they are universal from this point of view. Therefore, for us it is a universal application tool for the automotive industry. Ultimately, the work performed a comparative analysis of existing software products and libraries that allow the design of multi-agent systems. The analysis revealed two main drawbacks inherent in all products - analogs: the need for high user qualifications as a developer of software code, and low indicators of the possibilities of introducing intelligent methods into the structure of agents, worsens the indicators of their work.

Fanno Design of Blow-Off Lines in Heavy Duty Gas Turbine

2013 ◽  
Author(s):  
Marco Cioffi ◽  
Enrico Puppo ◽  
Andrea Silingardi
Keyword(s):  
Gas Turbines ◽  
Gas Flow ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Design Procedure ◽  
Flow Equation ◽  
Heavy Duty ◽  
Cross Sectional ◽  
Pipe Length ◽  
Choked Flow

In typical heavy duty gas turbines the multistage axial compressor is provided with anti-surge pipelines equipped with on-off valves (blow-off lines), to avoid dangerous flow instabilities during start-ups and shut-downs. Blow-off lines show some very peculiar phenomena and somewhat challenging fluid dynamics, which require a deeper regard. In this paper the blow-off lines in axial gas turbines are analyzed by adopting an adiabatic quasi-unidimensional model of the gas flow through a pipe with a constant cross-sectional area and involving geometrical singularities (Fanno flow). The determination of the Fanno limit, on the basis of the flow equation and the second principle of thermodynamics, shows the existence of a critical pipe length which is a function of the pipe parameters and the initial conditions: for a length greater than this maximum one, the model requires a mass-flow reduction. In addition, in the presence of a regulating valve, so-called multi-choked flow can arise. The semi-analytical model has been implemented and the results have been compared with a three-dimensional CFD analysis and cross-checked with available field data, showing a good agreement. The Fanno model has been applied for the analysis of some of the actual machines in the Ansaldo Energia fleet under different working conditions. The Fanno tool will be part of the design procedure of new machines. In addition it will define related experimental activities.

scholarly journals FIELD OF TASKS OF THE CONSTRUCTION OBJECT

2020 ◽  
pp. 78-83
Author(s):  
Elena Gorda
Keyword(s):  
Life Cycle ◽  
Information Technologies ◽  
Technical Condition ◽  
Point Of View ◽  
Information Modeling ◽  
Theoretical Point ◽  
Construction Design ◽  
Information Models ◽  
Merger Integration ◽  
Concept Classification

The generalization of the concept of the task in terms of information environments of construction [ISB] is performed. The approach to the presentation of such concepts as construction issues, construction problem, ontology, idea, concept, classification of problems, tasks, directions, objects included in the staging part of the tasks taking into account the specifics of the tasks solved within the developed information technologies in construction issues. The paper defines and investigates on the basis of methods of construction geodesy the actual tasks of construction, design, modeling, monitoring and their totality in the field of construction by means of information theory. An approach to the description of the technical condition of a construction object on the basis of information modeling in the management of the construction process and information modeling within the life cycle is proposed and described. Information modeling is a process, the results of each stage of which, ie information models of the building, differ greatly from each other depending on the stage of the life cycle of the object and the requirements for modeling in solving emerging problems. The construction object strongly depends on the stage of its existence: if during the design it is virtual, and during construction it gradually finds a real embodiment, then at a long stage of operation the building enters a period of stability and is no longer subject to significant changes. An information model is a variable object that depends on the range of tasks to be solved. Using the methods of construction geodesy in the field of construction, the field of problems, class of problems, the concept of the problem, the state of the problem, subtasks, chains of problems, problem solving and the result of solving the problem, the relationship between problems setting the transformation of aggregation, merger, integration. The urgency of the task from a theoretical point of view is determined by the expansion of the ontology of construction as a science, from an applied point of view is determined by the possibility of accurate formalization of regulatory information and documentation in construction.

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