bluuebunny/crossref_metadata_2025 huggingface dataset:
Determining Soil-Water Characteristic Curves from Mercury Intrusion Porosimeter Test Data Using Fractal Theory
Authors: Tao Gaoliang , Chen Yin , Xiao Henglin , Chen Qingsheng , Wan Juan
Published: February 2019

Accurate determination of soil-water characteristic curve (SWCC) is of immense importance for understanding the mechanical behavior of unsaturated soils. Due to the difficulty and long duration of experimental procedures, it is of great significance to estimate the SWCC by indirect methods. To address this issue, in this article an effective fractal method is proposed for predicting the SWCC based on mercury intrusion porosimeter (MIP) data. Only two characteristic parameters, namely the fractal dimension and air-entry value, are needed in the presented approach. Detailed procedures for determining the parameters are clearly elaborated. Due to the influence of sample size difference on the equivalent connected pore size, a sample scale effect coefficient is proposed to predict air-entry values. The concept of “critical pore size” is introduced to obtain the optimal fractal dimension, which can accurately reflect the fractal behaviour of SWCC samples. By comparisons between predicted and experimental SWCCs, the validation of the proposed method is verified. The comparisons reveal the good agreement between the proposed approach and laboratory experiments.
Adaptive Gains Control Scheme for PMSG-Based Wind Power Plant to Provide Voltage Regulation Service
Authors: Dai Jianfeng , Tang Yi , Yi Jun
Published: February 2019

High-penetration wind power will count towards a significant portion of future power grid. This significant role requires wind turbine generators (WTGs) to contribute to voltage and reactive power support. The maximum reactive power capacity (MRPC) of a WTG depends on its current input wind speed, so that the reactive power regulating ability of the WTG itself and adjacent WTGs are not necessarily identical due to the variable wind speed and the wake effect. This paper proposes an adaptive gains control scheme (AGCS) for a permanent magnet synchronous generator (PMSG)-based wind power plant (WPP) to provide a voltage regulation service that can enhance the voltage-support capability under load disturbance and various wind conditions. The droop gains of the voltage controller for PMSGs are spatially and temporally dependent variables and adjusted adaptively depending on the MRPC which are a function of the current variable wind speed. Thus, WTGs with lower input wind speed can provide greater reactive power capability. The proposed AGCS is demonstrated by using a PSCAD/EMTDC simulator. It can be concluded that, compared with the conventional fixed-gains control scheme (FGCS), the proposed method can effectively improve the voltage-support capacity while ensuring stable operation of all PMSGs in WPP, especially under high wind speed conditions.
Investigating Permeability of Coal Samples of Various Porosities under Stress Conditions
Authors: Kudasik Mateusz
Published: February 2019

Among the numerous factors that have an impact on coal permeability, coal porosity is one of the main parameters. A change in the mechanical stress applied to coal results in a change of porosity. The main objective of the conducted research was to answer the following question: is a decline in coal permeability a direct effect of a decrease in coal porosity, and does mechanical stress result solely in a porosity change? A study of coal porosity under mechanical stress conditions was conducted using a uniquely constructed measurement stand. The coal samples used were briquettes prepared from a granular coal material (middle-rank coal of type B—meta bituminous, upper carboniferous formation) from the “Zofiówka” coal mine, in Poland. In order to describe coal permeability, the Klinkenberg equation was used, as it takes into consideration the slippage effect, typical of porous media characterized by low permeability. On the basis of the obtained results, it was established that the values of the Klinkenberg permeability coefficient decrease as the mechanical stress and the corresponding reduction in porosity become greater. As the briquette porosity increased, the Klinkenberg slippage effect: (i) disappeared in the case of nitrogen, (ii) and was minor for methane. The briquettes used were characterized by various porosities and showed that mechanical stress results mainly in a change in coal porosity, which, in turn, reduces coal permeability.
Investigation of Elastomer Seal Energization: Implications for Conventional and Expandable Hanger Assembly
Authors: Patel Harshkumar , Salehi Saeed
Published: February 2019

Elastomer seals are extensively used in various wellhead and casing/liner hanger equipment as barriers for isolating fluids. Seal assemblies have been identified as one of the major cause of well control incidents. Majority of hangers utilize conventional weight- or mechanical-set slip-and-seal assembly. The objective of this paper is to conduct a detailed investigation of seal energization in conventional and relatively newer expandable type hanger seal assembly. To achieve the objective, the finite element modeling approach was employed. Three dimensional computer models consisting of concentric casings and annular elastomer seal element were constructed. Seal energization process was modelled by manipulating boundary conditions. Conventional seal energization was mimicked by applying rigid support at the bottom of elastomer element and compressing it from the top. Expandable hanger type seal energization was modelled by radially displacing the inner pipe to compress annular seal element. Seal quality was evaluated in terms of contact stress values and profile along the seal-pipe interface. Different amounts of seal energization were simulated. Both types of seal energization processes yielded different contact stress profiles. For the same amount of seal volumetric compression, contact stress profiles were compared. In case of conventional seal energization, contact stress profile decreases from the compression side towards support side. The seal in expandable hanger generates contact stress profile that peaks at the center of contact interface and reduces towards the ends. Convectional seal assembly has more moving parts, making it more prone to failure or under-energization. Finite Element Models were validated using analytical equations, and a good match was obtained. The majority of research related to elastomer seal is focused on material properties evaluation. Limited information is available in public domain on functional design and assessment of seal assembly. This paper adds novel information by providing detailed assessment of advantages and limitations of two different seal energization process. This opens doors for further research in functional failure modes in seal assembly.
From Wounded Knee to Sacred Circles: Oglala Lakota Ethos as “Haunt” and “Wound”
Authors: Meyer Craig A.
Published: February 2019

