bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of CNC Turning Operations with Multiple Performance Characteristics using Taguchi based Grey Relational Analysis
Authors: Lakshmikanthan P. , Prabu B.
Published: June 2018

This study investigates the optimization of CNC turning operation parameters for Al6061 nickel coated graphite (NCG) metal matrix composite using the Taguchi based grey relational analysis method. The turning operations are carried out with carbide cutting tool inserts. According to the Taguchi quality concept, 3-level orthogonal array was chosen for the experiments. The experiments are conducted at three different cutting speeds (125, 175, 225m/min) with feed rates (0.1, 0.15, 0.2mm/rev) and depth of cut (0.5, 1, 1.5mm) and different % of reinforcement (2.5%, 5%, 7.5%), signal to noise ratio and the analysis of variance are used to optimize cutting parameters. The effects of cutting speed, feed rate and depth of cut on surface roughness and MRR are analyzed. Mathematical models are developed by using the response surface method to formulate the cutting parameters experimental results shown that machining performance can be improved effectively by using this approach, the analysis of variance (ANOVA) is applied to identify the most significant factor for the turning operations according to the weighted sum grade of the GRG. The predict responses shows the models have more than 95% of confident level of R2 value, from the obtained confirmation experiment result, it is observed, there is a good agreement between the estimated value and the experimental value of the grey relational grade. This experimental study reveals that the grey-Taguchi and RSM can be applied successfully for multi response characteristic performances.
Formability of Heat Treated AA19000, AA5052 and Simulation using ABAQUS/CAE
Authors: Logesh K. , Bupesh Raja V.K. , Surryaprakash D. , Desigavinayagam R.
Published: June 2018

In this paper the formability of heat treated AA19000 and AA5052 aluminium alloys was studied through experimentation and finite element simulation. The aluminium alloys of 1mm thickness as received and annealed condition were subjected to tensile test and Erichsen cupping test. The experimental results showed that AA5052 possessed better formability than AA19000, due to its magnesium content. The material properties obtained from the tests were validated through simulation using ABAQUS/CAE.
Wear Rate Analysis of Ceramic Coated Brake Lining Material
Authors: Kavitha K.R. , Prakash S.
Published: June 2018

Brake lining is a layer of hard material attached to a brake shoe or brake pad to increase friction against the drum or disc. Asbestos, which was the conventional brake material, has an optimal performance in wear rate and thermal resistance but due to serious health-related hazards, asbestos became obsolete. This led to the development of eco-friendly brake materials. Lot of research has been going on with Non-Asbestos Organic materials (NAO) including non-metallic, semi-metallic, fully metallic and ceramic materials. Among that, Ceramic materials are nowadays popularly used as brake friction materials. This is because that the ceramic material possesses high strength and hardness, superior wear and abrasive resistance, withstands high temperature and thermal shock. In this paper the effect of ceramic coating on asbestos brake lining is investigated. The role of ceramic abrasives including Alumina (Al2O2) and Zirconium oxide (ZrO2) as a ceramic coating on the surface of asbestos brake lining has been carried out experimentally. The ceramic material was deposited on the layer of asbestos brake lining by plasma coating process. Several samples were prepared with different thickness (25Âµ, 35Âµ and 45Âµ) and wear characteristic were analyzed using abrasive wheel testing machine which is commonly used to test the abrasive resistance of solid materials. The results were compared with the standard sample (asbestos brake lining) and it was found that the ZrO2 coating on the surface of the asbestos brake lining of 45 microns thickness coating has shown reduced wear than the other.
Performance of CI Engine with Ceramic Oxide Coated Piston and Fuelled by Blended Rice Bran Oil
Authors: Sivashankari P. , Krishnamoorthy A. , Balaji K.N.
Published: June 2018

Due to depletion of fossil fuels, concerns about energy security and global warming make renewable energy resources more attractive. In this regard, using biodiesel seems to be a possible and feasible source of energy for transportation. This paper presents an investigation of the performance and emission characteristics of CI engine using 10% blend of rice bran oil as fuel and ceramic oxide coated piston.
Light Weight Freight Rolling Stock Bogie Frame: Design Methodology Validated with Field Oscillation Trials
Authors: Shukla S. , Kumar U. , Sharma S.K. , Gupta P. , Kumar A.
Published: June 2018

Indian railway has improved the laden to tare weight ratio by producing lighter as well as higher strength bogie frame of freight rolling stock. Bogie frame is the crucial component of the rail vehicle which carries static load in the form of gross weight and dynamic loads arising from various track and wheel irregularities. The three piece freight vehicle bogie frame comprises two side frames and one bolster. The side frame; fitted with three piece bogie frame and responsible for the ride quality of the freight vehicle, is considered in present study. The locations suitable for weight reduction are found by finite element analysis (FEA), using side frame solid model in MSC FEA environment. International standards of the association of American railroad (AAR specification M-203) [1] load cases and boundary conditions are deployed for analysis in the context of the operating scenario of Indian railways. Typical Indian railway track signatures are used as input for transient analysis. Time dependent stresses at critical speeds are used for fatigue strength evaluation as per Goodman diagram. The modified design is approx. 13.90% lighter and sustains 25.00 ton axle load in comparison of earlier 22.00 ton. Suggested topological changes have been compared by using frequencies of the initial and modified designs. Further, based on Indian railways running conditions, actual assessment and trial of the modified design bogie frame prototype has been carried out by Research Designs and Standards Organisation (RDSO) [2]. The results of the trial are found to be satisfactory and within the prescribed range.
An Approach to Minimization of Drive Train Noise Through Redesign of Engine Mounts
Authors: Biswas S.
Published: June 2018

