bluuebunny/crossref_metadata_2025 huggingface dataset:
An adaptive observer design approach for a class of discrete-time nonlinear systems
Authors: Srinivasarengan Krishnan , Ragot José , Aubrun Christophe , Maquin Didier
Published: March 2018

We consider the problem of joint estimation of states and some constant parameters for a class of nonlinear discrete-time systems. This class contains systems that could be transformed into a quasi-LPV (linear parameter varying) polytopic model in the Takagi-Sugeno (T-S) form. Such systems could have unmeasured premise variables, a case usually overlooked in the observer design literature. We assert that, for such systems in discrete-time, the current literature lacks design strategies for joint state and parameter estimation. To this end, we adapt the existing literature on continuous-time linear systems for joint state and time-varying parameter estimation. We first develop the discrete-time version of this result for linear systems. A Lyapunov approach is used to illustrate stability, and bounds for the estimation error are obtained via the bounded real lemma. We use this result to achieve our objective for a design procedure for a class of nonlinear systems with constant parameters. This results in less conservative conditions and a simplified design procedure. A basic waste water treatment plant simulation example is discussed to illustrate the design procedure.
Robust stabilization using a sampled-data strategy of uncertain neutral state-delayed systems subject to input limitations
Authors: Fezazi Nabil El , Haoussi Fatima El , Tissir El Houssaine , Alvarez Teresa , Tadeo Fernando
Published: March 2018

Stabilization of neutral systems with state delay is considered in the presence of uncertainty and input limitations in magnitude. The proposed solution is based on simultaneously characterizing a set of stabilizing controllers and the associated admissible initial conditions through the use of a free weighting matrix approach. From this mathematical characterization, state feedback gains that ensure a large set of admissible initial conditions are calculated by solving an optimization problem with LMI constraints. Some examples are presented to compare the results with previous approaches in the literature.
Decentralized stabilization of fractional positive descriptor continuous-time linear systems
Authors: Kaczorek Tadeusz
Published: March 2018

A method for decentralized stabilization of fractional positive descriptor linear systems is proposed. Necessary and sufficient conditions for decentralized stabilization of fractional positive descriptor linear systems are established. The efficiency of the proposed method is demonstrated on a numerical example.
Bounds on the rate of convergence for one class of inhomogeneous Markovian queueing models with possible batch arrivals and services
Authors: Zeifman Alexander , Razumchik Rostislav , Satin Yacov , Kiseleva Ksenia , Korotysheva Anna , Korolev Victor
Published: March 2018

In this paper we present a method for the computation of convergence bounds for four classes of multiserver queueing systems, described by inhomogeneous Markov chains. Specifically, we consider an inhomogeneous M/M/S queueing system with possible state-dependent arrival and service intensities, and additionally possible batch arrivals and batch service. A unified approach based on a logarithmic norm of linear operators for obtaining sharp upper and lower bounds on the rate of convergence and corresponding sharp perturbation bounds is described. As a side effect, we show, by virtue of numerical examples, that the approach based on a logarithmic norm can also be used to approximate limiting characteristics (the idle probability and the mean number of customers in the system) of the systems considered with a given approximation error.
Iterative methods for efficient sampling-based optimal motion planning of nonlinear systems
Authors: Ha Jung-Su , Choi Han-Lim , Jeon Jeong Hwan
Published: March 2018

This paper extends the RRT* algorithm, a recently developed but widely used sampling based optimal motion planner, in order to effectively handle nonlinear kinodynamic constraints. Nonlinearity in kinodynamic differential constraints often leads to difficulties in choosing an appropriate distance metric and in computing optimized trajectory segments in tree construction. To tackle these two difficulties, this work adopts the affine quadratic regulator-based pseudo-metric as the distance measure and utilizes iterative two-point boundary value problem solvers to compute the optimized segments. The proposed extension then preserves the inherent asymptotic optimality of the RRT* framework, while efficiently handling a variety of kinodynamic constraints. Three numerical case studies validate the applicability of the proposed method.
Stabilization of an epidemic model via an N-periodic approach
Authors: Cantó Begoña , Coll Carmen , Sánchez Elena
Published: March 2018

We analyze the evolution of an infectious disease by combining different groups of a population when the route of transmission is via encounters with free-living virulent organisms that can survive for a long time outside the individual. This study involves matrix analysis of lower triangular block matrices and some of their spectral properties. We propose an N-periodic control strategy in order to stabilize the disease around the disease-free equilibrium point.
Some classes of statistical distributions. Properties and Applications
Authors: Băncescu Irina
Published: March 2018

We propose a new method of constructing statistical models which can be interpreted as the lifetime distributions of series-parallel/parallel- series systems used in characterizing coherent systems. An open problem regarding coherent systems is comparing the expected system lifetimes. Using these models, we discuss and establish conditions for ordering of expected system lifetimes of complex series-parallel/parallel-series systems. Also, we consider parameter estimation and the analysis of two real data sets. We give formulae for the reliability, hazard rate and mean hazard rate functions.
Tripotents: a class of strongly clean elements in rings
Authors: Călugăreanu Grigore
Published: March 2018

