bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of thickness on metal to semiconductor transition in La doped BaSnO3 films deposited on high mismatch LSAT substrates
Authors: Kumar Akash , Maurya Sandeep , Chawla Sushobhita , Patwardhan Suren , Kavaipatti Balasubramaniam
Published: May 2019

1% La doped BaSnO3 thin films of different thicknesses, ranging from 15 to 300 nm, were obtained on single crystal Lanthanum Aluminate-Strontium Aluminate Tantalate [LSAT(001)] substrates via Pulsed Laser Deposition. The films grow epitaxially on these substrates (cube-on-cube epitaxy) and are almost relaxed with a strain of ≈0.51% for 300 nm films. All films show n-type conducting behavior with their conductivity varying from 65.36 S cm−1 to 465.11 S cm−1 as the thickness of the film is increased. Low temperature carrier concentration measurements indicate that the films are degenerate semiconductors. Films with a thickness ≥30 nm exhibit metal to semiconductor transition (MST) at low temperatures. Temperature dependent resistivity analysis of the films shows evidence of electron-electron interaction rather than weak localization as the governing transport mechanism below MST. The transition temperature shifts toward lower values at higher thicknesses, strengthening the metallic transport in such films.
Taylor-Couette flow of shear-thinning fluids
Authors: Cagney N. , Balabani S.
Published: May 2019

The flow between two concentric cylinders, one of which is rotating (Taylor-Couette flow), has been the focus of extensive research, due to the number of flow instabilities that may occur and its use in various industrial applications. We examine Taylor-Couette flow of Newtonian and shear-thinning fluids (solutions of xanthan gum in water/glycerol) using a combination of particle-image velocimetry and flow visualization for a wide range of Reynolds number, spanning the circular Couette flow, Taylor vortex flow, and wavy vortex flow regimes. Shear thinning is associated with an increase in the axial wavelength and has a nonmonotonic effect on the critical Reynolds number for transition to Taylor vortex flow and wavy vortex flow. The magnitude of vorticity and the strength of the radial jets transporting fluid away from the inner cylinder (“outward jets”) are both reduced in shear-thinning fluids relative to the Newtonian case; the vorticity in the shear-thinning fluids also tends to concentrate at the edges of vortices, rather than in the cores. In the wavy vortex flow regime for Newtonian fluids, the amplitudes of the waves at the “inward jets” (moving toward the inner cylinder) are low compared to those at the outward jets. However, for the shear-thinning fluids, the amplitudes of the waves at both the inward and outward jets tend to be significantly larger. Finally, shear thinning is associated with greater variations in time and space: we observe slow drifts in the axial positions of vortices and spatial variations in the amplitudes of the wavy instability, which are absent in Newtonian fluids.
On the role of vortical structures in aerodynamic performance of a hovering mosquito
Authors: Zhang Jun-duo , Huang Wei-Xi
Published: May 2019

Mosquitoes have slimmer wings, higher flapping frequencies, and much lower amplitudes than most other insects. These unique features signify special aerodynamic mechanisms. Besides the leading-edge vortex, which is one of the most common mechanisms of flapping-wing flight, mosquitoes have two distinctive mechanisms: trailing-edge vortex and rotational drag. In this study, the three-dimensional flow field around a hovering mosquito is simulated by using the immersed boundary method. The numerical results agree well with previous experimental data. Mechanisms unique to mosquitoes are identified from the instantaneous pressure and vorticity fields. The flow domains, containing several vortical structures produced by the flapping wings, are divided into different regions for quantitatively analyzing the contribution of vortical structures to the lift. Advection of the trailing-edge vortex and production of the leading-edge vortex each contribute peaks in lift. Passive deformation of the wings is also important, as it stabilizes delayed stall and decreases by 26% the maximum aerodynamic power required for hovering flight. In addition, the lift coefficient and power economy are improved as the Reynolds number increases, which explains the better ability of larger mosquitoes to seek and feed on hosts from the aerodynamic point of view.
Stochastic wave packet approach to nonadiabatic scattering of diatomic molecules from metals
Authors: Serwatka T. , Tremblay J. C.
Published: May 2019

In this contribution, we present a quantum dynamical approach to study inelastic scattering of diatomic molecules from metal surfaces at normal incidence. The dissipative dynamics obeys a stochastic Schrödinger equation describing the time-evolution of the system as a piecewise deterministic process. Energy exchange between the molecular vibrational degrees of freedom and the metal electrons is represented using operators in tensor product form, which are coupled via anharmonic transition rates calculated from first-order perturbation theory. Full dimensional observables are obtained by averaging over simulations in 4D—including the internal stretch, the distance to the surface, and the orientation angles—at different surface sites. The method is applied to the state-resolved scattering of vibrationally excited NO from Au(111), revealing important channels for quantized energy relaxation.
Spin wave propagation in ultrathin magnetic insulators with perpendicular magnetic anisotropy
Authors: Chen Jilei , Wang Chuangtang , Liu Chuanpu , Tu Sa , Bi Lei , Yu Haiming
Published: May 2019