Drive train noise is more annoying for passenger. For a V-hull base mine protected 4WD defence-vehicle, metallic noise was observed from drive train. To resolve this kind of NVH problem of complicated vehicle like defence required commending knowledge base and experience or say know-how. The critical constraint of subject vehicle was fixed position of engine or engine mounts and transfer case. This causes higher slope equivalent angle of first drive shaft with respect to the installation standard. Noise issue observed as consequence of aforesaid issue which has impact installation parameters of torsional, inertia and secondary coupling excitation frequencies. In this context, a structured methodology has been followed in present work for finding root causes and optimizing the design to come out with optimum solution. Engine mounts have major influence to finalize first drive line slope angle. Hence, re-designing and verification have been done for engine mounts considering its major design parameters and criteria (e.g. shape factors, shore hardness, static deflection and isolation efficiency). At the same time, effects of those changes have been verified theoretically and practically on vehicle. Pass by noise, cabin inside noise, isolation efficiency of front and rear mounts and vehicle floor vibration level were measured. The objective of the exercise is to find out a solution for minimization of drive-train noise.
Modeling of Deceleration Fuel Cut-off for LPG Fuelled Engine using Fuzzy Logic Controller
Authors: Setiyo M. , Munahar S. , Triwiyatno A. , Setiawan J.D.
Published: June 2018

At the time of deceleration, continuous LPG flow in LPG fuelled engine causing over fuel consumption and increasing exhaust emissions, while the engine does not need fuel. Therefore, this paper presents a simulation of deceleration fuel cut-off (DFCO) system. Given that the fuel system control is complex and non-linear, modeling with fuzzy logic controller (FLC) has been selected because of simple, easy to understand and tolerant to improper data. The engine modeling is divided into several sections, including intake manifold dynamics and engine dynamics. The input values were processed by the membership function. A series of simulation results indicate that DFCO can be applied. The combination of throttle valve position, engine speed and manifold pressure is able to cut LPG flow at deceleration. As a conclusion, DFCO system is promising to be applied on LPG-fuelled vehicles for saving fuel and reducing emissions.
Performance Analysis of Adaptive Control Technique for Aircraft Gas Turbine Engine
Authors: Ganesan S. , Jaganraj R. , Priyadharshini G.M.
Published: June 2018

This paper presents an adaptive control technique to compensate the thrust variation in an aircraft engine whose performance has been disturbed due to atmospheric conditions. The course of dysfunction appears when a large throttle transient is performed such that the engine switched from low to high speed mode. A relationship is observed between engine disturbance and the overshoot in engine shaft rpm or compressor discharge pressure or turbine temperature, which is determined to cause the thrust variation. This relationship is used to adapt a control. This method works very well up to the operability limit of an engine. Additionally, the type of disturbance identified from sensors data will be useful to implement the adaptive control in real time operation.
Effective EEDI Performance Achievement by MAN B and W G-Type Ultra Long Stroke Marine Diesel Engine: A Review
Authors: Mangesh V.L. , Mohan A.
Published: June 2018

Man Diesel and Turbo G-Type ultra long stroke marine diesel engine was introduced in October 2010.This ultra long stroke means it has been designed to have reduced engine speeds and there by achieving high efficiency ships with reduced fuel consumption as well as reduced CO2 emissions. The ultra long stroke diesel engine with capability of using large size propeller and there by engines with comparatively low speeds can be used for propulsions of large bulk carriers and oil tankers. This arrangement facilitates the effective implementation of EEDI. In this paper we review the effectiveness of this engine in implementation and achievement of EEDI and thereby achieving reduced CO2 emissions. In this paper, we also study the selection of propeller sizes to achieve the optimum design ship speeds and thereby comply with EEDI requirements.
Finite Element Modelling of Bi-Material Interface for Crack Growth Evaluation: Technical Note
Authors: Logesh M. , Palani S. , Shanmugan S. , Selvam M. , Harish K.A.
Published: June 2018

Finite element (FE) method is commonly used to study cracks in structures. In this paper, J-integral method is applied over FE model of a cracked body to determine stress intensity factor (SIF) in the domain of linear elastic fracture mechanics (LEFM). This paper formulates the J-integral methodology for 2D FE model using a coarse mesh with less degrees of freedom. Two cases , a finite plate with edge cracks and a normal crack growth in fiber metal laminated plate, are demonstrated. Numerical implementation and mesh refinement issues to maintain path independent J-integral values are explored.
Stability Analysis of Self-propelled Aerial Man Lift Vehicles
Authors: Palani S. , Shanmugan S. , Selvam M. , Harish K.A.
Published: June 2018

