bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking CO2 plumes in clay-rich rock by distributed fiber optic strain sensing (DFOSS): a laboratory demonstration
Authors: Zhang Yi , Xue Ziqiu , Park Hyuck , Shi Jiquan , Kiyama Tamotsu , Lei Xinglin , Sun Yankun , Liang Yunfeng
Published: July 2018

Monitoring the migration of pore pressure, deformation, and saturation plumes with effective tools is important for the storage and utilization of fluids in underground reservoirs, such as geological stores of carbon dioxide (CO2) and natural gas. Such tools would also verify the security of the fluid contained reservoir–caprock system. Utilizing the swelling strain attributed to pressure build‐up and the adsorption of supercritical CO2 on clay minerals, we tracked the fluid plume in a natural clay‐rich Tako sandstone at the laboratory core‐scale. The strain was measured by a high‐resolution distributed fiber optic strain sensing (DFOSS) tool. The strain changes induced by CO2 adsorptions on clay minerals were significantly greater than those caused by pore pressure alone. The distribution of the swelling‐strain signals effectively captured the dynamic breakthrough of the CO2 plume from the high‐ to low‐ permeability regions in the Tako sandstone. Besides revealing the in situ deformation state, the measured strain changes can track the movement of the CO2 plume as it enters the clay‐rich critical regions in the reservoir–caprock system. The present findings and potential future applications of DFOSS in the field are expected to enhance the monitoring and management of underground fluid reservoirs.
Balancing sub- and supra-salt strain in salt-influenced rifts: Implications for extension estimates
Authors: Coleman Alexander , Jackson Christopher , Duffy Oliver
Published: July 2018

The structural style of salt-influenced rifts may differ from those formed in predominantly brittle crust. Salt can decouple sub- and supra-salt strain, causing sub-salt faults to be geometrically decoupled from, but kinematically coupled to and responsible for, supra-salt forced folding. Salt-influenced rifts thus contain more folds than their brittle counterparts, an observation often ignored in extension estimates. Fundamental to determining whether sub- and supra-salt structures are kinematically coherent, and the relative contributions of thin- (i.e. gravity-driven) and thick-skinned (i.e. whole-plate stretching) deformation to accommodating rift-related strain, is our ability to measure extension at both structural levels. We here use published physical models of salt-influenced extension to show that line-length estimates yield more accurate values of sub- and supra-salt extension compared to fault-heave, before applying these methods to seismic data from the Halten Terrace, offshore Norway. We show that, given the abundance of ductile deformation in salt-influenced rifts, significant amounts of extension may be ignored, leading to the erroneous interpretations of thin-skinned, gravity-gliding. If a system is kinematically coherent, supra-salt structures can help predict the occurrence and kinematics of sub-salt faults that may be poorly imaged and otherwise poorly constrained.
Probability density function for radial anisotropy from fundamental mode surface wave data and the Neighbourhood Algorithm,
Authors: Beghein Caroline , Trampert Jeannot
Published: July 2018

We applied Sambridges Neighbourhood Algorithm (NA) to degree-8 fundamental mode Love and Rayleigh wave phase velocity maps between 40 and 150 s to find models of radial anisotropy in the upper 220 km of the mantle. The NA is a powerful tool to explore a multidimensional model space and retrieve an ensemble of models from which statistical inferences (posterior probability density functions (PPDFs) and trade-offs) can be made. We sought solutions for density anomalies and perturbations in the five elastic coefficients that describe transverse isotropy and obtained independent probability density functions for S-wave anisotropy, P-wave anisotropy, intermediate parameter η, Vp, Vs and density anomalies. We find robust departures from PREM in S-wave anisotropy (ξ) under cratons and oceans alike, with a clear change of sign in the anomalies with respect to the reference model at approximately 100 km depth. No significant difference is observed between cratons and oceans, both in the amplitude and depth variation of ξ. The signal within continents is clearly age related, with platforms and tectonically active regions characterized by a rapid decrease in ξ with depth, while cratons display a more constant signal. A similar age dependence in S-wave anisotropy is also observed beneath oceans: a strong and rapidly decreasing anisotropy for young oceans and a more constant anisotropy for older oceans. Perturbations in P-wave anisotropy (φ) are small and limited to the shallowest part of the continents. A small age-dependent signal for φ is observed beneath oceans. Anomalies in intermediate parameter η are similar to those in φ (but not globally correlated), but the deviation from PREM is stronger for η than for φ. Cratons appear to be devoid of any η anisotropy in the top 100 km. There is no obvious global correlation between deviations in φ and deviations in ξ, and the ratio between dη and dξ is clearly regionally variable, which cautions against the use of commonly used proportionality factors between these variables in inversions. In all regions, we found a good correlation between the equivalent isotropic P- and S-wave velocity anomalies, with a ratio d ln Vs/d ln Vp close to 1. Density anomalies were not sufficiently well resolved with fundamental mode data alone, but do not influence the results for anisotropy.
Late Pliocene marine pCO2 reconstructions from the Subarctic Pacific Ocean
Authors: Swann George , Kendrick Chris , Dickson Alex , Worne Savannah
Published: July 2018

