On Dynamic Compression of Risers: An Analytical Expression for the Speed of Compression Waves

2011 ◽  
Author(s):  
Rodrigo Mota Amarante ◽  
Marcos Mendes de Oliveira Pinto ◽  
Andre Luis Condino Fujarra
Keyword(s):  
Critical Load ◽  
Dynamic Compression ◽  
Ocean Current ◽  
Strict Sense ◽  
Compression Waves ◽  
Physical Experiments ◽  
Tangent Direction ◽  
Touchdown Point ◽  
Physical Phenomena ◽  
Theoretical Results

Several aspects of risers’ dynamics still demand extensive researches as to improve the understanding about physical phenomena involved, so check the adequacy among analytical and numerical results in offshore applications. Dynamic compression of risers is one of these subjects, which has extreme practical relevance in the sense of both design and structural analysis. In this work a riser is anchored at its top end and the other one remains resting on the seabed. Consider that the riser has quasi-vertical configuration. Thus, the angle between the tangent line at the top end and the vertical is small, and its tension on the vicinity of the touchdown point (TDP) is also small. The riser is statically subject to its own submerged weight and on it can act a horizontal ocean current. Furthermore, it supposed a harmonic motion imposed at the top in the tangent direction to the line, caused by local waves on the floating unit. Since the dynamic tension τ(s) changes cyclically in time and the tension T(s) in the TDP is small, it is possible that in this region, the first exceeds the second one in part of cycle’s wave. In these situations occurs a phenomenon known as dynamic compression, widely discussed in Aranha; Pinto and Silva (2001), Aranha; Pinto (2001), Ramos; Pesce (2003) and Fujarra; Simos (2006). During the dynamic compression occurs riser buckling-like. In a strict sense, the behavior of a riser is similar to a cable, although its bending stiffness is not null. Hence, risers have some resistance to buckling-like and can support a certain level of compression. The maximum loading of compression that can be measured in a riser segment is known as critical load (Pcr). Aranha; Pinto and Silva (2001) proposed a simple analytical formulation for the critical load. The aim of the present paper is to propose a simple analytical equation for the speed of compression waves that propagate from the TDP to the riser’s top end. This formulation depends on physical characteristics of the riser and the levels of tension to which it is submitted. As a result, it is possible to compare the theoretical results obtained with numerical simulations and physical experiments. The outcomes provide more understanding to the phenomenon of dynamic compression of risers.

scholarly journals USE OF MOBILE DEVICE SENSORS TO CONDUCT THE PHYSICAL EXPERIMENT

2019 ◽  
pp. 345-354
Author(s):  
Sergii Tereschuk ◽  
Vira Kolmakova
Keyword(s):  
Stem Education ◽  
Mobile Device ◽  
Mobile Application ◽  
Positive Impact ◽  
Physical Experiment ◽  
Science Journal ◽  
Conservation Of Energy ◽  
Physical Experiments ◽  
Physical Laws ◽  
Physical Phenomena

The concept of "sensor" in the system of physical experiment at school is considered in the article. The possibility of using sensors in physics lessons is substantiated: transformation of an input signal into an output is accompanied by transformation of one type of energy into another (according to the law of conservation of energy), and the functioning of the sensors are based on physical phenomena (physical effects or principles), which are described by the relevant physical laws. The article deals with the methodical aspects of using the Google Science Journal mobile application in physics lessons. This application allows you to use the sensors of your mobile device for a physical experiment. As an example we consider the frontal laboratory work "Determination of the period of oscillation of the mathematical pendulum". The method of its carrying out is offered in two approaches: the first one involves the traditional technique of conducting the experiment, and the second approach is using the mobile application Google Science Journal. The article shows that the use of smartphone sensors in physics lessons has perspectives in the context of STEM education. Thus, the use of the considered application is of current importance and requires further scientific and methodological research on its use in the high school physical experimentation system. The Science Journal mobile application can be used to connect external sensors, which will have a positive impact on the introduction of STEM education, and to use Arduino in the demonstration of physical experiments by a physics teacher. Connecting sensors using an Arduino microcontroller is particularly promising in creative lab work on physics.

scholarly journals Double Hopf Bifurcation in Microbubble Oscillators with Delay Coupling

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jinbin Wang ◽  
Rui Zhang ◽  
Lifenq Ma
Keyword(s):  
Hopf Bifurcation ◽  
Center Manifold ◽  
Two Dimensional ◽  
Main Attention ◽  
Dimensional Parameter ◽  
Center Manifold Reduction ◽  
Double Hopf Bifurcation ◽  
Physical Phenomena ◽  
Manifold Reduction ◽  
Theoretical Results