The objective of our research work is to perform the stability analysis of the aerial man lift vehicle. The stability analysis is performed using equilibrium force analysis and center of gravity analysis. A safe working load taking into account of drag forces on the bucket side-stream wind is established for six configurations depend up the AMLV traversing up or down over a flat or 10 degrees slope surface with its boom at rest or raised up at 65 degrees inclination angle. A standard square cross-section as well as tapered cross-section is also designed for the boom. For the considered designs, the calculated safe loads have been verified using stability pyramid and proved acceptable.
Determination of Suitable Hyper Elastic Material Model through Non-Linear Regression Analysis
Authors: Kamalakannan D. , Arun Baskar V. , Prabu B.
Published: June 2018

The material behaviour of elastomers can be simulated through Strain Energy Density (SED) function which can be defined by the following hyper plastic material models: (i) Neo-Hookean, (ii) Mooney-Rivlin, (iii) Yeoh and (iv) Ogden. The stress-strain relations of the above-mentioned SED functions for uni-axial tension, planar (pure shear) tension and equi-biaxial tension are validated with Treloarâ€™s data. Different combinations of Treloarâ€™s data are used to determine the co-efficient of SED functions of the above said models. These co-efficient values are determined using the software like ANSYS, MATLAB and POLYMATH and the validation of the results is carried out based on sum of squared error (SSE) which is calculated between the experimental values and predicted values. From the result, it is found that SSE less than 5 and closer to 0 can be taken as good prediction for selection of material model and co-efficient of material models. The engineering stress-strain behaviour of synthetic rubber (NBR) is obtained experimentally from uni-axial tension test and the co-efficient of SED functions are determined.
Flow Behaviour Analysis of Injection Mixer for CNG Engines using Computational Fluid Dynamics
Authors: Paullinga Prakash R. , Palani S. , Vijaya Kumar D. , Arun Kumar S. , Shanmugan S.
Published: June 2018

Use of gaseous fuels for fuelling the engines reduces reactive hydrocarbons and do not pose the problem of vaporization as with the liquid fuels. One of the problems of gaseous mixers is the ability to prepare a homogeneous mixing of air and fuel at a specific air-fuel ratio prior to entering the engine resulting high exhaust emissions. The objective of this project is to carry out three dimensional CFD analysis of CNG injection mixer to understand the flow behaviour of air fuel mixture and to optimize the design of injection mixer. The analysis was carried out by varying the injection position and injection inclination. The results of the CFD simulation could be used to understand the effect of position of fuel tube, injection inclination in the mixing of air and fuel. Further the results of the study would also be considered for the design modification.
Joint Effect of Imbalance and Supports Vibration on the Rotor Nonlinear Oscillations of Aircraft Device
Authors: Filipkovskii Sergey V.
Published: June 2018

In many devices and aggregates of aircrafts and other vehicles rotors are both sources of vibration and they are subjected to vibrational load from their supports. In this case, the disturbance load has a component with a frequency which is not a multiple with respect to the rotor speed. Here the method of analysis of forced oscillations of a rigid rotor on angular contact bearings with axial preload has been developed. The frequency responses of the system as well as orbits of spindle centers and PoincarÃ© maps with the joint action of imbalance and supports vibration have been obtained. When the rotor rotational speed and the frequency of supports vibration are of the same order, the resonance and super-resonance oscillations in the main modes are realized. The dependence of resonance modes on the angle of contact of ball-bearings has been studied. This work is intended to improve the numerical analysis of the dynamics and design of structures in the aerospace industry and transport engineering.
Stress and Vibrational Analysis of an Indian Railway RCF Bogie
Authors: Sharma Rakesh Chandmal , Palli Srihari , Koona Ramji
Published: June 2018

In the present work, static and dynamic finite element analyses are carried out on an Indian railway 6 ton RCF sleeper bogie. The geometrical CAD model of railway vehicle has been developed in UG-NX7.5 and has been exported to ANSYS12.1 package where finite element modelling and the required static and dynamic analyses have been performed. For dynamic response, modal, harmonic and transient dynamic analyses are carried out. First few natural modes of vibration of the bogie are extracted in Eigen frequency analysis and it is observed that the roll mode attained at a frequency which is well matched with the fundamental natural frequency calculated analytically. The harmonic peaks obtained are matching well with the natural frequencies obtained in modal analysis. Response to the ground excitation when the bogie passes over a bump is simulated in transient analysis.
Improving the Performance Characteristics and Emission Reduction of Small Diesel Engine Operated with Biodiesel Fuel
Authors: Abdelfattah Osama , Mourad M.A. , Youssef Ismail , Allam S.R. , Abd-El-Tawwab A.M.
Published: June 2018

This research aims to enhance the performance characteristics of diesel engine fuelled with biodiesel produced from waste cooking oils. The effects of fuel injection pressure (IP) on the performance characteristics of diesel engine and emission pollutants are investigated through experimental works using one cylinder diesel engine, direct injection using conventional petroleum diesel and two biodiesel blends (B5) from waste oil i.e. palm and sunflower oil. Five different IPs 100, 110, 130 and 140 kg/cm2, were used besides the original IP of 120 kg/cm2. Performance characteristics of diesel engine such as brake power, brake specific fuel consumption and exhaust emission such as CO, CO2, HC, NOx and PM have been measured while the engine speed is ranged from 1500 to 3500rpm and constant load (65%). The results showed a significant enhancement of the performance of diesel engine fuelled with biodiesel at an IP of 130 kg/cm2.
Optimization of Material Removal Rate and Surface Roughness for Wire Electric Discharge Machining of AA7075 Composites using Grey Relational Analysis
Authors: Ramanan G. , Edwin Raja Dhas J. , Ramachandran M.
Published: June 2018

