Kinematics and workspace analysis of a 3ppps parallel robot with u-shaped base

This paper presents the kinematic analysis of the 3-PPPS parallel robot with an equilateral mobile platform and a U-shape base. The proposed design and appropriate selection of parameters allow to formulate simpler direct and inverse kinematics for the manipulator under study. The parallel singularities associated with the manipulator depend only on the orientation of the end-effector, and thus depend only on the orientation of the end effector. The quaternion parameters are used to represent the aspects, i.e. the singularity free regions of the workspace. A cylindrical algebraic decomposition is used to characterize the workspace and joint space with a low number of cells. The dis-criminant variety is obtained to describe the boundaries of each cell. With these simplifications, the 3-PPPS parallel robot with proposed design can be claimed as the simplest 6 DOF robot, which further makes it useful for the industrial applications

A Fuzzy-based Framework to Support Multicriteria Design of Mechatronic Systems

Designing a mechatronic system is a complex task since it deals with a high number of system components with multi-disciplinary nature in the presence of interacting design objectives. Currently, the sequential design is widely used by designers in industries that deal with different domains and their corresponding design objectives separately leading to a functional but not necessarily an optimal result. Consequently, the need for a systematic and multi-objective design methodology arises. A new conceptual design approach based on a multi-criteria profile for mechatronic systems has been previously presented by the authors which uses a series of nonlinear fuzzy-based aggregation functions to facilitate decision-making for design evaluation in the presence of interacting criteria. Choquet fuzzy integrals are one of the most expressive and reliable preference models used in decision theory for multicriteria decision making. They perform a weighted aggregation by the means of fuzzy measures assigning a weight to any coalition of criteria. This enables the designers to model importance and also interactions among criteria thus covering an important range of possible decision outcomes. However, specification of the fuzzy measures involves many parameters and is very difficult when only relying on the designer's intuition. In this paper, we discuss three different methods of fuzzy measure identification tailored for a mechatronic design process and exemplified by a case study of designing a vision-guided quadrotor drone. The results obtained from each method are discussed in the end

The impact of and subsequent chronic pain on patients' daily lives

Aim: The aim of our study was to carry out a literature review and develop a model illustrating the domains of patients' lives that are impacted by herpes zoster (HZ) and subsequent chronic pain. Subjects and methods: Biomedical databases and online congress archives were searched using keywords related to HZ or post-herpetic neuralgia (PHN) and social, psychological or physical impact. A total of 733 abstracts were reviewed, and 29 publications containing concepts reported by patients were retained for the model. Wilson and Cleary’s model was used to organise the findings. Links between concepts were documented on three levels: hypothesis, observation and evidence. The final model illustrates the concepts impacted by HZ and PHN, relationships between these concepts and the level of evidence identified. Results: The concepts identified from the articles were grouped into the following categories: biological/ physiological, symptom status, functional status, health perceptions, characteristics of the individual, health-related quality of life (HRQOL), treatment and characteristics of the environment. Evidence exists showing that HZ-related pain directly impacts functional status, health perceptions and HRQOL. Conclusion: Patients report that all major domains of life are impaired by HZ or subsequent chronic pain. HZ and its painful and debilitating complications can have a substantial impact on physical, psychological, social and role functioning, HRQOL and activities of daily living. The impact on elderly patients needs to be further assessed with appropriately designed and validated instruments, with specific attention paid to dependence

Les qualifiés de la section des sciences de l’éducation du Conseil national des universités de 2000 à 2009

Dans ce texte, nous nous sommes intéressés aux caractéristiques des docteurs qualifiés aux fonctions de maître de conférences par la 70e section (celle des sciences de l’éducation) du Conseil national des universités (CNU) de 2000 à 2009, en analysant les données du ministère de l’Enseignement supérieur et de la Recherche concernant les qualifiés de la décennie 2000. Nous avons également étudié leur devenir et leur promotion aux fonctions d’enseignants-chercheurs en examinant les données des bases recensant les thèses et en procédant à des recherches complémentaires. Au total près de 1 000 cas individuels ont été étudiés. Les résultats montrent notamment que, si les taux de qualification des candidats sont relativement faibles (à peine plus d’un tiers, atteignant la moitié pour les thèses relevant de la discipline des sciences de l’éducation), sans différences significatives entre les hommes et les femmes, environ une personne qualifiée sur deux a ensuite trouvé un emploi de maître de conférences.We focused on the characteristics of doctors who qualified to become lecturers as part of the 70th section (that of educational sciences) of the national council of universities (CNU) from 2000 to 2009. We studied the data provided by the French ministry of higher education and Research and also examined the subsequent career paths of these doctors through an analysis of the PhD databases. Overall, almost 1,000 individual cases were studied. Findings reveal that while the qualification rates of applicants are relatively low (hardly over a third but a half for educational sciences-related PhDs) with no significant gap between men and women, about half of those who qualified then landed a post of lecturer.A lo largo de este texto nos interesamos en las características de los doctores de universidad, declarados aptos para ejercer la función de catedrático por la sección de las ciencias de la educación del Consejo Nacional de las Universidades (CNU) desde el 2000 hasta el 2009, analizando los datos del Ministerio de Enseñanza superior y de Investigación que se refieren a los doctorados de la década de los 2000. Estudiamos también su devenir y su promoción a los cargos de profesor de universidad-investigador analizando los datos de las bases que censan las tesis de doctorados y procediendo a investigaciones complementarias. En total más de 1.000 casos individuales fueron estudiados. Enseñan en efecto los resultados que, si los índices de calificación de las candidaturas son relativamente bajos (apenas más de la cuarta parte en general y la mitad para las tesis en ciencias de la educación), sin diferencia notable entre varones y mujeres, aproximadamente una de cada dos personas calificadas encontró un cargo de catedrático.In diesem Text haben wir uns für die Merkmale der Doktoren, die von der 70sten Abteilung (Erziehungswissenschaften) des Nationalen Universitätsrats (CNU) von 2000 bis 2009 zum Amt des Dozenten ausgezeichnet wurden, in dem wir die Daten des Ministeriums für Hochschulwesen und Forschung analysiert haben, die die Ausgezeichneten der 2000er Jahre betreffen. Wir haben auch ihre Laufbahn und ihre Beförderung als Lehrbeauftragte mit Lehr- und Forschungsauftrag durch die Analyse der verzeichneten Doktorarbeiten und mit Hilfe von Zusatzforschungen beobachtet. Insgesamt wurden rund 1 000 individuelle Fälle analysiert. Die Ergebnisse zeigen insbesondere, dass trotz der relativ niedrigen Qualifizierungsquoten der Bewerber (kaum mehr als ein Drittel, und fast die Hälfte für Doktorarbeiten im Bereich der Erziehungswissenschaften), ohne besonderen Unterschied zwischen Männern und Frauen, etwa jeder zweite Ausgezeichnete dann eine Stelle als Dozent bekommen hat