The development of large ice-sheets across the Northern Hemisphere during the late Pliocene and the emergence of the glacial-interglacial cycles that punctuate the Quaternary mark a significant threshold in Earths climate history. Although a number of different mechanisms have been proposed to initiate this cooling and the onset of major Northern Hemisphere glaciation, reductions in atmospheric concentrations of CO2 likely played a key role. The emergence of a stratified (halocline) water column in the subarctic north-west Pacific Ocean at 2.73 Ma has often been interpreted as an event which would have limited oceanic ventilation of CO2 to the atmosphere, thereby helping to cool the global climate system. Here, diatom carbon isotopes (δ13Cdiatom) are used to reconstruct changes in regional carbon dynamics through this interval. Results show that the development of a salinity stratification did not fundamental alter the net oceanic/atmospheric flux of CO2 in the subarctic north-west Pacific Ocean through the late Pliocene/early Quaternary. These results provide further insights into the long-term controls on global carbon cycling and the role of the subarctic Pacific Ocean in instigating global climatic changes.
Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5-5.0 seismic sequence of 2016-2017, central Italy.
Authors: Mildon Zoe , Roberts Gerald , Walker Joanna , Iezzi Francesco
Published: July 2018

In order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August–October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)).We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316–4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016–2017 A.D. sequence.We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the
U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages
Authors: Noble Stephen , Condon Daniel , Carney John , Wilby Philip , Pharaoh Timothy , Ford Trevor
Published: July 2018

U-Pb (zircon) ages for key stratigraphic volcanic horizons within the ~3200-m-thick Ediacaran-age Charnian Supergroup provide an improved age model for the included Avalonian assemblage macrofossils and, hence, temporal constraints essential for intercomparisons of the Charnian fossils with other Ediacaran fossil assemblages globally. The Ives Head Formation (Blackbrook Group), the oldest exposed part of the volcaniclastic Charnian Supergroup of the late Neoproterozoic Avalonian volcanic arc system of southern Britain, contains a bedding plane with an impoverished assemblage of ivesheadiomorphs that is constrained to between ca. 611 Ma and 569.1 ± 0.9 Ma (total uncertainty). Higher-diversity biotas, including the holotypes of Charnia, Charniodiscus, and Bradgatia, occupy the upper part of the volcaniclastic succession (Maplewell Group) and are dated at 561.9 ± 0.9 Ma (total uncertainty) and younger by zircons interpreted as coeval with eruption and deposition of the Park Breccia, Bradgate Formation. An ashy volcanic-pebble conglomerate in the Hanging Rocks Formation at the very top of the supergroup yielded two U-Pb zircon populations: an older detrital one at ca. 604 Ma, and a younger population at ca. 557 Ma, which is interpreted as the approximate depositional age. The temporal association of the fossiliferous Charnian Supergroup with comparable fossiliferous deep-water successions in Newfoundland, and the probable temporal overlap of the youngest Charnwood macrofossils with those from different paleoenvironmental settings, such as the Ediacaran White Sea macrofossils, indicate a primary role for ecological sensitivity in determining the composition of these late Neoproterozoic communities.
Nature, origin and evolution of a Late Pleistocene incised valley-fill, Sunda Shelf, Southeast Asia
Authors: Alqahtani Faisal , Johnson Howard , Jackson Christopher , Som Rapi
Published: July 2018

Understanding the stratigraphic fill and reconstructing the palaeo-hydrologyof incised valleys can help to constrain those factors that controlled their origin,evolution and regional significance. This condition is addressed throughthe analysis of a large (up to 18 km wide by 80 m deep) and exceptionallywell-imaged Late Pleistocene incised valley from the Sunda Shelf (SouthChina Sea) based on shallow three-dimensional seismic data from a large(11 500 km2), ‘merge’ survey, supplemented with site survey data (boreholesand seismic). This approach has enabled the characterization of the planformgeometry, cross-sectional area and internal stratigraphic architecture, whichtogether allow reconstruction of the palaeo-hydrology. The valley-fill displaysfive notable stratigraphic features: (i) it is considerably larger thanother seismically resolvable channel forms and can be traced for at least180 km along its length; (ii) it is located in the axial part of the Malay Basin;(iii) the youngest part of the valley-fill is dominated by a large (600 m wideand 23 m deep), high-sinuosity channel, with well-developed lateral accretionsurfaces; (iv) the immediately adjacent interfluves contain much smaller,dendritic channel systems, which resemble tributaries that drained intothe larger incised valley system; and (v) a ca 16 m thick, shell-bearing, Holoceneclay caps the valley-fill. The dimension, basin location and palaeohydrologyof this incised valley leads to the conclusion that it represents thetrunk river, which flowed along the length of the Malay Basin; it connectedthe Gulf of Thailand in the north with the South China Sea in the south-east.The length of the river system (>1200 km long) enables examination of theupstream to downstream controls on the evolution of the incised valley,including sea-level, climate and tectonics. The valley size, orientation andpalaeo-hydrology suggest close interaction between the regional tectonicframework, low-angle shelf physiography and a humid-tropical climatic setting.
Illuminating the seismicity pattern of the October 8, 2005, M = 7.6 Kashmir earthquake aftershocks
Authors: Gibbons Steven , Kværna Tormod
Published: July 2018

