Effect of velocity on roll/slip for low and high load conditions in polymer composite

In the last decade polymer composites are often used without lubrication on both low and high speed applications. Some of the application areas are marine, automotive and agriculture used as bearings and cams where roll-slip is the dominant mechanism. Limited studies are made for composites relating such applications where rolling/sliding condition influences the tribological behavior of the material. Investigating the roll-slip phenomenon for identifying the influence of velocity on frictional behavior can mark a boundary to map the use of composites with respect to its application. Moreover, the design of the material can be optimized to match the operating conditions. In the current research the polymer composite (with polyester matrix) has been tested under rolling-sliding condition for two different loads with 61N and 210N and with different speeds ranging from 10 rpm to 700 rpm. Ideal conditions in terms of roughness, slip ratio, surface temperature and ambient temperature were maintained to reduce the frictional heating. Using a 20% slip ratio the behavior of the material was observed for the tribological characteristics where the rate of increase of friction force follows a exponential pattern with increasing speeds. Nevertheless, on testing with high speeds a steady rate of increase in the friction curve was observed. Friction behavior of composites under different speeds is briefed with the microstructural characteristics for low and high loads

Factores motivacionales que conducen a un clima laboral satisfactorio para los trabajadores de la Gasolinera UNO – Matagalpa en el periodo 2013

La presente investigación tiene como objetivo el estudio del clima laboral de las empresas productivas y de servicio en el municipio de Matagalpa, en el periodo 2013, en este estudio se puntualizó como punto clave determinar y describir los factores motivacionales que conducen a un clima laboral y satisfactorio para los trabajadores de la Gasolinera UNO – Matagalpa, se enfocó en relacionar el clima laboral de la empresa con la teoría que plantean ciertos autores en sus aportes a estos temas. La importancia de este estudio es que se realizó con el propósito de crear una herramienta necesaria para mejorar el clima laboral que actualmente viven los trabajadores de la empresa UNO. La investigación es descriptiva, porque se trata de describir cada una de las situaciones que se presentan en la empresa para crear motivación y satisfacción laboral, se trabajó con una población y muestra de 36 empleados, se recolectó datos empleando dos instrumentos y técnicas de investigación como: la entrevista aplicada al gerente de la empresa y la encuesta al personal que labora para esta empresa. Este estudio permitió identificar y medir el grado de motivación de los trabajadores, las técnicas y los factores de motivación que emplea el gerente. Se recolectó datos de manera consolidada y se obtuvo conclusión a través de gráficos en el programa Excel, y se hizo posible obtener los parámetros que indicaron el clima laboral que se desarrolla entre los empleados de la empresa, y se concluyo que los trabajadores no cuentan con un clima laboral adecuado al desarrollo de sus funciones, ya que no gozan de planes de motivación, por lo tanto no existe un nivel alto de motivación y satisfacción labora

MEASURING POVERTY IN AN ULTRAPERIPHERAL REGION - THE CASE OF THE CANARY ISLANDS

The Canary Islands (one of Spain's 17 autonomous communities) is considered in the EC Treaty "ultra-peripheral region" which means: i) differences in the development processes and integration that justify certain specific policies (six out of the seven regions involved are among the poorest in the EU). This is related with remoteness, insularity, small size, difficult topography and climate, and the dependence on a small number of products; ii) the remoteness from the mainland countries and climatic conditions (tropical or subtropical) and, iii) the role of EU frontier and the geographical structure characterized by size and distance. With data of the Survey of Social Conditions (2001) we study the income inequality of individuals in The Canary Islands. Individuals are divided into various subgroups along several dimensions, such as island of residence, age, employment status etc. The difference in inequality between and within the various subgroups is studied using absolute-relative poverty line. We estimate poverty using a subjective approach too, where the level of the poverty line is derived using the opinion of the individual, rich or poor, on poverty. The subjective poverty line used is the Leyden Poverty Line based on subjective questions regarding income and economic welfare.

How Does an Interpreter Affect the Client-Counselor Relationship with a Client Who Is Deaf?

