The Multiobjective Optimization of a Prismatic Drive

The multiobjective optimization of Slide-o-Cam is reported in this paper. Slide-o-Cam is a cam mechanism with multiple rollers mounted on a common translating follower. This transmission provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. A Pareto frontier is obtained by means of multiobjective optimization. This optimization is based on three objective functions: (i) the pressure angle, which is a suitable performance index for the transmission because it determines the amount of force transmitted to the load vs. that transmitted to the machine frame; (ii) the Hertz pressure used to evaluate the stresses produced on the contact surface between cam and roller; and (iii) the size of the mechanism, characterized by the number of cams and their width

How do taxable income responses to marginal tax rates differ by sex, marital status and age ? Evidence from Spanish dual income tax

El objetivo de este trabajo es analizar cómo los contribuyentes españoles respondieron a la introducción del modelo de doble imposición del impuesto sobre la renta de las personas físicas en 2007. Los autores estiman la elasticidad de la renta imponible (Rentabilidad) respecto al tipo impositivo marginal neto para diferentes grupos de contribuyentes por sexo, estado civil y edad, separando el efecto sustitución del efecto renta. Para el análisis empírico, los autores utilizan microdatos del panel de la declaración del IRPF difundido por el Instituto Español de Estudios Fiscales. Los principales resultados muestran que la reforma fiscal de 2007 dio como resultado un rango de valores de elasticidad de 0,41 a 0,43, mientras que el efecto de renta estimado arroja un valor negativo de -0,18. Los resultados para los diferentes grupos de contribuyentes son los siguientes: la eliminación de los jubilados de la muestra reduce significativamente el ETI; la elasticidad es mayor para las mujeres que para los hombres; los solteros tienen una elasticidad considerablemente mayor que los contribuyentes casados; y el ETI disminuye con la edad. Además, los autores encuentran que el costo marginal de los fondos públicos aumentó después de la reforma, y la tasa impositiva marginal máxima está por encima de lo óptimo.The aim of this paper is to analyse how Spanish taxpayers responded to the introduction of the dual personal income tax model in 2007. The authors estimate the elasticity of taxable income (ETI) with respect to the marginal net tax rate for different groups of taxpayers by sex, marital status and age, separating the substitution effect from the income effect. For the empirical analysis, the authors use microdata from the Spanish personal income tax return panel disseminated by the Spanish Institute of Fiscal Studies. The main results show that the 2007 tax reform resulted in a range of elasticity values from 0.41 to 0.43, while the estimated income effect yields a negative value of –0.18. The results for the different taxpayer groups are as follows: the removal of retired people from the sample significantly reduces the ETI; elasticity is higher for women than for men; single people have a considerably higher elasticity than married taxpayers; and the ETI decreases with age. Additionally, the authors find that the marginal cost of public funds increased after the reform, and the top marginal tax rate is above optimal.Ministerio de Economía y Competitividad. Proyecto ECO2016-76506-C4-3-R, para Jorge Onrubia FernándezpeerReviewe

La desmemoria impuesta a los hombres que trajeron. Cartagena de Indias en el siglo XVI y XVII. Un depósito de esclavos

This paper will focus on the role slaves played in the city of Cartagena de Indias in the seventeenth century. It will also focus on how the city became a slave warehouse and the role they played in shaping this colonial society. Their jobs, dances, sociability and ethnic origin are presented as main characters in the shaping of this city.    El presente trabajo se centrará en el papel que los esclavizadosjugaron en la ciudad de Cartagena de Indias en el siglo XVII. Igualmente,cómo la ciudad se convirtió en un depósito de esclavos y el papel queestos fueron desempeñando en la conformación de esta sociedad colonial.Sus trabajos, sus bailes, sus formas de sociabilidad, sus etnias de origenson presentados como protagonistas principales de la conformación deesta ciudad.  

