bluuebunny/crossref_metadata_2025 huggingface dataset:
A multi-flow regimes model for simulating gas transport in shale matrix
Authors: Zhang P. , Hu L. , Wen Q. , Meegoda J. N.
Published: November 2015

The gas transport in shale matrix is of great research interest for optimised shale gas recovery. Pores and pore-throats in the gas-bearing shale are nano-scale, and hence transport of gas is governed by the slippage effect and Knudsen diffusion rather than viscous flow. Hence a proper mathematical model is needed for full understanding of shale gas transport. In this paper, a mathematical model that considers multi-flow regimes is proposed based on gas molecular kinetics theory. The flow regimes transition from slip flow to Knudsen diffusion, and can be adequately described by introducing a corrected intermolecular collision frequency. The proposed mathematical model predictions are compared with experimental data and found to match very well. Furthermore, the gas mass flux contributed by different flow regimes with the variation of Knudsen number is analysed. The numerical simulation results indicate that with the increase in Knudsen number, viscous flow becomes weakened, and the slippage flow reaches a peak and then decreases gradually. The contribution to the gas mass flux due to Knudsen diffusion starts at the early stage of transition flow, and becomes dominant at the later stage of transition flow.
Upper bound analysis of uplift capacity of a tapered plate anchor in cohesive soil
Authors: Zhao X. , Randolph M. F. , Wang D. , Gaudin C.
Published: November 2015

Helical anchors are used widely onshore and have recently been mooted as an innovative foundation method for lightweight offshore structures. From structural considerations, as the load requirement for each plate on a helical anchor increases, it becomes necessary to increase the diameter ratio of the central shaft to the plate, and even to replace the flat helical plate by a tapered plate, thicker at the shaft than at the outer edge. This article presents a simple upper bound analysis for a tapered plate attached to a central shaft and embedded in clay, as a basis for enabling simple calculations for optimising the geometry and spacing of the plates for a helical anchor. The solutions are verified by comparison with existing analytical solutions for particular cases and against finite-element simulations. Parametric studies are provided to explore the effects of the interface friction ratio, the shaft–plate diameter ratio, and the taper angle of the plate.
Boundary effects on ground surface rupture induced by normal faulting
Authors: Cai Q. , Ng C. W. W. , Hu P.
Published: November 2015

Although centrifuge modelling has been used for studying soil–bedrock interaction, the limited space available in a model container to simulate prototype situations imposes challenges. This article introduces and discusses boundary effects on surface fault ruptures induced by normal faulting in clay and nine-layered soil strata in a geotechnical centrifuge. Both a horizontal kinematically constrained boundary and an unconstrained boundary, representing two extreme cases in the field, were applied. Their effects on soil deformation and the location of surface fault rupture are thoroughly compared and discussed. For both the clay and the nine-layered soil strata, the unconstrained boundary shifted the induced settlement profile towards the footwall, extended the range of soil subjected to tension, increased the horizontal displacement of the soil at the hanging wall and extended the influence zone of the surface fault rupture when compared with the constrained boundary cases. Compared with the clay stratum, the influence zone of surface fault rupture in the nine-layered soil was significantly reduced under the constrained boundary. However, the main rupture in both the clay and nine-layered soil strata was located at the intersection of the bedrock fault plane and the ground surface, independent of the boundary condition.
Hydraulic performance of sand–clay mixtures: soil fabric perspective
Authors: Shaker A. A. , Elkady T. Y.
Published: November 2015

Soil fabric plays a fundamental role in the hydraulic conductivity of sand–clay mixtures. Current techniques for the examination of soil fabric are categorised as quantitative (e.g. mercury intrusion porosimetry) or qualitative (e.g. scanning electron microscopy (SEM)), and both types require special equipment and a skilled operator. In addition, during preparation for these techniques, specimen disturbance is of concern. This article introduces a rational approach to evaluate the effect of soil fabric on the hydraulic behaviour of sand–clay mixtures using key void ratios, namely the clay void ratio ec and the skeletal void ratio esk. A detailed experimental programme was devised to evaluate the hydraulic conductivity of a sand–natural clay mixture under different test parameters (clay content, initial compaction conditions and effective confining pressure). The information on mixture fabric inferred using key void ratios was observed to correlate well with the results of hydraulic conductivity tests. To verify the findings obtained using key void ratios, the particle arrangement within the sand–clay mixture was examined using SEM. SEM micrographs identified different arrangements of sand and clay particles and pore size characteristics depending on clay content in the mixture. These arrangements were consistent with that inferred using key void ratios. Therefore, use of key void ratios can be considered a vital and simple tool to understand the fabric of the studied sand–clay mixture and its impact on design.
A bounding surface hysteretic water retention model for deformable soils
Authors: Gallipoli D. , Bruno A. W. , D'onza F. , Mancuso C.
Published: November 2015