Magnetic thin films with perpendicular magnetic anisotropy (PMA) offer opportunities for studying magnetostatic forward volume mode (MSFVM) spin waves with isotropic propagation. Here, we realize the full reciprocal MSFVM spin wave propagation in a 30-nm-thick manganese doped yttrium iron garnet (YIG) with PMA by only applying an external field of 5 mT. The external magnetic field required for investigating the MSFVM spin waves in YIG is reduced by 34 times compared to the in-plane magnetized one. The spin wave group velocity and decay length are also investigated. Our finding paves the way for applications of isotropic magnonic computing systems and logic devices.
Optimal cooperation of a hydrogen storage system and fuel cell to supply electrical and thermal loads
Authors: Mehrjerdi Hasan
Published: May 2019

A framework is planned to supply electrical and thermal loads by joint application of a hydrogen storage system (HSS) and a fuel cell. The system, including electrical and thermal loads, is connected to the upstream network. The bidirectional operation is defined for the system, and the system can buy energy from the grid or sell energy to the grid. A water electrolyzer is applied to produce hydrogen from water and store electricity in the form of hydrogen. The stored hydrogen supplies the thermal loads, as well as the fuel cell. The electrical loads are directly connected to the grid and are supplied by the grid. The electricity is received from the fuel cell at hours 17 to 22. When the price of electricity is high, the electrical loads can receive their power from the fuel cell rather than the grid. Additionally, any excess electricity may be sold to the grid. The uncertainty in the thermal and electrical loads is modeled and formulated as stochastic programming. The hydrogen is fed to the fuel cell and the thermal loads. The proposed model minimizes the daily operational cost of the system. The results demonstrate that the daily operational cost of the system is $22.274 USD/day. The bidirectional operation reduces the daily operational cost by about 79%. The unceratinty increases the cost by about 15%.
Characterization of diamagnetism inside an ECR thruster with a diamagnetic loop
Authors: Correyero S. , Merino M. , Elias Paul-Quentin , Jarrige J. , Packan D. , Ahedo E.
Published: May 2019

The plasma-induced magnetic field in an electron cyclotron resonance plasma thruster is measured non-intrusively by means of a diamagnetic loop that encloses the plasma flow. The calibration process is described, and parasitic currents in the thruster walls and plasma oscillations are identified as the dominant sources of uncertainty. The integrated magnetic flux is seen to depend on the applied power and less significantly on the mass flow rate. The effect of the diamagnetic loop radius is also studied by testing two loops of different diameters. To estimate the perpendicular electron pressure in the plasma from the loop measurements, two plasma beam models, 1D and 2D, are used. While both models give similar results for the small loop, they differ significantly for the large loop, showing the relevance of 2D effects when a large diamagnetic loop is used.
On the influence of electron-beam metal evaporation on parameters of beam plasma in medium vacuum
Authors: Zolotukhin D. B. , Burdovitsin V. A. , Oks E. M. , Tyunkov A. V. , Yushkov Yu. G.
Published: May 2019

We present the results of an investigation of the gas-metal plasma formed by electron-beam evaporation with simultaneous ionization of a copper target in a rare gas (helium) atmosphere at a pressure of 2–12 Pa. It has been found that, in addition to the expected growth of the beam-plasma density, there is a non-monotonic change (growth followed by a decrease) in the electron temperature with the increasing evaporation rate. The indicated temperature behavior of beam-plasma electrons can be explained by a numerical balance model that describes the generation of the beam-plasma from the gas and metal components having different ionization potentials.
Behavioural change in primary care professionals undertaking online education in dementia care in general practice
Authors: Bentley Michael W. , Kerr Rohan , Ginger Margaret , Karagoz Jacob
Published: May 2019

A challenge facing general practice is improving the diagnosis, management and care of people with dementia. Training and education for primary care professionals about knowledge and attitudes about dementia is needed. Online resources can provide educational opportunities for health professionals with limited access to dementia training. An online educational resource (four modules over 3 h) was designed to assist primary care practitioners to develop a systematic framework to identify, diagnose and manage patients with dementia within their practice. Interviews and questionnaires (knowledge, attitudes, confidence and behavioural intentions), with practice nurses and international medical graduates working in general practices, were used to evaluate the resource. Participants’ knowledge, confidence and attitudes about dementia increased after completing the modules. Participants had strong intentions to apply a systematic framework to identify and manage dementia. In post-module interviews, participants reported increased awareness, knowledge and confidence in assessing and managing people with dementia, corroborating the questionnaire results. This project has demonstrated some early changes in clinical behaviour around dementia care in general practice. Promoting the value of applying a systematic framework with colleagues and co-workers could increase awareness of, and participation in, dementia assessment by other primary care professionals within general practices.
Music video as party political communication
Authors: Way Lyndon C. S.
Published: May 2019

