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This paper presents a newly observed phenomenon of upscaling of rocks’ properties using big data nanoindentation and analytics involving Gaussian mixture modeling (GMM), leading to characterizing the cross-scale mechanical properties of four shales and one sandstone. A large number (i.e., ~ 500) of statistical indentation measurements to depths of 6–8 μm were performed on each rock, resulting in continuous depth-dependent hardness and Young’s modulus data from unknown phases, which were then segmented at various depths to extract an array of discretized subdatasets. Two-dimensional GMM of each subdataset yields the number, fraction, and properties of mechanically distinct phases, and re-assembly of these results leads to clearly discernible property-depth curves. Such improved data analytics consisting of data segmentation, GMM deconvolution, and re-assembly enables the transformation of a massive number of chaotic curves from unknown phases into a few discernible lines corresponding to identified phases, from which the mechanical properties of individual phases are accurately determined at relatively small depths. With increasing depth, initially unique mechanical properties of individual phases undergo multistage merging at the intermediate mesoscale and progressively homogenize into a unified value at large depths or macroscale (e.g., > ~ 5 μm), which is regarded as the bulk rock’s properties. More importantly, such depth-dependent transition and progressive merging and homogenization actually manifest the micromechanics of nanoindentation on a heterogeneous composite, including the indentation surround effect and rock’s microstructure (e.g., sizes and spacings of different solid particles and their properties). Compared to different micromechanical upscaling models, this newly developed big data indentation technique and pertinent data analytics enable more accurate, multi-parameter, and cross-scale characterization of highly heterogeneous materials and explicitly uncover the multi-staged, progressively-homogenized, depth-dependent upscaling of elasticity from individual constituents at the nanoscale to merged virtual interface phases at the mesoscale and to bulk material at the macroscale.

Objectives The aim of this study was to evaluate the safety and performance of an extravascular (EV) implantable cardioverter-defibrillator (ICD). Background Limitations of existing transvenous and subcutaneous ICD systems include lead reliability and morbidity issues associated with ICD lead implantation in the vasculature or lack of pacing therapies (e.g., antitachycardia pacing) in subcutaneous systems. The EV defibrillator uses a novel substernal lead placement to address these limitations. Methods This was a prospective, nonrandomized, chronic pilot study conducted at 4 centers in Australia and New Zealand. Participants were 21 patients referred for ICD implantation. Patients received EV ICD systems. Data collection included major systemic and procedural adverse events, defibrillation testing at implantation, and sensing and pacing thresholds. Results Among 20 patients who underwent successful implantation, the median defibrillation threshold was 15 J, and 90% passed defibrillation testing with a ≥10-J safety margin. Mean R-wave amplitude was 3.4 ± 2.0 mV, mean ventricular fibrillation amplitude was 2.8 ± 1.7 mV, and pacing was successful in 95% at ≤10 V. There were no intraprocedural complications. Two patients have undergone elective chronic system removal since hospital discharge. In the 15 patients presently implanted, the systems are stable in long-term follow-up. Conclusions This first-in-human evaluation of an EV ICD demonstrated the feasibility of substernal lead placement, defibrillation, and pacing with a chronically implanted system. There were no acute major complications, and pacing, defibrillation, and sensing performance at implantation were successful in most patients. (Extravascular ICD Pilot Study [EV ICD]; NCT03608670 )

The objective of a geotechnical site-characterization program is to determine soil and rock stratigraphy, in-situ pore water pressure conditions, and soil and rock properties for analysis and design of geotechnical engineering infrastructure. It is best conducted using an integrated approach that combines various geo-disciplines to describe, evaluate, and determine expected site characteristics. The extensive advancement of tools and procedures in recent decades provides an opportunity to execute effective and thorough site-characterization programs routinely in practice. Yet, this is often not the case, and some may argue that today’s state-of-practice has regressed in recent decades. While contractual structures and budget restrictions may contribute to this lower level and quality of characterization, the technical knowledge and pragmatic strategies available are not always implemented.

Multiscale experiments were conducted to investigate the thixotropic behavior of a naturally occurring illite-rich marine clay with a moderate salinity and of a manufactured, highly purifie...

One of many barriers to the deployment of floating offshore wind turbines is the high cost of vessel time needed for soil investigations and anchor installation. A multiline anchor system is proposed in which multiple floating offshore wind turbines (FOWTs) are connected to a single caisson. The connection of multiple FOWTs to a single anchor introduces interconnectedness throughout the wind farm. Previous work by the authors has shown that this interconnectedness reduces the reliability of the FOWT below an acceptable level when exposed to survival loading conditions. To combat the reduction in system reliability an overstrength factor (OSF) is applied to the anchors functioning as an additional safety factor. For a 100 turbine wind farm, single-line system reliabilities can be achieved using the multiline system with an OSF of 1.10, a 10% increase in multiline anchor safety factors for all anchors in a farm.

