bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling Shallow Dents Using Local Regression Methods and Finite Element Analysis
Authors: Lockey Aaron , Santamaria Wilson , Gonzalez Gustavo 
Published: December 2014

Modern in-line inspections can detect shallow dents in pipelines, with depths less than 2% of pipeline diameter. These dents are very common in thin-walled, small diameter refined and multiproduct lines, and frequently coincide with longitudinal welds and girth welds.
Traditional dent assessment methods (such as the EPRG approach) can be conservative. Dents can have short predicted fatigue lives, but shallow dents are not known to be a major cause of pipeline failure, unless they are associated with a weld, a gouge, a crack, or severe pressure cycling. The conservatism affects both static failure assessments and fatigue assessments, resulting in high repair rates for shallow dents. This conservatism is partly due to:
• Limitations of how the dent shape is modelled in the assessment methods;
• Simplifications of the modelling of the stresses range;
• Limitations of the calculation of strains in a dent based on inspection measurements;
• Inability to model the changing cyclic stress range with changing dent shape.
This paper shows that high resolution geometry inspection data contains irregularities which need to be filtered and smoothed. Advanced local regression methods are shown to give effective smoothing by removing errors but retaining the important elements of the real dent shape. The smoothed dent shape is used with the strain estimation methodology given by ASME B31.8 Appendix R, and an appropriate strain limit (based on likely weld quality), to assess whether cracking is likely to have initiated during dent formation.
A methodology is then presented, based on Finite Element Analysis (FEA), which improves the accuracy of cyclic stress assessments of shallow smooth dents. The FEA model geometry is provided by the smoothed version of the measured dent shape. The pressure at which the dent shape was measured affects the calculated dent shape and stress as internal pressure varies: this effect is included in the model. The calculated cyclic stresses are used with S-N curves, such as those in BSI PD 5500, to estimate dent fatigue life.
This methodology is then applied to 88 dents in two pipelines operated by ExxonMobil in the UK, using detailed high resolution geometrical in-line inspection data, comprehensive pressure cycle measurement data and enhanced dent assessment using the FEA method. It is concluded that this methodology can significantly improve the operator’s pipeline integrity strategy.
Pipeline Safety Targets and the Connection to Social License
Authors: Kresic Walter , LeBlanc Len , Harron Lorna 
Published: December 2014

While North American pipeline integrity codes and regulations provide substantive prescriptive or goal setting objectives, there currently is not a consistent measurement approach for defining the levels of safety achieved. Standardized targets would drive consistent operator safety culture, enhance transparency for the public, and focus industry collaboration on technologies and innovation.
This paper provides the perspective of an operator on current status of where the pipeline industry is related to safety targets and social license in addition to where the pipeline industry could go in this arena. The intent is a ‘call to action’ for the leaders in the pipeline industry to collaborate on the establishment of the technical systems which define the current industry safety condition, the targets that must be achieved, and to show that the industry is innovating for further improvements; elements considered to be important to the achievement of social license.
A review of the current practices as well as a framework for industry advancement and advocacy will be explained. This will include an examination of safety measurement systems from around the world including other notable industries such as aviation and nuclear. Several measurement models will be highlighted including qualitative, semi-quantitative and quantitative. Importantly, this paper will highlight how operators, regulators, and codes organizations can link together for this common purpose and contribute to “social license”.
Recent Advances in Materials Development for Emerging SMA Applications
Authors: Coda Alberto , Cadelli Andrea , Butera Francesco 
Published: December 2014

Shape Memory Alloys (SMAs) are active metallic materials classified as “smart” or “intelligent” materials along with piezoelectric ceramic and polymers, electro-active plastics, electro-rheological and magneto-rheological fluids and others. SMAs show a multitude of different and dependent properties interesting for technological applications. These properties depend on the peculiar deformation mechanisms, accounting for the so-called shape memory effect. SMAs are nowadays used in quite different fields, like thermo-mechanical devices, anti-loosening systems, biomedical applications, mechanical damping systems, in some cases employed for large scale civil engineering structures. These multifunctional materials can be naturally considered as sensor-actuator elements demonstrating large possibilities for applications in high-tech smart systems. The use of SMAs in actuators offers an excellent technological opportunity to develop reliable, robust, simple and lightweight elements within structures or as stand-alone components that can represent an alternative to electro-magnetic actuators commonly used in several fields of industrial applications, such as automotive, appliances, consumer electronics and aerospace. NiTi-based SMAs demonstrated to have the best combination of properties, especially in terms of the amount of work output per material volume and the large amount of recoverable stress and strain. However, there are several limiting factors to a widespread diffusion of SMAs to technological fields. For instance, SMAs display a critical dependence of the shape-memory related properties, like transition temperatures, on their actual composition. For this reason, a great care in the production steps, mainly based on casting processes, is required. Another critical aspect, that is to be considered when dealing with SMAs, is the strong influence of their thermo-mechanical history on their properties. This may disclose interesting perspectives of application to smart devices in which different aspects of the shape memory phenomenology, like one and two way shape memory effect, pseudoelasticity, damping capacity, etc., are used. Last, but not least, one of the most debated aspects around NiTi alloys is microcleanliness. This concept is becoming increasingly important as the industrial market moves to smaller, lower profile devices with thinner structures.
In this work a general overview about the peculiar behavior of NiTi alloys along with their main issues, the shape memory components under development, and the main efforts and directions for materials improvement will be presented and discussed. A bird’s-eye view on the future opportunities of NiTi-based shape memory actuators for industrial applications will also be given.
Uniaxial, Pure Bending and Buckling Characterization of Superelastic NiTi Rods and Tubes: An Experimental Study
Authors: Watkins Ryan , Reedlunn Benjamin , Shaw John 
Published: December 2014