In automobile industries, usage of unconventional machining is increased due to their precision and accuracy. This research work is planned to upgrade the Wire Electric Discharge Machining (WEDM) process parameters by considering the impact of discharge current, pulse on time, pulse off time and servo speed rate. Tests have been led with these parameters for the measurement of metal removal rate and surface roughness for each of the trial run. This information has been used to fit a quadratic numerical model. Predicted information has been used as a graphical representation for demonstrating the impact of the parameters on chose reactions. Predicted information given by the models has been utilized as a part of an ideal parametric mix to accomplish the unrealistic yield of the procedure. Response surface method with grey relational analysis has been utilized for enhancement. The ideal value has been checked to the predicted value from the confirmation tests.
Parametric Optimisation of Torsional Vibration Dampers for Vehicle Power Transmission System Considering Damping Effect and Lightweight Design
Authors: Tan X. , Hua L. , Lu C. , Yang C. , Wang Y. , Wang S.
Published: June 2018

To reduce the torsional vibration of vehicle power transmission system (VPTS), a torsional vibration model with multiple degrees of freedom (MDOF) of VPTS was established. The scheme of equipping torsional vibration dampers (TVDs) on the driveshaft was employed by the calculation of the forced vibration and the free vibration of the VPTS. The energy method was used to optimize the parameters of single-stage, two-stage parallel and two-stage series TVDs based on the principle that balances the damping effect and lightweight design. On the basis of this, the parameters of the models incorporating TVD and elastic couplings were optimized. Results showed that the proposed method can ensure the damping effects of TVD and realize the lightweight design.
Modernization of Railway Track with Composite Sleepers
Authors: Sharma Rakesh Chandmal , Palli Srihari , Sharma Sunil Kumar , Roy Mritunjoy
Published: June 2018

Railway sleeper is an important component of railway network. Its clamping is also a critical issue in order to avoid any slippage and to maintain the alignment or cross level. Earlier, railway network used wooden sleepers worldwide. Further steel sleepers in parallel with wooden sleepers have been employed. Both are replaced with concrete sleepers with the advancements. With the modernization, the idea of railway sleepers with fibre composite materials has been introduced which is accepted worldwide due to its unique features over any other type of sleeper. This paper discuss about different composite material sleepers and review the important features associated with them i.e. composition, properties, advantages and limitations.
Endurance Brake Classification Control Based on the Generalized Growth and Pruning Radial Basis Function Neural Network
Authors: Shi Peilong , Yu Man , Lu Xiongwen , Zhao Xuan
Published: June 2018

Because of the difference of working principles and arrangements of endurance braking systems, including engine brake, exhaust brake and eddy current retarder, it is difficult to match braking manually more than two types of endurance braking systems working simultaneously on long downhill. Meanwhile, manipulating control on different slopes will distract the driver's attention and cause driving fatigue. Aiming at this problem, the endurance brake classification control strategy is proposed, setting the deceleration, road slope and the difference of current speed and target speed as an input and the endurance brake classification as an output variable. Considering velocity variation is related to these factors with strong nonlinear characteristics, Generalized Growth and Pruning Radial Basis Function neural network control is used to estimate the input deceleration. Tests were conducted to verify the accuracy of simulation model. Variable slopes are researched through simulation method. The results show that the system designed to achieve automatic matching control can effectively decelerate and keep the truck running stably.
Design, Analysis and Manufacture of a Solar Electric Vehicle
Authors: Cai L. , Dai N. , Qiu G. , Yan J. , Tan Z. , Deng M.
Published: June 2018

Solar energy is mainly used as an energy source for cars, replacing traditional energy source, gasoline. The structure of the solar electric vehicle, including the body structure, tires, engine systems, transmission systems and electrical circuit design was introduced briefly in the paper. Work principle and ideal performance are carefully analysed. In the laboratory, the vehicle model is designed and manufactured. Through the laboratory tests, it can be shown that the designed vehicle can travel with low speed with good endurance with no pollution to the air.
Ride Comfort Analysis of Sedan Car using Quarter Car Suspension System Modelling and Simulation
Authors: Qiu C.
Published: June 2018

With the application of high-tech technology in automobile industry, more attention is given to the ride performance which will directly affect the comfort and safety of the passenger/driver. This paper is focused on the study of vehicle ride performance using vehicle simulation model. Two degrees of freedom quarter car model of vehicle with Macpherson front suspension from Santana 2000Gsi saloon car is established. The parameters of the simulation model include the suspension stiffness, damping coefficient of shock absorber and the road excitation. The road surface excitation is gained by using white noise integral method. By inputting the calculated basic parameters into suspension simulation model, the ride performance can be evaluated. The parameters can be adjusted such that the vibration characteristics to be more intuitive, which further laid the basis for accurate vibration control.
Experimental and Computational Study of Effects of Viscosity of the Filter Media in a Developed Particulate Trapping System
Authors: Liu Y.
Published: June 2018