The M=7.6 October 8, 2005, Kashmir earthquake generated thousands of aftershocks. Existing catalogs are coarse, omitting data from key stations and not correcting bias. We target arrivals on unexploited regional stations with optimized signal processing. A multiple event Bayesian relocation results in far more structured clusters of seismicity. All arrival data for the Bayesloc program is provided for reproduction of results and further study. Aftershocks of the October 8, 2005, M=7.6 Kashmir earthquake continued for many weeks and covered a region extending over an aperture exceeding 100 km. Several hundred events were recorded well at teleseismic distances while many hundreds more are only observed at regional distances. Existing earthquake catalogs for this sequence are poor given an unfavorable distribution of stations, a complex tectonic setting, lack of local and near-regional data, and under-exploitation of the most sensitive stations. Advances in automated signal processing, improvements in seismic velocity models, and innovations in multiple event location algorithms have made it worthwhile revisiting this sequence and attempting a large-scale relocation of the aftershocks. A vast number of new phase readings have been made on permanent and temporary seismic stations both at regional and teleseismic distances and the Bayesian hierachical multiple event location program Bayesloc was employed in multiple stages, resulting in a far more structured distribution to the seismicity. The relocated aftershocks fall mainly into two distinct clusters. One cluster lies predominantly North East of the Balaklot-Bagh Thrust and South of the Main Central Thrust, with the October 8 main shock at its most northern point. The second cluster occupies the Indus-Kohistan Seismic Zone, North of the Main Central Thrust and South of the Main Mantle Thrust. Both clusters lie North East of a NW-SE trending boundary almost parallel to the southern part of the surface rupture. An East South East trending strand of earthquakes extends from the most northerly turning point of the Main Central Thrust into the Kashmir Basin, and a scattering of events are located North of this line and South of the Main Mantle Thrust. The new location estimates result in those aftershocks with the most similar focal mechanisms being far more spatially clustered than in previously published catalogs. Mapping global CMT solutions before and after the relocation contributes to the confidence in the new epicenters and provides a clearer picture of how the source parameters vary over the aftershock region. All files required to reproduce the results using the Bayesloc program are provided.
Tempo of magma degassing and the genesis of porphyry copper deposits
Authors: Chelle-Michou Cyril , Rottier Bertrand , Caricchi Luca , Simpson Guy
Published: July 2018

Porphyry deposits are copper-rich orebodies formed by precipitation of metal sulphides from hydrothermal fluids released from magmatic intrusions that cooled at depth within the Earth’s crust. Finding new porphyry deposits is essential because they are our largest source of copper and they also contain other strategic metals including gold and molybdenum. However, the discovery of giant porphyry deposits is hindered by a lack of understanding of the factors governing their size. Here, we use thermal modelling and statistical simulations to quantify the tempo and the chemistry of fluids released from cooling magmatic systems. We confirm that typical arc magmas produce fluids similar in composition to those that form porphyry deposits and conclude that the volume and duration of magmatic activity exert a first order control on the endowment (total mass of deposited copper) of economic porphyry copper deposits. Therefore, initial magma enrichment in copper and sulphur, although adding to the metallogenic potential, is not necessary to form a giant deposit. Our results link the respective durations of magmatic and hydrothermal activity from well-known large to supergiant deposits to their metal endowment. This novel approach can readily be implemented as an additional exploration tool that can help assess the economic potential of magmatic-hydrothermal systems.
The stratigraphic record and processes of turbidity current transformation across deep-marine lobes
Authors: Kane Ian , Pontén Anna , Vangdal Brita , Eggenhuisen Joris , Hodgson David , Spychala Yvonne
Published: July 2018