Using center manifold reduction methodswe investigate the double Hopf bifurcation in the dynamics of microbubble with delay couplingwith main attention focused on nonresonant double Hopf bifurcation. We obtain the normal form of the system in the vicinity of the double Hopf point and classify the bifurcations in a two-dimensional parameter space near the critical point. Some numerical simulations support the applicability of the theoretical results. In particularwe give the explanation for some physical phenomena of the system using the obtained mathematical results.

scholarly journals Metamaterials with engineered failure load and stiffness

2019 ◽  
Vol 116 (48) ◽  
pp. 23960-23965 ◽  
Author(s):  
Sai Sharan Injeti ◽  
Chiara Daraio ◽  
Kaushik Bhattacharya
Keyword(s):  
Mechanical Properties ◽  
Sensitivity Analysis ◽  
Critical Load ◽  
Failure Load ◽  
Weight Ratio ◽  
Fracture Load ◽  
Specific Load ◽  
Load To Failure ◽  
Failure Location ◽  
Theoretical Results

Architected materials or metamaterials have proved to be a very effective way of making materials with unusual mechanical properties. For example, by designing the mesoscale geometry of architected materials, it is possible to obtain extremely high stiffness-to-weight ratio or unusual Poisson’s ratio. However, much of this work has focused on designing properties like stiffness and density, and much remains unknown about the critical load to failure. This is the focus of the current work. We show that the addition of local internal prestress in selected regions of architected materials enables the design of materials where the critical load to failure can be optimized independently from the density and/or quasistatic stiffness. We propose a method to optimize the specific load to failure and specific stiffness using sensitivity analysis and derive the maximum bounds on the attainable properties. We demonstrate the method in a 2D triangular lattice and a 3D octahedral truss, showing excellent agreement between experimental and theoretical results. The method can be used to design materials with predetermined fracture load, failure location, and fracture paths.

Design-Oriented Analysis of Slow-Scale Bifurcations in Single Phase DC–AC Inverters via Autonomous Transformation Approach

2017 ◽  
Vol 27 (06) ◽  
pp. 1750086 ◽  
Author(s):  
Hao Zhang ◽  
Honghui Ding ◽  
Chuanzhi Yi
Keyword(s):  
Theoretical Analysis ◽  
Circuit Design ◽  
Single Phase ◽  
Underlying Mechanism ◽  
System Stability ◽  
Equivalent Model ◽  
Eigenvalue Sensitivity ◽  
Physical Experiments ◽  
Averaged Model ◽  
Theoretical Results

This paper deals with the design-oriented analysis of slow-scale bifurcations in single phase DC–AC inverters. Since DC–AC inverter belongs to a class of nonautonomous piecewise systems with periodic equilibrium orbits, the original averaged model has to be translated into an equivalent autonomous one via a virtual rotating coordinate transformation in order to simplify the theoretical analysis. Based on the virtual equivalent model, eigenvalue sensitivity is used to estimate the effect of the important parameters on the system stability. Furthermore, theoretical analysis is performed to identify slow-scale bifurcation behaviors by judging in what way the eigenvalue loci of the Jacobian matrix move under the variation of some important parameters. In particular, the underlying mechanism of the slow-scale unstable phenomenon is uncovered and discussed thoroughly. In addition, some behavior boundaries are given in the parameter space, which are suitable for optimizing the circuit design. Finally, physical experiments are performed to verify the above theoretical results.

On the dynamic compression of risers: an analytic expression for the critical load

2001 ◽  
Vol 23 (2) ◽  
pp. 83-91 ◽  
Author(s):  
J.A.P Aranha ◽  
M.O Pinto ◽  
R.M.C da Silva
Keyword(s):  
Critical Load ◽  
Dynamic Compression ◽  
Analytic Expression

scholarly journals Deviating Features of Protons, Neutrons and Electrons on a Nano Scale

2019 ◽  
Vol 3 (1) ◽  
Keyword(s):  
Gravitational Waves ◽  
Theoretical Background ◽  
Elementary Particles ◽  
Quantum Mechanical ◽  
Nano Scale ◽  
Physical Phenomena ◽  
Theoretical Results

In the previous fourteen years twin physics has been developed to reconcile descriptions of phenomena on quantum mechanical and astronomical scale, by considering them in a complementary way. After having identified several theoretical results as basic physical phenomena, elementary particles and gravitational waves, this model seems to be ready for exploring the region between the extremes of phenomena. In twin physics it is possible to describe two types of protons, three types of neutrons and four of electrons. The expected appearances of these types in nano structured material and the consequences for their features are considered in general. Because these descriptions can be presented in a geometrical way, they are relatively easily accessible. As assistance to workers in this field, the results focus less on the theoretical background and more on first steps towards experimental applications.