The paper presents a soil water retention model that takes into account the effects of void ratio and hydraulic hysteresis on the variation of degree of saturation. Based on a modified form of the van Genuchten equation, the model defines two bounding surfaces, namely a main drying surface and a main wetting surface, which delimit the region of admissible soil states in the space of degree of saturation, suction and void ratio. Suction and void ratio are then combined into a single auxiliary variable, termed scaled suction, and the main surfaces are recast as main curves in the plane of degree of saturation and scaled suction. The effects of both suction and void ratio on the drying/wetting behaviour of the soil are simply incorporated by relating degree of saturation to scaled suction. The soil is dried when the scaled suction is increased and is wetted when the scaled suction is decreased. The model assumes that, inside the region of admissible soil states, the derivative of degree of saturation with respect to the scaled suction depends on the distance of the soil state from the main curves. This assumption ensures a smooth transition of the drying and wetting paths towards their respective main curves. Interestingly, the derivative of degree of saturation with respect to scaled suction can be integrated in a closed form and all wetting and drying paths can therefore be described by two explicit equations (one for drying paths and one for wetting paths), where different wetting or drying paths are characterised by different values of the integration constant. The integration of the model in a closed form facilitates its implementation into numerical codes. The model requires seven parameters, whose values can be obtained from a single drying–wetting test. Predictions are validated against two different data sets published in the literature, which shows the capability of the model to capture the behaviour observed during laboratory tests on fine-grained soils.
The influence of experimental and sampling uncertainties on the probability of unsatisfactory performance in geotechnical applications
Authors: Mašín D.
Published: November 2015

While the effect of spatial variability on the probability of unsatisfactory performance in geotechnical applications is relatively well understood, comparatively less attention has been given in the literature to the effects of experimental (measurement scatter) and sampling (insufficient number of samples) uncertainties. In this paper, a general approach is developed to incorporate experimental and sampling uncertainties into probabilistic analyses based on random field methods. It is shown that, when compared with the standard approach which attributes the measured total soil variability to spatial variability, consideration of experimental uncertainty may significantly reduce the calculated probability of unsatisfactory performance. It is argued that this may be one of the reasons for an overestimation of the probability of unsatisfactory performance in geotechnical probabilistic simulations (another important reason is the spatial averaging of soil properties). Evaluation of the sampling uncertainty reveals that, although a relatively large number of samples is needed for spatial variability characterisation, a limited number of samples is sufficient to quantify the experimental uncertainty. It is pointed out that no adjustments of the existing random field-based software are needed to consider the additional uncertainties. To illustrate the proposed approach, two extensive experimental data sets on sand are presented: one reflecting total variability and the other quantifying experimental uncertainty. A hypoplastic model is calibrated against the two data sets and adopted in random field analyses of strip footing settlement.
Probabilistic identification of soil stratification
Authors: Li J. , Cassidy M. J. , Huang J. , Zhang L. , Kelly R.
Published: November 2015

Identification of soil stratification is vital to geotechnical structural design and construction where the soil layer, soil type and properties are necessary inputs. Although methods are available for classifying the soil profiling using measured cone penetration test (CPT) data, the identification of soil stratification at unsampled locations is still difficult due to significant variability of natural soil. The identification is further complicated by the considerable uncertainties in the CPT measurements and soil classification methods. This study aims to develop a probabilistic method to predict soil stratification at unsampled locations by explicitly filtering the uncertainties in soil classification systems. An established Kriging interpolation technique is used to estimate the CPT parameters which are further interpreted to identify the soil stratification. Equations are derived to quantify the degree of uncertainties reduced by this method. The approaches are illustrated using a database of 26 CPT tests recently sourced from a dike near Ballina, Australia. Results show that the majority of the uncertainties in the soil parameters are screened by a soil classification index. The remaining uncertainties are further filtered by the soil classification systems. A clear stratification with a high degree of confidence is obtained in both horizontal plane and vertical unsampled locations, which shows excellent agreement with the existing CPT tests. This study provides a methodology to clearly identify the soil strata and reduce the uncertainties in prediction of design properties, paving the way for a more cost-effective geotechnical design.
Stability of multi-anchor soil walls after loss of toe support
Authors: Bathurst R. J. , Miyata Y. , Konami T. , Miyatake H.
Published: November 2015

This paper reports the results of a novel experiment in which two nominally identical full-scale steel multi-anchor reinforced soil walls were taken to foundation failure by progressive loss of footing support. The 4-m high walls varied only with respect to reinforcement anchor lengths. The data show that facing displacements at end of construction and at time of foundation failure below the footing were greater for the wall with the shorter reinforcement lengths. Reinforcement loads at end of construction were best estimated using a working stress model proposed by the authors rather than current methods used in Japan and the UK. However, after significant loss of footing support, the Japanese Public Works Research Centre method gave more accurate and safer load predictions. Regardless, both the anchor rods and anchor plates had abundant reserve capacity to provide large margins of safety against internal tensile rupture and pullout modes of failure even after large foundation displacements.
A numerical study on offshore wind turbines embedded in sands
Authors: Pedram Behrang
Published: November 2015