Sedimentary facies in the distal parts of deep-marine lobes can diverge significantly from those predicted by classical turbidite models, and sedimentological processes in these environments are poorly understood. This gap may be bridged using outcrop studies and theoretical models. In the Skoorsteenberg Fm., a downstream transition from thickly-bedded turbidite sandstones to argillaceous, internally layered hybrid beds is observed. The hybrid beds have a characteristic stratigraphic and spatial distribution, being associated with bed successions which generally coarsen- and thicken-upwards reflecting deposition on the fringes of lobes in a dominantly progradational system. Using a detailed characterisation of bed types, including grain size, grain fabric and mineralogical analyses, a process-model for flow evolution is developed. This is explored using a numerical suspension capacity model for radially spreading and decelerating turbidity currents. The new model shows how decelerating sediment suspensions can reach a critical suspension capacity threshold beyond which grains are not supported by fluid turbulence. Sand and silt particles, settling together with flocculated clay, may form low yield-strength cohesive flows; development of these higher concentration lower boundary layer flows inhibits transfer of turbulent kinetic energy into the upper parts of the flow ultimately resulting in catastrophic loss of turbulence and collapse of the upper part of the flow. Advection distances of the now transitional to laminar flow are relatively long (several km) suggesting relatively slow dewatering (several hours) of the low yield strength flows. The catastrophic loss of turbulence accounts for the presence of such beds in other fine-grained systems without invoking external controls or large-scale flow partitioning, and also explains the abrupt pinch-out of all divisions of these sandstones. Estimation of the point of flow transformation is a useful tool in the prediction of heterogeneity distribution in subsurface systems.
Climbing Ripple Successions in Turbidite Systems: Depositional Environments, Sedimentation Rates, and Accumulation Times
Authors: Jobe Zane , Lowe Donald , Morris William
Published: July 2018

Climbing-ripple cross-lamination (CRCL) is most commonly deposited by turbidity currents when suspended load fallout and bedload transport occur contemporaneously. The angle of ripple climb reflects the ratio of suspended load fallout and bedload sedimentation rates, allowing for the calculation of the flow properties and durations of turbidity currents. Three areas exhibiting thick (> 50 m) sections of deep- water CRCL deposits are the focus of this study: 1) the Miocene upper Mount Messenger Formation in the Taranaki basin, New Zealand, 2) the Permian Skoorsteenberg Formation in the Tanqua depocenter of the Karoo basin, South Africa, and 3) the lower Pleistocene Magnolia Field in the Titan basin, Gulf of Mexico. Facies distributions and local contextual information indicate that CRCL in each area was deposited in an ‘off-axis’ setting where flows were expanding due to loss of confinement or a decrease in slope gradient. The resultant reduction in flow thickness, Reynolds number, shear stress, and capacity promoted suspension fallout and thus CRCL formation. CRCL in the New Zealand study area was deposited both outside of and within channels at an inferred break in slope, where flows were decelerating and expanding. In the South Africa study area, CRCL was deposited due to a loss of flow confinement. In the Magnolia study area, an abrupt decrease in gradient near a basin sill caused flow deceleration and CRCL deposition in off-axis settings. Sedimentation rate and accumulation time were calculated for 44 CRCL sedimentation units from the three areas using TDURE, a mathematical model developed by Baas et al. (2000). For Tc divisions and Tbc beds averaging 26 and 37 cm thick, respectively, average CRCL and whole bed sedimentation rates were 0.15 and 0.26 mm/s and average accumulation times were 27 and 35 minutes, respectively. In some instances, distinct stratigraphic trends of sedimentation rate give insight into the evolution of the depositional environment.CRCL in the three study areas is developed in very fine- to fine-grained sand, suggesting a grain size dependence on turbidite CRCL formation. Indeed, the calculated sedimentation rates correlate well with the rate of sedimentation due to hindered settling of very fine- and fine-grained sand-water suspensions at concentrations of up to 20% and 2.5%, respectively. For coarser grains, hindered settling rates at all concentrations are much too high to form CRCL, resulting in the formation of massive/structureless S3 or Ta divisions.
GPS sidereal filtering: coordinate- and carrier-phase-level strategies
Authors: Ragheb Ahmed , Clarke Peter , Edwards Stuart
Published: July 2018

Multipath error is considered one of the major errors affecting GPS observations. One can benefit from the repetition of satellite geometry approximately every sidereal day, and apply filtering to help minimize this error. For GPS data at 1 second interval processed using a double-difference strategy, using the day-to-day coordinate or phase residual autocorrelation determined with a 10 hour window leads to the steadiest estimates of the error-repeat lag, although a window as short as 2 hours can produce an acceptable value with >97% of the optimal lag’s correlation. We conclude that although the lag may vary with time, such variation is marginal and there is little advantage in using a satellite-specific or other time-varying lag in double-difference processing.We filter the GPS data either by stacking a number of days of processed coordinate residuals using the optimum “sidereal” lag (23h 55m 54s), and removing these stacked residuals from the day in question (coordinate space), or by a similar method using double-difference phase residuals (observational space). Either method results in more consistent and homogeneous set of coordinates throughout the dataset compared with unfiltered processing. Coordinate stacking reduces geometry-related repeating errors (mainly multipath) better than phase residual stacking, although the latter takes less processing time to achieve final filtered coordinates. Thus the optimal stacking method will depend on whether coordinate precision or computational time is the over-riding criterion.
The European Arctic: A Laboratory for Seismoacoustic Studies
Authors: Gibbons Steven , Asming Vladimir , Eliasson Lars , Fedorov Andrei , Fyen Jan , Kero Johan , Kozlovskaya Elena , Kværna Tormod , Liszka Ludwik , Näsholm Sven
Published: July 2018

