Analysis of an internal crack of pressure pipeline using ESPI and shearography

In this study, shearography and ESPI have been used for quantitative analysis of an internal crack of pipeline and both of them have proved to be suitable to qualitatively detect inside crack. However, shearography needs several critical? factors including the amount of shearing, shearing direction and induced load for the quantitative evaluation of the inside crack. In this study, the factors were optimized for the quantitative analysis and the size of cracks has been determined. Although the critical? factors in shearography have been optimized, it is difficult to determine the factors exactly because they are related to the details of cracks. On the other hand, ESPI is independent of the details of a crack and only the induced load plays an important role. The out-of-plane displacement was measured under the optimized load and the measured results were numerically differentiated, which resulted in an equivalent to the shearogram. The size of cracks can be determined quantitatively without any detail of a crack.     

Ejection of a flexible thread from a container due to the internal pressure

The author supposes that the internal pressure plays the leading part in the transfer of genetic material at the lowest life level. The general effect of the internal pressure on a relatively long flexible thread, situated in a container with a narrow hole, has been shown. It has been proved experimentally by means of a macroscopic model that the internal pressure is sufficient to unwind and propel the thread through the hole even under different unfavourable arrangements.The author expresses his appreciation of the valuable assistance rendered by J. Kaczér, V. Krejí, F. Kroupa and L. Pekárek and thanks them for their helpful discussions and valuable remarks.     

Resonance frequencies of a spherical aluminum shell subject to static internal pressure

Measurements of the vibrational response of a spherical aluminum shell subject to changes in the interior pressure clearly demonstrate that resonance frequencies shift higher as the pressure is increased. The frequency shift appears to be smaller for longitudinal modes than for bending wave modes. The magnitude of frequency shift is comparable to analytical predictions made for thin cylindrical shells. Changes in the amplitudes of resonance peaks are also observed. A possible application of this result is a method for noninvasively monitoring pressure changes inside sealed containers, including intracranial pressure in humans.     

Role of internal pressure in a ferroelastic phase transition

It is shown that the driving force of a ferroelastic phase transition is internal pressure. The pressure gives rise to symmetric deformation, whose energy accumulates as pressure increases and, at the phase transition point, is partially transferred into the energy of antisymmetric deformations.     

Effect of pressure on an intramolecular electron-transfer reaction induced by pulse-radiolysis

Abstract

The pressure dependence of an intramolecular electron-transfer reaction between p-nitrobenzoate and the pentaamminecobalt (III) species was studied with the aid of a combined high-pressure pulse-radiolysis technique. The resulting volume of activation of +7.5±0.3 cm³mol^?1 is ascribed to an intrinsic volume increase due to the reduction of Co(III) to Co(II) and some desolvation of the coordinated ligand during the electron-transfer process. The results are compared with related data obtained using conventional kinetic techniques.     

Dynamic response of an irreversible reaction system to a pulsed perturbation

The dynamic response of the ZGB surface reaction lattice gas model, for the catalyzed reaction , is studied by means of Monte-Carlo simulations in the neighborhood of its second order irreversible phase transition (IPT). It is found that shortly after driving a stationary configuration into the absorbing state, the relaxation of the system can be well described by a stretched exponential behavior. The dependence of the relaxation characteristic time and the induced changes on the coverage of the reactants, on both, the intensity and the period of the pulsed perturbation, are systematically investigated. The obtained insights can straightforwardly be extended to a wide variety of irreversible systems exhibiting second order IPT's, such as directed percolation, forest fire models, the contact process, branching annihilating walkers, catalyzed reactions, etc. Received 6 July 1998     

Dynamics of an elastic L-shaped ring coupled to an internal frame

Analyzed is the dynamics of an elastic L-shaped ring coupled to an elastic frame joined at discrete locations of the ring perimeter. The approximate ring model is evaluated adopting a two-dimensional model of a short shell joined to a narrow annular disk along one of its boundaries thus forming the L-shaped cross-section. Coupling the ring to an internal frame is accomplished by segmenting the ring. The frame impedance matrix relating forces and displacements at terminations is then applied at junctions of ring segments corresponding to these terminations.     

天然气管网压力能利用方案

以北京燃气集团西集镇天然气调峰示范站项目为例,建立LNG调峰装置调节管网天然气供应与消耗的平衡,提出天然气增压透平膨胀机预冷流程,采用气体轴承增压透平膨胀机回收利用天然气管网向用户供气调压过程中产生的冷能,提供给LNG液化系统预冷,可使流程中天然气液化功耗降低1.3%,提高了能源利用率以及天然气管网运行的经济性。     

Propagator of a particle characterized by an internal symmetry

We examine the propagators associated with particles characterized by an internal symmetry. Of particular interest is the case of spontaneously broken Kac-Moody algebra.     

Computing reaction paths of a bifurcation reaction: an action wave-front-based perspective

Application of Hamilton–Jacobi (HJ) equation to reaction systems which involve energy barrier(s) leading to the product is relatively new. Such problems are described by a new class of HJ equation, called the generalised HJ equation. This new HJ equation renders an anisotropic propagation for the wave front. In this paper, we describe the adaptation of the fast marching method (FMM) and the generalised HJ equation to understand a new class of reaction process where the energy barrier does not lead to the product; instead, a new class of states are detected along the reaction path of such reactions. These states are valley-ridge inflection point, branching point and potential energy ridge. Such reactions are characterised as bifurcation reactions. We have identified a new classical wave front, called the reaction action front (RAF) which distinctly separates the reaction system into a reactant zone and a product zone connected by a third zone, called ‘neck’. The RAF is an important tool to understand the bifurcation reaction and the associated reaction paths. We have also introduced a convenient way to compute the reaction path force (RPF) using the FMM. The RPF for a bifurcation reaction significantly differs from the reactions with energy barrier, and so, the RPF provides vital information about the occurrence of branching of a path. The method has been tested for the isomerisation reaction of methoxy radical (H₃C) to hydroxymethylene radical (H₂?OH).     