This paper presents a summary of the geotechnical engineering properties of low to medium overconsolidation ratio offshore inorganic clays derived from a high quality database. These properties, such as preconsolidation stress and undrained shear strength, are required for design of most offshore infrastructure and for assessment of offshore geohazards. The database was developed through a series of Joint Industry Projects using results from offshore site investigations performed worldwide. The key feature of the database is that it only contains results obtained using good to excellent quality samples that were tested using advanced laboratory procedures such as constant rate of strain consolidation and consolidated undrained triaxial and direct simple shear. A secondary objective of the paper was to examine common empirical correlations between index tests (e.g., water content, Atterberg limits) and soil design parameters using the new database. Such empirical correlations between simple and inexpensive index tests and more costly advanced laboratory tests can serve a valuable purpose in offshore infrastructure design. This is particularly the case for preliminary design at early stages of projects where little information is known about soil properties, for small projects with limited site characterization budgets, and international projects at locations where advanced laboratory tests performed to international standards are not available. The paper describes development of the database and presents summary results and plots for undrained shear strength, in situ stress state, and consolidation and flow parameters. Results from the empirical correlations investigated are presented and the paper concludes with recommendations on use of the data and correlations in practice. The recommendations are limited to clays of low to medium overconsolidation ratio and are not applicable to highly overconsolidated and desiccated clays. While the database primarily consists of offshore clays, the correlations presented should also be applicable to terrestrial clays.

A shared multiline anchor system may reduce material and installation costs for floating offshore wind farms, but the concept also expands the physical space over which the analysis of the system must be considered. The multiline anchor force is a combination of forces that originate from different floating offshore wind turbine (FOWT) platforms, and this interconnectivity mandates investigation of spatial coherence of waves over the area of the connected turbines. The goal of this work is to determine if anchor force characteristics are sensitive to spatial coherence of the wave field, or if an assumption of independent wave fields at different FOWT locations provides sufficiently accurate anchor load characterizations. Spatially coherent irregular wave fields are generated and applied to FOWT systems in 3-line and 6-line anchor systems, revealing negligible sensitivity of multiline anchor force to wave spatial coherence. These results are continued with a parametric study showing how wave characteristics affect correlation lengths of spatially coherent waves. A review of installed offshore wind turbine spacings is presented as a context for these results. In each section, regular waves are first used to examine the dynamics in a simple context, then irregular waves are used to more realistically simulate ocean conditions.

This paper describes the geology and geotechnical engineering properties of the Halden silt; a 10–12 m thick deposit of fjord-marine, low plasticity clayey silt. Over the last six years, the test site has been well characterized by combining the results from a number of geophysical and in situ tools, including; electrical resistivity tomography, multi-channel analysis of surface wave surveys, cone penetration testing, dissipation testing, in situ pore pressure measurements, seismic flat dilatometer testing, field vane testing, self-boring pressure meter testing, screw plate load testing and hydraulic fracture testing. The results from these investigations assist the interpretation of layering and in situ soil properties. Soil sampling and advanced laboratory testing have provided data for interpretation of geological setting and depositional history, soil fabric, strength, stiffness and hydraulic properties. However, interpretation of the stress history, based on oedometer tests and clay-based correlations to the cone penetration test, are unreliable. They contradict the depositional history, which suggests that the soil units at the site are near normally consolidated, except for some surface weathering and desiccation. Further, undrained shear strength interpretations are complex as the in situ tests are potentially influenced by partial drainage, and conventional undrained triaxial tests do not provide a unique (peak) undrained shear strength. Despite certain interpretation challenges the paper presents important reference data to assist in the interpretation and assessment of similar silts, and provide some guidance on important geotechnical properties for projects where limited design parameters are available. Halden research site: geotechnical characterization of a post glacial silt

Objectives The ASD2 (Acute Extravascular Defibrillation, Pacing, and Electrogram) study evaluated the ability to adequately sense, pace, and defibrillate patients with a novel implantable cardioverter-defibrillator (ICD) lead implanted in the substernal space. Background Subcutaneous ICDs are an alternative to a transvenous defibrillator system when transvenous implantation is not possible or desired. An alternative extravascular system placing a lead under the sternum has the potential to reduce defibrillation energy and the ability to deliver pacing therapies. Methods An investigational lead was inserted into the substernal space via a minimally invasive subxiphoid access, and a cutaneous defibrillation patch or subcutaneous active can emulator was placed on the left mid-axillary line. Pacing thresholds and extracardiac stimulation were evaluated. Up to 2 episodes of ventricular fibrillation were induced to test defibrillation efficacy. Results The substernal lead was implanted in 79 patients, with a median implantation time of 12.0 ± 9.0 min. Ventricular pacing was successful in at least 1 vector in 76 of 78 patients (97.4%), and 72 of 78 (92.3%) patients had capture in ≥1 vector with no extracardiac stimulation. A 30-J shock successfully terminated 104 of 128 episodes (81.3%) of ventricular fibrillation in 69 patients. There were 7 adverse events in 6 patients causally (n = 5) or possibly (n = 2) related to the ASD2 procedure. Conclusions The ASD2 study demonstrated the ability to pace, sense, and defibrillate using a lead designed specifically for the substernal space.