We describe the seismoacoustic monitoring network in Fennoscandia and North West Russia and present how it is being used to characterize infrasound studies in that part of the world. The history of the infrasound array network is presented, together with a description of array processing considerations, and examples of infrasound signals recorded from repeating explosions.
Comments on "Dual-rail asynchronous logic multi-level implementation"
Authors: Balasubramanian P
Published: July 2018

In this research communication, we comment on “Dual-rail asynchronous logic multi-level implementation” [Integration, the VLSI Journal 47 (2014) 148–159] by expounding the problematic issues, and provide some clarifications on delay-insensitivity, robust asynchronous logic, multi-level decomposition, and physical implementation.
Combining an innovative measurement technique with accurate simulation to analyze engine friction
Authors: Allmaier Hannes , Knauder Christoph , Sander David E , Reich Franz M.
Published: July 2018

The entanglement of an innovative measurement technique with an accurate simulation yields in total a powerful tool to investigate the friction power losses in engines under realistic operating conditions, as will be discussed in the following. While the total engine friction power losses and the friction of the valve train are measured experimentally, the friction power losses of the crank train journal bearings are calculated using simulation. The result is in an efficient and powerful determination of the individual engine subassemblies under realistic operating conditions ranging from idle to full load operation. The presented method can be used to assess the efficiency of various friction reduction measures like cylinder deactivation, (ultra)low viscosity lubricants or coatings and won in 2014 the Innovation award of Magna Logistics Europe.
OpenWIM - Open Science and Weigh in Motion Research (Poster Preprint)
Authors: Ogasawara Ivan
Published: July 2018

Although there are many papers publicly available about Weigh-in-Motion, alittle bit researchers publish their sources and data, which could allow abetter reproduction of their experiments and results. In this context, theOpen Science concept can help improve the WIM research throughcollaborative efforts and reproducible methods, using algorithms and datawith open access.The OpenWIM project was born upon this background as an open scienceinitiative, to provide a WIM researchers a repository with initialstructure that can then be converted into a framework for researchers todevelop and test new methods and technologies.
Malawi Hydro Generator Chain and Sprocket
Authors: Schindler Brandon
Published: July 2018

Malawi Hydro Generator Chain and Sprocket
Pulse Width Modulation (PWM) Signals Based on Spiking Neuronal Networks
Authors: Kandalaft Nabeeh , Ahmadi Arash , Jalilian Maisam , Nouri Moslem
Published: July 2018

This paper proposes a digital construction of PulseWidth Modulation (PWM) signals based on the Izhikevich neuronmodel using a Field Programmable Gate Array (FPGA) platform.The signals are intended for use in diverse electronics applicationssuch as robotics and power converters. A spiking pattern wasused to generate the input data and produce the PWM signals.A comparator was used to compare between the spiking patterndata and DC level parameters. The results validate that theproposed hardware can reproduce PWM signals with duty cyclesfrom 0% to 100%.
Linear static isogeometric analysis of an arbitrarily curved spatial Bernoulli-Euler beam
Authors: Radenković Gligor , Borković Aleksandar
Published: July 2018

The present research is focused on the linear analysis of a spatial Bernoulli-Euler beam. Metrics of the reference and deformed configurations are rigorously defined with respect to the convective coordinate frame of reference. No higher order terms are neglected which makes the formulation ideally suited for analysis of arbitrarily curved spatial beams in the frame of finite (but small) strain theory. The well-known issue of nonorthogonality of local coordinate system at an arbitrary point of a spatial beam is solved by the introduction of a new coordinate line that is orthogonal to the normal plane of the beam axis at each point. Generalized coordinates of the present model are translations of the beam axis and the angle of twist of a cross section. Two different parameterizations of this angle are discussed and implemented. Both geometry and kinematics are described with the same set of NURBS functions, in line with the isogeometric approach. Numerical analysis proved that the theoretical considerations are correct. An in-depth analysis of convergence properties has confirmed the fact that models with the highest interelement continuity have an improved accuracy per DOF, for problems that result in a smooth structural response.
A novel contact interaction formulation for voxel-based micro-finite-element models of bone
Authors: Bhattacharya Pinaki , Betts Duncan , van Lenthe G Harry
Published: July 2018

Voxel-based micro-finite-element (μFE) models are used extensively in bone mechanics research. A major disadvantage of voxel-based μFE models is that voxel surface jaggedness causes distortion of contact-induced stresses. Past efforts in resolving this problem have only been partially successful; i.e., mesh smoothing failed to preserve uniformity of the stiffness matrix, resulting in (excessively) larger solution times, whereas reducing contact to a bonded interface introduced spurious tensile stresses at the contact surface. This paper introduces a novel ‘smooth’ contact formulation that defines gap distances based on an artificial smooth surface representation while using the conventional penalty contact framework. Detailed analyses of a sphere under compression demonstrated that the smooth formulation predicts contact-induced stresses more accurately than the bonded contact formulation. When applied to a realistic bone contact problem, errors in the smooth contact result were under 2%, whereas errors in the bonded contact result were up to 42.2%. We conclude that the novel smooth contact formulation presents a memory-efficient method for contact problems in voxel-based μFE models. It presents the first method that allows modeling finite slip in large-scale voxel meshes common to high-resolution image-based models of bone while keeping the benefits of a fast and efficient voxel-based solution scheme.
A stabilising control strategy for Cyber-Physical Power Systems
Authors: Ekomwenrenren Etinosa , Alharbi Hatem , Elgorashi Taisir , Elmirghani Jaafar , Aristidou Petros
Published: July 2018