This paper compares the ultimate lateral capacity and stiffness of circular and square pile-towers embedded in two different sand deposits. The benefits of square pile-towers with respect to circular structures are brought out in this paper through a parametric study conducted by three dimensional finite element analyses. In the numerical models, the pile-towers are treated as an elastoplastic material while the soil is idealised using the Drucker–Prager constitutive model with a linearly increasing soil modulus. The effects of pile diameter, pile thickness, eccentricity and pile length for free-head pile-towers embedded in both sand deposits are investigated. The results illustrate that the stiffness and ultimate lateral capacity of a square pile-tower are substantially greater than a circular structure. Furthermore, the soil displacements and stresses at the ultimate capacity when a square pile-tower is adopted instead of circular structure are not considerable. The ultimate lateral capacities from the numerical models for both pile-tower configurations are compared with the usual techniques available in the literature, and the most suitable methods for these structures are illustrated, while the method adopted by Zhang et al. is ruled out.
Principal stress rotation as cause of cyclic mobility
Authors: Jefferies Michael , Shuttle Dawn , Been Ken
Published: November 2015

Principal stress rotation (PSR) has been known to act as ‘loading’ on soils since the seminal work of Arthur et al. some 30 years ago, using the directional shear cell. However, the key insight – reflected in the titles of the original papers – that soils yield under constant stress invariants if the principal stresses rotate, has been consistently neglected in virtually all constitutive models of soil as well as in all procedures/methods of geotechnical engineering practice. This neglect is a pity, as a rather simple softening (annealing) of yield surface size, proportional to the rotation of principal stress, captures much of soil behaviour that is measured in the cyclic simple shear test – an idealisation demonstrated in this paper using a minimal extension of the generalised critical state model NorSand (although the idealised effect of PSR could be implemented in any comparable model as the ideas are general). The extended model captures much of the behaviour encountered in the large body of test data on Fraser River sand. Equally, the implementation of PSR annealing makes clear that there is a further loading process for soil: it is suggested that the rotation of the strain increment direction is the missing additional factor. The model is provided as a downloadable, open-source code Excel/VBA program as a supplement to this paper.
Highway filter drains: precursors for maintenance management
Authors: Stylianides Theodoros , Frost Matthew W. , Fleming Paul R. , El-Jaber Ali , Mageean Mark , Huetson Andrew , Klimczak Tomasz
Published: November 2015

This paper conceptualises and presents a number of asset management building blocks required to establish holistic management for highway filter drains in the UK roads network. This is accomplished by evaluating current maintenance and management thinking and by identifying how existing strategies are lacking and potentially unsustainable. A condition assessment regime is hence described, tied to a measure of filter drain level of service (drainability) and an asset-specific ageing/renewal model that adopts six discreet condition bands is proposed. For this model to hold true, the Markov process is assumed to represent cumulative damage in a network. Drawing from relevant asset management concepts, a decision support tool to inform and optimise managerial decisions in respect to maintenance planning and resources allocation is also described.
Effect of nanosilica on durability and mechanical properties of high-strength concrete
Authors: Ganesh Prakasam , Ramachandra Murthy Avadhanam , Sundar Kumar Subramanian , Mohammed Saffiq Reheman M. , Iyer Nagesh R.
Published: November 2015

The effect of amorphous nanosilica particles on the mechanical properties and durability of two high-strength concrete (HSC) mixes was investigated. Nanosilica in powder form was used as a partial replacement of cement at dosages of 1 wt% and 2 wt%, and significant improvements in performance were observed for 2 wt% replacement of cement by nanosilica. Micromechanical studies were performed on the nano-modified HSCs to determine the impact of nanosilica on pozzolanic reactivity. Durability assessments such as the rapid chloride penetration test, water sorptivity test and water absorption test revealed significant resistance to chloride penetration, sorptivity and water absorption. These improvements can be mainly attributed to the larger specific surface area of nanosilica, which effectively stimulates both pozzolanic reactivity and the filler effect over the cementitious matrix.
Investigation of chloride diffusion in cement mortar via statistical learning theory
Authors: Liao Kuo-Wei , Chen Chun-Tao , Wu Bang-Ho , Chen Wei-Lun , Yeh Chih-Ming
Published: November 2015