Few studies have explored mental health services such as counseling that are specifically provided to those who are d/Deaf and hard of hearing (d/DHH). This qualitative study was intended as an early research effort within a young field to investigate the impact of having an interpreter present within the therapeutic context. Qualitative data were obtained from an online, open-ended survey of eight d/Deaf and/or hard of hearing counseling clients in which the counselor was hearing and an interpreter was used in the counseling process. It was found that that d/Deaf cultural competence on the part of the counselor is an important part of the client-counselor relationship for those who are d/Deaf and hard of hearing along with the desire to feel safe, understood and connected. Future research should seek to (a) replicate this study with a broader sample, (b) make adjustments in order to interact with the participants through interviews rather than an online survey, and (c) study topics such as specific therapy styles that may be most beneficial for the those who are d/DHH

Tribological behaviour of the low and high viscosity peek against steel using different contact pressures

In the market of polymers for tribological applications polyetheretherketone (PEEK) are often used for satisfying requests coming from industry regarding enhanced properties such as, thermal stability, friction and wear resistance. These properties promote the material to be used in so called high performance tribological applications. However, fundamental mechanisms governing friction and wear are not yet fully understood and neither is the influence of composition parameters. An important parameter is PEEK’s viscosity during manufacturing process which is heated up to semi-solid state, between its glass transition and melting temperature. This paper studies the friction and wear performance of low and high viscosity PEEK and pure PEEK under dry reciprocating sliding contact. The tests were performed in large scale specimens under flat-on-flat configuration to determine the transitions in tribological behaviour at different contact pressures. Tests were carried out at controlled atmosphere with 25 °C and a relative humidity of 50%. Contact pressures parameters were 4, 8 and 10 MPa used at a sliding speed of 20 mm/s. Post mortem analyses were carried out by means of 2-D surface topography and optical microscopy. The results show that the pure PEEK exhibits low coefficient of friction and wear rate when the contact pressure increase and similar behave for high and low viscosity PEEK

Friction torque, temperature and roughness in roll-slip phenomenon for polymer–steel contacts

The current study gives an insight of the roll-slip phenomenon of polymer-metal pair where priority is given to measurement techniques, test duration and the behavior of the polymer. A systematic tribological measurement was used to identify the friction torque from polymer –metal pairs where the friction torque from contact is obtained by subtracting the base torque of the test rig to exploit the absolute results. Base torque of the machine is almost constant, the changing can describe with linear trend line which is less than 0,5% per ten minutes. Measurements made for 3 hours shows that the friction force between the polyamide 6 (NaPA6) and structural steel (S33J2) has a polynomial of degree two with a function ( Ff = −1.5549 ⋅T 2 + 9.4031⋅T +13,126 ). Micrographs from the contact surface revealed the damage of roughness peaks during the course of testing. The involved wear mechanisms was investigated with roughness measurements and microscopy. The roughness plots also correlates with the micrograph where the rate of decrease in Ra in the initial stage is higher followed by a linear increase in the later stage. This can describe using polynomial function of degree as ( Ra = 0.029 ⋅T 2 + 0.3695⋅T + 2.4967 )

A novel measuring technique to evaluate frictional characteristics of roll-slip contacts in polymer-metal pairs

Tribology research is aimed for desirable frictional characteristic; especially in rolling/sliding of polymer-metal contacts which helps smooth operations and energy savings. Conventional roll-slip tests for few million cycles have significant deposit of polymer transfer layer on counterface, thus having a polymer-polymer contact instead of polymer-metal contact. Besides, backtransfer affecting the friction force was never explored. Studying these phenomenon individually and characterizing frictional property without the presence of transfer layer helps for a better understanding of the combined system. A new procedure for measuring friction torque at 20% slip ratio is adapted for varying speeds from 10 to 500 rpm. The observed friction-force increases rapidly at low-speeds and becomes linear at high-speeds. The micrographs of the contact surface prove no trace of transfer layer was found in the newly developed measuring process. Also specimen surface temperature never reached the effective level to affect friction properties

Library Research & Adobe Scholars: Lifelong Learning through Mentoring

i. The Library Research Scholars program pairs librarian faculty mentors with undergraduates on a yearlong journey of engaging with research and creating an intellectual product on a topic of their own devising. Each librarian mentor is paired with a Library Research Scholar whose research area of interest coincides with the librarian’s own area of expertise. As mentors, librarians work actively to guide their mentees through an open-ended, research inquiry process. Librarian faculty members from all departments of the library, including Technical Services, have served as mentors to Library Research Scholars. Librarian faculty mentors guide Research Scholars through a process of discovery. While Research Scholars enter the program with an idea of the topic they would like to explore, that idea becomes refined, reformulated, and fine-tuned over the course of the academic year with the help of a librarian mentor. From oral histories that celebrate the stories of a university’s LGBT community, to plays written about a city’s founders, librarian faculty mentors have guided their Research Scholars through the collaborative, open-ended research inquiry process that is inherent in the development of complex research projects. Many of the resulting scholarly projects exemplify critical engagement with archives, general collections, and community research. Through mentoring and modeling, Library Research & Adobe Scholars build scholarly habits outside of the traditional classroom to support their lifelong learning habits of mind