The cyber-physical nature of electric power systems has increased immensely over the last decades, with advanced communication infrastructure paving the way. It is now possible to design wide-area controllers, relying on remote monitor and control of devices, that can tackle power system stability problems more effectively than local controllers. However, their performance and security relies extensively on the communication infrastructure and can make power systems vulnerable to disturbances emerging on the cyber side of the system. In this paper, we investigate the effect of communication delays on the performance and security of wide-area damping controllers (WADC) designed to stabilise oscillatory modes in a Cyber-Physical Power System (CPPS). We propose a rule-based control strategy that combines wide-area and traditional local stabilising controllers to increase the performance and maintain the security of CPPS. The proposed strategy is validated on a reduced CPPS equivalent model of Great-Britain (GB).
The Synthesis of Function Generating Mechanisms for Periodic Curves Using Large Numbers of Double-Crank Linkages
Authors: Hessein
Published: July 2018

This paper presents a methodology for synthesizing planar linkages to approximate anyprescribed periodic function. The mechanisms selected for this task are the slider-crankand the geared five-bar with connecting rod and sliding output (GFBS), where any numberof double-crank (or drag-link) four-bars are used as drivers. A slider-crank mechanism,when comparing the input crank rotation to the output slider displacement,produces a sinusoid-like function. Instead of directly driving the input crank, a drag-linkfour-bar may be added to drive the crank from its output via a rigid connection betweenthe two. Driving the input of the added four-bar results in a function that modifies thesinusoid-like curve. This process can be continued through the addition of moredrag-link mechanisms to the device, progressively altering the curve toward any periodicfunction with a single maximum. For periodic functions with multiple maxima, a GFBS isused as the terminal linkage added to the chain of drag-link mechanisms. The synthesisprocess starts by analyzing one period of the function to design either the terminal slidercrankor terminal GFBS. MATLAB’s fmincon command is then utilized as the four-bars areadded to reduce the structural error between the desired function and the input–outputfunction of the mechanism. Mechanisms have been synthesized in this fashion to includea large number of links that are capable of closely producing functions with a variety ofintriguing features
Study of Homogeneous Bubble Nucleation in Liquid Carbon Dioxide by a Hybrid Approach Combining Molecular Dynamics Simulation and Density Gradient Theory
Authors: Langenbach Kai , Heilig Manfred , Hasse Hans
Published: July 2018

A new method for predicting homogeneous bubble nucleation rates of pure compounds from vapor-liquid equilibrium (VLE) data is presented. It combines molecular dynamics simulation on the one side with density gradient theory using an equation of state (EOS) on the other. The new method is applied here to predict bubble nucleation rates in metastable liquid carbon dioxide (CO2). The molecular model of CO2 is taken from previous work of our group. PC-SAFT is used as an EOS. The consistency between the molecular model and the EOS is achieved by adjusting the PC-SAFT parameters to VLE data obtained from the molecular model. The influence parameter of density gradient theory is fitted to the surface tension of the molecular model. Massively parallel molecular dynamics simulations are performed close to the spinodal to compute bubble nucleation rates. From these simulations, the kinetic prefactor of the hybrid nucleation theory is estimated, whereas the nucleation barrier is calculated from density gradient theory. This enables the extrapolation of molecular simulation data to the whole metastable range including technically relevant densities. The results are tested against available experimental data and found to be in good agreement. The new method does not suffer from typical deficiencies of classical nucleation theory concerning the thermodynamic barrier at the spinodal and the bubble size dependence of surface tension, which is typically neglected in classical nucleation theory. In addition, the density in the center of critical bubbles and their surface tension is determined as a function of their radius. The usual linear Tolman correction to the capillarity approximation is found to be invalid.
Energy and Water Consumption Characterization of Portuguese Indoor Swimming Pools
Authors: Cardoso Bruno J. , Gaspar Adélio Rodrigues , Góis José Carlos , Rodrigues Eugénio
Published: July 2018