Salt damage is frequently found in coastal structures and is known to be one of the leading causes of concrete degradation. To ensure a concrete structure with adequate resistance against such a threat, chloride ion diffusion in concrete needs to be thoroughly investigated. Although chloride diffusion in concrete has attracted significant attention from researchers, the method to determine the chloride ion concentration remains the subject of debate. In this study, a series of tests was first conducted on cement mortars less than 168 d old. A model based on statistical learning theory and adopting the least-squares support vector machine was developed. Comparison with the experimental results revealed that the model could provide an accurate prediction of chloride ion concentration. Moreover, the proposed model, unlike the conventional Fick's law approach, is applicable to cement mortars of differing compositions and ages, thus contributing to its applicability to practical engineering. The test variables included age, depth (measured position), dimensions of diffusion and the presence of a reinforcement bar. All the specimens were mixed with fresh water and cured in salt water.
Effect of fibres on the strength and behaviour of GPC columns
Authors: Ganesan Namasivayam , Abraham Ruby , Deepa Raj Sivarajan , Namitha Krishnan
Published: November 2015

Geopolymers are alternative binders to ordinary Portland cement binder, and in geopolymer concrete (GPC) geopolymer gel is used as a binder. In the present study, the effect of steel fibres on the strength and behaviour of GPC columns under monotonic axial compression is studied. In total, 30 GPC columns with l/d ratios of 6 and 9 were cast and tested. The main variables considered in this study include different values of volume fraction of fibres such as 0·25% (19·62 kg/m3), 0·5% (39·24 kg/m3), 0·75% (58·86 kg/m3) and 1% (78·48 kg/m3) for each l/d ratio. Experimental results reveal that the addition of steel fibres slightly improves the axial strength and significantly improves the stress–strain behaviour of columns. A theoretical model for the stress–strain behaviour is proposed, and this model predicts the response of plain and fibre-reinforced GPC columns satisfactorily.
Optical performance of cadmium sulfide/silicon nanowire heterostructure arrays prepared by SILAR technique
Authors: Yang Haigang , Cao Weiwei , Jiang Yurong , Hao Ruiting , Song Guilin , Chang Fanggao
Published: November 2015

Cadmium sulfide/silicon (CdS/Si) nanowire (NW) heterostructure arrays were prepared using the successive ionic layer adsorption and reaction technique based on etched Si NW templates using p-type (100) silicon wafer. Synthesized CdS/Si NW heterostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and their optical properties were measured using a ultraviolet–visible spectrophotometer. The results of reflectance spectra show the absorption edge at 460, 470 and 480 nm for 20, 30 and 40 cycles, respectively. XRD analysis indicates the formation of CdS with hexagonal (wurtzite) structure. Also, the presence of CdS was confirmed by both SEM and energy dispersive X-ray. The effect of cycle times on the photoluminescence intensity was also studied. The absorption and emission edges shift slightly towards long wavelength with increasing cycles of adsorption of CdS.
Studies on cadmium telluride–cadmium selenide bilayer
Authors: Balakrishnan Lakshmi Shree , Subramanian Selva Priya , Perchamy Therasa Ranjani , Sridharan Madanagurusamy
Published: November 2015

Group II–VI elements of the periodic table are suitable for electronic and optoelectronic applications. Cadmium selenide (CdSe) and cadmium telluride (CdTe) bilayer films were deposited onto well-cleaned glass substrates using vacuum evaporation technique. These films were analyzed using X-ray diffraction, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDAX) and UV-visible spectrophotometry to study their microstructural, morphological and optical properties. Crystallinity of CdSe film increased with increase in film thickness, which in turn favored the crystallinity of the CdTe layer deposited over CdSe. The CdTe/CdSe bilayer showed globular surface morphology, and the grain size of the films measured by FE-SEM micrographs range from 16 to 31 nm. EDAX analysis confirmed the presence of cadmium (Cd), selenium (Se) and tellurium (Te). Two electronic transitions were observed in the optical band gap of the CdTe/CdSe bilayer whose energy levels lie in between the energy band gap of the bulk CdTe and CdSe semiconductors. These electronic transitions are mainly due to the spin orbit split of valence band energy levels.
Study on the electronic and optical properties of La-, Ce- and Nd-doped SnO2
Authors: Shao Tingting , Zhang Fuchun
Published: November 2015

To study the influence of rare earth element doping on the electronics structure and properties of SnO2, the lattice parameters, band structures, density of states, electron density differences and optical properties are investigated by density functional theory based on the plane wave pseudopotential method. The calculated results show that the bond lengths change the most due to La doping and the least for Nd, which indicates that the lattice distortion caused by rare-earth-doped SnO2 is related to the covalent radius of the doping atom. The band gap of SnO2 reduces the most due to La doping, but it is found that spin-up levels are in the forbidden band for Nd doping. The results show that Nd-doped SnO2 is half-metal material due to the existence of spin-up f electrons, and significant hybrid effects are induced by Nd 4f and O 2p states. The charge density difference shows that rare earth doping causes redistribution of the electrons of SnO2, and the metal property enhances. La atoms lose the most electrons and Nd atoms lose the least, which is consistent with the calculated results of band gaps. The calculated results of optical properties show that the imaginary part of the dielectric function has a red shift and the optical anisotropy of SnO2 is not strong, which indicates that the SnO2 crystal may have a preferred orientation along [0 0 1].
Air injection to mitigate liquefaction under light structures
Authors: Marasini Narayan Prasad , Okamura Mitsu
Published: November 2015