This paper describes the geology and geotechnical engineering properties of a sensitive marine clay deposit at a research site located in Newbury, Massachusetts (MA) in the northeast USA. Results from in situ testing, soil sampling, and laboratory testing are presented. The clay is locally known as Boston Blue Clay (BBC) which is a glacial marine clay that was deposited approximately 14,000 years ago in the greater Boston, MA area during retreat of the Laurentide Ice Sheet. The thickness, stress history, and soil properties of BBC can vary significantly depending on location. At the Newbury research site, the BBC deposit consists of a shallow thin desiccated crust underlain by a 12-meter thick low plasticity clay with an overconsolidation ratio ranging from 2 to 3. Sensitivity of the clay ranges from approximately 10 to 30, based on field vane and fall cone measurements. In situ testing performed at the site included seismic piezocone and field vane. Soil sampling was performed using a variety of samplers including Sherbrooke block, fixed piston thin-walled Shelby tube, and a thick-walled drive sampler. A full suite of advanced laboratory tests was performed on the various quality samples collected, which ranged from very poor (thick-walled drive sampler) to excellent (Sherbrooke block), including constant rate of strain consolidation, consolidated undrained triaxial and direct simple shear. The efficacy of the Recompression and SHANSEP procedures to mitigate sample disturbance was evaluated using results from the advanced laboratory test program. The paper presents data from these advanced tests as well as other soil classification, index, and engineering properties based on in situ measurements and laboratory test results. A synopsis of constructed facilities built on and in BBC within the greater Boston area is also presented.

This paper presents the first effort to investigate the effects of uniform and nonuniform prestraining on the mechanical properties of nanostructured multilayers. Thin muscovite sheets were first subjected to a loading–unloading cycle under unidirectional compression and cantilever bending modes that induce uniform and nonuniform prestraining, respectively, and then probed by nanoindentation to characterize their Young’s modulus and hardness. Optical and electron microscopy and X-ray diffraction were also used to uncover prestraining-induced microstructure alterations. Precompression in the c* direction to a stress of 45 MPa induces elastic uniform straining and causes negligible alteration to the microstructure. Such a prestrained specimen possesses unaltered Young’s modulus and hardness. However, the nonuniformly prestrained specimens that were subjected to cantilever bending, even though bending is macroscopically purely elastic, exhibit decreased Young’s modulus and hardness, and such reduction depends on the magnitude of bending strains. The Young’s modulus decreases by up to 41.0%, from 69.5 to 41.0 GPa at 0 to ~ 6% bending strains, respectively, while the maximum hardness reduction is 40.4%. Such distinction induced by different prestraining modes stems from the bending-induced nonuniform straining as well as the muscovite’s unique nanoscale layered structure. Owing to the relatively weaker and reversible electrostatic interlayer bonding, bending-induced strain gradient along the c* direction causes relative interlayer slip and hence bonding switch and, upon unloading, leads to the formation of basal plane corrugation and subsurface blisters. Such structural incoherence and imperfections induced by even elastic bending reduce the Young’s modulus and hardness. These findings shed light on the processing–structure–property relationships for other nanostructured multilayers as well as the origin of variability of elastic modulus of muscovites reported in the literature.

This research assesses the reliability of floating offshore windfarms utilizing two different anchor configurations: a conventional single-line system in which each anchor is loaded by a single mooring line and a multiline system in which each anchor is loaded by three mooring lines. While there are advantages to adopting a multiline system for floating offshore wind farms, the interconnectedness of this concept introduces disadvantages, such as reduction of system reliability and the potential for cascading failures among multiple structures. The reduction in system reliability is investigated here by running Monte-Carlo simulations in which mooring line and anchor demands and capacities are sampled from probability distributions. Demand distributions are generated through dynamic simulations with environmental conditions corresponding to the 500-year storm. Failure of mooring lines or anchors are initiated when their capacity is exceeded by their demand. The results of this research show that the reliability of the multiline system degrades significantly when progressive failures are taken into consideration. This research also shows that design considerations, such as the sizing of mooring lines and anchors and designing for single-line or multiline loads, significantly influence the system reliability of a floating offshore wind farm.

Thixotropy-governed temporal microfabric evolution, in a naturally occurring illitic marine clay and a manufactured kaolinitic clay at their respective liquid limits, was probed quantitatively by both one-dimensional X-ray diffraction (1DXRD) and 2DXRD via orientation index (OI) and texture index (TI) respectively. Results showed that the two fabric indexes, OI and TI, continuously evolved nonmonotonically but consistently during the thixotropic hardening periods of up to 125 days. Due to the initial remolding-induced large-strain shearing, both clays started with a fabric consisting of highly parallel-oriented clay particles. With increasing time, the OI varied from 23.1 to 36.6 and from 3.8 to 4.5, while their TI ranged from1.004 to 1.008 and 1.010 to 1.029 for the kaolinitic and illitic clays, respectively. Moreover, the same trend of changes between the OI and TI for both clays indicated that the two XRD-based techniques are applicable to characterizing the temporal microfabric changes in soft clays undergoing thixotropic hardening. The fabric evolution may result from various microscale particle rearrangements, likely including clay particle reorientation, aggregation, and flocculation, which in turn are controlled by interparticle forces. The two XRD-based techniques are also discussed in terms of their advantages and can expectedly shed light on similar studies of time-dependent behavior of soft clays.