Oglala Lakota ethos manifests a pre-Socratic/Heideggerian variant of ethos: ethos as “haunt”. Within this alternative to the Aristotelian ethos-as-character, Oglala ethos marks out the “dwelling place” of the Oglala Lakota people. That is, the Oglala Lakota ground their cultural- and self-identity in the land: their ethology, in effect, expresses an ecology. Thus, an Oglala Lakotan ethos cannot be understood apart from its nation’s understanding of the natural world—of its primacy and sacredness. A further aspect of the Oglala Lakotan ethos rests in the nation’s history of conflict with EuroAmericans. Through military conflict, forced displacement, and material/economic exploitation of reservation lands, an Oglala Lakota ethos bears within itself a woundedness that continues to this day. Only through an understanding of ethos-as-haunt, of cultural trauma or woundedness, and of the ways of healing can Oglala Lakota ethos be fully appreciated.
A Modified Design of a Hexagonal Circular Photonic Crystal Fiber with Large Negative Dispersion Properties and Ultrahigh Birefringence for Optical Broadband Communication
Authors: Biswas Shovasis Kumar , Arfin Rishad , Habib Ashfia Binte , Amir Syed Bin , Zahir Zunayeed Bin , Islam Mohammad Rezaul , Hussain Md. Shahriar
Published: February 2019

In this paper, we propose a modified design of a hexagonal circular photonic crystal fiber (HC-PCF) which obtains a large negative dispersion and ultrahigh birefringence simultaneously. The optical properties of the proposed HC-PCF were investigated using the finite element method (FEM) incorporated with a circular perfectly matched layer at the boundary. The simulation results showed large negative dispersion of −1044 ps/nm.km and ultrahigh birefringence of 4.321 × 10−2 at the operating wavelength of 1550 nm for the optimum geometrical parameters. Our proposed HC-PCF exhibited the desirable optical properties without non-circular air holes in the core and cladding region which facilitates the fabrication process. The large negative dispersion of the proposed microstructure over the wide spectral range, i.e., 1350 nm to 1600 nm, and high birefringence make it a suitable candidate for high-speed optical broadband communication and different sensing applications.
An Approach to Robust INS/UWB Integrated Positioning for Autonomous Indoor Mobile Robots
Authors: Liu Jianfeng , Pu Jiexin , Sun Lifan , He Zishu
Published: February 2019

The key to successful positioning of autonomous mobile robots in complicated indoor environments lies in the strong anti-interference of the positioning system and accurate measurements from sensors. Inertial navigation systems (INS) are widely used for indoor mobile robots because they are not susceptible to external interferences and work properly, but the positioning errors may be accumulated over time. Thus ultra wideband (UWB) is usually adopted to compensate the accumulated errors due to its high ranging precision. Unfortunately, UWB is easily affected by the multipath effects and non-line-of-sight (NLOS) factor in complex indoor environments, which may degrade the positioning performance. To solve above problems, this paper proposes an effective system framework of INS/UWB integrated positioning for autonomous indoor mobile robots, in which our modeling approach is simple to implement and a Sage–Husa fuzzy adaptive filter (SHFAF) is proposed. Due to the favorable property (i.e., self-adaptive adjustment) of SHFAF, the difficult problem of time-varying noise in complex indoor environments is considered and solved explicitly. Moreover, outliers can be detected and corrected by the proposed sliding window estimation with fading coefficients. This facilitates the positioning performance improvement for indoor mobile robots. The benefits of what we propose are illustrated by not only simulations but more importantly experimental results.
Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering
Authors: Su Yarong , Shi Yuanzhen , Wang Ping , Du Jinglei , Raschke Markus B , Pang Lin
Published: February 2019

In surface-enhanced Raman scattering (SERS), both chemical (CE) and electromagnetic (EM) field effects contribute to its overall enhancement. However, neither the quantification of their relative contributions nor the substrate dependence of the chemical effect have been well established. Moreover, there is to date no understanding of a possible coupling between both effects. Here we demonstrate how systematically engineered silver and gold planar and nanostructured substrates, covering a wide range of field enhancements, provide a way to determine relative contributions of chemical and electromagnetic field-enhancement in SERS measurements of benzenethiol. We find a chemical enhancement of 2 to 14 for different vibrational resonances when referencing against a vibrational mode that undergoes minimal CE. The values are independent of substrate type and independent of the enhancement of the electromagnetic intensity in the range from 1 to 106. This absence of correlation between chemical and electromagnetic enhancement resolves several long-standing controversies on substrate and intensity dependence of the chemical enhancement and allows for a more systematic design of SERS substrates with desired properties.
ESTIMATING NORMAL DURATION OF RENOVATION FOR MULTISTORY APARTMENT BUILDING CONSIDERING EXTENSION-TYPE RENOVATION PROJECTS
Authors: Yoon Jongsik , Yu Ilhan
Published: February 2019