A cost effective, portable particulate management system was developed, prototyped, and evaluated for further application and commercialization, which could remove and dispose particulate matter suspended in air efficiently and safely. A prototype of the present system was built for experimental assessment and validation. The experimental data showed that the developed particulate management system can effectively clean the air by capturing the particles inside it. Effects of viscosity of filter medium on the performance of the developed system were also discussed. The present system is very flexible, whose size and shape can be scaled and changed to be fit for different applications. Its manufacturing cost is less than $10. Based on the experimental validation results, it was found that the present system can be further developed, commercialized, and applied for a variety of industries. The experiments and experimental data were simulated and validated using computer fluent dynamics. A relatively good agreement was achieved between the experimental and computational results.
De/politisering van de Waarheid: complottheorieën, alternatieve feiten en nepnieuws in het tijdperk van de postwaarheid
Authors: Harambam Jaron
Published: June 2018

The Truth dominates many public discussions today. Conventional truths from established epistemic authorities about all sorts of issues, from climate change to terrorist attacks, are increasingly challenged by ordinary citizens and presidents alike. Many have therefore proclaimed that we have entered a post-truth era: a world in which objective facts are no longer relevant. Media and politics speak in alarmist discourse about how fake news, conspiracy theories and alternative facts threaten democratic societies by destabilizing the Truth – a clear sign of a moral panic. In this essay, I firstly explore what sociological changes have led to (so much commotion about) the alleged demise of the Truth. In contrast to the idea that we have moved beyond it, I argue that we are amidst public battles about the Truth: at stake is who gets to decide over that and why. I then discuss and criticize the dominant counter reaction (re-establishing the idea of one objective and irrefutable truth), which I see as an unsuccessful de-politisation strategy. Basing myself on research and experiments with epistemic democracy in the field of science studies, I end with a more effective and democratic alternative of how to deal with knowledge in the complex information landscape of today.
De terugkeer van Alledaags Racisme. Een gesprek met Philomena Essed over alledaags racisme, wetenschap en activisme
Authors: Schaap Julian , Essed Philomena
Published: June 2018

In recent societal debates on racism in the Netherlands, cultural anthropologist Philomena Essed has become one of the key faces of Dutch research on racism. Over three decades ago, Essed published a monograph entitled Alledaags Racisme (Everyday Racism), which gave rise to substantial debate within and beyond academia on the existence of racism – especially of a more implicit, everyday variation – in the Netherlands. For the first time since 1984, Alledaags Racisme is granted a new edition and has arguably only gained in relevance in a time when issues regarding race-ethnicity are increasingly politicized (e.g. the ‘Black Pete’ debate; ethno-racial profiling by police forces). Discussing – but also going beyond – this debate, this article reports a conversation between Julian Schaap and Essed on contemporary everyday racism, the sociology of race-ethnicity, and the epistemology and methodology of research that is distinctly political.
VEIN v0.2.2: an R package for bottom–up vehicular emissions inventories
Authors: Ibarra-Espinosa Sergio , Ynoue Rita , O'Sullivan Shane , Pebesma Edzer , Andrade María de Fátima , Osses Mauricio
Published: June 2018

Abstract. Emission inventories are the quantification of pollutants from different sources. They provide important information not only for climate and weather studies but also for urban planning and environmental health protection. We developed an open-source model (called Vehicular Emissions Inventory – VEIN v0.2.2) that provides high-resolution vehicular emissions inventories for different fields of studies. We focused on vehicular sources at street and hourly levels due to the current lack of information about these sources, mainly in developing countries.The type of emissions covered by VEIN are exhaust (hot and cold) and evaporative considering the deterioration of the factors. VEIN also performs speciation and incorporates functions to generate and spatially allocate emissions databases. It allows users to load their own emission factors, but it also provides emission factors from the road transport model (Copert), the United States Environmental Protection Agency (EPA) and Brazilian databases. The VEIN model reads, distributes by age of use and extrapolates hourly traffic data, and it estimates emissions hourly and spatially. Based on our knowledge, VEIN is the first bottom–up vehicle emissions software that allows input to the WRF-Chem model. Therefore, the VEIN model provides an important, easy and fast way of elaborating or analyzing vehicular emissions inventories under different scenarios. The VEIN results can be used as an input for atmospheric models, health studies, air quality standardizations and decision making.
A Reexamination of Earnings Persistence on the Incremental Value Relevance of Earnings Levels and Earnings Changes
Authors: Yang Simon
Published: June 2018

This study reexaminesthe role of earnings persistence as to understand the incremental value relevance of earnings levels and earnings changes in explaining stock returns in the stock market of U.S. The results show that earnings levels and earnings changes together provide the higher value relevant information than each earnings variable alone in explaining stock returns. An increase in earnings persistence, approximated by different time-serial and firm-specific measures, puts more (less) value relevant weight on earning changes (levels). However, the complementary value relevance between earnings levels and earnings changes is somehow weak, implying that a possibly deteriorating valuation role for earnings levels and earnings changes may occur in the recent years for the U.S. stock market.
Getting to the “Source” of Feedback-Seeking: Impact of Feedback-Seeking on Supervisor Stress
Authors: Krasman Joe
Published: June 2018