Time-dependent response of floating ice to a steadily moving load

1988 ◽  
Vol 186 ◽  
pp. 25-46 ◽  
Author(s):  
R. M. S. M. Schulkes ◽  
A. D. Sneyd
Keyword(s):  
Steady State ◽  
Critical Load ◽  
Asymptotic Expansions ◽  
Moving Load ◽  
Field Measurements ◽  
Exact Expression ◽  
Time Development ◽  
Time Dependent ◽  
Line Load ◽  
Theoretical Results

When a steadily moving load is applied to a floating ice plate, the disturbance will generally approach a steady state (relative to the load) as time t → ∞. However, for certain ‘critical’ load speeds the disturbance may grow continuously with time, which represents some danger to vehicles driving on ice. To understand this phenomenon and the overall time development of the ice response, this paper analyses the problem of an impulsively applied, concentrated line load on a perfectly elastic homogeneous floating ice plate. An exact expression for the ice deflection is derived, and then interpreted by means of asymptotic expansions for large t in the vicinity of the source. The spatial development of the disturbance is analysed by considering asymptotic expansions as t → ∞ near an observer moving away from the load. Theoretical results are compared with field measurements, and some hitherto unexplained features can be understood.

scholarly journals A Shift in Theoretical Attention for the Properties of Bulk Materials to Those of the Borders

2019 ◽  
Vol 4 (1) ◽  
Keyword(s):  
Magnetic Field ◽  
Molecular Size ◽  
Elementary Particles ◽  
Neutron Decay ◽  
Bulk Materials ◽  
Physical Phenomena ◽  
Theoretical Results

In the previous fourteen years twin physics has been developed to reconcile descriptions of phenomena on a quantummechanical and astronomical scale, by considering them in a complementary way, according to the conviction of Heisenberg. The deduction of the central formula is presented in a visual way by using complementary colors, thus side-stepping theoretical difficulties and making the model more accessible. The examples are presented in a geometrical way. The obtained theoretical results have been identified with basic physical phenomena, like the forces of nature, elementary particles and neutron decay. Moreover, it is possible to describe two types of protons, three types of neutrons and four types of electrons. One type of electron is related to electricity at the border of bulk materials. It is accompanied by a finite magnetic field, restricted to a space of about molecular size.

scholarly journals Simulation of radioelectronic means non-stationary bounce flow and its intensity estimation procedure

2019 ◽  
pp. 18-25
Author(s):  
A. T. Kurilyak ◽  
S. S. Sokolov
Keyword(s):  
Random Process ◽  
Estimation Procedure ◽  
Linear Filter ◽  
Filter Parameter ◽  
Practical Applications ◽  
Optimal Value ◽  
Radio Electronics ◽  
Transcendental Functions ◽  
Physical Phenomena ◽  
Theoretical Results

Unsteady bounce flow is a Poisson flow modulated in intensity by a stationery random process. Flows of this class, known as double stochastic flows, are found in application for describing in addition to the unsteady flow of failures of radio electronics means, a number of physical phenomena in the Earth’s magnetosphere, meteorology and medicine. The problem of registration is the choice of the optimal value of the linear filter parameter, which provides the minimum total root-mean-square error of estimating the flow rate. The obtained theoretical results, based on solving the Wiener-Hopf education, confirmed the presence of the optimal value of the filter parameter for a wide class of random process modulating the flow in intensity. However, when performing mathematical transformations, several approximations of transcendental functions were used, which influenced the accuracy of the results, but allowed to obtain solutions important for practical applications. As part of the study, an algorithm and a computer program for stimulating the implementation of a nonstationary flow and the procedure for forming the relative error of estimating its intensity have been developed. The simulation results combined with the theoretical results, obtained for the exponential autocorrelation function of the modulating random process are presented.

scholarly journals Relation between Planck’s Constant and Speed of Light, Predicting Proton Radius More Accurately

2019 ◽  
Vol 11 (5) ◽  
pp. 1
Author(s):  
Anna C. M. Backerra
Keyword(s):  
Gravitational Waves ◽  
Conversion Factor ◽  
Elementary Particles ◽  
Accurate Prediction ◽  
Quantum Mechanical ◽  
Speed Of Light ◽  
Proton Radius ◽  
Definition Of ◽  
Physical Phenomena ◽  
Theoretical Results

In twin physics, descriptions of phenomena on a quantum-mechanical as well as astronomical scale are reconciled by considering them in a complementary way. This is in agreement with the view of Heisenberg and carried out by using the definition of complementarity as given by Max Jammer. The obtained theoretical results can be identified with basic physical phenomena like the forces of nature, a series of elementary particles and gravitational waves. If the proton as described by twin physics is combined with the early ideas of Einstein about the energetic equivalence of mass and radiation, a relation between the Planck’s constant and the speed of light is found, in which the mass and radius of the proton occur, together with a factor four. This factor acts as a conversion factor from mass to radiation. Besides of that, this relation leads to a more accurate prediction of the radius of the proton.

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