Relations between political parties and music are fraught with issues over effectiveness,
limitations and opportunities. On the one hand, political parties and movements use the appeal of popular
music to attract audiences who otherwise may not be attentive to their views. On the other hand, mixing the
two has seen music and politics “reduced to their lowest common denominator” (Street 1988, 50). Here, I examine how political parties employ popular music to
articulate party specific discourses. Leaning on Multimodal Critical Discourse Studies and musicology, I
analyse the lyrics, visuals and musical sounds of musical advertisements prepared for two Turkish political
events: A parliamentary election campaign and a presidential referendum campaign. Through a detailed analysis
I reveal the discourses articulated, how these are articulated and the strengths and shortcomings of musical
advertisements as a means of communicating party political discourses.
Discourse, music and political communication
Authors: Way Lyndon C. S.
Published: May 2019

Political communication is expressed in politicians’ speeches, campaign advertisements and government statements. Politics are also articulated in music, in both traditional political contexts such as anthems and party political broadcasts as well as less traditional contexts including songs, promotional videos and live performances. There is a wide spectrum of opinions as to exactly what are relations between music and politics, though most scholars acknowledge it can communicate meanings, though again, what these are remains contentious. One way to better understand relations between music and politics and meanings expressed in music is to closely examine these issues through the prism of discourses analysis. Through such an examination, not only what is being communicated becomes clear, but also how this is done, contributing to the fields of political communication, musicology and discourse studies.
Study of microstructure degradation and rejuvenation evolution for F-class gas turbine blade
Authors: Tang W. S. , Xiao J. F. , Nan Q. , Gao S. F. , Zhang J. , Li Y. J.
Published: May 2019

Service degradation of F-class gas turbine blade and its microstructure evolution during a simple rejuvenation process are investigated, and then microhardness of the rejuvenated blade is evaluated. The results show that the turbine blade suffers from significant service degradation such as spheroidising, coarsening and rafting of the γ′ phase. It is also verified that the γ′ precipitates microstructure could be recovered and even improved by a full solution followed by two-step aging. The proper solution temperature is necessary to dissolve the deformed γ′ precipitates and allows optimum reprecipitation during next aging. The microstructure of the rejuvenated blade all shows bimodal distribution with coarse and fine γ′ precipitates. The microhardness is higher and more uniformly distributed than that of the service-exposed blade.
Photon momentum induced precision small forces: a static and dynamic check
Authors: Manske Eberhard , Fröhlich Thomas , Vasilyan Suren
Published: May 2019

Practical means of generation and calibration of the small precision forces in static and dynamic regimes around 1 Hz by the usage of radiation pressure effect from 1 W continuous wave visible (diode) laser light is presented. The additive effect of the transfer of photon momentum, caused by non-overlapping multiply reflecting laser beam locked within a quasi-passive and/or active macroscopic cavity system, is employed. The effective laser power (partially trapped experimentally) is amplified, such that the optically generated forces are increased from hundreds of pN to sub-

N level. The results presented in this paper should be seen as a means for extending the edge of practically verifiable lower limits of SI-traceable force metrology.
A New Ranking based Semantic Hashing Method for Deep Image Retrieval
Authors: Gong Haihua , Xing Kai , Li Zitian , Zhang Menghan , Zhong Chunlin , Du Wenwen
Published: May 2019

Visual search in millions of samples in high-dimensional feature space is computationally expensive and challenging. A natural solution is to reduce the dimension of image representation by mapping each sample into compact binary code. In this paper, we propose a Ranking Based Semantic Hashing (RBSH) method to tackle with this problem. Observing that semantic structures carry complementary information, this paper takes advantage of semantic supervision for training high quality hashing, the semantic mapping between the high-dimensional feature space of samples and the reduced representation space of binary code, with the help of pre-trained word2vec. Specifically, the proposed method learns the mapping based on two criteria: the contrastive ranking loss and the orthogonality constraint. The former preserves the ordering of relative similarity in image pairs, while the latter makes different bit in the hash stream as orthogonal as possible. Extensive experimental study has been conducted on VOC2012 and ILSVRC2014 image sets, demonstrating that the proposed approach generally outperforms the state-of-the-art hashing techniques based methods in image search.
Adaptive Sampling for Image Compressed Sensing Based on Deep Learning
Authors: Zhong Liqun , Wan Shuai , Xie Leyi
Published: May 2019

The compressed sensing (CS) theory has been applied to image compression successfully as most image signals are sparse in a certain domain. In this paper, we focus on how to improve the sampling efficiency for network-based image compressed sensing by using our proposed adaptive sampling algorithm. We conduct content adaptive sampling to achieve a significant improvement. Experiments results indicate that our proposed framework outperforms the state-of-the-arts both in subjective and objective quality. An average of 1-6 dB improvement in peak signal to noise ratio (PSNR) is observed. Moreover, the proposed work reconstructs images with more details and less image blocking effects, leading to apparent visual improvement.
Super-resolution Geometry Processing Technology for Ill-sampled Astronomical Images
Authors: Zhang Shixue , Ling Jianyong , Huang Chunyu
Published: May 2019