During large earthquakes, soil liquefaction has repeatedly damaged many buildings with shallow foundations. Many researchers have continuously worked to develop more reliable countermeasure techniques apposite to the foundation soils of existing buildings. However, most countermeasure techniques available in the current practice are either too expensive or applicable only to new construction sites. Lowering the degree of saturation by artificially injecting air is a newly developed, innovative technique that significantly improves the liquefaction strength of soil. This paper describes a series of centrifuge tests for evaluating the effectiveness of this technique by applying it to the foundation soil underlying shallow foundations of relatively light structures, such as residential buildings. Models of saturated medium dense sand beds with shallow foundations were shaken in a centrifuge. Except for benchmark models, air was injected into the soil in-flight before the shaking event, which lowered the degree of saturation of the soil in the desaturated zone from 100% before air injection to approximately 85%. The test results show that air injection effectively reduced both foundation settlement and pore pressures generated below the foundation.
Use of viscous pore fluids in dynamic centrifuge modelling
Authors: Adamidis Orestis , Madabhushi Gopal Santana Phani
Published: November 2015

The scaling laws that arise from dynamic centrifuge modelling contain an inconsistency regarding the scaling of time between dynamic and diffusion events. This problem can be resolved by reducing the permeability of the soil, with the help of high-viscosity pore fluids. Hydroxypropyl methylcellulose is a water-soluble cellulose ether that is widely used to create such fluids. In this paper, the effects that concentration, temperature, ageing and shearing rate have on the viscosity of hydroxypropyl methylcellulose solutions are examined and equations that quantify them are presented. This information is meant to act as a guideline for the preparation of high-viscosity pore fluids for dynamic centrifuge tests.
Behaviour of fibre-reinforced concrete beams on grade
Authors: Briggs Michael A. , Valsangkar Arun J. , Thompson Adrian
Published: November 2015

The University of New Brunswick's Geotechnical Research Group has an ongoing research programme investigating the behaviour of steel-fibre-reinforced concrete (SFRC) beams on grade. The development of a state-of-the-art behavioural model of SFRC slabs on grade requires that numerous intermediate steps be investigated. With this approach, testing of beams representing two-dimensional components of SFRC slabs has been completed. The purpose of this experimental programme was to obtain pre- and post-cracking response data for beams on grade subjected to repetitive loads and to compare the observed response of these beams with monotonically loaded beams on grade.
Robust superhydrophobicity by candle soot deposition on plasma-treated PETG
Authors: Salapare Hernando S. , Guittard Frédéric
Published: November 2015

Surface etching was achieved by exposing poly(ethylene glycol-co-1,3/1,4 cyclohexanedimethanol terephthalate) (PETG) samples to oxygen plasma produced in reactive-ion etching configuration of a radiofrequency plasma device. The surface modifications on the sample surfaces were determined by employing water contact angle measurements and profilometry. Enhanced wettability was observed for the plasma-treated samples together with a general increase in the surface roughness for the plasma-treated samples as compared to the control samples due to surface etching. Superhydrophobic candle soot coatings with a maximum water contact angle of 164° were deposited on the control and plasma-treated samples. Durability tests such as water and ethanol immersions were performed on the samples with the results demonstrating that samples with higher surface roughness values exhibited better candle soot coating adhesion to the PETG samples.
Two surface gradients of polyethylene glycol for a reduction in protein adsorption
Authors: Gooch Nathan W. , Hlady Vladimir
Published: November 2015

Polyethylene glycol (PEG) coatings have been commonly used in reducing protein adsorption with the intent of improving a biomaterial’s biocompatibility. To elucidate the role of PEG surface density in reducing protein adsorption, two types of grafted PEG surface density gradients were evaluated for the adsorption and desorption of albumin and fibrinogen, two blood proteins. PEG density gradients were characterized using contact angle measurements and X-ray photoelectron spectroscopy. Total internal reflection fluorescence was used to measure protein adsorption kinetics and adsorption profiles on the two types of PEG gradients. The PEG gradient generated by the flow method decreased adsorption of both proteins in proportion to the PEG surface density; however, their desorption by buffer solution from the grafted PEG layer was not complete. In contrast, desorption of two proteins from the grafted PEG layer generated by a UV oxidation method resulted in near-zero adsorbed amount. The difference between the two types of gradients might have originated from counter-diffusion of PEG and water molecules occurring during the flow method procedure.
Using bulk properties of UV-polymerized thin layers for fiber modification
Authors: Bahners Thomas , Gutmann Jochen S.
Published: November 2015