Periodic elements in a ring generate special classes of strongly clean elements. In particular, elements b such that b = b3+, which are called tripotents and include idempotents, negative of idempotents and order 2 units, are strongly clean. Such elements are determined in 2×2 matrix rings over commutative domains or over arbitrary division rings and for rings of integers modulo n.
Anti-plane crack in human bone. I. Mathematical modelling
Authors: Crăciun Eduard Marius , Marin Marin , Răbâea Adrian
Published: March 2018

We consider an anti-plane crack in a bone, considered as an initially deformed orthotropic, linear elastic composite material. Elastic incremental fields in the composite material are obtained following theories of Guz’s representation and of Riemann-Hilbert problem. Critical values of crack propagation angle are determined using Sih’s generalized criterion.
Generalized Horadam Polynomials and Numbers
Authors: Djordjevic Snezana S. , Djordjevic Gospava B.
Published: March 2018

We consider the polynomials hn,m(x) (m ≥ 2) and the numbers hn,m (x = 1), which are the generalized Horadam polynomials and the generalized Horadam numbers, respectively. We also consider the polynomials h(s)
n,m(x)- convolutions of the polynomials hn,m(x), and the sequence of numbers h(s)
n,m- convolutions of the numbers hn,m, where s ≥ 0.
Transverse vibrations analysis of a beam with degrading hysteretic behavior by using Euler-Bernoulli beam model
Authors: Groza Ghiocel , Mitu Ana-Maria , Pop Nicolae , Sireteanu Tudor
Published: March 2018

The paper is based on the analytical and experimental results from [14], [15] and reveals, by mathematical methods, the degradation of ma- terial stifiness due to the decrease of the first natural frequency, when the driving frequency is slightly lower than the first natural frequency of the undegradated structure. By considering the vibration of the uni- form slender cantilever beam as an oscillating system with degrading hysteretic behavior the following equation is considered subjected to the boundary conditions To approximate the solution of the this problem, we use the method of Newton interpolating series (see [6]) and the Taylor series method (see [8]).
Laplace operators on holomorphic Lie algebroids
Authors: Ionescu Alexandru
Published: March 2018

The paper introduces Laplace-type operators for functions defined on the tangent space of a Finsler Lie algebroid, using a volume form on the prolongation of the algebroid. It also presents the construction of a horizontal Laplace operator for forms defined on the prolongation of the algebroid. All the Laplace operators considered in the paper are also locally expressed using the Chern-Finsler connection of the algebroid.
Commutator Subgroups of Generalized Hecke and Extended Generalized Hecke Groups
Authors: Kaymak Şule , Demır Bilal , Koruoğlu Özden , Şahin Recep
Published: March 2018

Let p and q be integers such that 2 ≤ p ≤ q; p + q > 4 and let Hp,q be the generalized Hecke group associated to p and q: The generalized Hecke group Hp,q is generated by X(z) = -(z-λp)-1 and Y (z) = -(z+ λq)-1 where λp = 2 cos ≤ π/p and λq = 2 cos π/q . The extended generalized Hecke group H̅p,q is obtained by adding the reection R(z) = 1/z̅ to the generators of generalized Hecke group Hp,q: In this paper, we study the commutator subgroups of generalized Hecke groups Hp,q and extended generalized Hecke groups H̅p,q.
Exact Formula for Computing the Hyper-Wiener Index on Rows of Unit Cells of the Face-Centred Cubic Lattice
Authors: Mujahed Hamzeh , Nagy Benedek
Published: March 2018

Similarly to Wiener index, hyper-Wiener index of a connected graph is a widely applied topological index measuring the compactness of the structure described by the given graph. Hyper-Wiener index is the sum of the distances plus the squares of distances between all unordered pairs of vertices of a graph. These indices are used for predicting physicochemical properties of organic compounds. In this paper, the graphs of lines of unit cells of the face-centred cubic lattice are investigated. The graphs of face-centred cubic lattice contain cube points and face centres. Using mathematical induction, closed formulae are obtained to calculate the sum of distances between pairs of cube points, between face centres and between cube points and face centres. The sum of these formulae gives the hyper-Wiener index of graphs representing face-centred cubic grid with unit cells connected in a row. In connection to integer sequences, a recurrence relation is presented based on binomial coefficients.
Power sums in hyperbolic Pascal triangles
Authors: Németh László , Szalay László
Published: March 2018

In this paper, we describe a method to determine the power sum of the elements of the rows in the hyperbolic Pascal triangles corresponding to –4, q} with q ≥ 5. The method is based on the theory of linear recurrences, and the results are demonstrated by evaluating the kth power sum in the range 2 ≤ k ≤ 11.
Weighted Entropic Copula from Preliminary Knowledge of Dependence
Authors: Panait Ioana
Published: March 2018

This paper introduces a weighted entropic copula from preliminary knowledge of dependence. Considering a copula with common distribution we formulate the weighted entropy dependence model (WMEC). We give an approximator for the copula function of this problem. Also, we discuss some asymptotical properties regarding the unknown parameters of the model.
On Remotest set and Random controls in Kaczmarz algorithm
Authors: Popa Constantin
Published: March 2018