In order to improve the cell sensitivity or to satisfy the needs of a large field of view, a large size CCD pixel is usually chosen as detection unit in optical imaging systems. However, this methodology cannot meet the Nyquist sampling theorem, and thus generate ill-sampling images. In other words, the geometric resolution of images in optical diffraction limited systems is directly restricted by the size of CCD pixel. In this paper, a carefully designed optical mask is implemented to ensure loseless images before CCD sampling. By applying spatial spectral filtering technology, we can acquire images with appropriate resolution. The method presented in this paper significantly abates the resolution decline due to ill-sampling. By mathematical deduction and simulation, the geometric super resolution images can be achieved.
Chinese Movie Comment Sentiment Analysis Based on HowNet and User Likes
Authors: Liu Yanqiu , Duan Zekun
Published: May 2019

Emotional information in movie comments is critical to sentiment analysis, Sentiment analysis, which focuses on classify the comments into positive class and negative class according to sentiment lexicon, is one of the studies. Most of the existing researches are centered on sentiment words and user rating, while the user’s attitude towards comments are ignored. And, considering that Chinese is the second largest language in the world. In this paper, in order to get this point to be considered, we propose a method for Chinese movie comments sentiment analysis based on HowNet and user likes which we called HAL. Our research consists of four parts. First, we use HowNet sentiment lexicon to get a new lexicon in the field of movies. Second, we use the new lexicon and word segmentation tool named Jieba to segment the movie comments. Third, we use the user likes and sentiment words to get the positive feature and negative feature. Finally, we train the movie comment data using three models (SVC, LinearSVC, LogisticRegression). The experimental results show that our method performs better than HowNet-based method in Chinese movie comment sentiment analysis.
Segmentation of MR Breast Cancer Images based on DWT and K-means algorithm
Authors: Yuan Gaoteng , Liu Yihui , Huang Wei
Published: May 2019

Breast-conserving surgery followed by radiotherapy to the whole breast and boost irradiation to the lumpectomy cavity (LC) is the standard strategy for the early stage breast cancer patients. Accurate segmentation of the target volume is a prerequisite for accurate radiotherapy, which directly affects the success or failure of tumor treatment. The current delineation of target is mainly done by manual drawing, which is time-consuming, laborious and easy to be affected by subjective factors. To solve this problem, we enhance the MR breast images using DWT (discrete wavelet transform) to get more detail of MR image feature firstly. Secondly, we use K-means algorithm to classify the feature vectors and establish the image segmentation model. Finally, compared with the traditional threshold segmentation method, the model is most suitable for automatic delineation of radiotherapy target area and the setting of optimal parameters are obtained. This method can realize the accurate automatic delineation of target area basically, and solve the problem of lack of accuracy and standardization in current tumor bed delineation.
A Wearable Vision-To-Audio Sensory Substitution Device for Blind Assistance and the Correlated Neural Substrates
Authors: Ye Yaozu , Wang Kaiwei , Hu Weijian , Li Huabing , Yang Kailun , Sun Lei , Chen Zuobing
Published: May 2019

There are a very few people who have the ability to “see” the surroundings by the echoes, which is called echolocation. The study of the brain mechanism of echolocation can not only help to improve the blind assistance device, but also provides a window into the research of brain’s plasticity. In this paper, we developed a wearable system to transform the spatial information captured by camera into a voice description and fed it back to blind users which is inspired by echolocation. After our online virtual scene training, users can easily discriminate object location in the camera’s view, motion of the objects, even shape of the objects. Compared with natural echolocation, it’s easier to learn and be applied in daily life. In addition, the device achieves high spacial resolution. In this study, two trained blind subjects and two non-trained sighted subjects were tested by using functional Magnetic Resonance Imaging (fMRI). We obtain the fMRI images of the subjects’ brain activity when they were listening to the sound of the wearable prototype. Intriguingly, we find that after training with the blind assistance system, the blind’ visual area of the brain have been activated when they are dealing with the acoustic feedback from the device.
Image Completion Based on Gans with a New Loss Function
Authors: Huang Ying , Wang Maorui , Qian Ying , Lin Shuohao , Yang Xiaohan
Published: May 2019

Recently, many approaches based on deep learning have demonstrated amazing capabilities in varieties of challenging image tasks, such as image classification, object detection, semantic and instance segmentation, and so on. These methods are more capable of extracting deeper features than traditional methods, which is critical for different kinds of image tasks. Similarly, these methods are gradually applied to the work of image completion of natural images. In consideration of the fact that most of the current methods would lead to blurring and fake results, we propose an image completion method based on the generation adversarial network. We use the network structure of the encoder and decoder to obtain the high-level feature information of the image and generate reasonable pixel values to fill the missing regions. Besides, we construct a new joint loss function based on SSIM evaluation indicators, which can retain the similarity between two images as much as possible. Our proposed method can keep the completion regions consistent with the surrounding pixels, which makes the images look more realistic. We evaluate on our datasets with our proposed method and compare with other methods in this paper, our results are sharper and more realistic than the previous ones.
Face Anti-Spoofing Using Texture-Based Techniques and Filtering Methods
Authors: Hasan Md Rezwan , Hasan Mahmud S M , Li Xiang Yu
Published: May 2019