Although the tensile behavior of shape memory alloys (SMAs) is relatively well understood, the effects of other modes of loading on SMA behavior are still unknown. To examine the influence of loading and specimen geometry on structural behavior and phase transformation morphology, this work presents an experimental characterization of commercially-available superelastic NiTi rods and tubes under tensile, compressive, pure bending and column buckling loading. At room temperature and under isothermal loading conditions, the mechanical response for each loading configuration and structural geometry is measured and stereo digital image correlation is used to capture local displacement and strain phenomena (such as strain localization and propagating phase boundaries).
It is found that the length and cross-sectional geometry of NiTi structures affects the nature of stress-induced phase transformation; in particular, transformation induced strain localization. During uniaxial tension, the rod specimens exhibit strain localization and propagating phase transformation fronts along well-defined load plateaus, and phase boundaries manifest as diffuse propagating necks. The tube specimens also exhibit localization/propagation phenomena, but fronts consist of distinct angled finger-like features due to the relatively thin-walled cross-section. During uniaxial compression, both forms exhibit (now well-known) tension-compression asymmetry in their mechanical responses, no propagating fronts are observed, and distinct load plateaus are absent. During pure bending, the moment-curvature responses of both forms exhibit plateaus during localizing forward and reverse transformations. In the case of the rod, high curvature localizes and propagates along the specimen; whereas, finger-like high strain regions develop along the tensile side of the tube. During column buckling, the structures are loaded into the post-buckling regime yet recover their straight forms upon unloading. Localization is observed, but only for high length/diameter aspect ratio tubes and has little affect on the mechanical response. Therefore, due to the varying phase transformation behaviors observed, understanding geometric and material effects on phase transformation, along with the resulting effects on the material response, is necessary to predict SMA beam behavior.
Effects of Piezoceramic Actuator in Quasistatic Use
Authors: Riemenschneider Johannes , Huxdorf Oliver , Opitz Steffen 
Published: December 2014

In the field of smart structures, piezoceramic actuators are wildly used for vibration reduction and acoustic manipulation of structures. Those applications typically run at frequencies between 10 Hz and 10k Hz. Prominent examples are the piezoceramic actuators implemented in helicopter rotor blades to twist them dynamically for higher harmonic control (HHC) or individual blade control (IBC). Once the actuators are implemented it would be a great benefit to also use them to statically change the blade twist (higher twist for take-off and landing — for higher lift; lower twist for high speed forward flight — for reduced drag). Staying with this example it can be found that sensing the twist displacement is not an easy task at all (see [1, 2]), so it would be most desirable, to use open loop control. In order to do that, the transfer function has to be known accurately. Unfortunately measurements show that the amplitudes for such very low frequencies behavior behave strongly non linear. This paper presents experimental results investigating the influence of the frequency on the amplitude — especially going for frequencies in the lower mHz region. A variety of piezoceramic actuators has been investigated: from stacks to patch type, d33 as well as d31 effect actuators.
A second focus of this paper is the reaction of piezoceramic actuators on the application of a constant DC voltage. The drift that occurs has to be taken into consideration.
A third focus of this paper is the dependency of a displacement output of such an actuator at a constant applied DC voltage on the voltages that the actuator had seen before. This topic is of special importance for aerodynamically effective surfaces that are driven by piezoceramic actuators and should be analyzed (generation of polars) in static conditions.
Modeling and Experimentation of Thickness Mode E/M Impedance and Rayleigh Wave Propagation for Piezoelectric Wafer Active Sensors on Thick Plates
Authors: Kamas Tuncay , Giurgiutiu Victor , Lin Bin 
Published: December 2014