Normal (typical) project duration is estimated at the initial stage of a renovation project and is an important reference for project control. However, its estimation has not been researched extensively owing to the complexity and uncertainties of renovation. Thus, a model was developed for predicting the duration of sustainable apartment renovation. Experts were asked to estimate a baseline schedule for extension-type renovation projects, factors that influence critical path activities, and the range of project durations considering these factors. An equation for estimating the duration of a renovation project was developed, and the range of project durations was derived using a MCS to reflect uncertainty. The proposed model was validated by applying it to actual cases. The case study shows that the model would be more suitable for complex renovation construction (i.e., more than two buildings or vertical extension). The model can be applied to various renovation projects and used as a reference for determining contract time. It can fill the knowledge gap of construction duration forecasting by adapting the concept of control activities to simplify the assessment of uncertainties in renovation of apartments, and can be applied for forecasting sustainable renovation time for other project types or in other locations.
The Double-peaked Radio Light Curve of Supernova PTF11qcj
Authors: Palliyaguru Nipuni T. , Corsi Alessandra , Frail Dale A. , Vinkó Jozsef , Wheeler J. Craig , Gal-Yam Avishay , Cenko S. Bradley , Kulkarni Shrinivas R. , Kasliwal Mansi M.
Published: February 2019

We present continued radio and X-ray follow-up observations of PTF11qcj, a highly energetic broad-lined Type Ic supernova (SN), with a radio peak luminosity comparable to that of the γ-ray burst (GRB) associated SN 1998bw. The latest radio observations, carried out with the Karl G. Jansky Very Large Array, extend up to ∼5 yr after the PTF11qcj optical discovery. The radio light curve shows a double-peak profile, possibly associated with density variations in the circumstellar medium (CSM), or with the presence of an off-axis GRB jet. Optical spectra of PTF11qcj taken during both peaks of the radio light curve do not show the broad Hα features typically expected from H-rich circumstellar interaction. Modeling of the second radio peak within the CSM-interaction scenario requires a flatter density profile and an enhanced progenitor mass-loss rate compared to those required to model the first peak. Our radio data alone cannot rule out the alternative scenario of an off-axis GRB powering the second radio peak, but the derived GRB parameters are somewhat unusual compared to typical values found for cosmological long GRBs. On the other hand, Chandra X-ray observations carried out during the second radio peak are compatible with the off-axis GRB hypothesis, within the large measurement errors. We conclude that VLBI measurements of the PTF11qcj radio ejecta are needed to unambiguously confirm or rule out the off-axis GRB jet scenario.
ALMA Observations of the Massive Molecular Outflow G331.512-0.103. II. Physical Properties, Kinematics, and Geometry Modeling
Authors: Hervías-Caimapo Carlos , Merello Manuel , Bronfman Leonardo , Åke-Nyman Lars , Garay Guido , Lo Nadia , II Neal J. Evans , López-Calderón Cristian , Mendoza Edgar
Published: February 2019

We present observations and analysis of the massive molecular outflow G331.512-0.103, obtained with Atacama Large Millimeter/submillimeter Array band 7, continuing the work from Merello et al. Several lines were identified in the observed bandwidth, consisting of two groups: lines with narrow profiles, tracing the emission from the core ambient medium; and lines with broad velocity wings, tracing the outflow and shocked gas emission. The physical and chemical conditions, such as density, temperature, and fractional abundances are calculated. The ambient medium, or core, has a mean density of

cm−3 and a temperature of ∼70 K. The SiO and SO2 emission trace the very dense and hot part of the shocked outflow, with values of

cm−3 and T ∼ 160–200 K. The interpretation of the molecular emission suggests an expanding cavity geometry powered by stellar winds from a newborn UCHII region, alongside a massive and high-velocity molecular outflow. This scenario, along with the estimated physical conditions, is modeled using the 3D geometry radiative transfer code MOLLIE for the SiO(J = 8 − 7) molecular line. The main features of the outflow and the expanding shell are reproduced by the model.
A New Generation of Cool White Dwarf Atmosphere Models. III. WD J2356–209: Accretion of a Planetesimal with an Unusual Composition
Authors: Blouin S. , Dufour P. , Allard N. F. , Salim S. , Rich R. M. , Koopmans L. V. E.
Published: February 2019

WD J2356−209 is a cool metal-polluted white dwarf whose visible spectrum is dominated by a strong and broad sodium feature. Although it was discovered nearly two decades ago, no detailed and realistic analysis of this star had yet been realized. In the absence of atmosphere models taking into account the nonideal high-density effects arising at the photosphere of WD J2356−209, the origin of its unique spectrum had remained nebulous. We use the cool white dwarf atmosphere code presented in the first paper of this series to finally reveal the secrets of this peculiar object and details about the planetesimal that polluted its atmosphere. Thanks to the improved input physics of our models, we find a solution that is in excellent agreement with the photometric observations and the visible spectrum. Our solution reveals that the photosphere of WD J2356−209 has a number density ratio of