User authentication for an accurate biometric system is the demand of the hour in today’s world. When somebody attempts to take on the appearance of another person by introducing a phony face or video before the face detection camera and gets illegitimate access, a face presentation attack usually happens. To effectively protect the privacy of a person, it is very critical to build a face authentication and anti-spoofing system. This paper introduces a novel and appealing face spoof detection technique, which is primarily based on the study of contrast and dynamic texture features of both seized and spoofed photos. Valid identification of photo spoofing is anticipated here. A modified version of the DoG filtering method, and local binary pattern variance (LBPV) based technique, which is invariant to rotation, are designated to be used in this paper. Support vector machine (SVM) is used when feature vectors are extracted for further analysis. The publicly available NUAA photo-imposter database is adapted to test the system, which includes facial images with different illumination and area. The accuracy of the method can be assessed using the false acceptance rate (FAR) and false rejection rate (FRR). The results express that our method performs better on key indices compared to other state-of-the-art techniques following the provided evaluation protocols tested on a similar dataset.
Alarm Audit and Enforcement: Automating the Integrity of Alarms for Manufacturing Systems
Authors: Ault T. , Yang L.
Published: May 2019

This work details the development of a continuous monitoring system technology to track the compliance of alarms in a manufacturing environment. A problem arose due to having simultaneous capital projects and continual process optimization work at several production sites. With continual changes to the control systems, a project was developed to ensure that alarm adjustments never violated established safety thresholds for systems. A technique was used to rationalize alarms using a risk based objective analysis to establish safety thresholds for each alarm. Then a tool was developed that continually cross-referenced alarm safety server with process control network to immediately notify management and engineering of any adjustments that violated alarm and safety rules for the site. This work led both to improved site safety and to an improvement of alarm metrics due to greater confidence in adjusting alarms with this audit tool. One site saw a monthly reduction of the quantity alarms by 55% and the elimination of alarm floods.
Experiment and Simulation on Heavy Oil Production with Steam Flooding in Heterogeneous Reservoir
Authors: Maneeintr K , Sasaki K , Boonpramote T
Published: May 2019

Heavy oil has long been known as one of the main energy sources due to the huge amount of reserves. Heavy oil production depends on reservoir characteristics like permeability, reservoir pressure as well as oil viscosity. The difficulty to produce this oil is its high viscosity. The practical technology to produce this heavy oil is to use steam as steam-flooding method to reduce oil viscosity. However, the huge energy consumption in steam-flooding operation can impact the operating cost as well as a project life. Therefore, the objectives of this study are to measure the viscosity and correlate the results with temperature and to simulate the oil production by using STARS, a CMG program. Moreover, the effects of parameters like well distance, injection rate and permeability on the oil production are also investigated. The simulation results show that oil viscosity and permeability play significant roles in heavy oil production. Also, the higher oil recovery can be obtained by increasing the steam injection rate and shorten the well spacing. These conditions can be applied to use in the real field for heavy oil production. The major benefit of this practice is to reduce the steam consumption and fuel costs and increase more oil production thus extending the economic project life.
Potential and future: utilization of waste material on strength characteristics of marine clay
Authors: Jamaludin N , Mohd Yunus N Z , Jusoh S N , Pakir F , Ayub A , Zainuddin N E , Hezmi M A , Mashros Nordiana
Published: May 2019

The utilization of waste materials has been a sustainable approach to soil improvement that took an interest in a number of researchers. Statistics show that out of the 76 percent of solid waste that is collected in Malaysia, only 5% is recycled while 95% of waste were dumped at landfills. This shows that there is a need to reutilize waste materials. This paper aims to discuss the different types of waste materials which are demolished tile material (DTM), demolished concrete material (DCM) and coal ash waste to improve the properties of marine clay. Experimental studies have been conducted by varying percentages of waste materials ranging from 5 – 15% with curing periods of 0, 7 and 28 days. Unconfined compressive strength test (UCS) was performed in order to determine the strength of these mixtures. The results obtained were that for both DCM and coal ash waste when mixed with marine clay would increase the strength of soil with increasing curing period. While for DTM, the strength of soil decreases with the immediate addition of additive but will later increase its strength gradually. Hence, the outcome obtained from this study is that both DCM and coal ash is suitable for the stabilization of marine clay soil while DTM is suitable for long term stabilization on marine clay.
Effect of water salinity on the compaction of Sabkha soils
Authors: Messad Ali , Yahia Debbab Oussama , Moussai Belkacem
Published: May 2019