This paper discusses theoretical and experimental analyses of the standing harmonic waves through the electro-mechanical impedance spectroscopy (EMIS) and guided surface acoustic waves (SAW) through the guided wave propagation (GWP) analyses. Both EMIS and GWP analyses have been carried out by utilizing piezoelectric wafer active sensors (PWAS) for in situ structural inspection. PWAS has recently been extensively employed in many applications such as nuclear-structural as well as aero-structural health monitoring and non-destructive evaluations (NDE). EMIS method is utilized for high frequency local modal sensing to determine the dynamic characteristics of PWAS bonded on nuclear-structural component for in-situ ultrasonics. Rayleigh waves a.k.a., SAW, were generated in relatively thick isotropic elastic plates. Rayleigh waves have the property of propagating close to the plate surface, with rapid attenuation with depth. The polarization of Rayleigh waves lies in a plane perpendicular to the surface so that the effective penetration depth is less than a wavelength. Rayleigh waves are a high frequency approximation of the first symmetric (S0) and anti-symmetric (A0) Lamb wave modes. As the frequency becomes very high the S0 and the A0 wave speeds coalesce, and both have the same value. This value is exactly the Rayleigh wave speed and becomes constant along the frequency.
In the first part of the study, simplified theoretical constrained PWAS-EMIS model is briefly discussed in relatively high frequency range (in MHz order of magnitude) in terms of thickness mode. Analytical predictive thickness mode impedance simulations of PWAS bonded on plate-like host structures are presented in corresponding with the experiments. For the experimental analyses, PWAS transducers are affixed on isotropic elastic plates such as aluminum plate in relatively high thickness and on a rail I-beam. The extent of the agreement between the experimental and analytical EMIS analyses of PWAS in thickness mode is presented. The study is followed with GWP tests through the pitch-catch method. Rayleigh wave signal packets which are generated in the relatively thick plate and a rail I-beam in high frequency region are assessed along with the experimental thickness mode PWAS-EMIS results. The tuning curve of Rayleigh wave is determined to show the tuning effect of the structure thickness on producing a dominant Rayleigh wave mode. The significant usage of the tuned Rayleigh wave mode is essentially discussed for the applications in the in-situ inspection of relatively thick structures such as nuclear power plant structures. The paper ends with summary, conclusions and suggestions for future work.
Piezo-Optical Active Sensing With PWAS and FBG Sensors for Structural Health Monitoring
Authors: Lin Bin , Giurgiutiu Victor 
Published: December 2014

This paper presents the investigation of piezo-optical active sensing methodology for structural health monitoring (SHM). Piezoelectric wafer active sensors (PWAS) have emerged as one of the major structural health monitoring (SHM) technology; with the same installation of PWAS transducers, one can apply a variety of damage detection methods; propagating acousto-ultrasonic waves, standing waves (electromechanical impedance) and phased arrays. In recent years, fiber Bragg gratings (FBG) sensors have been investigated as an alternative to piezoelectric sensors for the detection of ultrasonic waves. FBG have the advantage of being durable, lightweight, and easily embeddable into composite structures as well as being immune to electromagnetic interference and optically multiplexed.
In this paper, the investigation focused on the interaction of PWAS and FBG sensors with structure, and combining multiple monitoring and interrogation methods (AE, pitch-catch, pulse-echo, phased-array, thickness mode, electromechanical impedance). The innovative piezo-optical active sensing system consists of both active and passive sensing. PWAS and FBG sensors are bonded to the surface of the structure, or are integrated into structure by manufacturing process. The optimum PWAS size and excitation frequency for energy transfer was determined. The FBG sensors parameters (size, spectrum, reflectivity, etc.) for ultrasonic guided waves sensing were also evaluated. We focused on the optimum FBG length and design to improve the sensitivity, coverage, and signal to noise ratio. In this research, we built the fundamental understanding of different sensors with optimum placement. Calibration and performance improvements for the optical interrogation system are also discussed. The paper ends with conclusions and suggestions for further work.
Self-Powered Event Detection Sensors With Integrated Safety Electronics for Initiation and Switching in Munitions
Authors: Rastegar Jahangir , Feng Dake , Pereira Carlos 
Published: December 2014

