bluuebunny/crossref_metadata_2025_split huggingface dataset:
MHD flow and heat transfer of a magnetite–water nanofluid in porous medium under the effects of chemical reaction
Authors: Amini Meysam , GhasemiKafrudi Esmaeil , Habibi Mohammad Reza , Ahmadi Azin , HosseinNia Akram 
Published: March 2017

Purpose
Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a magnetite nanofluid (here Fe3O4–water nanofluid) impinging a flat porous plate under the effects of a non-uniform magnetic field and chemical reaction with variable reaction rate.

Design/methodology/approach
Similarity transformations are applied to reduce the governing partial differential equations with boundary conditions into a system of ordinary differential equations over a semi-infinite domain. The modified fourth-order Runge–Kutta method with the shooting technique which is developed for unbounded domains is conducted to give approximate solutions of the problem, which are then verified by results of other researchers, showing very good agreements.

Findings
The effects of the volume fraction of nanoparticles, permeability, magnetic field, chemical reaction and Schmidt number on velocity, temperature and concentration fields are examined and graphically illustrated. It was found that fluid velocity and temperature fields are affected strongly by the types of nanoparticles. Moreover, magnetic field and radiation have strong effects on velocity and temperature fields, fluid velocity increases and thickness of the velocity boundary layer decreases as magnetic parameter M increases. The results also showed that the thickness of the concentration boundary layer decreases with an increase in the Schmidt number, as well as an increase in the chemical reaction coefficient.

Research limitations/implications
The thermophysical properties of the magnetite nanofluid (Fe3O4–water nanofluid) in different conditions should be checked.

Practical implications
Stagnation flow of viscous fluid is important due to its vast industrial applications, such as the flows over the tips of rockets, aircrafts, submarines and oil ships. Moreover, nanofluid, a liquid containing a dispersion of sub-micronic solid particles (nanoparticles) with typical length of the order of 1-50 nm, showed abnormal convective heat transfer enhancement, which is remarkable.

Originality/value
The major novelty of the present work corresponds to utilization of a magnetite nanofluid (Fe3O4–water nanofluid) in a stagnation flow influenced by chemical reaction and magnetic field. It should be noted that in addition to a variable chemical reaction, the permeability is non-uniform, while the imposed magnetic field also varies along the sheet. These, all, make the present work rather original.
The analysis of ion exchange resin adsorb Li from ash solution
Authors: Nie Xiang , Zhao Shanshan , Li Yanheng 
Published: March 2017

Purpose
This paper aims to take the four resin as adsorbent and coal ash alkaline solution as the material and use the single factor experimental method to study absorption influence factors for each resin to absorb lithium. At the same time, the authors got the special properties of some kinds of resin and compared the test results of each resin at the optimum factors.

Design/methodology/approach
Because many factors affect the test, this study uses the method of comparison and control variables. This method study on the influencing factors of ion exchange resin adsorption Li+.

Findings
In these adsorption experiments, the basic resin adsorption effect is more obvious. The optimum adsorption conditions are as follows: resin quality is 0.1 g, the volume of fly ash solution is 100 ml, magnetic stirrer speed is 140 r/min and the adsorption time is 60 min. Under these conditions, the adsorption rate of Li+ could reach 25.17 per cent aluminum.

Originality/value
Li extracted from coal ash can not only relieve the lithium resources in short supply but can also provide a new mode to the field of coal resources in recycling economy and transition economy. At the same time, the extraction of Li resources will provide an important reserve of raw materials for the future of nuclear power plant.
Coconut fibre-reinforced cement-stabilized rammed earth blocks
Authors: Raj Shubham , Mohammad Sher , Das Rima , Saha Shreya 
Published: March 2017

Purpose
This study aims to investigate the optimum proportion of coconut fibre and cement suitable for rammed earth wall construction. Coconut fibres and cement can be easily incorporated into the soil mixture which adds strength and durability to the wall. This paper highlights the salient observations from a systematic investigation on the effect of coconut fibre on the performance of stabilized rammed earth blocks.

Design/methodology/approach
Stabilization of soil was done by adding Ordinary Portland Cement (2.5, 5.0, 7.5 and 10.0 per cent by weight of soil), whereas coconut fibre in length about 15 mm was added (0.2, 0.4, 0.6, 0.8 and 1.0 per cent by weight of soil) as reinforcement. Thirty types of mixes were created by adding different proportions of cement and fibre to locally available soil and compacting the mix at constant compaction energy in three layers with Proctor rammer.