In this paper we analyse the Kaczmarz projection algorithm with Remotest set and Random control of projection indices and provide a suficient condition such that each projection index appears infinitely many times during the iterations.
Consequences of a Spectacle? Alleged Match-Fixing in the National Basketball Association Western Conference Finals of 2002
Authors: Muniowski Łukasz
Published: March 2018

No major professional sports league epitomizes Guy Debord’s idea of the spectacle more than the NBA. The league was the first to understand the importance of highlights and global expansion, and participated in creating the first branded superstar in Michael Jordan. Naturally there are some controversies surrounding the rise to its present-day status, like the (supposedly) fixed 1985 draft or Michael Jordan’s (supposedly) enforced first retirement. One of the most controversial events in recent league history took place during Game Six of the 2002 Western Conference Finals between the Los Angeles Lakers and the Sacramento Kings. A lot of controversial calls by the referees allowed the Lakers to win the game and eventually the series. As the Lakers were about to get eliminated, the league officials allegedly encouraged referees to force a Game Seven. The problem with the allegations was that they were made public by former referee Tim Donaghy, who himself used to bet on games. David Stern, the league’s former commissioner was referring to Donaghy’s gambling addiction as the reason for the falsity of his statements. My paper uses the game in question as a case study in order to present the spectacular aspects of the NBA.
Justice at Sport Clubs According to the Theory of Utilitarianism and Libertarianism
Authors: Zimányi Róbert G. , Geczi Gábor
Published: March 2018

Today’s sport clubs are exposed to turbulently changing circumstances to which they must adapt. If we want to talk about quality sport clubs, we have to find the qualitative criterion that justifies them. This must then be accepted by society as well. Such aspects of quality and evaluation may show justice. Only one truth exists. Thus the question is how and by what principles we should interpret it. Justice can play a key role in the operation of sport clubs as a moral element. This justice must not necessarily be linked to equality. The goal of this study is to interpret justice as a quality factor in sport clubs. The other goal of the study is to present some theories of justice related to sport. The study examines Bentham’s utilitarianism, Mill’s higher pleasures, and the ideas of libertarianism concerning justice. The theories of justice in addition to social processes also play a key role in today’s sport clubs. During the interpretations, it is important to distinguish between competitive and non-competitive sport clubs in relation to justice. It also depends on the practical applicability of the theory of justice. The practical application of theories of justices should be thoroughly investigated in the life of sport clubs. Then the sport clubs’ management must decide which theory of justice should be introduced. The key question concerns how to apply it consistently in practice while taking into account the interests of existing and prospective members. Finding the potential qualitative key factors for the sport clubs’ qualification is a complex activity. Besides happiness and justice, many other ancient and presently valued virtues can be relevant qualities and distinctive aspects among sport clubs.
1. Simultaneo Ensemble – Bringing Our History Into the Future / A New Pedagogical Approach of Music-Making Developed from “Bottega Dell'arte”
Authors: Franchini Cecilia
Published: March 2018

How much can contemporary artists and audiences learn from the past? The mission and activity of Simultaneo Ensemble - SIM - is presented. How SIM laboratory, grouping performers from the seven Music Academies of Veneto, encourages musicians to explore, perform and promote italian music composers and their works. This article will consider the relationship between research into historical concert programs and the creation of adventurous and compelling chamber music concerts for contemporary audiences. Learn how to enhance the position of chamber music activity trough projects that have suceeded in bringing people together toward common goals via the arts.
2. Rhythmical Creativity in Duple and Triple Meter of Students of Early-School Education in the Light of Their Stabilised Musical Aptitudes and Rhythm Readiness to Improvise
Authors: Kołodziejski Maciej
Published: March 2018

The article presents the results of (author's) own research on the students of earlyschool education imitation and the rhythmical improvisation in the light of their stabilised musical aptitudes measured with Edwin E. Gordon's AMMA test and also Edwin E. Gordon's readiness to rhythm improvisation readiness record (RIRR). In the first part of the research the students imitated some rhythmical patterns diversified in terms of difficulty in duple and triple meter and the subsequent part concerned guiding the oral rhythmical dialogue (on the BAH syllable) by the teacher with the application of various rhythmical motives in different metres. The students' both imitative and improvising performances were rated by three competent judges. What was undertaken was searching for the relations between musical aptitudes, improvisation readiness and the pupils' rhythmical imitation and improvisation abilities.
4. Assessment Typologies Used Within the Discipline Theory, Solfeggio, Musical Dictation
Authors: Duţică Luminiţa
Published: March 2018

Assessment is a distinct stage within the teaching process, aiming to measure the level of the knowledge, skills and competences acquired within a given time frame. The discipline Theory, Solfeggio, Musical Dictation involves a synthesis between the theoretical and the practical side of the matter, and, as a result, it uses specific assessment tools for each side. Modern assessment methods involve personalized systems based on the diversification of types of docimological tests, quizzes, practical tests, etc. In this study we will present a series of personal contributions referring to the contents specific to the discipline Theory, Solfeggio, Musical Dictation taught at university.
8. Possible Approaches to the Concept of Collaborative Teaching in the “Music Analysis” Course. Benefits and Challenges
Authors: Vlahopol Gabriela
Published: March 2018