Modeling of Laterally Sliding Motion of a Magnetic Clamp

A sliding magnetic clamp is used to hold a thin aluminum panel during a milling operation. The design includes a permanent magnet group follower (slave module) which slides laterally over the panel attracted by another permanent magnet group (master module) attached to the industrial robot end effector from the machined side of the panel.The lateral sliding motion of the slave module in response to the master module motion is studied using a transfer function based motion model established considering the lateral magnetic stiffness.The model is validated experimentally

Machining of titanium metal matrix composites : progress overview

ABSTRACT: The TiC particles in titanium metal matrix composites (TiMMCs) make them difficult to machine. As a specific MMC, it is legitimate to wonder if the cutting mechanisms of TiMMCs are the same as or similar to those of MMCs. For this purpose, the tool wear mechanisms for turning, milling, and grinding are reviewed in this paper and compared with those for other MMCs. In addition, the chip formation and morphology, the material removal mechanism and surface quality are discussed for the different machining processes and examined thoroughly. Comparisons of the machining mechanisms between the TiMMCs and MMCs indicate that the findings for other MMCs should not be taken for granted for TiMMCs for the machining processes reviewed. The increase in cutting speed leads to a decrease in roughness value during grinding and an increase of the tool life during turning. Unconventional machining such as laser-assisted turning is effective to increase tool life. Under certain conditions, a “wear shield” was observed during the early stages of tool wear during turning, thereby increasing tool life considerably. The studies carried out on milling showed that the cutting parameters affecting surface roughness and tool wear are dependent on the tool material. The high temperatures and high shears that occur during machining lead to microstructural changes in the workpiece during grinding, and in the chips during turning. The adiabatic shear band (ASB) of the chips is the seat of the sub-grains’ formation. Finally, the cutting speed and lubrication influenced dust emission during turning but more studies are needed to validate this finding. For the milling or grinding, there are major areas to be considered for thoroughly understanding the machining behavior of TiMMCs (tool wear mechanisms, chip formation, dust emission, etc.)

Time-dependent Effects in Photospheric-Phase Type II Supernova Spectra

Spectroscopic modeling of Type II supernovae (SNe) generally assumes steady-state. Following the recent suggestion of Utrobin & Chugai, but using the 1D non-LTE line-blanketed model atmosphere code CMFGEN, we investigate the effects of including time-dependent terms that appear in the statistical and radiative equilibrium equations. We base our discussion on the ejecta properties and the spectroscopic signatures obtained from time-dependent simulations, investigating different ejecta configurations, and covering their evolution from one day to six weeks after shock breakout. Compared to equivalent steady-state models, our time-dependent models produce SN ejecta that are systematically over-ionized, affecting helium at one week after explosion, but ultimately affecting all ions after a few weeks. While the continuum remains essentially unchanged, time-dependence effects on observed spectral lines are large. At the recombination epoch, HI lines and NaID are considerably stronger and broader than in equivalent steady-state models, while CaII8500A is weakened. If time dependence is allowed for, the HeI lines at 5875A and 10830A appear about 3 times stronger at one week, and HeI10830A persists as a blue-shifted absorption feature even at 6 weeks after explosion. Time dependence operates through the energy gain from changes in ionization and excitation, and, perhaps more universally across SN types, from the competition between recombination and expansion, which in-turn, can be affected by optical-depth effects. Our time-dependent models compare well with observations of the low-luminosity low-velocity SN 1999br and the more standard SN 1999em, reproducing the Halpha line strength at the recombination epoch, and without the need for setting unphysical requirements on the magnitude of nickel mixing.Comment: 19 pages, 18 figures, accepted for publication in MNRAS, high-resolution of the paper at http://hermes.as.arizona.edu/~luc/pap_ddt/pap_ddt.ps.g