The surface properties of fibers can be regarded as instrumental toward innovative functional textiles as applied in many high-end industries. Accordingly, not only the modification of surface chemistry, but also of the physical and morphological properties is an important objective in modern materials science and technology. Besides other powerful chemical and physical techniques, UV-induced graft copolymerization and photopolymerization are interesting ways to improve or introduce surface functionalities of the fiber. While the majority of reported work focused on the surface of the deposited thin layer itself and its potential effect on – for example, wettability, adhesion, protein adsorption and microbial activity, this paper reviews earlier studies by the authors which were devoted to bulk properties of these thin, less than 500-nm thick layers and the resulting effect on fiber properties. One major factor is the high and controllable cross-linking of polymerized layers, which affects mechanical, thermal and chemical stability. This results in interesting applications as thin barrier coating in view of improved fiber stability in critical environments and stress conditions, examples of which are reported in this paper. A recent observation is the effect of the controlled cross-linking on the mobility of monomers and electrical charges in the thin layer, which could open an avenue toward thin-layer capacitors and energy storage on textiles.
The measurement of creep of mortar under fully controlled conditions
Authors: Neville A. M.
Published: November 2015

Summary

It is suggested that the chemical composition of cement is a vital factor in creep of mortar. A new loading apparatus for the measurement of creep is described, and results of tests with three different cements are presented.
The protection and manipulation of electrical-resistance strain gauges of the bonded-wire type for use in concrete, particularly for internal strain measurement
Authors: Hondros G.
Published: November 2015

Summary

This report descrihes techniques whereby electrica/resistance strain gauges, of the bonded-wire type, can be used to measure strain at any point in a concrete or reinforced concrete member. Some observations are recorded on long-time stability of gauges and instances are recorded where they have been successfully employed to measure internal concrete strains and strains in reinforcing bars.
Study on behaviour and strength of SFRC under combined action of compression and shear
Authors: Wang Zhiliang , Yang Dong , Wang Jianguo
Published: November 2015

Steel fibre reinforced concrete (SFRC) has been gaining popularity in load-carrying members because of its positive contribution to both concrete strength and energy absorption capacity. This paper presents both experimental and theoretical study of the fibre reinforcing effect on the concrete failure mechanism. The compression/shear tests of cubic steel fibre reinforced concrete specimens with fibre volume fractions of 0%, 1·5% and 3% are conducted in the wedge shear apparatus. Their failure patterns are analysed at macro- and meso-scale levels. Subsequently, these experimental data are analysed by a twin-shear strength theory. One concise compression/shear failure criterion is then developed for SFRC. It is found that the predicted results by this criterion agree well with those by experiments. Finally, the changes of concrete twin-shear strength parameters with the fibre volume fraction are explored.
The effectiveness of FRP strips in repairing moderately and severely damaged RC beam–column connections
Authors: Shrestha Rijun , Smith Scott T. , Samali Bijan
Published: November 2015

An effective means to increase the shear resistance of shear deficient reinforced-concrete (RC) beam–column connections is by bonding fibre-reinforced polymer (FRP) composites. The majority of research to date has focused on the strengthening of two-dimensional reinforced-concrete connections with fibre-reinforced polymer; that is, the strengthening of virgin (undamaged) connections. This paper reports the results of tests on the effectiveness of fibre-reinforced polymer strips in repairing two-dimensional connections with different degrees of damage. The results of tests assessing the effectiveness of fibre-reinforced polymer strips in strengthening virgin connections are also reported. All test specimens are extensively instrumented and their behaviour and failure comprehensively documented. In the case of the repaired specimens, instrumentation is concentrated on the fibre-reinforced polymer around the damage region, thus enabling the strength contribution and behaviour of the fibre-reinforced polymer repair to be closely monitored. The results of this experimental programme enable a better understanding of the strengthening and repair effect of fibre-reinforced polymer strips in reinforced-concrete beam–column connections, and the results will also facilitate the future development and calibration of analytical and numerical models.
Shear strength of reinforced concrete dapped-end beams using mechanism analysis
Authors: Yang K.-H. , Ashour A. F. , Lee J.-K.
Published: November 2015