In the workplace, feedback-seeking occurs between two parties - a seeker (e.g. subordinate) who asks for feedback and a source (e.g. supervisor) who responds. This study examines the impact of feedback-seeking on sources' role overload, role conflict, and stress. A survey was conducted of supervisors. Results showed that frequency of being sought for feedback is positively related to sources' stress. In addition, role overload, but not role conflict, fully mediated this relationship. These findings suggest that feedback-seeking may have a downside for sources. Specifically, if sources are asked for feedback too often, they may fall behind in their work and experience role overload and stress. Recommendations are put forth for preventing feedback-seeking from having a negative impact on sources.
Communication Vagueness in the Literature Review Section of Journal Article Submissions
Authors: Onwuegbuzie Anthony J.
Published: June 2018

Evidence has been provided about the importance of avoiding American Psychological Association (APA) errors in the abstract, body, reference list, and table sections of empirical research articles. Specifically, authors are significantly more likely to have their manuscripts rejected for publication if they fail to avoid APA violations—and, thus, do not write with discipline—in these sections. In addition to adhering to APA, writing with discipline also includes avoiding communication vagueness. Thus, I analyzed communication vagueness in the literature review section of 71 manuscripts submitted to the journal Research in the Schools over a 3-year period. Findings revealed that the frequency of communication vagueness differed in relation to the following: (a) number of APA errors, (b) gender of lead author, (c) genre of manuscript, and (d) adjudication decisions. In particular, certain communication vagueness categories were statistically significant and practically significant predictors of whether or not a manuscript is rejected for publication by the editor. Implications of these findings are discussed.
Women’s Leadership Experiences: A Study of Ivorian Women Primary School Principals
Authors: Oyeniran Rassidy , Anchomese Ishmael Bonjah
Published: June 2018

Concerns about women educational leaders, their performance within primary schools, their approaches to leadership, including the hindrances experienced in the school headship have received few if any attention in Côte d’Ivoire. This paper analyses how women principals lead their schools and contributed to schools’ advancement in challenging situations that stand in their ways. The authors used a qualitative approach to collect data through in-depth semi-structural interviews with five female principals in Ivorian elementary schools. Findings showed that women influence directly teachers’ commitment and indirectly students’ learning process as well, particularly those who have learning difficulties. Data also revealed that these female used to create an environment and academic support that gives attention to children, as these learning conditions are similar to that of their actual life at home. Based on the findings, we assumed that women leadership could be a significant contribution to students’ learning course, which in turn positively influence the school improvement. That is even consistent with the literature, which remains constant in the assertion that women leaders own some abilities, such as being caring, attentive, patient. In this regard, educational practitioners, policy makers and stakeholders should pay more attention to women primary school principals for empowering them to display their know-how, expertise and talent useful for the students’ learning process. That seems a possible backup for Ivorian education system to reduce the low academic achievement and enhance schools’ performance.
Sin pretensiones ni rebajamientos (Antología)
Authors: Pérez Estrada Francisco
Published: June 2018

Francisco Pérez Estrada (1913- 1982), granadino, abogado, poeta, antropólogo social, ensayista e investigador de nuestro folclor. Realizó sus estudios en Nicaragua, Argentina, España y México. Presidente del
Seguridad y racismo: pensamiento crítico centroamericano
Authors: Flores Aguilar Alejandro , Arena Clara , Gómez Juan Pablo
Published: June 2018

Su propósito es promover el pensamiento producido desde Centroamérica por investigadores e investigadoras de la región.
Editorial
Authors: Rodríguez Wendy Bellanger
Published: June 2018

Los días 15 y 16 de mayo de 2014 se realizó en la Universidad Centroamericana el VIII Congreso Interdisciplinario de Invesitgación, organizado por el equipo de la Dirección de Investigación de Vicerrectoría Académica. Como siempre, el Congreso constituyó el medio más importante que existe en la UCA para dar a conocer las mejores y más recientes investigaciones realizadas en la universidad desde sus Facultades, Centros e Institutos
El portafolio digital como soporte de la práctica reflexiva en la formación docente
Authors: Rodrigues Renata , Rodríguez-Illera José Luis
Published: June 2018

El artículo presenta los resultados de una investigación que analiza el nivel de calidad reflexiva de los profesores, en el marco de un programa innovador de formación docente que introduce la práctica reflexiva, mediada y gestionada a través de un portafolio digital. Aporta a la discusión sobre nuevos usos de un portafolio digital para mejorar los procesos de reflexión por parte del profesorado y sobre modelos alternativos de formación docente; analiza los diferentes niveles de reflexión de los participantes; e identifica los obstáculos para lograr niveles de mayor profundidad
Small Arms Survey 2013: Una amenaza cotidiana. Capítulo 9. Puntos de inflexión: La evolución de las pandillas en Nicaragua
Authors: Rodgers Dennis , Rocha José Luis
Published: June 2018