The concept of Collaborative Teaching is one of the innovative approaches to learning, which has changed the view of traditional teaching methods by involving two or more teachers in training a single group. The process involves a variety of flexible teaching methods that meet the learning needs of all students, while developing their communication, collaboration, critical thinking and creativity skills. Artistic education in the university environment contains two main biases, theoretical and practical (performance), which are divergent in the way of manifestation and collaboration between teachers. The applicability of the concept of Co-Teaching in performance is relatively intuitive, with a sporadic concretisation and no visible results in students' evolution. As regards the theoretical part of the musicians, the collaboration in the teaching process could be an important tool for correlating the information obtained at different disciplines in different fields (harmony, counterpoint, music history, folklore, aesthetics, stylistics, music theory, music analysis, etc.), but also to actively acknowledge the importance of a complex vision on the formation of a complete musician.
9. An Analysis of the Vocal Ensembles from the Opera “I Puritani” by Vincenzo Bellini
Authors: Simionescu Cristina
Published: March 2018

I Puritani is the masterpiece that crowned the creation of the Italian composer Vincenzo Bellini, being remarked and appreciated for the richness of his melodicity and profound symbols filled with the inspiration and creativity of a creator. This was the last of the ten works composed by Bellini, whose disappearance was premature, at only 33 years, but the passion and talent with which he created revealed a work dominated by essence and emotion, which establishes a close connection between chant and the poetic text, providing new expressive valences to the lyrical universe. The extremely difficult and demanding vocal writing raises serious challanges, the Bel-canto style meaning not only a “beautiful chant” but also a difficult texture, a certain specific phrasing and a spread of spectacular acute tones.
10. Interpretative Performances: Elisabeth Leonskaya And Paul Badura-Skoda
Authors: Tudor Brînduşa
Published: March 2018

In the complex road of deciphering and understanding a musical work, an important step for the pianist (performer or professor) is represented by the choice of reference interpretations according to some famous musicians. Elisabeth Leonskaya and Paul Badura - Skoda are among the most distinguished representatives of the contemporary school of piano.
11. Basic Practice Methods in University General Piano Classes
Authors: Raducanu Cristina Andra
Published: March 2018

The purpose of this article was to present and analyse some practicing piano methods which are used during secondary piano lessons at the university. The final goal was to show the benefits of these practice strategies in the process of learning a new piano piece. Experience demonstrated that in order to keep students motivated, there is a need for them to know how to approach and study a new repertoire and to be sure that implementing these practice methods will help them gain the necessary skills which will enable them to fluently perform a musical piece.
1. The Acting Student’s Choreographic Training. Several Cognitive Objectives
Authors: Șușu Petre , Crețu Carmen Mihaela , Bălăiță Aurelian
Published: March 2018

Dance is an artistic genre that is more and more frequently used in theatre productions. The syncretism of theatre and dance can take many shapes, from inserting dance sequences in dramatic performances, to new artistic genres, such as dance theatre. Due to the fact that they offer manifold innovating possibilities for artistic expression in a greatly audience-oriented universal language, theatrical forms that include dance, and especially the artistic genre of dance theatre are increasingly often put on stage by directors who work in Romania. Thus, training actors in the area of dance at a high level of performance that allows them to approach these types of syncretic artistic genres becomes a priority for the Romanian theatre school. The director, one of the stakeholders in higher education theatre schools, is the one who decides both the form of a performance and an actor’s involvement (or lack thereof) in that certain performance. Limited or stimulated by the actor’s training level, the director is also a beneficiary of the education the acting student receives in drama school. This study aims at identifying the opinions of ten Romanian directors on the matter of the choreographic categories and skills the acting student acquires during his years of training at a higher education institution. We have used qualitative methodology research, based on semi-structured interviews, applied to a cross-section of ten directors from Bucharest, Cluj-Napoca, Constanţa, Craiova, Iaşi, and Tg. Mureş. This article tackles the issue of cognitive didactic objectives and students’ cognitive competencies that have been emphasized during the conversations with the aforementioned directors.
3. Practice Through Movement and Practice Through Motionlessness
Authors: Leșe Ana-Cristina
Published: March 2018

Through this paper we address the students from theatre and music specialists, but also all people interested in elements belonging to Tai Chi practice, considering that these, once introduced into a specific physical exercise program, are beneficial for the development of the respiratory capacity and also for a good physical and mental balance that support the professional skills. These two expressions used in the majority of martial arts, dung-gong movement practice and jing-gong motionless practice are yin and yang aspects and are based on the balance between motion and stillness of the body and the mind.
4. The Feldenkrais Method in the Puppeteer’s Training from the Perspective of Nicolas Gousseff’s Handheld Puppets Workshops
Authors: Ciofu Anca-Mihaela
Published: March 2018