Algeria is nowadays bustling with extensive infrastructure projects (highways, roads, railways, etc) where most of them are planned to be constructed over areas covered with Sabkha soils. These soils are recent saline sediments widely distributed in Algeria and other countries. In this study, the effect of water salinity on the compaction characteristics of the Sabkha soils of Chott El-Hodna (Algeria) was investigated. The standard Proctor tests were performed using distilled water and Sabkha brine, and the compaction characteristics were determined using conventional water content and fluid content methods. The results indicate that the conventional water content procedure used to plot the compaction curve overestimate the maximum dry unit weight and underestimate the optimum moisture content.
Computation of vertical bearing capacity factor Nc of strip footing by FEM
Authors: Ty Phuor , S H Harahap Indra , Cheng Yee Ng
Published: May 2019

Thispaper presents the computation of vertical bearing capacity factor N
c of the smooth and rough strip footings using the finite element algorithm based elasto-viscoplasticstrain method. The soil behaviour is idealized as elastic perfectly plastic satisfying the Mohr Coulomb yield criterion with only non-associated flow rules because it tends to treat the actual behaviour of soil in which value of its frictional angle is always different from that of dilative angle. The bearing resistance is computed using the superposition assumption in Terzaghi classical equation in the way that the surcharge pressure and the unit weight of soil are neglected. Consequently, N
c is determined. The comparison of the present solutions with the previous published works including experimental and numerical studies have been presented and discussed. The results reveal in close agreement with the existing published data. In the nutshell, by applying the non-associated soil flow rule representing the real behaviour of soil, the conservation of the superposition assumption is confirmed. Therefore, it could conclude that the results obtaining from these techniques may be confidently applied to a wide range of soil bearing resistance problems. The magnitudes of the factors for a rough footing base provide the same values as the smooth footing for the entire range of soil friction angles (phi).
Geochemistry characterisation of marine clay
Authors: Saleh Samaila , Asmawisham Alel Mohd Nur , Mohd Yunus Nor Zurairahetty , Ahmad Kamarudin , Ali Nazri , Abang Hasbollah Dayang Zulaika , Asnida Abdullah Rini
Published: May 2019

In evaluating a suitable type of stabiliser, investigating geochemical characteristics is important for improving the properties of soil. This paper assessed the geochemistry of marine clay samples collected from Batu Pahat, Johor, Malaysia. The parameters investigated were pH, loss on ignition (LOI) and the quantities of sulphate, chloride, nitrate and carbonate ions. The results revealed that the clay was an acidic soil with pH of 3.25 and containing 8% of organic matter. The clay also contained 6,071 mg/l, 281 mg/l and 22 mg/l of sulphate, chloride and nitrate ions, respectively. Sulphate and chloride ions from acid rain and decomposed organic matters are the leading causes of acidity found in clay. Further investigation of the physical properties of the soil further indicated that it belonged to a group of clay having high plasticity (CH) and is unsuitable for construction purposes in its natural condition. The concentration of sulphate ions in the clay sample also advocated that the soil is not suitable to be stabilised using cement or lime due to the risk of the formation of a complex compound of calcium sulphoaluminate hydrate (ettringite). Additionally, the sulphate in the marine clay is likely to attack the concrete of the foundation of future infrastructures that may be built in the study area.
Flexural strength properties of porous concrete pavement incorporating nano black rice husk ash
Authors: Jaya R P , Mohamad Idris A , Mohd Ibrahim M Y , Hainin M R , Yaacob H , Hassan N A , Mohd Haziman W I , Ekarizan S
Published: May 2019

Rice husk ash (RHA) as replacement material in the conventional concrete mixture has widely investigated around the world. However, there is a lack of study on nanoparticle produced from black rice husk ash (BRHA) used as a replacement material in porous concrete pavement mixture. Therefore, this study aims to evaluate the flexural strength properties of porous concrete pavement containing nano black rice husk ash. A nano BRHA dosage of 0, 10, 20, 30 and 40% by weight of binder used throughout the experiments. The total cementitious content used was 450 kg/m3 with a water/binder ratio of 0.34. It found that there appears to be an optimum replacement of approximately 10% nano BRHA, during which time the flexural strength and flexural activity index increase significantly.
Drivers behaviour on expressways: headway and speed relationships
Authors: Puan O. C. , Mohamed A. , Idham M. K. , Ismail C. R. , Hainin M. R. , Ahmad M. S. A. , Mokhtar A.
Published: May 2019

