Nondestructive characterization of pipeline materials

There is a growing need to quantitatively and nondestructively evaluate the strength and toughness properties of pipeline steels, particularly in aging pipeline infrastructure. These strength and toughness properties, namely yield strength, tensile strength, transition temperature, and toughness, are essential for determining the safe operating pressure of the pipelines. For some older pipelines crucial information can be unknown, which makes determining the pressure rating difficult. Current inspection techniques address some of these issues, but they are not comprehensive. This paper will briefly discuss current inspection techniques and relevant literature for relating nondestructive measurements to key strength and toughness properties. A project is in progress to provide new in-trench tools that will give strength properties without the need for sample removal and destructive testing. Preliminary experimental ultrasonic methods and measurements will be presented, including velocity, attenuation, and backscatter measurements

Relationship between near-surface ultrasonic shear-wave backscatter and grain size in metals

Backscattered ultrasonic microstructural noise can be used to estimate grain size in metals. However for normal-incidence immersion measurements the ring-down of the front-wall echo creates a ”dead zone” where backscattered grain noise cannot be quantified. This poses a problem for near-surface grain sizing efforts. In this paper we explore the use of mode-converted 45-degree shear waves for near-surface grain sizing using a water immersion setup. We discuss how to accurately relate grain noise arrival time with depth of sound penetration in the metal. Then for a set of Ni-alloy specimens having near-equiaxed microstructures we correlate various backscattered noise attributes with grain sizes determined from micrographs. These noise attributes include both time-domain and frequency-domain characteristics. The backscattered grain noise attributes correlate well with grain size, and are relatively insensitive to modest changes in the transducer tilt angle

Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size

Ultrasonic flaw sizing—An overview

The time-of-flight diffraction (TOFD) technique is one of the most common sizing methods in practical use by industry today. This method was developed over 40 years ago and is based on the technology and state of knowledge present at that time. A combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing

Ultrasonic and magnetic Barkhausen emission measurements for characterization of pipeline steels

To ensure that the aging pipeline infrastructure in the USA can be safely operated, the mechanical properties of the pipe materials must be verified. It is hypothesized that characterization of the pipeline steels and their microstructures through nondestructive methods will allow for the estimation of the mechanical properties of interest, namely yield strength, tensile strength, toughness, and ductile-to-brittle transition temperature. This work will discuss how material properties, such as microstructure and chemical composition, affect the mechanical properties as well as strategies for measuring the material properties nondestructively using magnetic Barkhausen emission and ultrasonic velocity and attenuation measurements. Preliminary results on a limited sample set will be shown and challenges encountered will be discussed

Resource Selection of Free-ranging Horses Influenced by Fire in Northern Canada

Free-ranging or feral horses (Equus ferus caballus) were important to the livelihood of First Nations and indigenous communities in Canada. The early inhabitants of the boreal region of British Columbia (BC) capitalized on naturally occurring wildfires and anthropogenic burning to provide forage for free-ranging horses and manage habitat for wildlife. This form of pyric herbivory, or grazing driven by fi re via the attraction to the palatable vegetation in recently burned areas, is an evolutionary disturbance process that occurs globally. However, its application to manage forage availability for free-ranging horses has not been studied in northern Canada. Across Canada, there are varying levels of governance for feral and free-ranging horses depending on the provincial jurisdiction and associated legislation. The BC Range Act (Act) allows range tenure holders to free-range horses that they own for commercial operations on Crown land. Big-game guide outfitters as range tenure holders are provided grazing licences or grazing permits under the Act with an approved range use plan. Guide outfitters and other range tenure holders have incorporated fi re ecology as part of their rangeland management in mountainous portions of the boreal forest of northeastern BC to promote mosaics of vegetation height and species composition across the landscape to meet nutritional requirements of their free-ranging horses. Using resource selection function models, we evaluated the influence of pyric herbivory on boreal vegetation and use by horse herds occupying 4 distinct landscapes. We found that horses preferentially selected recently burned areas and areas that burned more frequently when they were available. We also found that horses avoided steep slopes and forest cover types. Fire and the ecological processes associated with it, including pyric herbivory, are important considerations when managing boreal rangelands in northeastern BC. Because historical fi re regimes of the boreal region of Canada differ from the arid regions of the United States inhabited by feral horses, the role of pyric herbivory in altering horse distributions in the United States is limited

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

From short-term store to multicomponent working memory: The role of the modal model

The term “modal model” reflects the importance of Atkinson and Shiffrin’s paper in capturing the major developments in the cognitive psychology of memory that were achieved over the previous decade, providing an integrated framework that has formed the basis for many future developments. The fact that it is still the most cited model from that period some 50 years later has, we suggest, implications for the model itself and for theorising in psychology more generally. We review the essential foundations of the model before going on to discuss briefly the way in which one of its components, the short-term store, had influenced our own concept of a multicomponent working memory. This is followed by a discussion of recent claims that the concept of a short-term store be replaced by an interpretation in terms of activated long-term memory. We present several reasons to question these proposals. We conclude with a brief discussion of the implications of the longevity of the modal model for styles of theorising in cognitive psychology