Although the Feldenkrais method is quite well-known and used in relation to dance, music, and acting, it is rather uncommon to associate it with animation theatre. The puppeteer’s art is a profession that requires motor skills and sustained physical effort, which demands that the animating actor has an extended consciousness of oneself and of the space. Therefore, the Feldenkrais method can be a useful instrument in the puppeteer’s education and training, as the placing of the body in a relaxed stance, one which helps in the management of pain and effort, facilitates the conscious and creative learning of animation techniques, with an emphasis on the coordination and fluidity of movement. These are learning principles of the art of animation that are successfully used by Nicolas Gousseff, an artist that was formed at ESNAM (École Supérieure Nationale des Arts de la Marionnette de la Charleville-Mézières), and who has specialized in handheld puppets and using the actor’s body as a performative space for this type of animation.
5. Coregraphic Arts Education from the Intercultural Perspective
Authors: Todi Cristina
Published: March 2018

Theatre, dancing and singing are arts born out of a common body that share the same idea and means of expression - the human body, these arts manifesting through the most important condition - the artist. The openings exhibited in the theatrical space, spiritless in some people, pragmatic in others, pass on the intimate message of dancing: substance, essence, density.
Assessing Outcomes in People With Chronic Ankle Instability: The Ability of Functional Performance Tests to Measure Deficits in Physical Function and Perceived Instability
Authors: Madsen Leif P. , Hall Emily A. , Docherty Carrie L.
Published: March 2018

Study Design

Laboratory-based, cross-sectional study.

Background

Functional performance tests (FPTs) assess short bouts of unilateral hops for either distance or speed. More research is needed to identify specific FPTs that may be useful for measuring asymmetry outcomes related to functional performance and perceived instability deficits in individuals with chronic ankle instability (CAI).

Objectives

To identify FPTs that are sensitive to subjective and objective deficits associated with CAI.

Methods

Twenty-four subjects with unilateral CAI (10 male, 14 female; mean ± SD age, 20.7 ± 3.0 years) and 24 healthy, matched controls (10 male, 14 female; age, 20.1 ± 2.6 years) completed 5 unilateral FPTs in random order. Mean FPT scores and functional symmetry percentages were calculated and compared between groups using 2 separate 1-way multivariate analyses of variance (MANOVAs). Perceived instability symmetry percentages were compared between groups using a Mann-Whitney U analysis.

Results

There were no differences in the mean FPT scores (P>.05) or functional symmetry percentages (P>.05) between groups for any of the 5 FPTs. However, participants with CAI perceived greater instability when using their involved limb during the side hop (P = .02), 6-meter crossover hop (P = .003), lateral hop (P = .007), and figure-of-eight hop (P = .008).

Conclusion

There were no differences in mean functional scores between groups for all 5 FPTs, and each group performed symmetrically. Regardless, administering a visual analog scale following the completion of the side hop, 6-meter crossover hop, lateral hop, and figure-of-eight hop tests captures subjective reports of perceived instability in the involved limb that can be compared bilaterally throughout treatment. J Orthop Sports Phys Ther 2018;48(5):372–380. Epub 30 Mar 2018. doi:10.2519/jospt.2018.7514
Hop Distance Symmetry Does Not Indicate Normal Landing Biomechanics in Adolescent Athletes With Recent Anterior Cruciate Ligament Reconstruction
Authors: Wren Tishya A.L. , Mueske Nicole M. , Brophy Christopher H. , Pace J. Lee , Katzel Mia J. , Edison Bianca R. , Vandenberg Curtis D. , Zaslow Tracy L.
Published: March 2018

Background

Return-to-sport protocols after anterior cruciate ligament reconstruction (ACLR) often include assessment of hop distance symmetry. However, it is unclear whether movement deficits are present, regardless of hop symmetry.

Objectives

To assess biomechanics and symmetry of adolescent athletes following ACLR during a single-leg hop for distance.

Methods

Forty-six patients with ACLR (5–12 months post surgery; 27 female; mean ± SD age, 15.6 ± 1.7 years) were classified as asymmetric (operative-limb hop distance less than 90% that of nonoperative limb [n = 17]) or symmetric (n = 29) in this retrospective cohort. Lower extremity biomechanics were compared among operative and contralateral limbs and 24 symmetric controls (12 female; mean ± SD age, 14.7 ± 1.5 years) using analysis of variance.

Results

Compared to controls, asymmetric patients hopped a shorter distance on their operative limb (P<.001), while symmetric patients hopped an intermediate distance on both sides (P≥.12). During landing, the operative limb, regardless of hop distance, exhibited lower knee flexion moments compared to controls and the contralateral side (P≤.04), with lower knee energy absorption than the contralateral side (P≤.006). During takeoff, both symmetric and asymmetric patients had less hip extension and smaller ankle range of motion on the operative side compared with controls (P≤.05). Asymmetric patients also had lower hip range of motion on the operative, compared with the contralateral, side (P = .001).