A new class of self-powered acceleration event detection sensors are presented that are powered by electrical energy harvested during munitions launch by integrated piezoelectric elements. The sensors are provided with a novel safety electronic and logic circuitry that is used to differentiate the firing event from all accidental events such as accidental drops, transportation vibration, and the like. When the launch conditions are detected from the magnitude of the experienced acceleration as well as its duration, the remaining electronics and logics circuitry of the device is enabled. The developed self-powered sensors may also be used in place of G-switches in munitions and other industrial and commercial devices with the advantage of activating not only from the magnitude of the experienced acceleration but also from its duration. The latter capability is essential in many munitions and commercial applications to avoid false switching event. For example in some cases dropping of around over a hard surface may impart higher peak acceleration than actual firing. And in many industrial and commercial devices and equipment, high-G and very short duration shock loadings do not cause damage and G-switches used to deactivate the device may not be desired to trip.
Prototypes of the developed piezoelectric-based self-powered event detection sensors as standalone sensors and as switches for detecting and opening or closing circuitry upon detection of shock or vibration loading with prescribed magnitude and duration thresholds with integrated electronics and logics circuitry have been designed, fabricated and successfully tested for a number of munitions and industrial applications. In this paper the design and operation of such devices and their testing are described.
Artificial Hair Sensors: Electro-Mechanical Characterization
Authors: Phillips David M. , Slinker Keith A. , Ray Cody W. , Hagen Benjamin J. , Baur Jeffery W. , Dickinson Benjamin T. , Reich Gregory W. 
Published: December 2014

Performance demands of future unmanned air vehicles will require rapid autonomous responses to changes in environment. Towards this goal, we expect that the next generation flight control systems will include advanced sensors beyond the contemporary array. One promising scenario correlates measurements of flow footprints over aircraft surfaces with aerodynamic data to aid navigation and feedback control algorithms. As a sensor for this concept, we construct artificial hair sensors (AHSs) based on glass microfibers enveloped in an annular, radially-aligned piezoresistive carbon nanotube (CNT) forest to measure air flow in boundary layers. This study includes an analysis of the sensitivity based on laboratory scale electromechanical testing.
The sensors in this work utilize nine micron diameter S2 glass fibers as the sensing mechanism for coupling to boundary layer air flows. The annular CNT forest resides in a fused silica microcapillary with electrodes at the entrance. The sensor electrical transduction mechanism relies on the resistance change of the CNT forest due to changes in both the bulk and contact resistance as a function of mechanical loading on the fiber. For the electromechanical analysis, the sensors are controllably loaded to measure both the force and moment acting at the base of the hair and the resulting deflection of the CNT forest inside of the microcapillary is measured to estimate the stress on the forest and the pressure between the forest and the electrode. The electrical responses of the sensors are compared to the mechanical state of the CNT forest. This work represents the development of a characterization tool to better understand and control the response of CNT based AHSs.
Draft Genome Sequences of Antibiotic-Resistant Commensal Escherichia coli
Authors: Garrett Meghan , Parker Jennifer , Stephens Craig M. 
Published: December 2014

ABSTRACT

Antimicrobial resistance is a significant public health issue. We report here the draft genome sequences of three drug-resistant strains of commensal
Escherichia coli
isolated from a single healthy college student. Each strain has a distinct genome, but two of the three contain an identical large plasmid with multiple resistance genes.
Complete Genome Sequence of the Embu Virus Strain SPAn880
Authors: Ibrahim M. Sofi , Antwerpen Markus , Georgi Enrico , Vette Philipp , Zoeller Gudrun , Meyer Hermann 
Published: December 2014

ABSTRACT
We report the complete genome sequence of the Embu virus. The genome consists of 185,139 bp and is nearly identical to that of the Cotia virus. This is the first report on the Embu virus genome sequence, which has been considered an unclassified poxvirus until now.
Complete Genome Sequence of Haemophilus influenzae Strain 375 from the Middle Ear of a Pediatric Patient with Otitis Media
Authors: Mell Joshua Chang , Sinha Sunita , Balashov Sergey , Viadas Cristina , Grassa Christopher J. , Ehrlich Garth D. , Nislow Corey , Redfield Rosemary J. , Garmendia Junkal 
Published: December 2014

ABSTRACT

Originally isolated from a pediatric patient with otitis media,
Haemophilus influenzae
strain 375 (Hi375) has been extensively studied as a model system for intracellular invasion of airway epithelial cells and other pathogenesis traits. Here, we report its complete genome sequence and methylome.
Draft Genome Sequence of Bacillus subtilis GXA-28, a Thermophilic Strain with High Productivity of Poly-γ-Glutamic Acid
Authors: Zeng Wei , Chen Guiguang , Tang Zhen , Wu Hao , Shu Lin , Liang Zhiqun 
Published: December 2014

ABSTRACT

Bacillus subtilis
GXA-28 is a thermophilic strain that can produce high yield and high molecular weight of poly-γ-glutamic acid under high temperature. Here, we report the draft genome sequence of this strain, which may provide the genomic basis for the high productivity of poly-γ-glutamic acid.