Indoor swimming pools have high water and energy (electricity and natural gas) consumption levels due to the need to provide suitable thermal comfort conditions (temperature and relative humidity) to its occupants and to counterbalance losses (evaporation, ventilation, etc.). In Portugal, most of the swimming pool facilities belong to the municipalities and their operation represent a considerable financial burden. This work intent to characterize and benchmark the energy (electrical and thermal) and water consumption of five sport complexes with indoor swimming pools, located in two cities of the Centre of Portugal. The four most commonly performance indicators used in the literature were calculated and analyzed according to the operating time and services. Some measures are suggested to enhance the energy efficiency as well as to reduce the consumptions.
Investigation of the LTC fuel performance index for oxygenated reference fuel blends
Authors: Niemeyer Kyle Evan , Daly Shane , Cannella William , Hagen Christopher
Published: July 2018

A new metric for ranking the suitability of fuels in LTC engines was recently introduced, based on the fraction of potential fuel savings achieved in the FTP-75 light-duty vehicle driving cycle. In the current study, this LTC fuel performance index was calculated computationally and analyzed for a number of fuel blends comprised of n-heptane, isooctane, toluene, and ethanol in various combinations and ratios corresponding to octane numbers from 0 to 100. In order to calculate the LTC index for each fuel, computational driving cycle simulations were first performed using a typical light-duty passenger vehicle, providing pairs of engine speed and load points. Separately, for each fuel blend considered, single-zone naturally aspirated HCCI engine simulations with a compression ratio of 9.5 were performed in order to determine the operating envelopes. These results were combined to determine the varying improvement in fuel economy offered by fuels, forming the basis for the LTC fuel index. The resulting fuel performance indices ranged from 36.4 for neat n-heptane (PRF0) to 9.20 for a three-component blend of n-heptane, isooctane, and ethanol (ERF1). For the chosen engine and chosen conditions, in general lower-octane fuels performed better, resulting in higher LTC fuel index values; however, the fuel performance index correlated poorly with octane rating for less-reactive, higher-octane fuels.
Breast ultrasound tomography versus magnetic resonance imaging for clinical display of anatomy and tumor rendering: Preliminary results
Authors: Ranger Bryan
Published: July 2018

*Abstract**Objective: *To determine the clinical display thresholds of an ultrasoundtomography (UST) prototype relative to magnetic resonance (MR) forcomparable visualization of breast anatomy and tumor rendering.*Materials and Methods: *The study was compliant with HIPAA, approved bythe IRB, and performed after obtaining informed consent. Thirty-six womenwere imaged with MR and our UST prototype. The UST scan generatedreflection, sound speed and attenuation images. The reflection images werefused with the components of sound speed and attenuation images thatachieved thresholds to represent parenchyma and/or solid masses using animage arithmetic process. Qualitative and quantitative comparisons of MRand UST clinical images were used to identify anatomical similarities, andoptimized thresholds for tumor shapes and volumes.*Results: *Thresholding techniques generated UST images comparable to MRfor visualizing fibrous stroma, parenchyma, fatty tissues, and tumors, ofwhich 25 were cancer and 11 benign. Optimized sound speed thresholds of1.46±0.1 km/s and 1.52±0.03 km/s were identified to best represent theextent of fibroglandular tissue and solid masses, respectively. Anarithmetic combination of attenuation images using the threshold of0.16±0.04 dB/cm further characterized benign from malignant masses. Nosignificant difference in tumor volume was noted between benign ormalignant masses by UST or MR (p>0.1) using these universal thresholds.*Conclusion: *UST demonstrated the ability to image and render breasttissues in a manner comparable to MR. Universal UST threshold values appearfeasible for rendering of the size and distribution of benign and malignanttissues without intravenous contrast.
Microservices: a Language-based Approach
Authors: Guidi Claudio , Lanese Ivan , Mazzara Manuel , Montesi Fabrizio
Published: July 2018

Microservices is an emerging development paradigm where software isobtained by composing autonomous entities, called (micro)services. However, microservice systems are currently developed using general-purpose programminglanguages that do not provide dedicated abstractions for service composition. Instead, current practice is focused on the deployment aspects of microservices, in particular by using containerization. In this chapter, we make the case for a language-based approach to the engineering of microservice architectures, which we believe is complementary to current practice. We discuss the approach in general, and then we instantiate it in terms of the Jolie programming language.
The Holos Reactor: A Distributable Power Generator with Transportable Subcritical Power Modules
Authors: Filippone Claudio , Jordan Kelly
Published: July 2018