Este capítulo se apoya en un trabajo de campo profundo y de largo plazo con el fin de ofrecer un análisis comparitivo de la trayectoria evolutiva, durante el período posterior a la guerra fría, de las pandillas asociadas a dos barrios de Managua, la capital de Nicaragua: Elías Blanco y Luis Fanor Hernández (estos nombres son seudónimos). Se centra en las tendencias cambiantes en el uso de armas ligeras por parte de los miembros de las pandillas, explorando los diferentes tipos de armas que han usado en diversos momentos de su historia, la naturaleza variable del mercado clandestino de armas, el apogeo y la decadencia de los actores armados, y la evolución constante de la relación entre pandillas y sus comunidades locales.
Saneamiento en territorios indígenas de Nicaragua: Un proceso en construcción dentro de la Autonomía Regional
Authors: Lorío Gema
Published: June 2018

La Investigación aborda la situación de la gobernanza de los recursos naturales, y los procesos de demarcación y titulación en América Latina y Nicaragua. Particularmente hace énfasis en los resultados de un estudio de caso aplicado en un territorio Mayagna (Tuahka) de la Costa Caribe nicaragüense. En éste se presenta el proceso y estrategia que ha seguido el gobierno territorial en relación a la demarcación y titulación de la propiedad.
Contratos civiles y mercantiles
Authors: Herrera Espinoza Jesús Juseth , Guzmán García Jairo José
Published: June 2018

En la tercera edición de “Contratos civiles y mercantiles” los autores han pretendido poner al día la fenomenología contractual tanto en su teoría general como en el desarrollo de los particulares contratos contenidos en los Códigos Civil y Mercantil. En dicha obra se han ajustado, ampliado y mejorado temas que incorporan las nuevas meditaciones que sobre la doctrina se han realizado, ajustándola a su realidad y a la cada vez más cambiante práctica negocial globalizada
Diagnóstico de contaminación atmosférica por emisiones diésel en la zona metropolitana de San Salvador y Santa Tecla
Authors: Miranda Mejía José Remberto , Martínez Gómez Samuel , Hernández-Miranda John Figerald Kenedy , Figueroa René Leonel , Aguirre Noé
Published: June 2018

Desde hace muchos siglos la humanidad conoce algunas formas de usar el petróleo. Las emanaciones superficiales de este han sido utilizadas como fuente de luz y calor, pero su uso intensivo es relativamente moderno. El combustible diésel es un aceite ligero fraccionado del petróleo con fracciones que tienen un límite de 350 °C en su punto de ebullición. El motor diésel es más eficiente que el de gasolina, pero por sus características es mucho más contaminante para la atmósfera. Se considera como contaminante de la atmósfera a toda sustancia ajena a composición normal atmosférica que se incorpora y permanece en ella durante un tiempo considerable.Entorno, mayo 2016, número 61: 7-16
Big Data, análisis de datos en la nube
Authors: Rosa Urrutia Verónica Idalia , Rivera-Pleitez José Guillermo
Published: June 2018

Big Data en El Salvador es novedoso, por lo que el objetivo de esta investigación es elaborar una guía metodológica en la que se reflejara el uso de herramientas Big Data para almacenar, procesar y analizar grandes cantidades de datos, con el fin de poder obtener conclusiones que ayuden en la toma de decisiones. Para esta investigación se hizo uso de dos dataset con información sobre registro de productos alimenticios y medicamentos. Los datos fueron almacenados y procesados por medio de herramientas Big Data, tales como Hadoop y Hive, R para análisis estadístico, finalizando con la creación de visualizaciones en Google chart, Jqplot y D3. La investigacion se llevó a cabo durante los meses de febrero a noviembre de 2015.Entorno, mayo 2016, número 61: 17-24
Modelo de vivienda urbana sostenible: buscando alternativas para cambiar de rumbo
Authors: Muñoz Márquez Coralia Rosalía
Published: June 2018

El deterioro actual del medio ambiente está alcanzando niveles cada vez más alarmantes. Aunque existen esfuerzos significativos en diferentes áreas de la arquitectura y la construcción, la vivienda urbana edificada por el sector formal ha comenzado su migración hacia nuevas propuestas en forma muy lenta.Los costos elevados de las propuestas sostenibles y el rechazo del usuario a esquemas y sistemas constructivos no tradicionales son algunas de las variables que limitan el avance hacia alternativas que brinden las condiciones que un usuario espera de una vivienda, sin elevar su costo sustancialmente, reduciendo su impacto ambiental.Esta investigación pretende salvar la brecha existente entre las diferentes alternativas de arquitectura y construcción sostenible con la oferta actual de vivienda urbana formal, presentando aquellos cambios factibles de implementar en las propuestas de proyectos habitacionales, específicamente en los que están dirigidos a los sectores de menor poder adquisitivo En una primera etapa, la investigación definirá el modelo a nivel de diseño arquitectónico y funcionalidad. En una segunda, evaluará las alternativas de materiales y sistemas constructivos y su costo, para finalmente desarrollar y evaluar un prototipo.Entorno, mayo 2016, número 61: 25-39
Internet de las cosas: aplicación en monitoreo de un sistema de generación fotovoltaico
Authors: Flores Cortez Omar Otoniel , Rosa German Antonio
Published: June 2018