Conclusion

Both symmetric and asymmetric patients offloaded the operative knee; symmetric patients achieved symmetry, in part, by hopping a shorter distance on the contralateral side. Therefore, hop distance symmetry may not be an adequate test of single-limb function and return-to-sport readiness. J Orthop Sports Phys Ther 2018;48(8):622–629. Epub 30 Mar 2018. doi:10.2519/jospt.2018.7817
Review of the Factors that Influence the Condition of Wax Deposition in Subsea Pipelines
Authors: Junyi Koh , Hasan Nurul
Published: March 2018

When crude oil is transported via sub-sea pipeline, the temperature of the pipeline decreases at a deep depth which causes a difference in temperature with the crude oil inside. This causes the crude oil to dissipate its heat to the surrounding until thermal equilibrium is achieved. This is also known as the cloud point where wax begins to precipitate and solidifies at the walls of the pipeline which obstruct the flow of fluid. The main objective of this review is to quantify the factors that influence wax deposition such as temperature difference between the wall of the pipeline and the fluid flowing within, the flow rate of the fluid in the pipeline and residence time of the fluid in the pipeline. It is found the main factor that causes wax deposition in the pipeline is the difference in temperature between the petroleum pipeline and the fluid flowing within. Most Literature deduces that decreasing temperature difference results in lower wax content deposited on the wall of the pipeline. The wax content increases with rising flow rate. As for the residence time, the amount of deposited wax initially increases when residence time increases until it reaches a peak value and gradually decreases. Flow-loop system and cold finger apparatus were used in literature investigations to determine the trends above. Three new models are generated through a regression analysis based on the results from other authors. These new models form a relationship between temperature difference, flow rate, residence time and Reynolds number with wax deposition. These models have high values of R-square and adjusted R-square which demonstrate the reliability of these models.
Stress Analysis of Thin-Walled Laminated Composite Beams under Shear and Torsion
Authors: Ali Jaffar Syed Mohammed , Hrairi Meftah , Mohamad Masturah
Published: March 2018

An educational software which can aid students in the stress analysis of thin wall open sections made of composite material has been developed. The software enables students to easily calculate stresses in different shapes of thin wall open section and evaluate the stresses in each ply under shear and torsion. Results obtained through this software have been validated against ANSYS. The software is intended to be an educational tool for effective teaching and learning process on thin-walled structures, aircraft structures and composite structures courses.
Suppressing Aluminum Carbide in Welding Aluminum Silicon Carbide Composite
Authors: Kothari Mitul , Hung Wayne NP
Published: March 2018

Weldability of aluminum-based metal matrix composite A359/SiC/10p using gas tungsten arc welding and R356.0 filler material is investigated. The welding current, welding speed, and preheat temperature affect the weld quality significantly. Finite element analysis is successfully applied to map the weldment temperature during preheating and welding. During mechanical testing of welded specimens, a crack propagates in the parent composite or in the weld, but not in the stronger zone between the weld and the parent material. The weld region contains reasonably uniform distribution of SiC particles due to high viscosity of the molten weld and its fast cooling rate. Proper control of heat input and addition of silicon-rich filler material hinder the interface reaction between aluminum matrix and the reinforcing SiC particles, and successfully suppresses the formation of harmful aluminum carbide flakes in the weld. The average tensile and flexural strengths of optimally welded specimens approach those of the parent composite while its ductility exceeds that of the parent material.
Micro Electro Discharge Machining for Nonconductive Ceramic Materials
Authors: Ali Mohammad Yeakub , Sabur Abdus , Banu Asfana , Maleque Md. Abdul , Adesta Erry YT
Published: March 2018

In micro-electro discharge machining (micro-EDM) of nonconductive ceramics, material is removed mainly by spalling due to the dominance of alternating thermal load. The established micro-EDM models established for single spark erosion are not applicable for nonconductive ceramics because of random spalling. Moreover, it is difficult to create single spark on a nonconductive ceramic workpiece when the spark is initiated by the assisting electrode. In this paper, theoretical model of material removal rate (MRR) as the function of capacitance and voltage is developed for micro-EDM of nonconductive zirconium oxide (ZrO2). It is shown that the charging and discharging duration depend on the capacitance and resistances of the circuit. The number of sparks per unit time is estimated from the single spark duration s derived from heat transfer fundamentals. The model showed that both the capacitance and voltage are significant process parameters where any increase of capacitance and voltage increases the MRR. However, capacitance was found to be the dominating parameter over voltage. As in case of higher capacitances, the creation of a conductive carbonic layer on the machined surface was not stable; the effective window of machining 101 - 103 pF capacitance and 80 - 100 V gap voltage or 10 - 470 pF capacitance and 80 - 110 V gap voltage. This fact was confirmed EDX analysis where the presence of high carbon content was evident. Conversely, the spark was found to be inconsistent using parameters beyond these ranges and consequently insignificant MRR. Nevertheless, the effective number of sparks per second were close to the predicted numbers when machining conductive copper material. In addition, higher percentage of ineffective pulses was observed during the machining which eventually reduced the MRR. In case of validation, average deviations between the predicted and experimental values were found to be around 10%. Finally, micro-channels were machined on nonconductive ZrO2 as an application of the model.
Characterization of Carbon Nanotube Reinforced Aluminium Nano-composite using Field Emission Scanning Electron Microscope
Authors: Abdullahi Umma , Maleque Md. Abdul , Ali Mohammad Yeakub
Published: March 2018