This paper presents a laboratory investigation of undrained triaxial shear behavior of a natural low-plasticity silt from Halden, Norway in the intact, disturbed, and reconstituted states. Sherbrooke block sample and reconstituted specimens were subjected to simulated tube sampling in a triaxial stress path cell system prior to reconsolidation and undrained shear to assess the effects of disturbance on undrained shear behavior, undrained shear strength, and effective stress friction angle. Shear stress and pore-pressure development were evaluated relative to that measured for the undisturbed reference state, i.e., that measured on specimens from the intact block sample. Specimens trimmed from fixed-piston tube samples collected from the field site were tested for comparative purposes. Collectively, the results demonstrated that neither the volumetric method of evaluating sample quality for clays nor shear wave velocity tracked sample disturbance well for this low-plasticity silt. Relative to the reference intact block sample tests, simulated tube sampling resulted in an increasingly pronounced dilative-type behavior during postdisturbance undrained shear and a general increase in undrained shear strength. Specimens from the block sample that were subjected to simulated tube sample disturbance had similar stress–strain behavior as that from conventional anisotropically consolidated triaxial compression tests conducted on specimens from the tube samples, suggesting that significant alteration of the intact soil state occurred during tube sampling. Practical suggestions for selection of undrained shear strength for intact low-plasticity silts that exhibit dilative behavior such as the Halden silt are proposed.

Background Antitachycardia pacing (ATP) success rates as low as 50% for fast ventricular tachycardias (VTs) have been reported providing an opportunity for improved ATP to decrease shocks. Objective The purpose of this study was to determine how a new automated antitachycardia pacing (AATP) therapy would perform compared with traditional burst ATP using computer modeling to conduct a virtual study. Methods Virtual patient scenarios were constructed from magnetic resonance imaging and electrophysiological (EP) data. Cardiac EP simulation software (CARPEntry) was used to generate reentrant VT. Simulated VT exit sites were physician adjudicated against corresponding clinical 12-lead electrocardiograms. Burst ATP comprised 3 sequences of 8 pulses at 88% of VT cycle length, with each sequence decremented by 10 ms. AATP was limited to 3 sequences, with each sequence learning from the previous sequences. Results Two hundred fifty-nine unique ATP scenarios were generated from 7 unique scarred hearts. Burst ATP terminated 145 of 259 VTs (56%) and accelerated 2.0%. AATP terminated 189 of 259 VTs (73%) with the same acceleration rate. The 2 dominant ATP failure mechanisms were identified as (1) insufficient prematurity to close the excitable gap; and (2) failure to reach the critical isthmus of the VT. AATP reduced failures in these categories from 101 to 63 (44% reduction) without increasing acceleration. Conclusion AATP successfully adapted ATP sequences to terminate VT episodes that burst ATP failed to terminate. AATP was successful with complex scar geometries and EP heterogeneity as seen in the real world.

While the offshore wind industry has shown a steady trend towards floating turbines, costs of these systems remain high. A multiline anchor concept may significantly reduce the high cost of floating wind, in which floating turbines share anchors. This work investigates the potential cost benefit of implementing a multiline anchor system relative to the conventional single-line anchor system over a range of spatial parameters. The OC4 DeepCwind semisubmersible platform is used to design catenary mooring systems for different water depths and turbine spacings. In all cases, the maximum anchor force in the 3-line anchor system is less than or equal to that of the single-line anchor system. Cost models for the mooring lines, anchors, installation and geotechnical site investigation are presented and discussed. In a 100-turbine farm, the multiline anchor system results in a 9–19% reduction in stationkeeping costs, with high and low estimates for the cost models additionally included. Larger reductions in the combined line and anchor cost result from mooring system configurations with smaller ratios of water depth to turbine spacing. Due to perimeter effects in the multiline configuration, larger cost reductions can be achieved for larger farm sizes.

A comprehensive study is presented of the characteristics of calcareous concretions in the Connecticut Valley varved clay (CVVC), a glacial lake sediment, probed by an array of investigations, including compositional analyses via X-ray powder diffraction and energy-dispersive X-ray spectroscopy, mechanical property mapping by nanoindentation, selective dissolution, microstructure examination by optical and electron microscopy, and stable isotope analyses, with an objective to resolve some long-standing questions on their origin and growth mechanisms. Results show that these concretions are of a biogenic origin and consist of ~40 wt% primary host sediments and ~ 60 wt% secondary calcite post-depositionally precipitated as pore infills and inter-particle cement. The highly consistent layering and dry density between the carbonate-free host sediments in the concretions and in-situ varved sediments manifest that the precipitated calcite causes no disturbance to the original stratification and structure of the varved sediments. Moreover, both the mechanical properties (i.e., Young's modulus and hardness) and calcite concentration in concretions exhibit a radially decreasing pattern slightly disturbed by the sediments' layered textures. Further supported by the radial distribution patterns of stable carbon and oxygen isotopes, the CVVC concretions grow in a concentric pattern. A conceptual ion transport model is proposed to further interpret the growth mechanisms. These concretions grow radially in a nearly closed sediment system with diffusion-controlled transport of HCO3− from decaying organic matter and Ca2+ from porewater at direction-dependent rates dominated by the pore characteristics of the local host sediments. The diverse concretion morphologies are attributed to the different growth rates in different directions affected by the heterogeneous layering and pore sizes of the host sediments.

Offshore wind turbine (OWT) monopile foundations are subjected to cyclic loading from wind, waves, and operational loads from rotating blades. Lateral monopile capacity can be significantly affected by cyclic loading, causing failure at cyclic load amplitudes lower than the failure load under monotonic loading. For monopiles in clay, undrained clay behavior under short-term cyclic soil-pile loading (e.g. extreme storm conditions) typically includes plastic soil deformation resulting from reductions in soil modulus and undrained shear strength which occur as a function of pore pressure build-up. These impacts affect the assessment of the ultimate and serviceability limit states of OWTs via natural frequency degradation and accumulated permanent rotation at the mudline, respectively. This paper introduced novel combinations of existing p-y curve design methods and compared the impact of short-term cyclic loading on monopiles in soft, medium, and stiff clay. The results of this paper indicate that short-term cyclic loading from extreme storm conditions are unlikely to significantly affect natural frequency and permanent accumulated rotation for OWT monopiles in stiff clays, but monopiles in soft clay may experience significant degradation. Further consideration is required for medium clays, as load magnitude played a strong role in both natural frequency and permanent rotation estimation.