En este artículo se presentan los resultados obtenidos de la investigación denominada “Internet de las cosas: interconexión de un sistema de generación fotovoltaico para su monitoreo desde la nube”, desarrollada durante 2015 en la Utec, y cuyo objetivo es el diseño e implementación de un sistema electrónico de bajo costo que permitiera el monitoreo vía internet del voltaje producido por un panel solar.A continuación se describen tanto los procedimientos realizados como los frutos obtenidos a partir de la investigación. Se realizó una revisión teórica del “estado del arte” en cuanto a los conceptos y herramientas tecnológicas utilizados. La metodología usada fue la experimentación-multimodal (Cegarra, 2004); y al final se presentan los resultados obtenidos: el principal, un prototipo electrónico completamente funcional e implementado en las instalaciones de la Utec. Siendo estos logros de suma satisfacción e importancia, por lo que esta investigación solo es el inicio de una serie de proyectos dentro del área.Entorno, may 2016, issue 61: 40-46
Realidad Aumentada en la educación
Authors: Díaz Campos Bladimir
Published: June 2018

El uso de las tecnologías en la vida diaria se vuelve cada vez más necesario. La educación sobre todo en los jóvenes, el uso de las tecnologías rivaliza mucho por la atención tanto dentro como fuera del salón de clases compitiendo por el tiempo invertido para la adecuada comprensión y aprendizaje. Una de esas tecnologías que está ganando terreno es la Realidad Aumentada, la cual al contrario de la realidad virtual, define sobre los objetos reales objetos digitales creados por computadora, En la actualidad en el mercado existe una infinidad de soluciones que involucran a la Realidad Aumentada, entre las más conocidas está la de la publicidad, por lo que adentrarse a este mundo y sobre todo para la educación, conlleva a una serie de cuestionamientos y adecuaciones necesarias de la tecnología para esta rama en particular.Entorno, mayo 2016, número 61: 47-53
Aproximación preliminar al impacto socioeconómico de los sistemas de captación de agua de lluvias en El Salvador
Authors: Aramendi Goitia Pablo , Canales-Marroquín de Ramírez Lissette Cristalina , Aguilar Flores Marco Antonio
Published: June 2018

Existen varios proyectos de instalación de sistemas de captación de agua de lluvias en El Salvador. Tras su instalación, el impacto socioeconómico de dichos sistemas no ha sido debidamente evaluado. El presente estudio, mediante una aproximación cualitativa, pretende realizar una evaluación preliminar del impacto socioeconómico de dichos sistemas, para que en un futuro se puedan implementar metodologías de recogida de datos cuantitativos y así realizar una correcta evaluación del impacto socioeconómico de los futuros proyectos de captación de agua de lluvias en El Salvador.Entorno, mayo 2016, número 61: 54-67
La tecnología como factor de competitividad: recientes indicadores internacionales de desempeño
Authors: Rodríguez Argueta Claudia María
Published: June 2018

Ante la vertiginosidad de los avances tecnológicos, los procesos de investigación, desarrollo e innovación desempeñan un papel trascendental para las industrias salvadoreñas como factor de competitividad internacional; sin embargo, El Salvador es uno de los países a escala mundial que menos invierte en investigación y desarrollo (I&D) en relación con la producción nacional. Otro indicador que visibiliza la brecha existente en el país en los temas de ciencia, tecnología e innovación es el rezago en el número de artículos en publicaciones científicas y técnicas.Por otro lado, a escala global, se vislumbran tendencias económicas que infieren algunas ventanas de oportunidad, tales como la denominada cuarta revolución industrial digital, en la cual las tecnologías de la información y comunicación jugarán un papel clave en la productividad y competitividad de las industrias y el comercio, así como en el desarrollo de nuevas actividades productivas de mayor intensidad tecnológica.En el Índice Global de Tecnología de la Información 2015, del Foro Económico Mundial, El Salvador mejoró su ranking mundial, pasando de la posición 93 a la 80; entre 143 países evaluados. Empero, se deberán ir mejorando las condiciones claves en este índice, tales como el acceso a internet en la población, para ir reduciendo la brecha digital a escala nacional, así como la necesidad de una mayor inversión en I&D en los sectores empresarial y académico y, paralelamente, la implementación de nuevas políticas de desarrollo para ir fortaleciendo la economía digital y la sociedad del conocimiento, que conlleven hacia una transformación productiva en el país.Entorno, mayo 2016, número 61: 68-75
Implementación de un entorno de aprendizaje virtual integrando herramientas de e-learning y CMS
Authors: Aguirre Ayala Carlos Antonio , Hernández Montoya Marvin Elenilson
Published: June 2018

La investigación tiene como objetivo describir las diferentes plataformas de e-learning, así como las soluciones de administradores de contenido (CMS) existentes en el mercado. Asimismo, se implementa un portal virtual integrando Moodle y Joomla a través de una extensión llamada Joomdle. Con este tipo de soluciones se podrá proporcionar al usuario mayor facilidad al momento de llevar cursos virtuales.Entorno, mayo 2016, número 61: 76-90