This paper describes result of a study on driver’s car following behaviour on Malaysian high-speed highways. Drivers’ car following behaviour can considered as one of the main factors that causes road accidents to occur such as rear end collision between vehicles on highways. The aim of the study was to examine the safe following distance adopted by drivers on expressways at various operating speeds. An automatic traffic recording device attached with pneumatic tubes was used to record traffic movement at three selected expressway segments in Malaysia for six consecutive days. More than one hundred thirty three thousand (133,000) headway and speed data were involved in the analysis. The distance headway and associated speed collected were classified into five vehicle following categories by vehicle type, i.e. all vehicles, car following car, car following heavy goods vehicle (HGV), HGV following HGV, and HGV following car. Linear regression models were used to develop relationship between distance headway and speed. The relationships developed can be regarded as reliable since the R2-values for each of the relationships is in the range of 0.80 to 0.99 and can be used to estimate a safe following distance perceived by a driver at a given speed. The driver’s average response time on an expressway is 3.06 sec which is 1.9 sec longer than those who are driving on a two-lane single-carriageway road. Such a variation in response time indicates that the level of aggressiveness of drivers on a two-lane single-carriageway road are higher than the drivers on an expressway.
Walkability assessment tool for a developing country
Authors: Nasrin S. , Afifah F.
Published: May 2019

In Dhaka, which is the capital city of Bangladesh, significant percentages of commuters walk to meet their daily commuting demand. However, there is scarcity of research in Dhaka for walkability assessment. This research tried to overcome that scarcity by developing a measurement tool to assess the walking environment. Methodological approach adopted by this research is the combination of subjective and objective method. Assessment results were converted into 1-point scale. Results showed that Dhaka is seriously lack of good quality footpath and disable facilities. Excessive noise pollution is also one of the significant issues for pedestrians in Dhaka. Any other similar cities walking environment can be assessed by this approach.
Car following behaviours on multilane highways in Kuwait: a case study on 6th ring road
Authors: Alenzi E. , Puan O. C. , Hassan S. A.
Published: May 2019

Reckless driving causes around 35% of all the road accidents in Kuwait. This study aims to evaluate the relationship between speed and headway of traffic for highways in Kuwait. The data were collected at 6th ring road in Kuwait for a week. The data were classified and analysed to estimate the behaviour of small, medium and large cars in addition to trucks. The analysis shows that the 33.68% of the cars are flowing in a speed between 70 and 80 km/hr. The effect of classified car (small, medium, large and truck) to the car-following pattern were determined based on the average headway of the cars. It was found that the Small – Small following pattern has the minimum average headway in all lanes with headway of 1.62 s. Also, the maximum average headway is for Medium – Medium car following pattern with headway of 8.01 s. It was found that there is no relationship between the type of following pattern and the headway in which it supports the previous studies conclusion that only the driver behaviour, weather conditions and road quality affect the headway. Finally, a linear regression for data was plotted to estimate relationship of the average headway as a function of speed for 16 different following patterns. It was found that the accuracy of linear regression for small and medium cars is larger than the accuracy for large cars and trucks.
Investigation of the microstructure adjustment by velocity variations during the directional solidification of Al-Ag-Cu with the phase-field method
Authors: Hötzer J. , Kellner M. , Kunz W. , Nestler B.
Published: May 2019

Directional solidification is a favored process to manufacture homogeneous microstructures which lead to macroscopically unique properties for a material. The dependence of the spacing and type of the arising microstructure from the solidification velocity for constant velocities is extensively investigated. However the effect of changes in the solidification velocity on the resulting microstructure adjustment processes is still unclear. Therefore large-scale (3D+t) simulations of the ternary eutectic system Ag-Al-Cu with changing solidification velocities are conducted with a phase-field model based on the grand potential approach. To study the spatially complex rearrangement process during velocity changes in statistical representative volume elements, simulations with different velocity profiles are calculated in large-scale domains. The results show, that the evolving microstructure continuously rearranges by splitting and merging of the rods despite constant growth conditions. By increasing the velocity, the microstructure refines by splitting of the Al2Cu phase. Whereas by decreasing the velocity, the microstructure coarsens by overgrowing events of both intermetallic phases.
Solidification path and phase transformation in super-austenitic stainless steel UNS S31254
Authors: Marin Raphaël , Combeau Hervé , Zollinger Julien , Dehmas Moukrane , Rouat Bernard , Lamontagne Aude , Cardinaux David , Lhenry-Robert Lucile
Published: May 2019

The solidification path and the σ-phase precipitation mechanism of UNS S31254 alloy were studied on the basis of directional solidified experiments accompanied by scanning electron microscopy observations and energy dispersive X-ray a nalysis. The resulting temperatures of solidification paths and phase transformation were compared with Gulliver-Scheil and equilibrium calculations predicted using ThermoCalc© software. It was confirmed that the experimental solidification path was in agreement with the thermodynamic calculations. The complementarity of the results have made it possible to propose a solidification path and a σ-phase precipitation mechanism for the UNS31254 steel.
Impact of gravity-related phenomena on the grain structure formation: comparative study between horizontal and vertical solidification of a refined Al-20wt.%Cu alloy
Authors: Soltani H , Reinhart G , Benoudia M C , Zahzouh M , Nguyen-Thi H
Published: May 2019