Carbon nanotubes (CNT) is a promising fibrous materials for development of nanocomposite especially aluminium (Al) matrix nanocomposites as CNT exhibited extraordinary mechanical properties and high aspect ratios. The dispersion is the main factor for a quality CNT-Al nanocomposite that affects the uniformity in mixture leading to the enhanced mechanical and wear behaviour. The present study emphasizes on the characterization of carbon nanotube dispersion by means of field emission scanning electron microscope after synthetization of new nanocomposite. The mixing of the reinforcement and matrix powders was performed in ball mill for 2 hours at 250 rpm. The result shows the homogeneous distribution was observed from the experiment. The morphological characterization under FESEM provides insight features of CNT-Al nano-composite with the ball milling parameter on the sintering.
STRATEGIES FOR ENHANCING KINDERGARTEN STUDENTS’ ENGLISH SKILS THROUGH LEARNING IN REAL-LIFE CONTEXTS
Authors: Ambarini Ririn
Published: March 2018

Early learning experiences are crucial to establish the foundation for the acquisition of knowledge and skills that will affect later learning and behaviour. As teaching English at the early age is very crucial, learning experiences should be thoughtfully planned and guided by the teacher. It is found out that there are still many kindergarten students who still find difficulties in learning English vocabularies for  the strategies and teaching learning media that are conveyed by the the teachers are not sufficient to support the English class in kindergarten and the English teaching learning process is still teacher-centered with less interaction between teachers and students and also between students and students. The effects of those conditions make the students pay less attention on the English activities given by their teachers, respond passively to the questions and the instructions from the teachers, and give unhappy expression when joining the English activities. Having a look at those problems, the strategies in the process of teaching learning, will contribute to the output of students’ learning. In this article, it will discuss six strategies to improve kindergarten students’ English skills through learning in real-life contexts. Those strategies are knowing the early stages of learning, developing the activities of learning in real-life contexts, developing the activities of integrated learning, developing an effective literacy environment, developing the activities of learning early numeracy in real-life contexts, and creating a supportive learning Environment.
Evaluación de la capacidad depuradora de las plantas acuáticas del Paraguay
Authors: Marecos O. , Vely R. , Inchaustti A. , Argüello L. , Gutiérrez E. , Colmán A.
Published: March 2018

La necesidad de una gestión ecosistémica del agua, siguiendo los principios del desarrollo sostenible hace que se adopten sistemas naturales que aprovechan y potencian los procesos físicos, químicos y bacterianos que ocurren a diario en la naturaleza. El trabajo pretende evaluar de manera comparativa la eficiencia de los humedales artificiales en las lagunas de estabilización con respecto a la remoción de las cargas contaminantes nitrogenadas y fosforadas. Como parte de la investigación se recopilaron los datos resultantes de investigaciones anteriores realizadas en nuestro país. El estudio presenta resultados que demuestran que mediante el uso de estas plantas se pueden ser eficases en la remoción de los contaminantes más comunes de las aguas.
Análisis de la implementación de los programas de Educación Media Alternativa y a Distancia de la modalidad de jóvenes y adultos
Authors: Zavala María Victoria , Molinas Santana Graciela María Delia , Speratti Mendoza Hugo Matías
Published: March 2018

Este trabajo pretende dar un panorama sintético del Informe Final de Investigación, presentado al MEC en el mes de febrero del presente año.El trabajo se ha centrado en un acercamiento a las ofertas educativas de la Educación Media Alternativa y a Distancia. El objetivo general del estudio es analizar el proceso de implementación curricular de la Educación Media Alternativa (EMAJA) y la Educación Media a Distancia para Jóvenes y Adultos (EMADJA).Algunas conclusiones resaltantes son que las infraestructuras en la que se desarrollan las ofertas, en su mayoría se realizan en espacios utilizados para Educación Escolar Básica (EEB) y la Educación Inicial (EI), resultando inadecuados a la edad de los participantes. Se resalta la ausencia de un documento curricular oficial en EMAJA; en EMADJA, si bien se cuenta con este documento que declara el énfasis en Nuevas Tecnologías, las evidencias recogidas denotan la ausencia de medios tecnológicos. Las evidencias del proceso de implementación son escasas. Los docentes que se desempeñan en las mismas, cuentan con certificación para el desempeño docente además de compartir con los y las participantes la alta valoración social de la oferta que representa dignidad, posibilidades sociales y económicas.
Relación entre la implementación del aprendizaje cooperativo y el logro en el aprendizaje individual de estudiantes universitarios
Authors: Valdez Fátima
Published: March 2018