, which is the highest ever found in a white dwarf. Since we do not know how long ago the accretion episode stopped (if it has), we cannot precisely determine the composition nor the mass of the accreted planetesimal. Nevertheless, all scenarios considered indicate that its composition is incompatible with that of chondrite-like material and that its mass was at least 1021 g.
On the Possible Mechanism of GLE Initiation
Authors: Firoz K. A. , Gan W. Q. , Li Y. P. , Rodríguez-Pacheco J. , Kudela K.
Published: February 2019

With the goal of understanding the initiations of solar energetic particle (SEP) (MeV) and ground-level enhancement (GLE) (GeV) particles, we have studied relative timings at approximately the Sun between temporal evolutions of the particles and some electromagnetic radiation components representing flares and shocks. Results show that GLE onsets appear after flare prompt onsets and m-type II onsets, while the GLE-associated SEP onsets appear before the flare prompt onsets and m-type II onsets, thus specifying that the GLE-associated SEPs originate over the flare initial phases and get accelerated intensively over the flare prompt phases associated with coronal shocks. The flare initial phase is found always earlier than the coronal mass ejection (CME) initial phase, further justifying that the MeV particles are initiated particularly by the flare initial phases and are accelerated to GeV energetic by flare prompt phases associated with the coronal shocks. On the contrary, most of the non-GLE-SEP onsets appear well after the flare prompt onsets and m-type II onsets, demonstrating that the non-GLE-SEPs mostly generate over the most intense part of the flare rise phases associated with the coronal shocks. In another development, the relative timings of flare prompt onset and peak times to the m- and DH-type II onsets show that usually the m-type II bursts commence before the flare peaks and DH-type II bursts commence after the flare peaks, signifying that the coronal shocks manifested in m-type II bursts operate over the flare main acceleration phases, while the coronal shocks manifested in DH-type II bursts operate over the flare decay and/or CME propagation phases, thereby suggesting that the evolution of the particles accelerated at the flare main acceleration phases can be prolonged by the shocks associated with the CME propagation phases.
Synopsis of New World Sigalphinae (Hymenoptera, Braconidae) with the description of two new species and a key to genera
Authors: Sharkey Michael J. , Penteado-Dias Angélica Maria , Smith M. Alex , Hallwachs Winnie , Janzen Daniel
Published: February 2019

We describe and illustrate Paphanuspaloisp. n., first generic record for Brazil, and Minangapatriciamadrigalae, first generic record for Costa Rica. We present illustrated keys for the New World genera of Sigalphinae, and the New World species of Paphanus and Minanga. Minangapatriciamadrigalaesp. n. was reared from caterpillars of Chloropteryx nordicariaDHJ01 (Geometridae).
Bioconversion of Dried Leaves from Algerian Date Palm (Phoenix dactylifera L.) to Biogas by Anaerobic Digestion
Authors: Djaafri Mohammed , Kalloum Slimane , Soulimani Ahmed Elamine , Khelafi Mostefa
Published: February 2019

This work aimed to study anaerobic digestion of a new substrate made from the waste of Algerian date palm (Phoenix dactyliferaL.) in order to evaluate its biogas production capacity. The lignocellulosic component biodegradability and the process stability were also tested. Two reactors were launched with the same concentration of 20g total solid (TS)/L. A physical pre-treatment (grinding) of dried leaves lowered the substrate size below 2 mm. The theoretical methane yield (499 - 538 mL CH4/g of Volatile Solids (VS)) indicated a high substrate methanogen potential. The tested methane and biogas yield reached 130±6 mL CH4/gVS and 197±6 mL/g VS respectively. The biodegradability through the volatiles solid reduction was 29%. The total alkalinity (TA) value increased from the beginning to the end, due to the substrate nature which gave a high buffering capacity of the medium. During the stable process, a higher Chemical Oxygen Demand (COD) removal was reached with a value of 77.58%. The majority of the biogas yield was generated during the same period, which confirmed that the anaerobic digestion process stability is indispensable. Finally, this study was an opportunity to better exploit local by-products for the bioenergy production.
Environmental Impact on Biodegradation Speed and Biodegradability of Polyethylene and Ipomoea Batatas Starch Blend
Authors: Abioye Abiodun Ayodeji , Oluwadare Oreofe Praise , Abioye Oluwabunmi Pamilerin
Published: February 2019

All over the world, even in developing countries, plastics have quickly become one of the most common things found around. Unsurprisingly, this has caused a major waste management problem, particularly because synthetic polymers do not break down and degrade like organic waste. As a result, an alternative is being sought out in biopolymers. This study explores the suitability of a biopolymer blend;Ipomoea batatasmixed with low density polyethylene (LDPE) at various compositions. Biodegradation of this biopolymer blend was observed periodically when produced samples ofIpomoea batatas/LDPE were buried in loamy sand over a period of 28 days. Results show that produced biopolymers are environmentally compatible and bio-degradable. It was also observed that the sample blend with equal portions by weight ofIpomoea batatas(50%) and LDPE (50%) showed the most optimum pattern of degradation. There was steady degradation over the study period and the rate of degradation observed showed sustainability.
An Approach to Systems-of-Systems Structural Analysis through Interoperability Assessment: Application on Moroccan Case
Authors: Ed-Daoui Ilyas , Koulou Aicha , El Hami Norelislam , El Hami Abdelkhalak , Itmi Mhamed , Hmina Nabil
Published: February 2019

