Search results for "CONTACT"
showing 10 items of 1003 documents
Comparing the efficiency of wastewater treatment technologies through a DEA metafrontier model
2011
Abstract The assessment of economic and technical efficiency is a useful tool to select the most appropriate technology for wastewater treatment. However, traditional models require that the units being assessed operate with the same technology. To overcome this limitation, we investigate the viability of using a non-concave metafrontier approach that is based on data envelopment analysis (DEA) to calculate the techno-economic efficiency and technological gap ratios (TGRs) of wastewater treatment plants (WWTPs) operating with non-homogeneous technologies. The model is applied to a sample of 99 Spanish WWTPs, encompassing four alternative technologies: activated sludge; aerated lagoon; trick…
A New Quasi-Static Cylindrical Roller Bearing Model to Accurately Consider Non-Hertzian Contact Pressure in Time Domain Simulations
2012
The accuracy of the fatigue life calculations in rolling bearing simulations is highly dependent on the precision of the roller-raceway contact simulations. Several different methods exist to simulate these pressure distributions and in time domain bearing simulations, where many contacts need evaluation, the simple and time efficient methods are more popular, yielding erroneous life estimates. This paper presents a new six degree of freedom frictionless quasi-static time domain cylindrical roller bearing model that uses high precision elastic half-space theory to simulate the contact pressures. The potentially higher computational demand using the advanced contact calculations is addressed…
Optimization of the contact surface shape of a shrinkage fit
1998
Amongst many processes existing today for the assembly of two cylindrical parts, the shrinkage fit is commonly used. However, in the calculation methods, the contact surfaces are assumed to be perfect. Therefore, in order to apply these, the standards necessitate very small geometrical tolerances. The objective of the present paper is to show that it is possible to take into account form defects by closely conformed contact modelling and to have a good representation of reality: form defects always exist to an increasing extent and are inherent in all kinds of manufacturing processes. Finally, it is shown that the presence of defects can be beneficial, allowing optimization from both a mech…
Adaptive interaction robot control with estimation of contact force
2008
Abstract This paper deals with a new adaptive force-position control of a robotic manipulator based on force estimation. First, an adaptive position controller is derived with contact force component as estimated parameters. Second, a supervisory external loop is added in order to regulate the contact force to the desired value. Extensive simulations with 2-DOF manipulator illustrate the followed approach.
Finite Element Method Analysis of a Spur Gear with a Corrected Profile
2007
The difference between the stress value calculated by a two-dimensional finite element model of spur gears and those obtained by the rules in ISO 6336 was evaluated. Hertz theory, which provides information on the extension of the contact area and the maximum value of the contact pressure, was used to choose the dimensions of the elements. The mesh was created using the stress analytical solution relative to a model consisting of two cylinders in contact. Analogous optimization was executed for the mesh of the teeth feet; a mesh of 15 elements was considered optimum, because it minimized the difference to 0.5 per cent in the bending stress calculation. Stress values, obtained using the fin…
Finite element analysis of two total knee joint prostheses
2012
Aim of this work is to compare two different total knee prostheses that differ mainly in the shape of the polyethylene (PE) component inserted between the femoral and tibial plates. The best solution between them has been originally reshaped in order to reduce stress peaks. The study procedure has been divided into the following steps. First step is the digitalisation of the shape of the prostheses by means of a 3D laser scanner. The morphology of two prototypes of the prostheses has been acquired by elaborating multiple Moire fringe patterns projected on their surfaces. Second step consisted on the manipulation of these data in a CAD module, that is the interpolation of raw data into NURBS…
Friend or foe? : attitudes to and beliefs about English in Finland expressed by Finnish as a second language learners
2011
Tutkin pro gradu -työssäni S2-oppijoiden käsityksiä englannin kielen käytöstä ja asemasta Suomessa. Aiemmat tutkimukset englannin kielen käytöstä ja asemasta Suomessa ovat keskittyneet suomalaisten äidinkielenpuhujien käsityksiin. Tämän tutkielman tarkoituksena on selvittää minkälaisia käsityksiä S2-oppijoilla on englannin käytöstä ja asemasta Suomessa sekä heidän omassa elämässään että yleisemmällä tasolla. Lisäksi tutkin S2-oppijoiden asenteita englannin kieltä kohtaan. Tutkimus pyrkii samalla nostamaan esiin S2-oppijoiden käsityksiä englannin kielen mahdollisesta vaikutuksesta suomen kieleen sekä S2-oppimiseen ja -opettamiseen. Tutkimuksen aineisto kostuu sekä kirjallisesta että suullise…
The Use of Cluster Analysis to Segment Clients of a Sport Center in Spain
2005
Abstract This research examines the motivation profiles of 218 consumers at a sport center in Valencia, Spain. We employed the Motivation in Sport Scale (MISS–Sport Center) with the following eight motives (factors): Positive Affect, Social Contact, Physical Exercise, Coping Strategy, Challenge, Body Image, Competition, and Entertainment. There were significant differences in consumers’ motives across gender, age, and marital status. We identified five motivation profiles using the eight motives of MISS–Sport Center: Non-Competitive Leisure-Oriented Exercisers, Practical Social Entertainers, Affective Users, Enthusiastic Sportspersons, and Passive Participants. There were differences in dem…
Novel modified poly vinyl chloride blend membranes for removal of heavy metals from mixed ion feed sample
2017
Herein, an attempt has been made to prepare a novel membrane with good efficiency for removal of heavy metal ions namely lead (Pb), cadmium (Cd) and chromium (Cr). 4-amino benzoic acid (ABA) was covalently grafted onto the poly vinyl chloride (PVC) backbone by CN bond to enhance the hydrophilicity. 1H NMR and ATR-IR spectroscopy analysis confirmed the chemical modification of PVC. Further the modified polymer was blended in different compositions with polysulfone (PSf) for optimization. Morphological changes that occurred in blend membranes, due to the incorporation of modified PVC was studied by AFM and SEM techniques. The effect on hydrophilicity and performance of blends owing to incorpo…
El management de las conductas socioemocionales. Una aproximación teórica y empírica desde el caso de los agentes de "contact centers"
2020
How is a specific type of emotion-related work conducts formed today? What principles guide these conducts and what effects do they have on those who work? The study of Contact Center agents allows us to understand how a set of personal qualities such as patience and good treatment of others, certain desires and personal impulses or even intimate sensations such as anguish or individual expectations have become managerialized emotions that end up modifying the inner attitudes of these agents. Within this framework, we propose a theoretical approach that integrates the work of Weber, Foucault and Elias, which invites us to reflect on a socio-emotional manner of leading one?s life (Lebensfu?h…