El presente trabajo reporta la investigación realizada con el objetivo de analizar la relación entre la implementación del aprendizaje cooperativo y el logro del aprendizaje individual de estudiantes universitarios. Las técnicas empleadas para la recolección de los datos fueron la encuesta y la observación, aplicadas por medio de dos cuestionarios semiestructurados y una guía de observación de clases a estudiantes de Psicopedagogía de la Universidad Iberoamericana, en el periodo de agosto a diciembre de 2010
La extensión universitaria: análisis de su organización y gestión en facultades de la Universidad Nacional de Asunción
Authors: Torres de Ruiz María Luisa
Published: March 2018

Este estudio analiza la organización y la gestión de la extensión universitaria en siete facultades de la Universidad Nacional de Asunción (UNA): Facultad de Ciencias Exactas y Naturales, Facultad de Odontología, Facultad de Filosofía, Facultad de Ciencias Veterinarias, Facultad de Ciencias Agrarias, Facultad Politécnica y Facultad de Arquitectura Diseño y Arte. El trabajo de campo se desarrolló entre los meses de mayo y octubre de 2011. Para esta investigación se realizó un estudio de tipo descriptivo, de diseño no experimental, y se adoptó el enfoque mixto: cuali-cuantitativo. Las técnicas e instrumentos utilizados para la recolección de datos fueron la encuesta, con un cuestionario abierto y otro cerrado, y la entrevista, aplicadas a directivos, docentes y estudiantes de las facultades en estudio, y el análisis de documentos oficiales de las mismas. Los resultados revelan que las siete facultades de la UNA poseen en su estructura órganos de gestión encargados de la extensión universitaria, así como una organización y gestión establecidas en sus organigramas y en los documentos normativos de la misma universidad y de cada facultad
Proyecto interinstitucional de investigación – acción “Colonias de Verano”
Authors: Iberoamericana Universidad
Published: March 2018

Desde su creación, la Universidad Iberoamericana viene propiciando proyectos sociales a través de alianzas estratégicas con organismos gubernamentales y no gubernamentales con el propósito de retornar a la sociedad los saberes que se desarrollan en la misma. Dentro del marco-convenio entre la SNNA, las Aldeas Infantiles SOS y la Universidad Iberoamericana, se propuso en esta ocasión un proyecto interdisciplinario para atender de manera integral a las familias en situaciones de vulnerabilidad. El proyecto fue presentado a fondos concursables y adjudicado en la primera convocatoria de la Fundación Parque Tecnológico Itaipú – Paraguay (FPTI-PY) para la ejecución de proyectos de retorno social por becarios de Itaipú. El proyecto “COLONIAS DE VERANO” se presentó en dos etapas. En una primera etapa, con los niños y las niñas del Centro Abierto 02 de la SNNA, del Centro Comunitario “Rinconcito de Luz” de las Aldeas Infantiles SOS y de los niños y niñas que acudieron a la Plaza Italia. En un segundo momento, con las madres de familia de los niños y niñas que acuden a los centros mencionados.
La universidad paraguaya en el Marco del Bicentenario
Authors: Alcaráz de Vázquez Patricia Rosana , Vázquez González César Antonio
Published: March 2018

Villarrica del Espíritu Santo, ciudad conocida con el nombre de “Cuna de Cultura”, pues cuenta con personajes ilustres que realizaron aportes importantes a la cultura nacional, como por ejemplo no podemos dejar de citar al poeta “Manuel Ortiz Guerrero”, al Dr. “Efraím Cardozo” (hijo de Ramón I. Cardozo), Helio Vera, y las personas que actualmente nos representan como embajadores de nuestra tierra, el Dr. “Ramiro Domínguez” y el maestro de cámara “ Diego Sánchez Haase”.
A New Functional Classification for Improved Multimodal Designs
Authors: Stamatiadis Nikiforos , Kirk Adam
Published: March 2018

The Functional Classification System (FCS) that is in use in the USA and throughout the world was developed in the 1970s as a basis for communication between designers and planners. It sought to establish a common framework for classifying roadways based on mobility and access. Since its inception, the application of the FCS has expanded, and is now used throughout the entire project development process and influences all transportation project development phases, from programming and planning through design and into maintenance and operation decisions. However, the focus of the FCS is narrow; it balances only mobility and access. The limited contextual definitions (urban and rural), do not provide the dynamic range of design elements and guidance needed to balance other competing project needs. A flexible framework that replaces the FCS and facilitates optimal geometric design solutions that take into account context, functions, and user needs has been developed. The proposed FCS expanded context in order to recognize the lack of suburban and rural community (Main Street) contexts and addressed the lack of balancing modal needs through consideration of driver, bicyclist and pedestrian needs. The new classification system communicates improved information to the designer so that balanced designs can be achieved through documented prioritization of roadway users. The proposed classification identifies user groups, which include drivers, pedestrians, and bicyclists. Fundamental design elements for each mode are also identified, and design ranges for each are provided based on the overall roadway network type. The correlation results of context, roadway types, and users is displayed in the Expanded FCS matrix. This allows for the development of a multimodal, context-based design with some degree of flexibility. Each matrix cell defines the various users (drivers, bicyclists, and pedestrians) and identifies those characteristics to be balanced.