In this paper, we propose an indicator to systems-of-systems (SoS) structural analysis through dependencies evaluation which is based on interoperability and exchange inefficiency assessments, with dependencies representing links between component systems within the SoS. Interoperability is a quality that can be viewed from various perspectives. Therefore, we propose an illustrative classification for interoperability that embraces: barriers, scopes and levels. Our study involves a set of metrics to assess each interdependency’s interoperability barriers within the SoS through interoperability levels. Two different case studies, from the Moroccan economic infrastructure, are presented to apply the proposed approach. Results are cross-compared and evaluated.
Optimization of Parameters Influencing the Quality Loss of Machine Motorized Spindle Using Design Exploration and Taguchi Methods
Authors: Ahmed Elhaj A.I. , Li Shu Sen , Helal Wasim M.K.
Published: February 2019

The quality loss caused by tolerance of factors can be reduced when the nominal values of design-factors are carefully chosen. Therefore, the parametric optimization method is significant to an optimally define the Quality Loss cost (QLc). In this work, the Design Exploration (DE) and Taguchi Methods along with unforced Rotordynamic analysis have been used to find the optimal levels of factors affecting the QLc. Under definite constraints, the mathematical models are developed for an optimization problem and then utilized to develop Machine Motorized Spindle (MMS). In order to find the optimal levels of the factors, the sensitivities of factors on structural weight and First-Order-Nature-Frequency (FONF) has been analyzed using Response-Surface (RS) method, while the Taguchi method is used to find the QLc. The results found shown that there are significant enhancements in signal-to-noise ratio for structural weight and FONF. The QLc has been saved to about more than half-time by comparing to its initial values. The results also indicated that the proposed optimization approach is feasible and successful in improving dynamic characteristics and QLc saving for the MMS. Keywords: Machine Motorized Spindle, Finite Element Method, Unforced Vibration, Rotordynamic Analyses, Response Surface Method, Taguchi Quality Loss cost.
Springback Suppression of AZ31 Magnesium Alloy Sheet in Draw Bending at Elevated Temperature
Authors: Katahira Takashi , Uemori Takeshi , Yoshida Tetsuya , Takiguchi Michihiro , Naka Tetsuo , Lawanwong Komgrit , Yoshida Fusahito
Published: February 2019

In recent years, warm forming of magnesium sheets has been investigated by many researchers since the ductility of the sheets becomes considerably higher due to low CRSS (critical resolved shear stress) at high temperatures (e.g., [1]-[3]). In the present research, the springback of AZ31 magnesium sheet was investigated by performing a draw-bending experiment at several temperatures from 20 °C (room temperature) to 200 °C at drawing speeds ranging from 0.01 to 1.0 mm/s. From the experiment, it was found that the springback was remarkably reduced at 200 °C, especially at a low forming speed, since the flow stress was very low under such a forming condition, and furthermore, the stress relaxation effect was dominant. The effects of temperature and forming speed on springback were discussed.
Macroscopic and Microscopic Non-Uniform Deformations of Polycrystalline Pure Copper during Uniaxial Tensile Test with High Stress Gradient
Authors: Taniguchi Akito , Maeyama Takatoshi , Uchida Makoto , Kaneko Yoshihisa
Published: February 2019

Metallic materials usually have microscopically heterogeneous structures, such as polycrystalline structures, affecting macroscopic mechanical characteristics. Both macroscopic and microscopic non-uniform deformations of polycrystalline pure copper under a moderate stress gradient were investigated. In this study, macroscopic and microscopic non-uniform deformations under higher stress gradients are investigated. Uniaxial tensile tests using three-curve specimens with different curvatures and grain sizes were performed. In order to evaluate the heterogeneous strain field in the specimen surface, the development of the displacement field was measured using the digital image correlation method (DIC). The stress field was evaluated by coupling the DIC and finite-element methods. In smaller-grain specimens, a strong strain concentration was generated in the minimum cross-section area. Although a strong strain concentration was also confirmed in a larger-grain specimen, the strain field depended not only on the specimen shape but also on the microscopic heterogeneity. This microstructure-driven non-uniform deformation was also observed in the specimen with a larger curvature radius. These results indicated that the macroscopic non-uniform deformation should be estimated by the material parameter related to the microscopic heterogeneity.
High Temperature Deformation Behavior and Processing Maps of AZ31 Alloy Deformed in Tension versus Compression
Authors: Rao Kamineni Pitcheswara , Suresh Kalidass , Prasad Yellapregada Venkata Rama Krishna
Published: February 2019