Underwater cast and cured geopolymers with Si/Al ratios of 1.78 and 2.00, synthesized from Class C fly ash and metakaolin, were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and unconfined compression, to understand the interactions between the geopolymer slurry and curing saline solutions and pertinent effects on its strength development. Slurries of geopolymers and Class G oil well cement were cast into porous molds that were immediately submerged into 0, 15, and 35 ppt saline solutions for 28 days curing, during which the pH of curing solutions was monitored. While the oil well cement exhibits a decreased compressive strength in high-salinity solutions, the strength of the two geopolymers increases with the curing solution's salinity. The underlying mechanisms are the chemical exchanges between the curing solution and geopolymer slurry, particularly the leaching or ingress of alkali ions (e.g., Na+, OH−) via diffusion, which depends upon the curing solution's salinity.

Shales are a class of multiscale, multiphase, hybrid inorganic-organic composite materials exhibiting both frictional and cohesive behavior, and it is very challenging to characterize and interpret their complex mechanical properties. A statistical nanoindentation approach with pertinent viable data analytics was developed to probe the mechanical properties of shales across different length scales. Grid nanoindentation experiments with continuous stiffness measurement performed on shales to relatively large depths of 6–8 µm obtained massive data, which were processed by the new data analytics: segmentation at selected depths of a great number (e.g., >500) of continuous Young's modulus versus indentation depth curves obtained from unknown constituent phases yielded multiple discretized sub-datasets that were processed to extract individual phases’ elastic moduli at respective segmentation depths via probability density function (PDF)-based deconvolution; these depth-dependent Young's moduli of each phase were then fitted by a newly proposed surround effect model, leading to determination of the properties of both individual phases at the nano/micro-scales (i.e., virtually infinitesimal depths) and the bulk rock at the macroscale (i.e., ~10–100 µm depths). A significant advantage of this massive data-based indentation approach is that the mechanical properties of composite materials such as shales can be probed across different scales by a single measurement technique. In addition, a new criterion, termed Bin Size Index, was formulated for selecting depth-dependent, rational, optimized bin sizes for PDF construction. For the studied shales, results show that five mechanically-distinct phases are discerned, including a virtual interface phase between hard and soft constituents accounting for a majority of indents. Coincidently, the Young's modulus of the bulk rock is nearly the same as that of the interface phase, suggesting that the macroscopic properties of similar composites may be estimated from measurements on the interface of two phases with contrasting mechanical properties. Finally, this approach can guide the selection of appropriate indentation depths to probe the mechanical properties of both highly heterogeneous bulk materials at the macroscale and their individual constituent phases at the nano/micro-scale.

This paper presents a laboratory investigation of the influence of simulated tube-sampling disturbance on lightly overconsolidated intermediate soils by varying their plasticity and degree ...

Sampling and laboratory testing of soils is often necessary to evaluate site-specific soil properties. Prior research has been primarily performed for clays, producing accepted practices th...

The ASD2 (Acute Extravascular Defibrillation, Pacing, and Electrogram) study evaluated the ability to adequately sense, pace, and defibrillate patients with a novel implantable cardioverter-defibrillator (ICD) lead implanted in the substernal space.Subcutaneous ICDs are an alternative to a transvenous defibrillator system when transvenous implantation is not possible or desired. An alternative extravascular system placing a lead under the sternum has the potential to reduce defibrillation energy and the ability to deliver pacing therapies.An investigational lead was inserted into the substernal space via a minimally invasive subxiphoid access, and a cutaneous defibrillation patch or subcutaneous active can emulator was placed on the left mid-axillary line. Pacing thresholds and extracardiac stimulation were evaluated. Up to 2 episodes of ventricular fibrillation were induced to test defibrillation efficacy.The substernal lead was implanted in 79 patients, with a median implantation time of 12.0 ± 9.0 min. Ventricular pacing was successful in at least 1 vector in 76 of 78 patients (97.4%), and 72 of 78 (92.3%) patients had capture in ≥1 vector with no extracardiac stimulation. A 30-J shock successfully terminated 104 of 128 episodes (81.3%) of ventricular fibrillation in 69 patients. There were 7 adverse events in 6 patients causally (n = 5) or possibly (n = 2) related to the ASD2 procedure.The ASD2 study demonstrated the ability to pace, sense, and defibrillate using a lead designed specifically for the substernal space.