On earth, gravity-related phenomena are unavoidable, such as thermo-solutal convection caused by density gradients in the melt and buoyancy when the liquid phase is denser than the solid phase. Such phenomena can drastically affect both the grain density and their morphology during equiaxed solidification processes. For these reasons, fundamental studies comparing the influence of solidification parameters with and without gravity effects are important to obtain benchmark data, which are useful to understand and then control the final structure of materials in industrial processes. In the present work, the impact of the solidification parameters on the dendritic grain structure formation and on the final grain size and shape was investigated in situ by using X-radiography for different growth orientations with respect to gravity. In a first step, experiments were carried out with various solidification parameters and with the furnace in horizontal position, with the main surface of the sample being perpendicular to gravity to limit gravity-related phenomena. In a second step, experiments were carried out with identical solidification parameters but with the furnace in a vertical position, and for two solidification directions (upward and downward). A comparative study between horizontal and vertical experiments was carried out. Phenomena related to gravity have been highlighted and their respective impact on the solidification front propagation was analysed.
Microstructure in A356/AA6xxx after bimetallic casting with flux coating
Authors: Opsal Bakke Aina , Arnberg Lars , Li Yanjun
Published: May 2019

This work focuses on bimetallic casting between A356 alloy melt and profiles of AA6xxx wrought aluminum alloys through a gravity casting process, with the aim to improve the component’s mechanical properties. However, combining two aluminum alloys is difficult due to the stable aluminum oxide present on the surface of the aluminum inserts and the advancing liquid melt front. The oxide layer strongly reduces the wettability between aluminum melt and solid metal. It will also prevent diffusion and formation of a metallurgical bond. In order to obtain sound metallic bonding between the two alloys, different surface treatments, including flux coating and chemical treatments of the profiles have been tested. The influences of preheating temperature and melt flow modes on the quality of the bimetallic casting have been addressed. Based on a detailed microstructure characterization of the bonding layer in the casting, by using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), the solidification structure development at the interface has been discussed. Results showed that when flux coating was applied, magnesium diffused to the insert surface and prevented formation of a metallurgical bond. Without flux coating, a metallurgical bond was achieved due to slight melting of the insert surface.
A novel route to the coupling of molecular dynamics and phase-field simulations of crystal growth
Authors: Bollada P C , Men H , Fang C , Jimack P K , Fan Z , Mullis A M
Published: May 2019

Molecular dynamic simulations, ab initio (DFT) calculations and experimental evidence suggests that there is a liquid-solid transition region which may be characterised by an order parameter. In this interface region the order parameter is not observed to be symmetrical, rather it tends to be steep on the solid side and exponentially decreasing on the liquid side. The order parameter in phase field computations is, to date, always assumed to give a symmetrical interface region. Hence, we ask how to extend the phase field model to give a profile that fits this data, and how such a model affects the simulation.
Mechanisms of TiAl alloys isomorphic inoculation from cryo-milled Ti-Al-Nb powders
Authors: Zollinger J. , Kennedy J.R. , Brodu E. , Rouat B. , Bouzy E.
Published: May 2019

Isomorphic inoculation has recently been introduced by the authors as a successful method to grain refine cast titanium aluminides [1]. Analyses of the cast grain size together with introduced particle size distributions revealed anomalously high grain refinement efficiency which was attributed to the particles breaking up during the holding stage prior to solidification [2]. In the present work, the microstructure of the inoculant powders is investigated in both the cryo-milled state as well as after simulated thermal cycles to reproduce their heating and holding in the melt. Results show that milling time does not impact the grain size in the particles, only their size distributions. Heat treatments between 1500 and 1600°C for short periods of time allowed the activation energy for grain growth and evaluation of the grain size evolution in the particles during the isomorphic inoculation process to be determined. Assuming that grain boundary melting is the predominant break up mechanism, a model to estimate dissolution of the powders is presented which includes diffusion and fluid flow. Despite its relative simplicity, the predicted number of particles remaining after heating and holding, which lead to grains in the as-cast structure, are in good agreement with the measured grain size. Finally, the paper summarizes the main features and mechanism making isomorphic inoculation a promising route for grain refining as-cast alloys.
Online Modelling of Heat Transfer, Solidification and Microstructure in Continuous Casting of Steel
Authors: Louhenkilpi S , Miettinen J , Laine J , Vesanen R , Rentola I , Moilanen J , Visuri V-V , Heikkinen E-P , Jokilaakso A
Published: May 2019

Advanced numerical simulation models for continuous casting of steel were developed in Finland by Casim Consulting and Aalto University in cooperation with the University of Oulu and the steel industry. The aim was to develop models that are scientifically rigorous, but also computationally fast enough to be used in online applications. The models developed are a transient three-dimensional heat transfer model, CastManager, and a solidification and microstructure model, IDS. The computing time of these models are short, and they are integrated together in one online concept. This concept is installed in the automation systems of four slab casters in Finland. Testing and validation work is in progress. The system simulates the important heat transfer, solidification and microstructural phenomena in continuous casting online. The future aim is that this information will be used for online quality control and for optimizing the process conditions to avoid formation of defects. Many quality indices have already been developed. A steady state version of the CastManager tool has also been developed, called Tempsimu.