Phase Steering and Focusing Behavior of Ultrasound in Cementitious Materials

Deterioration of civil infrastructure system (CIS) raises not only safety issues but also socio-economic concerns. In order to meet the high demand of structural condition assessment and health monitoring, development of quick, reliable and accurate NDE methods became critical issues recently. Compared to metal structures, NDE for cement-based materials is still premature and requires further development

Mode Conversion of Guided Waves by Defects in Pipes

The corrosion of pipework is a major problem for the oil and gas and petro-chemical industries. Large facilities operate hundreds of kilometres of pipes which may carry corrosive substances. General wall-thinning and localised pitting corrosion can occur both from the inside and the outside of pipe walls. A high proportion of these pipes are insulated, so that even the external defects cannot be detected by conventional NDE techniques without the expense of removing of the insulation

Detection of Aircraft Component Defects Using Low Voltage Excitation of Ultrasonic Transducers

Large areas of composite primary structure are now to be found both on civil and military aircraft throughout the world and the inspection of these structures contributes significantly to overall operating costs. Therefore methods to reduce the inspection time, whilst maintaining an acceptable minimum defect detection capability, are required in order to optimize the potential cost saving benefits offered by using that carbon fiber composite material

The Lamb Wave Inspection of Chemical Plant Pipework

Corrosion in pipework is a major problem, particularly in the oil, gas, chemical and petro-chemical industries. Since a high proportion of industrial pipelines are insulated, this means that even external corrosion cannot readily be detected without the removal of the insulation, which in most cases is prohibitively expensive. There is therefore an urgent need for the development of a quick, reliable method for the detection of corrosion under insulation (CUI)

Four Transducer Ultrasonic Array for Detecting and Sizing Defects in Plate and Pipe Materials

Ultrasonic pulse-echo techniques are widely used for detection and sizing of defects. However, studies over recent years have shown that the detection and sizing capability of many of the widely accepted ultrasonic techniques do not provide accuracy required to assure safety, reliability or maintainability. While certain types and orientations of defects can be detected, others may go undetected. Even after detection, studies have shown that the ability to size defects is far from accurate. [1,2,3

Crack Length Determination by Ultrasonic Methods

Accurate calculation of the stress intensity factor on a given component under load relies on an accurate size determination of the flaws present in the component. The challenge to the NDE community has been development of reliable techniques to provide that accurate size determination. Many research groups have investigated this problem using ultrasonic methods with summaries of their techniques and results provided by various authors [1–3]. In general, the techniques developed fall into three general categories; (1) determination of crack length from signal amplitude measurements, (2) determination of crack length from time-of-flight measurements, and (3) determination of crack length using diffracted waves. Sketches of representative techniques in each category are shown in Figure 1

The Inspection of Chemical Plant Pipework Using Lamb Waves: Defect Sensitivity and Field Experience

Corrosion and pitting defects in pipework are major problems in the oil, chemical and other industries. These defects can occur at the outer or inner surface of the pipe and can lead to a serious loss of pipe wall thickness. As a high proportion of industrial pipelines are insulated, this means that even external corrosion cannot readily be detected without the removal of the insulation, which in most cases is prohibitively expensive.</p

Detection of Creep Damage by Ultrasonics

Creep damage is known to affect the service life of fossil plant components. Nondestructive examination for the detection of such damage is important for assessing the remaining service life of the affected component. Ultrasonic methods have been investigated for use as inservice inspection tools in a project being funded by the Electric Power Research Institute (RP 1865–7). This on-going research has shown that the velocity of sound waves is altered by the material damage (cavitation at grain boundaries). The amount of change in the velocity can be correlated to the amount of damage. Other EPRI projects have developed a methodology to correlate the amount of cavitation to remaining service life of the material. Development of these ultrasonic methods will allow rapid performance of a volumetric examination during a short plant outage to detect the damage and estimate the remaining service life

Human Bocavirus NS1 and NS1-70 Proteins Inhibit TNF-α-Mediated Activation of NF-κB by targeting p65.

Human bocavirus (HBoV), a parvovirus, is a single-stranded DNA etiologic agent causing lower respiratory tract infections in young children worldwide. Nuclear factor kappa B (NF-κB) transcription factors play crucial roles in clearance of invading viruses through activation of many physiological processes. Previous investigation showed that HBoV infection could significantly upregulate the level of TNF-α which is a strong NF-κB stimulator. Here we investigated whether HBoV proteins modulate TNF-α-mediated activation of the NF-κB signaling pathway. We showed that HBoV NS1 and NS1-70 proteins blocked NF-κB activation in response to TNF-α. Overexpression of TNF receptor-associated factor 2 (TRAF2)-, IκB kinase alpha (IKKα)-, IκB kinase beta (IKKβ)-, constitutively active mutant of IKKβ (IKKβ SS/EE)-, or p65-induced NF-κB activation was inhibited by NS1 and NS1-70. Furthermore, NS1 and NS1-70 didn't interfere with TNF-α-mediated IκBα phosphorylation and degradation, nor p65 nuclear translocation. Coimmunoprecipitation assays confirmed the interaction of both NS1 and NS1-70 with p65. Of note, NS1 but not NS1-70 inhibited TNF-α-mediated p65 phosphorylation at ser536. Our findings together indicate that HBoV NS1 and NS1-70 inhibit NF-κB activation. This is the first time that HBoV has been shown to inhibit NF-κB activation, revealing a potential immune-evasion mechanism that is likely important for HBoV pathogenesis

Effective theories of single field inflation when heavy fields matter

We compute the low energy effective field theory (EFT) expansion for single-field inflationary models that descend from a parent theory containing multiple other scalar fields. By assuming that all other degrees of freedom in the parent theory are sufficiently massive relative to the inflaton, it is possible to derive an EFT valid to arbitrary order in perturbations, provided certain generalized adiabaticity conditions are respected. These conditions permit a consistent low energy EFT description even when the inflaton deviates off its adiabatic minimum along its slowly rolling trajectory. By generalizing the formalism that identifies the adiabatic mode with the Goldstone boson of this spontaneously broken time translational symmetry prior to the integration of the heavy fields, we show that this invariance of the parent theory dictates the entire non-perturbative structure of the descendent EFT. The couplings of this theory can be written entirely in terms of the reduced speed of sound of adiabatic perturbations. The resulting operator expansion is distinguishable from that of other scenarios, such as standard single inflation or DBI inflation. In particular, we re-derive how certain operators can become transiently strongly coupled along the inflaton trajectory, consistent with slow-roll and the validity of the EFT expansion, imprinting features in the primordial power spectrum, and we deduce the relevant cubic operators that imply distinct signatures in the primordial bispectrum which may soon be constrained by observations.Comment: (v1) 25 pages, 1 figure; (v2) references added and typos corrected, to appear in Journal of High Energy Physic