Current and future climate-related coastal impacts such as catastrophic and repetitive flooding, hurricane intensity, and sea level rise necessitate a new approach to developing and managing coastal infrastructure. Traditional &ldquo, hard&rdquo, or &ldquo, grey&rdquo, engineering solutions are proving both expensive and inflexible in the face of a rapidly changing coastal environment. Hybrid solutions that incorporate natural, nature-based, structural, and non-structural features may better achieve a broad set of goals such as ecological enhancement, long-term adaptation, and social benefits, but broad consideration and uptake of these approaches has been slow. One barrier to the widespread implementation of hybrid solutions is the lack of a relatively quick but holistic evaluation framework that places these broader environmental and societal goals on equal footing with the more traditional goal of exposure reduction. To respond to this need, the Adaptive Gradients Framework was developed and pilot-tested as a qualitative, flexible, and collaborative process guide for organizations to understand, evaluate, and potentially select more diverse kinds of infrastructural responses. These responses would ideally include natural, nature-based, and regulatory/cultural approaches, as well as hybrid designs combining multiple approaches. It enables rapid expert review of project designs based on eight metrics called &ldquo, gradients&rdquo, which include exposure reduction, cost efficiency, institutional capacity, ecological enhancement, adaptation over time, greenhouse gas reduction, participatory process, and social benefits. The framework was conceptualized and developed in three phases: relevant factors and barriers were collected from practitioners and experts by survey, these factors were ranked by importance and used to develop the initial framework, several case studies were iteratively evaluated using this technique, and the framework was finalized for implementation. The article presents the framework and a pilot test of its application, along with resources that would enable wider application of the framework by practitioners and theorists.

The prediction of ultimate and fatigue demands for the design of offshore wind turbines (OWTs) requires accurate simulation of the dynamic response of OWTs subject to time-varying wind and wave loads. The magnitude of damping in an OWT system significantly influences the dynamic response, however, some sources of damping, such as foundation damping, are not explicitly considered in design guidelines and may increase damping significantly compared to commonly assumed values in design. Experimental and analytical studies have estimated the magnitude of foundation damping to be between 0.17% and 1.5% of critical, and this paper investigates how increased damping within this range affects load maxima and fatigue damage for a hypothetical 5MW OWT subjected to a variety of wind, wave, and operational conditions. The paper shows that increased damping effects the greatest percentage reduction of ultimate moment demands and fatigue damage when the OWT rotor is parked and feathered. In such cases, the aerodynamic damping is relatively low, allowing for additional damping from the foundation to account for a relatively larger proportion of the total system damping. Incorporating foundation damping in design guidelines may lead to more efficient structures, which is a crucial factor in overcoming the high cost barrier associated with offshore wind development.

The paper presents hydrogeologic properties for a leaky till–mantled fractured bedrock aquifer system based on geophysical and hydraulic tests performed at a drumlin located in northeastern Massachusetts, USA. The site profile consists of a fractured bedrock aquifer overlain by a 30 m thick unweathered, coarse-grained till aquitard. Steady state, decadal scale, hydraulics varied little until seasonal irrigation pumping was initiated in recent years, causing a substantial annual drawdown in the aquifer and leakage from the overlying till. High frequency hydraulic head data sets collected in monitoring wells record the hydraulic response to the irrigation pumping. These data sets, together with results from small scale slug and purge tests performed in monitoring wells, are used to characterize the hydrogeologic behavior of this groundwater system. Geophysical logging performed in bedrock wells confirmed the presence of numerous flowing fractures. The large-scale continuum analysis of the fractured bedrock aquifer response to the irrigation pumping yields transmissivity values consistent with those determined from the small-scale, short-term purge test results. The low hydraulic conductivity till has a significant impact on the drawdown behavior of the fractured bedrock aquifer. Calibrated values from the collective data sets and analyses result in the following properties for the 30 m thick unweathered till: hydraulic conductivity K′ = 7.2 × 10−9m/s, transmissivity T′ = 2.3 × 10−8m2/s, and storativity S′ = 2.7 × 10−4, and for the underlying fractured bedrock aquifer: T = 6.5 × 10−6m2/s with an average fracture aperture of 46 μm and hydraulic conductivity Kf= 1.3 × 10−3m/s. These results should describe similar unweathered coarse-grained till–mantled fractured bedrock aquifer systems and provide useful data for preliminary analyses prior to any site-specific investigations.

The contribution of foundation damping to offshore wind turbines (OWTs) is not well known, though researchers have back-calculated foundation damping from “rotor-stop” tests after estimating aerodynamic, hydrodynamic, and structural damping with numerical models. Because design guidelines do not currently recommend methods for determining foundation damping, it is typically neglected. This paper investigates the significance of foundation damping on monopile-supported OWTs subjected to extreme storm loading using a linear elastic two-dimensional finite element model. The effect of foundation damping primarily on the first natural frequency of the OWT was considered as OWT behavior is dominated by the first mode under storm loading. A simplified foundation model based on the soil-pile mudline stiffness matrix was used to represent the monopile, hydrodynamic effects were modeled via added hydrodynamic mass, and 1.00% Rayleigh structural damping was assumed. Hysteretic energy loss in the foundation was converted into a viscous, rotational dashpot at the mudline to represent foundation damping. Using the logarithmic decrement method on a finite element free vibration time history, 0.17%-0.28% of critical damping was attributed to foundation damping. Stochastic time history analysis of extreme storm conditions indicated that mudline OWT foundation damping decreases the maximum and standard deviation of mudline moment by 7–9%.