The effect of the applied state-of-stress on the processing maps depicting the mechanisms for hot working of hot extruded Mg-3Al-1Zn alloy has been evaluated. Flow stresses at various temperatures in the range 300 – 500 °C and strain rates in the range 0.0003 – 1 s-1 have been measured by deforming in compression and in tension. Processing maps have been developed from the respective flow stress data at a strain of 0.1. The maps are essentially similar irrespective of the mode of deformation – compression or tension, and exhibited two domains in the temperature and strain rate ranges: (1) 375 – 500 °C and 0.0003 – 0.01 s-1, and (2) 450 – 500 °C and 0.1 – 1 s-1. On the basis of slower strain rates, high tensile ductility, and the apparent activation energy (152 kJ/mole closer to that for self-diffusion), Domain #1 is interpreted in terms of the occurrence of climb controlled dynamic recrystallization. In Domain #2, which occurs at higher strain rates and has an apparent activation energy near to 165 kJ/mole, dynamic recrystallization occurs that involves second order pyramidal slip {11-22} <11-2-3> and recovery by cross-slip of screw dislocations. The state-of-stress imposed on the specimen (compression or tension) does not have any significant effect on the processing maps or the kinetics of hot deformation.
Forming Limit Evaluation with Perturbation Approach Considering Through-Thickness Normal Stress
Authors: Hu Qi , Li Xi Feng , Chen Jun
Published: February 2019

To predict material’s formability in the hydroforming processes, the plane stress assumption would be invalid. The instability perturbation approach proposed by Hu et al. [1] is extended with the through-thickness normal stress by combining Hill’48 and Hosford’s yield criteria. The influences of through-thickness normal stress on the predicted forming limit strains in the forms of traditional Forming Limit Diagram (FLD) and equivalent plastic strain (EPS) based FLD (epFLD) are investigated. The results show that forming limit curves (FLCs) in both forms of FLD enhance with increasing through-thickness normal stress under proportional and non-proportional loadings. This new model can be utilized to study the effects of fluid pressure on the formability of orthotropic thin sheets.
A Computational Simulation of Martensitic Transformation in Polycrystal TRIP Steel by Crystal Plasticity FEM with Voronoi Tessellation
Authors: Trinh Truong Duc , Iwamoto Takeshi
Published: February 2019

TRIP steel shows excellent mechanical properties such as greatly high strength, ductility and toughness by means of the appropriate combination of the strain-induced martensitic transformation (SIMT) behavior and the deformation behavior of each phase at crystal scale. In the past, the effect of grain size in the austenite on the deformation behavior of TRIP steel is investigated by introducing the grain size into a generalized model for the kinetics of SIMT. In order to validate the size-dependent kinetics modelling, it is necessary to simulate the deformation and SIMT behavior of the polycrystalline for the different grain size at the crystal scale. This study focuses on an investigation of SIMT behavior in polycrystalline TRIP steel by finite element simulation. The constitutive formula for monocrystalline TRIP steel including transformation strain in each variant system derived on the basis of the continuum crystal plasticity theory is applied. For the polycrystalline model, Voronoi tessellation is employed. The deformation behavior with a patterning process of martensitic phase in two different numbers of grains with initial crystal orientations for describing the deformation-related length scale is simulated under plane strain condition with two planar slip systems by a cellular automata approach.
Epífitas vasculares do Parque Nacional Serra de Itabaiana, Sergipe, Brasil
Authors: Araújo Kelianne , Santos Josuel Lima , Fabricante Juliano Ricardo
Published: February 2019

O objetivo do presente trabalho foi realizar um levantamento florístico das epífitas vasculares do Parque Nacional Serra de Itabaiana, Sergipe. A falta de pesquisa sobre epifitismo no estado de Sergipe motivou o estudo no Parque Nacional Serra de Itabaiana (PARNASI), que detém uma grande importância para a conservação de espécies no estado. Diante disso, o trabalho buscou responder as seguintes perguntas: quantas e quem são as espécies de epífitas vasculares que ocorrem no PARNASI?; a quais categorias ecológicas as epífitas amostradas pertencem?; e qual a similaridade florística epifítica do PARNASI com outras áreas estudadas no Brasil? O inventário foi realizado através de caminhadas por todo o local (busca ativa), com coleta, herborização e acervo, no Herbário da Universidade Federal de Sergipe (ASE), de amostras de todas as espécies epífitas vasculares presentes no local. Foram coletadas 47 espécies distribuídas em 29 gêneros e 10 famílias. Os resultados da análise de similaridade demonstraram uma baixa semelhança florística entre a área de estudo e demais regiões brasileiras. O elevado número de táxons exclusivos nas áreas, estudadas e comparadas, revelam a grande importância de cada local para a conservação das espécies epífitas.
Primeiro registro de leucismo no cachorro-do-mato Cerdocyon thous (Linnaeus, 1766) (Carnivora: Canidae) no Brasil
Authors: Oliveira Leandro Da Silva , Gomes Varjão Iardley Cícero , Machado Pereira Luiz Cezar , Nicola-Pereira Patrícia Avello
Published: February 2019