A mechanism analysis based on the upper-bound theorem of concrete plasticity is developed to predict the critical failure plane and corresponding shear capacity of reinforced concrete dapped-end beams. Failure modes observed in physical tests of reinforced concrete dapped-end beams are idealised as an assemblage of two moving blocks separated by a failure surface of displacement discontinuity. The developed mechanism analysis rationally represents the effect of different parameters on failure modes; as a result, the predicted shear capacity is in good agreement with test results. On the other hand, empirical equations specified in the Precast/Prestressed Concrete Institute design method and strut-and-tie model based on ACI 318-05 highly underestimate test results. The shear capacity of dapped-end beams predicted by the mechanism analysis and strut-and-tie model decreases with the increase of shear span-to-full beam depth ratio when failure occurs along diagonal cracks originating at the bottom corner of the full-depth beam, although the shear span-to-full beam depth ratio is ignored in the Precast/Prestressed Concrete Institute design method.
Influence of beam cross-section, loading arrangement and aggregate type on shear strength
Authors: Sagaseta J. , Vollum R. L.
Published: November 2015

This paper describes 14 tests on simply supported and continuous reinforced concrete beams which were designed to investigate the influences of aggregate type, loading arrangement and shear reinforcement ratio on shear strength. The beams were rectangular in cross-section with a/d ∼ 3·5 (where a is the shear span and d the effective depth). Marine dredged gravel was used in ten beams (two without shear reinforcement) and limestone in the remaining four (two without shear reinforcement). The cracks typically passed around the gravel aggregate but through the limestone aggregate. Aggregate fracture was found only to reduce the shear strength of the beams without shear reinforcement. The factors of safety for shear failure implicit in Eurocode 2, BS 8110 and CSA A.23.3-04 are examined with data from this project and elsewhere. Eurocode 2 is shown to provide the lowest factor of safety for most beams. This is particularly significant for rectangular sections where Eurocode 2 can give lower factor of safety for shear than flexural failure which is undesirable. An amendment is proposed to address this.
critical review of ionic liquids for the pretreatment of lignocellulosic biomass
Authors: Reddy Prashant
Published: November 2015

Ionic liquids have been the subject of active research over the course of the last decade and have in the past been touted as one of the most promising technologies for revolutionising the chemical and petro-chemical industries. The sheer abundance of potential ionic liquid structures coupled with their tuneable physico-chemical properties has endeared ionic liquids to the scientific community across a broad range of disciplines with potential applications that include pharmaceuticals, electrolytes, thermal energy storage media and liquid mirror telescopes. Within the context of a biorefinery for the production of biofuels and other bio-based products from renewable resources, the unique abilities of some ionic liquids to selectively dissolve biomass components or whole native biomass have been demonstrated. This ability has sparked extensive investigations of ionic liquids for the pretreatment of different biomass types, particularly for the production of cellulosic biofuels. However, the esoteric nature of ionic liquids persists and constructing a fundamental framework for correlating ionic liquid structures with useful applications remains a significant challenge. In addition to the above, the more practical challenges of toxicity, high costs, high viscosities, low solids loading and complex recycling are key factors hindering the wide-scale uptake of ionic liquids as pretreatment solvents in a commercial biorefinery. This critical review provides insights from academic studies and the implications thereof for elevating ionic liquids from the status of ‘promising’ to ‘commercialisable’ in the pretreatment of biomass. It is vital that key hurdles for the commercialisation of ionic liquids in the form of high costs, high viscosities, poor water tolerance, toxicity, low solids loading and recovery/recycling be addressed.
Computer‐Based Testing and Construction of an Item Bank Database for Medical Education in Korea
Authors: Huh Sun
Published: November 2015

A number of medical schools in Korea have been using computer-based testing (CBT) for evaluating their students’ scientific and/or clinical performance since the early 1990s. Introducing CBT to medical education would have several advantages: first, presenting figures and audio-video files of clinical content is simple with CBT, making it possible to evaluate medical students’ competency with navigating more realistic clinical situations at minimum cost; second, CBT enables automatic item analysis and score reporting. To establish CBT, constructing an item bank with item parameters such as difficulty or discriminating parameters will be needed. To select more psychometrically sound items, analysis of the items according to item response theory is necessary. CBT has already been introduced in high stakes tests like the United States Medical Licensing Examination and the Medical Council of Canada Qualifying Examination. The National Health Personnel Examination Board in Korea is also planning to introduce a CBT-based version of the National Medical Examination soon. Thus all medical schools in Korea will need to introduce CBT and construct item banks to prepare their students for their licensing examinations and to measure the students’ competency more accurately
Characteristics and Limitations of Bedside Teaching Instructional Models
Authors: Kim Young Jon , Lim Cheol Il
Published: November 2015