Unlike most onshore geotechnical projects, conducting offshore site investigations is often difficult and technically challenging due to the harsh ocean environment. Hence, an important cost consideration is minimizing the number of soundings for an offshore project while ensuring reliable and safe designs. This study examines the possibility of reducing the number of soundings at site by using practical numerical tools to predict cone tip resistance (qt ) at unsampled locations. Prediction errors were quantified within a probabilistic framework. Two prediction approaches, i.e. 2D linear regression and Kriging, were adopted. Site investigation data from an existing offshore wind farm with homogeneous stiff clay deposit were collected and analyzed. Result shows that in a homogeneous soil deposit, it is possible to use as little as 20% of the available data to predict the remaining 80% qt profiles with small error. Monopile deformation under typical design load was also calculated using shear strength derived from the qt profile at each wind turbine location. The small spatial variation of monopile deformation suggests that a reduction in the number of geotechnical soundings for sites with uniform soil conditions would not significantly impact the foundation design.

Offshore wind energy has become a promising source of renewable energy in recent years with many installed farms around the world successfully producing energy. As preliminary wind resource studies reveal, in the US much of the potential could be tapped in deeper water where floating solutions become favorable. The efficiency of floating offshore platforms is being studied and demonstrated in pilot projects such as Hywind in Scotland. In order to reduce the substructure cost in offshore wind projects, which is usually 25-30%, a novel shared anchor concept has been studied with spar supported turbines. Simulations are carried out with National Renewable Energy Laboratory’s (NREL) OC3 Hywind floating system and 5MW wind turbine. A similar study has been carried out with semisubmersible platforms earlier. Comparing the statistics of the net anchor forces from both the types of platforms reveals decreased anchor forces in case of spar due to large force cancellation and decreased response to wave action. Given the shared anchor concept in-principle reduces the material cost with reduced number of anchors than the conventional anchor types; further reduction in anchor forces in case of spar supported platform would be more cost-beneficial with more material savings.

Soil and groundwater from the Neponset River floodplain deposit that receive high concentrations of deicing agents from nearby highways were investigated. The silty sand floodplain is separated by a silty aquitard from the underlying aquifer that serves as a public water supply. We made a transport-based assessment of the capacity of the aquitard to protect the underlying aquifer. One hundred seventeen soil samples and 469 groundwater samples collected during a period of 4 yr from boreholes and 10 wells grouped in two well clusters were analyzed for dissolved Cl concentration. The soil characterization and groundwater monitoring results agreed, showing a very slow change in subsurface Cl contamination with time. These data also calibrated a vertical one-dimensional advective-dispersive transport model across the deposits. Advective transport dominated only in the top 3.37 m of the floodplain deposit, with dispersion being the main transport mechanism below this depth. Due to the silty nature of the aquitard, dispersion rather than diffusion was the main transport mechanism into the floodplain-aquitard system. Soil and groundwater quality data confirmed a Cl concentration at the floodplain surface near the highway runoff drainage outlets of 2450 mg L. The model estimated a vertical dispersivity at the site of 8 mm and a vertical hydrodynamic dispersion coefficient of 3.71 × 10 m s. These data confirmed the aquitard's capacity to contain deicing agents, protecting the underlying aquifer from contamination.

A new permeameter is proposed for performing laboratory hydraulic conductivity tests on gravels with hydraulic conductivity values ranging from 0.1 to 1 m/s. A small diameter riser is connected to a large diameter cylinder, which holds the coarse-grained specimen saturated in a water bath. The release of pneumatic pressure, applied to the free surface in the riser, induces an underdamped oscillatory response of the water level in the riser, similar to an underdamped in situ slug test response in monitoring wells. A closed-form model is used to analyze the measured oscillatory hydraulic head data to calibrate the minor losses in the permeameter and the hydraulic conductivity of the specimen by performing tests without and with a specimen. The average model error of calibrated pressure head values in the riser for the tests considered are about 5% of the initial displacement of about 2 cm. The hydraulic conductivity values are calibrated considering the replicate tests, the tests of different speci...

The objective of this study was to survey Canadian parents on their attitudes and beliefs about bicycle helmet legislation and to compare responses from parents living in provinces with and without legislation.A national survey of 1002 parents of children aged under 18 years was conducted. Chi-square tests were used to compare responses from the surveyed parents in the different jurisdictions.Responses from parents living in provinces with legislation (n = 640) and without legislation (n = 362) were as follows: concern for injury (63% vs. 68%, nonsignificant [NS]); believe helmets are effective (98% vs. 98%, NS); child always wears a helmet (74% vs. 69%, NS); support legislation for children (95% vs. 83%, p.001); support legislation for all ages (85% vs. 75%, p.001); support police enforcement (83% vs. 76%, p = .003); believe legislation decreases the amount of time their child bicycles (5% vs. 8%, NS).Parents are highly supportive of bicycle helmet legislation in Canada. They believe that bicycle helmets are effective and that legislation does not decrease the amount of time a child spends bicycling. There was also a high level of support for legislation across all ages, and for police enforcement.Attitudes et croyances des parents au sujet du port obligatoire du casque de vélo : comparaison entre provinces avec et sans législation.L’objectif de l’étude était d’effectuer un sondage auprès de parents canadiens sur leurs attitudes et leurs croyances au sujet de la législation du port du casque chez les cyclistes et de comparer les réponses des parents vivant dans une province ayant légiféré dans ce domaine et celles de ceux vivant dans une province n’ayant pas légiféré.Un sondage national a été réalisé auprès de 1 002 parents d’enfants âgés de moins de 18 ans. Des tests du chi-carré ont été utilisés pour comparer les réponses des parents dans les différentes provinces.Les réponses des parents vivant dans une province ayant légiféré (n = 640) ou ne l’ayant pas fait (n = 362) s’établissent respectivement comme suit : sont préoccupés par les accidents de vélo (63 % et 68 %, non significatif [NS]); croient que le port du casque de vélo est une mesure efficace (98 % et 98 %, NS); l’enfant porte toujours un casque de vélo (74 % et 69 %, NS); sont favorables à une loi visant les enfants (95 % et 83 %, p0,001); sont favorables à une loi visant les cyclistes de tous âges (85 % et 75 %, p0,001); sont favorables à l’application de la loi par les services de police (83 % et 76 %, p = 0,003); croient que la loi réduit la durée d’utilisation de la bicyclette par leur enfant (5 % et 8 %, NS).Les parents sont largement favorables à la législation du port du casque chez les cyclistes au Canada. Ils croient que le casque de vélo est une mesure efficace et que la loi n’a pas pour effet de réduire la durée d’utilisation de la bicyclette par leur enfant. Ils sont également largement favorables à une loi visant les cyclistes de tous âges et à l’application de la loi par les services de police.