Variações polimórficas podem atuar nas alterações cromáticas, que, em excesso, causam a hiperpigmentação (indivíduos melânicos), e quando deficientes são responsáveis pela hipopigmentação (indivíduos albinos, leucísticos ou com piebaldismo) e podem estar associadas com aspectos ecológicos, fisiologia e outros processos biológicos. No Brasil, o leucismo foi observado em poucas espécies de carnívoros, podendo representar um evento esporádico nesse grupo de animais, uma vez que as alterações cromáticas de hipopigmentação podem causar efeitos negativos sobre os indivíduos, como vulnerabilidade aumentada à predação. Ainda assim, observou-se um indivíduo de Cerdocyon thous, nas dependências do Campus de Ciências Agrárias da UNIVASF, zona rural de Petrolina, Pernambuco, que apresentou leucismo. Ao ser avistado, o canídeo apresentou as mesmas características comportamentais de outros espécimes normais, com a fuga para áreas adjacentes com vegetação natural.
La reparación integral de las víctimas con enfoque en la violencia de género
Authors: Chinchilla Fuentes Luis Ovidio
Published: February 2019

El camino que la  humanidad ha  recorrido  para obtener el reconocimiento y respeto de  derechos fundamentales ha sido muy largo y espinoso, pero no ha sido en vano. Uno de los mayores logros ha sido  el reconocimiento de la persona humana como sujeto de Derecho Internacional Público, obteniéndose la facultad de demandar en una instancia internacional con el objetivo de exigir el respeto de sus derechos.

 Otro de los grandes logros obtenidos actualmente ha sido que el concierto de naciones, los tribunales internacionales en derechos humanos, así como los Comités de las convenciones de derechos humanos de Naciones Unidas hayan establecido parámetros para reparar a las víctimas tras una violación de derechos humanos.

 De igual forma, se han logrado integrar los temas de género y la violencia que sufren las mujeres por el hecho de ser mujeres en diversas convenciones a nivel mundial y regional. Las condenas internacionales han contribuido a que los Estados sean cada vez más conscientes de las obligaciones que contraen, particularmente sobre la existencia de obligaciones específicas en torno a la violencia por razón de género contra la mujer.

 Sin embargo, uno de los más grandes obstáculos al que se enfrentan los Estados es qué medios utilizar para cumplir con las obligaciones internacionales y cómo reparar una violación de derechos humanos.

 Dicho obstáculo ha motivado  el presente artículo, que a través de un análisis dogmático y práctico ayude al lector a entender principalmente como reparar una violación a derechos humanos con enfoque en casos de violencia por razón de género contra la mujer a la luz de algunas consideraciones generales.
The Impact of Mobile Language Learning (WhatsApp) on EFL Context: Outcomes and Perceptions
Authors: Alghamdy Rashed Zannan
Published: February 2019

Seeking to identify the impact of mobile language learning (WhatsApp) on the achievements of EFL learners, a quasi-experimental design study was applied at Al-Baha University in Saudi Arabia. This study examines the impact of mobile language learning in enhancing EFL students’ English skills ability when learning English as a foreign language context.

Particularly, the study intends to investigate the impact of mobile language learning (WhatsApp) in comparison to traditional learning in learning English skills on the achievement of EFL learners. Thus, the participants in this study included 48 male learners, aged 18–22 years, preparatory year at Al-Baha University.

The results highlighted that there are significant differences between the mean scores of the EFL learners who were taught English in the Mobile language learning (WhatsApp), and those who were taught English by using the traditional learning (the control group) in the post-test. This difference was in favour of the experimental group. However, the findings revealed that are not statistically significant differences between the EFL learners in the experimental classes and the students in the control groups in their English achievement test score at the pre-test.

Furthermore, the results of this research revealed that most EFL learners claimed that they were enthusiastic to join English lessons through WhatsApp groups and expressed the belief that working in a WhatsApp group can boost their motivation and their academic results. Also, most EFL learners highlighted that using mobile language learning method (WhatsApp) enabled them to increase their social skills, confidence, while helping them to create positive relationships with their colleagues and the teacher.

However, there were some obstacles and barriers to join WhatsApp learning groups, such as lack of access to the internet and lack of tendency to share and participate in the WhatsApp group.
The Discourse Analysis of E-Business Instant Communication from the Perspective of Politeness Principle
Authors: Guo Tingting , Zhao Zhenxia
Published: February 2019

With the popularity and frequency of e-business activities, e-business instant communication plays an increasingly important role in e-business, and the appropriate and reasonable use of business language usually directly influences the economic interests. Therefore, the present study takes politeness principle as the theoretical framework and the participants’ chat records of e-business instant communication as the research data, and adopts the methodologies of discourse analysis and interview to explore the language use in e-business activities from the perspective of politeness principle. And the present study finds that servicers and customers use different linguistic resources from the perspective of politeness principle out of different interest pursuit. More specifically, servicers strictly observe the six maxims having no violations in e-business instant communication, while customers go against Tact Maxim, Generosity Maxim, Approbation Maxim and Modesty Maxim and usually comply with Agreement Maxim and Sympathy Maxim, nevertheless, they violate Agreement Maxim and Sympathy Maxim on special occasion in e-business instant communication. What’s more, if customers can strictly observe Agreement Maxim and Sympathy Maxim, and servicers can study how to avoid and deal with customers’ violation to Agreement Maxim and Sympathy Maxim successfully, enterprises, servicers and customers will benefit.
The Relationship Between English Language Proficiency and Politeness in Making Requests: A Case Study of ESL Saudi Students
Authors: Alshakhi Abdullah
Published: February 2019