Findings
Samples were tested for compressive strength and tensile strength, and failure patterns were analysed. The use of cement and fibre increases ultimate strengths significantly up to an optimum limit of 0.8 per cent fibre content, provides a secondary benefit of keeping material bound together after failure and increases residual strength. Benefits of fibre reinforcement includes both improved ductility in comparison with raw blocks and inhibition of crack propagation after its initial formation.

Originality/value
After analysing the results, it is recommended to use 0.8 per cent fibre and 5-10 per cent cement by weight of soil to achieve considerable strength. This research may add a value in the areas of green and sustainable housing, waste utilization, etc.
Traveltime approximation in vertical transversely isotropic layered media
Authors: Ravve Igor , Koren Zvi 
Published: March 2017

ABSTRACTThe well‐known asymptotic fractional four‐parameter traveltime approximation and the five‐parameter generalised traveltime approximation in stratified multi‐layer transversely isotropic elastic media with a vertical axis of symmetry have been widely used for pure‐mode and converted waves. The first three parameters of these traveltime expansions are zero‐offset traveltime, normal moveout velocity, and quartic coefficient, ensuring high accuracy of traveltimes at short offsets. The additional parameter within the four‐parameter approximation is an effective horizontal velocity accounting for large offsets, which is important to avoid traveltime divergence at large offsets. The two additional parameters in the above‐mentioned five‐parameter approximation ensure higher accuracy up to a given large finite offset with an exact match at this offset. In this paper, we propose two alternative five‐parameter traveltime approximations, which can be considered extensions of the four‐parameter approximation and an alternative to the five‐parameter approximation previously mentioned. The first three short‐offset parameters are the same as before, but the two additional long‐offset parameters are different and have specific physical meaning. One of them describes the propagation in the high‐velocity layer of the overburden (nearly horizontal propagation in the case of very large offsets), and the other characterises the intercept time corresponding to the critical slowness that includes contributions of the lower velocity layers only. Unlike the above‐mentioned approximations, both of the proposed traveltime approximations converge to the theoretical (asymptotic) linear traveltime at the limit case of very large (“infinite”) offsets. Their accuracy for moderate to very large offsets, for quasi‐compressional waves, converted waves, and shear waves polarised in the horizontal plane, is extremely high in cases where the overburden model contains at least one layer with a dominant higher velocity compared with the other layers. We consider the implementation of the proposed traveltime approximations in all classes of problems in which the above‐mentioned approximations are used, such as reflection and diffraction analysis and imaging.
Review paper: Virtual sources and their responses, Part I: time‐reversal acoustics and seismic interferometry
Authors: Wapenaar Kees , Thorbecke Jan 
Published: March 2017

ABSTRACTA focusing acoustic wave field, emitted into a medium from its boundary, converges to a focal spot around the designated focal point. Subsequently, the focused field acts as a virtual source that emits a field propagating away from the focal point, mimicking the response to a real source at the position of the focal point. In this first part of a two‐part review paper on virtual sources and their responses, we define the focusing wave field as the time reversal of an observed point‐source response. This approach underlies time‐reversal acoustics and seismic interferometry. We analyse the propagation of a time‐reversed point‐source response through an inhomogeneous medium, paying particular attention to the effect of internal multiples. We investigate the differences between emitting the focusing field from a closed boundary and from an open boundary, and we analyse in detail the properties of the virtual source. Whereas emitting the time‐reversed field from a closed boundary yields an accurate isotropic virtual source, emitting the field from an open boundary leads to a highly directional virtual source and significant artefacts related to multiple scattering. The latter problems are addressed in Part II, where we define the focusing wave field as an inverse filter that accounts for primaries and multiples.
A seismic reflection from isotropic‐fractured fluid‐saturated layer
Authors: Krylova Anna , Goloshubin Gennady 
Published: March 2017

ABSTRACTAverage elastic properties of a fluid‐saturated fractured rock are discussed in association with the extremely slow and dispersive Krauklis wave propagation within individual fractures. The presence of the Krauklis wave increases P‐wave velocity dispersion and attenuation with decreasing frequency. Different laws (exponential, power, fractal, and gamma laws) of distribution of the fracture length within the rock show more velocity dispersion and attenuation of the P‐wave for greater fracture density, particularly at low seismic frequencies. The results exhibit a remarkable difference in the P‐wave reflection coefficient for frequency and angular dependency from the fractured layer in comparison with the homogeneous layer. The biggest variation in behaviour of the reflection coefficient versus incident angle is observed at low seismic frequencies. The proposed approach and results of calculations allow an interpretation of abnormal velocity dispersion, high attenuation, and special behaviour of reflection coefficients versus frequency and angle of incidence as the indicators of fractures.
Modelling and straight‐ray tomographic imaging studies of cross‐hole radio‐frequency electromagnetic data for mineral exploration
Authors: Li Yongxing , Smith Richard S. 
Published: March 2017