Holos is a distributable modular nuclear power generator with enhanced safety features. Holos design objectives include production of affordable pollutant-free electricity and process heat with the safest melt-tolerant and proliferation resistant fuels. The design leverages commercial tech- nologies utilized for the conversion of thermal energy into conditioned electricity. Holos can op- erate as a stand-alone electric island at sites with no power grid infrastructure and can be scaled- up or clustered to meet local electric demands. Specialized configurations of Holos generators can be airlifted and timely deployed to supply emergency electricity and process heat to disaster areas and to inaccessible remote locations. The proposed distributable electric generator is com- prised within dimensions and weight requirements compatible with International Standard Or- ganization (ISO) transport containers, and is formed by subcritical power modules protected from shock stressors during transport. Holos coupled core becomes critical and enables power generation only when multiple subcritical power modules are positioned near one another. Cool- ing of Holos fuel relies only on environmental air during operations with passive decay-heat re- moval. Depending on configurations, Holos fuel cycle is 12-20 years, with 8%-15% enriched nuclear fuel sealed at all times and contained within replaceable fuel cartridges. At the end of the fuel cycle, the fuel cartridges fit within licensed transport and storage canisters for long term storage with low decommissioning cost. Holos power conversion components can be recondi- tioned when the fuel cartridges are replaced at the end of their fuel cycles and the generator can be re-licensed to resume operation for a total generator life-span of 60 years. In this design, the thermodynamic cycle utilized to convert the core thermal energy into electricity is based on the Brayton power cycle. In some configurations, the design integrates and couples a bottoming Rankine power cycle operating with organic fluids to enhance efficiency, convert decay thermal energy into electricity and support process heat applications. Holos waste heat recovery and con- version feature also relaxes thermal loading requirements at underground spent fuel repositories. The power conversion components utilized in this design are off-the-shelf, with power ratings comparable to those forming aviation jet engines and gas turbines commercially available worldwide. This approach simplifies the design and enables factory certification following the regulatory and quality assurance programs applied by the aviation industry. Holos innovative architecture provides the means to support a distributable power source satisfying various appli- cations’ requirements with enhanced safety and substantial cost reductions, thus making Holos generators competitive, and synergetic with technology sourced on renewable energy.
Assistive Robot to Aid with Catheter Insertion
Authors: Martin-Wegryn Vanessa , Berg Devin R.
Published: July 2018

There is an overlap between those who need to insert a urinary catheter and those who have tremors, such as the elderly or those who have multiple sclerosis. Currently, there are no proposed solutions to aid those with hand tremors insert a catheter comfortably. The shaking motion of a tremor can make catheter insertion painful because the patient will have difficulty inserting the catheter into the small opening of the urethra. If the shaking motion of the tremor was reduced or suppressed, the catheter would enter the body more smoothly and in turn make the cathing process easier and more comfortable. In addition, an automated device would help the patient insert the catheter more steadily into the body. This paper discusses a preliminary idea for an assistive robotic device that would aid with catheter insertion for hand tremor patients. A demonstration was constructed to show how the device is intended to work, and an in depth overview was completed to select the best tremor suppression technique. Finally, further work is discussed on how to move the design forward and prepare the device for testing.
Tensile shear strength and dynamic mechanical analysis of 6063 aluminium alloy and 304 stainless steel by spot welding
Authors: SANUSI ABDUL RAZAK
Published: July 2018

Mechanical properties of dissimilar metal of spot welding were tested and analyzed based on the variation in welding currents and welding times. From visual observation, the largest weld nugget recorded was 7.43 mm at 5 kA, meanwhile the smallest was 6.4 mm at 3 kA. It was found that weld nugget size increase with the increment of weld current and extension of weld time. Based on tensile result, the largest weld nugget size of 7.43 mm produced the highest tensile strength, 31.99 N/mm2 mean while the smallest weld nugget 6.4 mm produced 29.40 N/mm2. The results show that weld nugget size affect the tensile shear strength, and with the increment of weld current and extension of welding time, tensile shear strength increase. Dynamic mechanical properties defined the storage modulus, loss modulus and damping capacity of dissimilar metal spot welded. It was found that at 10 Hz frequency between 70°C to 350°C, with heating rate of 10°C/minute, the storage modulus increase with increment in weld current and the extension of weld time to 8 s. Meanwhile the loss modulus decrease with the increased of weld current and weld time. Same pattern happen to damping capacity, the value dropped with the increases of welding current and welding time.
Porosity, pore size and compressive strength of self compacting concrete using sea water
Authors: erniati  , tjaronge muhammad wihardi , irfan Ulva ria
Published: July 2018

Indonesia is the largest archipelago in the world, so it has much territory that the quality of the source water is not qualified as mixing water in construction. Besides, construction of concrete in areas that are likely quantity of water or fresh water is very minimal or even nothing then the sea water cannot be avoided in mixing concrete. This research was an experimental study, the samples for compressive strength test are cylindrical premises size of 10 mm×20 mm. The porosity relation, compressive power, age and model of porosity relationship with SCC concrete compressive strength which using sea water is discussed in this paper. Compressive strength testing is following the standard ASTM 39/C 39-99. Universal Testing Machine (UTM) was used in the testing of compressive strength. A test specimen for porosity created by taking part of the cylinder and then slashed with a size of approximately 2 cm×3 cm with a 0.003 mm thick. The type and pore size and porosity were analyzed by using a polarizing petrography microscope Olympus BX 51-P. The result of the research was increased the compressive strength and density of microstructures in line with the decrease in porosity and pore size of concrete and concrete age. Compressive strength relations (σ ss ) and porosity (p ss ) the SCC used seawater can be approximated equation σ ss = σ o (1-p)K, with σ o = 119.6 and K = 7.502.