Liquid jet response to internal modulated ultrasonic radiation pressure and stimulated drop production

Experimental evidence shows that a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate within the jet when the acoustic frequency is near to or above the cutoff frequency. Modulated radiation pressure is used to stimulate large amplitude deformations and the breakup of the jet into drops. The jet response to the modulated internal ultrasonic radiation pressure was monitored along the jet using (a) an optical extinction method and (b) images captured by a video camera. The jet profile oscillates at the frequency of the radiation pressure modulation and where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P.L. Marston and R.E. Apfel, J. Acoust. Soc. Am. 67, 27-37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Though aspects of the perturbation growth can be approximated from Rayleigh's analysis of the capillary instability, some detailed features of the observed jet response to modulated ultrasound are unexplained neglecting the effects of gravity.     

天然气管道泄漏的声-压耦合识别方法

为了提高对城市燃气管道泄漏检测的准确性,该文提出了一种基于声波与压力波耦合的识别方法,并通过实验考察了它的可行性。实验发现管道的气体泄漏引起了两个显著特征,即泄漏噪声与压力下降。泄漏噪声的强度随泄漏量增大而增大,但噪声的频率基本保持不变;管道内压力降低的速率与泄漏量大小正相关。据此发展了一种基于相关算法的泄漏耦合识别方法,通过判别泄漏噪声与压力降是否同时出现,以及相关函数值大小与阈值对比,来判别泄漏是否发生及其大小。实验验证了耦合识别方法的有效性,并展示了比单一信号识别方法更好的抗干扰能力。     

Initiation of a reaction in aluminum-Teflon multilayer thin-film samples by drop-hammer impact loading

Experimental results on the initiation of samples composed of alternating layers of aluminum foil (0.65, 4, 10, or 20 μm in thickness) and Teflon films (20 or 50 μm) by drop-hammer impact loading are presented. In contrast to powdery mixtures, lamellar compositions have a rigorously controlled surface area of contact of the interacting components. The light flash signifying the event of initiation and the impact pressure were recorded with a photodiode and a tensiometer, respectively. It was established that, under typical condition of initiation of HEs, the aluminum-Teflon lamellar samples are deformed as brittle materials. At a certain pressure, after the stage of elastic compression, a rapid disintegration (within 30 μs) with the formation of local reaction initiation sites at shear surfaces of individual segments occurs. The results obtained are indicative of the mechanochemical nature of the interaction between aluminum and Teflon layers under impact loading conditions.     

Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by Ar+2ions,produced by atomic-to-molecular conversion of Ar+ions in the first several milliseconds after the cessation of the discharge.This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional(1D)model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional(2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes.     

The attenuation coefficient of an acoustic wave propagating in a turbulent flow in a long pipeline

Results of experiments on measuring the attenuation coefficient for acoustic waves propagating in long oil and petroleum product pipelines are presented. A comparison of experimental results with theory is performed. An approximate dependence of the attenuation coefficient on the dimensionless parameter of the flow is proposed.     

A solution to the Navier-Stokes inequality with an internal singularity

We consider weak solutions to the time dependent Navier-Stokes equations of incompressible fluid flow in three dimensional space with an external force that always acts against the direction of the flow. We show that there exists a solution with an internal singularity. The speed of the flow reaches infinity at this singular point. In addition, the solution has finite kinetic energy.The author was supported in part by a Sloan Foundation Fellowship     

Investigation of the design of a metal-lined fully wrapped composite vessel under high internal pressure

In this study, a Type III composite pressure vessel (ISO 11439:2000) loaded with high internal pressure is investigated in terms of the effect of the orientation of the element coordinate system while simulating the continuous variation of the fibre angle, the effect of symmetric and non-symmetric composite wall stacking sequences, and lastly, a stacking sequence evaluation for reducing the cylindrical section-end cap transition region stress concentration. The research was performed using an Ansys^® model with 2.9 l volume, 6061 T6 aluminium liner/Kevlar^® 49-Epoxy vessel material, and a service internal pressure loading of 22 MPa. The results show that symmetric stacking sequences give higher burst pressures by up to 15%. Stacking sequence evaluations provided a further 7% pressure-carrying capacity as well as reduced stress concentration in the transition region. Finally, the Type III vessel under consideration provides a 45% lighter construction as compared with an all metal (Type I) vessel.     

The interference between a giant atom and an internal resonator

The Jaynes–Cummings model plays an important role in quantum entanglement and state measurements. Here, we discuss how to realize it in a waveguide-mediated interaction system, which comprises a giant atom and a resonator. We show the vacuum Rabi splitting and discuss how to achieve a unidirectional transport. We extend the Purcell effect in cQED to this waveguide QED system, showing how to control the giant atom decay rate. Our design can further be built experimentally and has application in quantum manipulation.     

Radiation transfer for a homogeneous half-space with an internal source

The emergent flux for radiation transfer in a homogeneous half-space with internal source solved in terms of the diffuse reflection problem. An efficient method of analysis which utilizes trial functions based on Cases eigenvalues is developed for solving the problem. Numerical results are given and compared with the previous results.