Introduction L'objectif de l'étude était d'effectuer un sondage auprès de parents canadiens sur leurs attitudes et leurs croyances au sujet de la législation du port du casque chez les cyclistes et de comparer les réponses des parents vivant dans une province ayant légiféré dans ce domaine et celles de ceux vivant dans une province n'ayant pas légiféré. Méthodologie Un sondage national a été réalisé auprès de 1 002 parents d'enfants âgés de moins de 18 ans. Des tests du chi-carré ont été utilisés pour comparer les réponses des parents dans les différentes provinces. Résultats Les réponses des parents vivant dans une province ayant légiféré (n = 640) ou ne l'ayant pas fait (n = 362) s'établissent respectivement comme suit : sont préoccupés par les accidents de vélo (63 % et 68 %, non significatif [NS]); croient que le port du casque de vélo est une mesure efficace (98 % et 98 %, NS); l'enfant porte toujours un casque de vélo (74 % et 69 %, NS); sont favorables à une loi visant les enfants (95 % et 83 %, p $lt; 0,001); sont favorables à une loi visant les cyclistes de tous âges (85 % et 75 %, p $lt; 0,001); sont favorables à l'application de la loi par les services de police (83 % et 76 %, p = 0,003); croient que la loi réduit la durée d'utilisation de la bicyclette par leur enfant (5 % et 8 %, NS). Conclusion Les parents sont largement favorables à la législation du port du casque chez les cyclistes au Canada. Ils croient que le casque de vélo est une mesure efficace et que la loi n'a pas pour effet de réduire la durée d'utilisation de la bicyclette par leur enfant. Ils sont également largement favorables à une loi visant les cyclistes de tous âges et à l'application de la loi par les services de police.

A repeatable preparation method is useful for investigating systematic variations in behavior across a range of soil types (e.g., gradation, plasticity) and test conditions (e.g., stress level, stress history). Existing methods for preparation of laboratory specimens can be generally categorized into those for cohesionless and cohesive soils, thereby focusing on a narrow range of soils and test conditions. The applicability of these conventional preparation techniques for soils with intermediate (or transitional) properties and behaviors are relatively unknown. In this study, a range of intermediate soils that are not amenable to traditional sand-like or claylike characterization are prepared using a slurry deposition technique and evaluated in oedemetric consolidation, undrained monotonic triaxial shear, and both undrained monotonic and undrained cyclic direct simple shear by three researchers at two separate universities. Results indicate that the slurry technique developed herein can produce uniform mixtures of nonplastic, low-plasticity, and high-plasticity soils, with repeatable behaviors obtained from singular mixtures for all test methods. Evaluation of specimen response across this range of soils exhibits systematic trends of increasing compressibility with increasing plasticity and a transition from dilative to contractive tendencies with increasing soil plasticity. Collectively, these results for synthetic mixtures of silica silt and kaolin clay suggest that the slurry deposition technique is applicable to fine-grained, intermediate soils across a range of plasticity from nonplastic to high-plasticity soils.

An overview of offshore wind turbine (OWT) foundations is presented, focusing primarily on the monopile foundation. The uncertainty in offshore soil conditions as well as random wind and wave loading is currently treated with a deterministic design procedure, though some standards allow engineers to use a probability-based approach. Laterally loaded monopile foundations are typically designed using the American Petroleum Institute p-y method, which is problematic for large OWT pile diameters. Probabilistic methods are used to examine the reliability of OWT pile foundations under serviceability limit states using Euler‐Bernoulli beam elements in a two-dimensional pile‐spring model, non-linear with respect to the soil springs. The effects of soil property variation, pile design parameters, loading and large diameters on OWT pile reliability are presented. Copyright © 2014 John Wiley & Sons, Ltd.

Results from microcompression testing of micron-sized saltwater individual kaolinite flocs with different ageing times of up to 152 days show that the rearrangement of flaws or weak links towards a more uniform distribution contributes to the thixotropic increase in floc mechanical properties. Evidence of this newly identified thixotropism of clay flocs is provided by the Weibull moduli of floc stiffness and yield shear strength, which are well fitted using the stretched exponential thixotropy model. The Weibull modulus is a good quantitative descriptor of the thixotropic evolution of clay floc microstructure.