ABSTRACTRadio‐frequency electromagnetic tomography (or radio imaging method) employs radio‐frequency (typically 0.1–10 MHz) electromagnetic wave propagation to delineate the distribution of electric properties between two boreholes. Currently, the straight‐ray imaging method is the primary imaging method for the radio imaging method data acquired for mineral exploration. We carried out synthetic studies using three‐dimensional finite‐element modelling implemented in COMSOL Multiphysics to study the electromagnetic field characteristics and to assess the capability of the straight‐ray imaging method using amplitude and phase data separately. We studied four sets of experiments with models of interest in the mining setting. In the first two experiments, we studied models with perfect conductors in homogeneous backgrounds, which show that the characteristics of the electromagnetic fields depend mainly on the wavelength. When the borehole separations are less than one wavelength, induction effects occur; conductors with simple geometries can be recovered acceptably with amplitude data but are incorrectly imaged on the phase tomogram. When the borehole separations are longer than two wavelengths, radiation effects play a major role. In this case, phase tomography provides images with acceptable quality, whereas amplitude tomography does not provide satisfactory results. The third experiment shows that imaging with both original and reciprocal datasets is somewhat helpful in improving the imaging quality by reducing the impact of noise. In the last experiment, we studied models with conductive zones extended into the borehole plane with different lengths, which were not accurately recovered with amplitude tomography. The experiment implies that it is difficult to determine the extent of a mineralised zone that has been intersected by one of the boreholes. Due to the large variation of the wavelength in the radio‐frequency range, we suggest investigating the local electric properties to select an operating frequency prior to a survey. We conclude that straight‐ray tomography with either amplitude or phase data cannot provide high‐quality imaging results. We suggest using more general methods based on full electromagnetic modelling to interpret the data. In circumstances when computational time is critical, we suggest saving time by using either induction methods for borehole separations less than one wavelength or wave‐based methods (only radiation fields are considered) for borehole separation larger than two wavelengths.
Analysing two‐dimensional effects in central loop transient electromagnetic sounding data using a semi‐synthetic tipper approach
Authors: Yogeshwar P. , Tezkan B. 
Published: March 2017

ABSTRACTWe present a simple and feasible approach to analyse and identify two‐dimensional effects in central loop transient electromagnetic sounding data and the correspondingly derived quasi two‐dimensional conductivity models. The proposed strategy is particularly useful in minimising interpretation errors. It is based on the calculation of a semi‐synthetic transient electromagnetic tipper at each sounding and for each observational transient time point. The semi‐synthetic transient electromagnetic tipper is derived from the measured vertical component of the induced voltage and the synthetically calculated horizontal component. The approach is computationally inexpensive and involves one two‐dimensional forward calculation of an obtained quasi two‐dimensional conductivity section. Based on a synthetic example, we demonstrate that the transient electromagnetic tipper approach is applicable in identifying which transient data points and which corresponding zones in a derived quasi two‐dimensional subsurface model are affected by two‐dimensional inhomogeneities. The one‐dimensional inversion of such data leads to false models. An application of the semi‐synthetic transient electromagnetic tipper to field data from the Azraq basin in Jordan reveals that, in total, eight of 80 investigated soundings are affected by two‐dimensional structures although the field data can be fitted optimally using one‐dimensional inversion techniques. The largest semi‐synthetic tipper response occurs in a 300 m‐wide region around a strong lateral resistivity contrast. The approach is useful for analysing structural features in derived quasi two‐dimensional sections and for qualitatively investigating how these features affect the transient response. To avoid misinterpretation, these identified zones corresponding to large tipper values are excluded from the interpretation of a quasi two‐dimensional conductivity model. Based on the semi‐synthetic study, we also demonstrate that a quantitative interpretation of the horizontal voltage response (e.g. by inversion) is usually not feasible as it requires the exact sensor position to be known. Although a tipper derived purely from field data is useful as a qualitative tool for identifying two‐dimensional distortion effects, it is only feasible if the sensor setup is sufficiently accurate. Our proposed semi‐synthetic transient electromagnetic tipper approach is particularly feasible as an a posteriori approach if no horizontal components are recorded or if the sensor setup in the field is not sufficiently accurate.
The benefits of coinfection: trematodes alter disease outcomes associated with virus infection
Authors: Wuerthner Vanessa P. , Hua Jessica , Hoverman Jason T. 
Published: March 2017

Summary

Coinfections are increasingly recognized as important drivers of disease dynamics. Consequently, greater emphasis has been placed on integrating principles from community ecology with disease ecology to understand within‐host interactions among parasites. Using larval amphibians and two amphibian parasites (ranaviruses and the trematode Echinoparyphium sp.), we examined the influence of coinfection on disease outcomes.