The acquisition of language as well as the acquisition of social consideration, or politeness, are two sets of separate skills. However, the lack of language knowledge by an English language learner can result in social mistakes that can be perceived as impolite by native speakers. The present study aimed to explore the relationship between English language proficiency and politeness in making requests at retail shops, specifically focusing on Saudi students in the United States. There were five participants in this study: two Saudi ESL students with low English proficiency; two Saudi Ph. D. students with advanced English proficiency, and an American waiter who speaks English as a native language. The study was conducted by using a qualitative research method in two phases. The first phase included observing all participants during interaction, and the second phase included interviewing a server at one of the restaurants where the students visited. The main findings revealed that there was no strong correlation between politeness and English language proficiency in making requests. However, there were some factors found in this study that contributed to politeness level, such as intonations and the use of politeness markers.
Just Say Know to Drugs! A High School Pharmacology Enrichment Program for a Rural Population
Authors: Hamrick Lucas A. , Harter Stephanie R. , Fox Carrie L. , Dhir Meghna , Carrier Raeann L.
Published: February 2019

Context

Just Say Know to Drugs! is a summer pharmacology enrichment program for high school students. First-year osteopathic medical students serve as teachers, introducing students to pharmacology while acquiring teaching skills.

Objective

To assess the effects of a pharmacology program on high school students and to understand the effects of teaching this program on first-year osteopathic medical students.

Methods

The influence of a pharmacology STEM (science, technology, engineering, and mathematics) enrichment program on high school students’ career interests and student teacher preparedness was determined by a pre- and posttest, as well as a postprogram survey.

Results

Data from all 37 participating high school students and 10 of 16 student teachers (medical students and undergraduate assistants) were evaluated in the study. Survey findings suggested that this STEM program increased student awareness and knowledge of pharmacology, osteopathic medicine, and scientific research. Furthermore, student teachers thought that they developed the necessary skills to communicate and educate populations with diverse science backgrounds and comprehension levels. The immersion of high school students in the scientific content significantly increased student awareness of pharmacology (paired t test, P<.0001).

Conclusion

The Just Say Know to Drugs! program delivered benefits for both high school students and student teachers.
SNARE-CNN: a 2D convolutional neural network architecture to identify SNARE proteins from high-throughput sequencing data
Authors: Le Nguyen Quoc Khanh , Nguyen Van-Nui
Published: February 2019

Deep learning has been increasingly and widely used to solve numerous problems in various fields with state-of-the-art performance. It can also be applied in bioinformatics to reduce the requirement for feature extraction and reach high performance. This study attempts to use deep learning to predict SNARE proteins, which is one of the most vital molecular functions in life science. A functional loss of SNARE proteins has been implicated in a variety of human diseases (e.g., neurodegenerative, mental illness, cancer, and so on). Therefore, creating a precise model to identify their functions is a crucial problem for understanding these diseases, and designing the drug targets. Our SNARE-CNN model which uses two-dimensional convolutional neural networks and position-specific scoring matrix profiles could identify SNARE proteins with achieved sensitivity of 76.6%, specificity of 93.5%, accuracy of 89.7%, and MCC of 0.7 in cross-validation dataset. We also evaluate the performance of our model via an independent dataset and the result shows that we are able to solve the overfitting problem. Compared with other state-of-the-art methods, this approach achieved significant improvement in all of the metrics. Throughout the proposed study, we provide an effective model for identifying SNARE proteins and a basis for further research that can apply deep learning in bioinformatics, especially in protein function prediction. SNARE-CNN are freely available at https://github.com/khanhlee/snare-cnn.
Malacologic benthic fauna of the Socorro Island Littoral, Revillagigedo, Mexico
Authors: Mille-Pagaza SR , Pérez-Chi A , Holguín-Quiñones O
Published: February 2019

A survey on rocky shore mollusks was conducted in some bays of Socorro Island during February and May 1991 and March 1992. Specific richness and composition were analyzed for all expeditions. Relative density and frequency were analyzed only for the last two. The Importance Value Index (IVI) and Jaccard and Morisita similarity indexes were also calculated. Gastropods were the most diverse mollusks in the island, with 23 species in February, 33 in May and 39 in March. Vargas Lozano Bay had the highest total specific richness in all expeditions (25 in February, 30 in May and 33 in March) due to weak waves that produce greater bottom stability, and a great nutrient contribution from the ships that arrive to the island. Playa Blanca NE Bay showed the highest relative density in May (38.9%) and Playa Norte E Bay in March (24.1%). The IVI showed that the same species obtained the highest levels in all bays and expeditions. In May and March, Isognomon janus and Mitrella baccata were the most common species in all bays. Jaccard and Morisita indexes showed three principal assemblies. Grayson, Binners and Braithwaite were the most similar bays, characterized by strong waves and the presence of some tide pools on the shore. The second group consists of Vargas Lozano and Playa Blanca SO Bays which have protected rocky shores. Playa Blanca NE and Playa Norte E Bays form the third group because of their particular conditions; the first one has a well-developed coral reefnext to the beach, and the second one has a narrow supra and intertidal fringe.