As a preliminary approach to developing a bedside teaching program, this study analyzed the instructional models that have been suggested for bedside teaching. The objects of analysis were four models: the ‘Cox model,’ which is composed of an experience cycle and an explanation cycle; the ‘best teaching practice model’ by Janicik and Fletcher; the ‘twelve tips to improve bedside teaching’ by Ramani; and the SNNAPS model for outpatient education by Wolpaw, Wolpaw, and Papp. This study was conducted in three steps. First, we identified the major components of each model and analyzed their characteristics and limitations. Second, we compared each model in terms of four aspects: the learner, learning interaction, learning context, and organization management. Third, on the basis of prior analysis, the possibilities and potential problems of the models were explored. Based on this review of the existing instructional design models, we proposed an additional four key elements for designing a bedside teaching program: multi-layered learners, various learning environments and contexts, time management by using media, and self-directed design.
The Qualitative Research about Students’ Experience of Students Internship: A Case from the Catholic University of Daegu School of Medicine
Authors: Choi Son-Hwan , Yoon Tae-Hong
Published: November 2015

The purpose of this study was to establish a better operation plan for medical school student internship by gaining a deeper understanding of the student internship process. Toward this end, an investigation was carried out using in-depth interviews of students with experience as student internship at Catholic University of Daegu School of Medicine. Students who participated in the student internship program at Catholic University of Daegu School of Medicine took part in the clinic twice every two-week period for a total of four weeks as a member of the care team. The students performed several activities during their internships, including for example history taking, physical examinations, keeping medical records, simulation of writing prescriptions, clinical skills, patient education, night work, and rounds with the attending professor. In this study were analyzed the contents of a student internship, the difference in clerkship, the competence of the faculty, student participation attitudes and the overall effect of the internship on the students. It was found that the in-depth contents, passion of members including professors and students, especially the role of the professor, was more important component than the contents of the internship program or clinical training. The student-intern system was revealed to have the following positive characteristics: 1) education deeper than clerkship was performed through one-on-one faculty-student interaction, and 2) students’ experience was broadened.
New Challenges for Korean Medical Education: Enhancing Students’ Abilities to Deal with Uncertain Ill‐Defined Problems
Authors: Choi Ikseon , Yoon Bo Young
Published: November 2015

Over the last century, medical education in North America has evolved by identifying educational challenges within its own socio-cultural context and by appropriately responding to these challenges. A discipline-based curriculum, organ-system or integrated curriculum, problem-based curriculum, and competency-based curriculum are historical examples of the educational solutions that have been developed and refined to address specific educational challenges, such as students’ lack of basic scientific knowledge, lack of integration between scientific knowledge and clinical practice, and lack of clinical practice. In contrast, Korean medical education has evolved with the influence of two forces: (1) the adoption of educational solutions developed in North America by pioneers who have identified urgent needs for medical education reform in Korea over the last three decades, and (2) the revitalization of Korean medical schools’ curricula through medical education accreditation and national medical licensing examination. Despite this progressive evolution in Korean medical education, we contend that it faces two major challenges in order to advance to the next level. First, Korean medical education should identify its own problems in medical education and iteratively develop educational solutions within its own socio-cultural context. Secondly, to raise reflective doctors who have scientific knowledge and professional commitment to deal with different types of medical problems within a continuum from well-defined to ill-defined, medical education should develop innovative ways to provide students with a balanced spectrum of clinical problems, including uncertain, ill-defined problems.
Primary osteogenic sarcoma of breast
Authors: Srikala Jwala
Published: November 2015

A 60-years-old lady presented with a firm to hard mass in right breast. She was investigated with a mammogram and ultrasound which showed a mass of indeterminate nature with extensive calcifications. An ultrasound guided core biopsy of the mass was performed which was reported as a sarcomatous mass and excision biopsy was requested. Excision biopsy concluded that the mass was an osteogenic sarcoma in the background of a phyllodes tumor. Patient underwent a definitive mastectomy two weeks later. Keywords: Primary osteogenic sarcoma; breast cancer; phyllodes tumor
Management issues in mixed gonadal dysgenesis (45,X/46,XY mosaicism)
Authors: H Babulreddy , G Mounika , S Rakesh , J Ramesh , S Nagesh
Published: November 2015

Mixed gonadal dysgenesis (45X/46XY and its variants) is a form of sex chromosome DSD (disorders of sex development). The clinical presentation of such patients is highly variable and mild variants may go unnoticed. Here we discuss a 16-year-old patient with mixed gonadal dysgenesis (45X/46 XY mosaicism) who was being reared as male, who presented to us with gynaecomastia and the subsequent management issues in such patients. Keywords: disorders of sex development (DSD); Gynaecomastia; testicular biopsy; 45X/46 XY mosaicism
Grappling with the Data Explosion in Oncology
Authors: Warner Jeremy L ,   Assistant Professor of Medicine and Biomedical Informatics, Division of Hematology & Oncology, Departments of Medicine and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, US
Published: November 2015

This editorial reports on the paper “Advances in Website Information Resources to Aid in Clinical Practice” presented at the American Society of Clinical Oncology Annual Congress, Chicago, Illinois, US, June 2015.