Our first objective was to examine how priority effects (the timing and sequence of parasite exposure) influence infection and disease outcomes in the laboratory. We found that interactions between the parasites were asymmetric; prior infection with Echinoparyphium reduced ranaviral loads by 9% but there was no reciprocal effect of prior ranavirus infection on Echinoparyphium load. Additionally, survival rates of hosts (larval gray treefrogs; Hyla versicolor) infected with Echinoparyphium 10 days prior to virus exposure were 25% greater compared to hosts only exposed to virus.

Our second objective was to determine whether these patterns were generalizable to multiple amphibian species under more natural conditions. We conducted a semi‐natural mesocosm experiment consisting of four larval amphibian hosts [gray treefrogs, American toads (Anaxyrus americanus), leopard frogs (Lithobates pipiens) and spring peepers (Pseudacris crucifer)] to examine how prior Echinoparyphium infection influenced ranavirus transmission within the community, using ranavirus‐infected larval wood frogs (Lithobates sylvaticus) as source of ranavirus. Consistent with the laboratory experiment, we found that prior Echinoparyphium infection reduced ranaviral loads by 19 to 28% in three of the four species.

Collectively, these results suggest that macroparasite infection can reduce microparasite replication rates across multiple amphibian species, possibly through cross‐reactive immunity. Although the immunological mechanisms driving this outcome are in need of further study, trematode infections appear to benefit hosts that are exposed to ranaviruses. Additionally, these results suggest that consideration of priority effects and timing of exposure are vital for understanding parasite interactions within hosts and disease outcomes.
Soil biota suppress positive plant diversity effects on productivity at high but not low soil fertility
Authors: Luo Shan , De Deyn Gerlinde B. , Jiang Bin , Yu Shixiao 
Published: March 2017

SummaryPlant community productivity commonly increases with increasing plant diversity, which is explained by complementarity among plant species in resource utilization (complementarity effect), or by selection of particularly productive plant species in diverse plant communities (selection effect). Recent studies have also shown that soil biota can drive the positive plant diversity–productivity relationship by suppressing productivity more in low‐ than in high‐diversity plant communities. However, much remains unknown about whether soil fertility plays a role in determining how soil biota affect plant diversity–productivity relationships.We hypothesized that under high soil fertility conditions, negative soil biota effects dominate, which reduces plant monoculture biomass more than that of high‐diversity plant communities. Conversely, under low soil fertility conditions, we hypothesized positive soil biota effects dominate, which facilitates plant resource partitioning and enhances community‐level biomass in high‐diversity plant communities. Hence, we expected positive plant diversity–community productivity relationships under low and high soil fertility conditions but caused by different mechanisms.We tested these hypotheses using woody seedlings and set up plant assemblages with four species richness levels (one, two, four and eight species), and grew them in sterilized and unsterilized (sterilized soil + living soil inoculum) soils at two nutrient levels (low versus high fertility).We found that at high fertility negative soil biota effects dominated and suppressed plant community biomass more in high‐diversity plant communities than in monocultures, resulting in reduced complementarity effects of diverse plant communities and a non‐significant plant species richness–community biomass relationship in unsterilized soil. Whereas at low fertility soil biota had net neutral to positive effects on plant community biomass but the beneficial effects did not increase with increasing plant species richness. Instead, soil biota neutrally affected the positive plant species richness–community biomass relationship, presumably due to non‐specific effects of beneficial soil biota.Synthesis. Soil biota and soil fertility interactively determine plant species richness–community biomass relationships. Moreover, soil biota modulate the complementary resource use among plant species. These findings suggest that environmental context plays an important role in determining whether and how soil biota generate the biodiversity–productivity relationship. Future studies would benefit from revealing the mechanisms underlying the interactive effects of soil biota, soil fertility, and plant diversity on ecosystem functioning.
Evidence in the Networked Governance of Regional Decarbonisation: A Critical Appraisal
Authors: Weller Sally , Tierney John 
Published: March 2017

AbstractThis paper examines the use of evidence in collaborative policy making focusing on the challenges of implementing national decarbonisation policies in regional areas. Its case study of a staged policy intervention to promote the ‘transition to a low carbon economy’ in Victoria's coal‐dependent Latrobe Valley reveals the selective use of evidence to support policy directions that emerged from the interaction of policy knowledge and the political mood. The paper shows how local conditions can be manipulated to enable the production of evidence consistent with the policy objective, but also suggests that despite combining orchestrated evidence with customised forms of networked governance, it is not possible to suppress or deflect unresolved political disagreements.