A Formulation of Complexity-Based Rules for the Preliminary Design Stage of Robotic Architectures

International audienceIn this paper we propose a formulation capable of measuring the complexity of robotic architectures at the conceptual-design stage. The motivation lies in providing a tool to the robot designer when selecting the best alternative among various candidates generated at the early stages of the design process, when a parametric design is not yet available. While the performance evaluation of a robot includes many criteria, we focus on: the kinetostatic, the elastostatic and the elastodynamic performances; workspace volume; actuation complexity and the life-cycle cost. Within the realm of conceptual design, characterized by the absence of a mathematical model, it is not possible to optimize the performance at hand using classical mathematical programming methods. In this paper, a set of rules derived from robotics knowledge is outlined. These rules are then used to formulate a complexity measure used to filter-out less promising architectures at the conceptual stage. The complete formulation is applied to the development of a six-degree-of-freedom robot with low topological complexity, high performance and low actuation-system complexity. A complexity-comparison between the proposed architecture, the DIESTRO and the PUMA robots, is also provided

Kinetostatic design of an innovative Schoenflies-motion generator

International audienceIn this paper, a novel parallel robot is introduced. The robot, a Schoenflies-Motion Generator (SMG), is capable of a special class of motions, namely, those produced with serial robots termed SCARA, an acronym for Selective-Compliance Assembly Robot Arm. These motions involve three independent translations and one rotation about an axis of fixed direction. Such motions are known to form a subgroup of the displacement group of rigid-body motions, termed the Schoenflies subgroup. The SMG is composed of two identical four-degree-of-freedom serial chains in a parallel array, sharing one common base and one common moving platform. The proximal module of each chain is active and has two controlled axes, the motors being installed on the fixed base. The links can thus be made light, thereby allowing for higher operational speeds. The distal module, in turn, is passive and follows the motions of its active counterpart, the whole mechanism giving, as a result, a four-degree-of-freedom motion to its end-platform

Rhizospheric actinomycetes from organic crops of native potato (Solanum tuberosum): isolation, phenotypic characterization, molecular identification, and impact on biocontrol of Phytophthora infestans (Mont.) de Bary

Potato (Solanum tuberosum L.) is the fourth most consumed food crop in the world, whose production in Peru is diminished due to phytosanitary problems and high costs of chemical fertilizers. In the present work, 32 actinomycetes isolated from the rhizosphere of organic native potato crops collected in the town of Cabana, Lucanas, Ayacucho, were characterized phenotypically and evaluated for their in vitro antagonistic capacity against Oomycete phytopathogen Phytophthora infestans. The characterization tests showed that 97% of the actinomycetes were able to assimilate glucose, sucrose, and mannitol; as well as producing extracellular enzymes like amylases (100%) and cellulases (50%). Furthermore, the growth in laboratory culture was better in the range of pH 5.5-8.5 and temperature 28-30 °C. From the tests of antagonism in oat agar (71.9%) and rye agar (31.2%), three strains were selected according to the native potato variety were selected as CAB10-J2 (Ccompis), CAB9-CA4 (Cuchipa-akan) and CAB5-F5 (Futis) with pathogen inhibition rates of 80.05, 77.47 and 37.5% respectively. The strains were identified by molecular tests as members of the genus Streptomyces and owners of polyketide synthase (PKS) genes. It is concluded that the rhizospheric actinomycetes of potato are producers of bioactive compounds capable of remarkably inhibiting the pathogen Phytophthora infestans, being able to be considered candidates in biological control programs of the "potato blight".Potato (Solanum tuberosum L.) is the fourth most consumed food crop in the world, whose production in Peru is diminished due to phytosanitary problems and high costs of chemical fertilizers. In the present work, 32 actinomycetes isolated from the rhizosphere of organic native potato crops collected in the town of Cabana, Lucanas, Ayacucho, were characterized phenotypically and evaluated for their in vitro antagonistic capacity against Oomycete phytopathogen Phytophthora infestans. The characterization tests showed that 97% of the actinomycetes were able to assimilate glucose, sucrose, and mannitol; as well as producing extracellular enzymes like amylases (100%) and cellulases (50%). Furthermore, the growth in laboratory culture was better in the range of pH 5.5-8.5 and temperature 28-30 °C. From the tests of antagonism in oat agar (71.9%) and rye agar (31.2%), three strains were selected according to the native potato variety were selected as CAB10-J2 (Ccompis), CAB9-CA4 (Cuchipa-akan) and CAB5-F5 (Futis) with pathogen inhibition rates of 80.05, 77.47 and 37.5% respectively. The strains were identified by molecular tests as members of the genus Streptomyces and owners of polyketide synthase (PKS) genes. It is concluded that the rhizospheric actinomycetes of potato are producers of bioactive compounds capable of remarkably inhibiting the pathogen Phytophthora infestans, being able to be considered candidates in biological control programs of the "potato blight"

In vitro assessment of plant growth-promoting potential of rhizosphere actinomycetes from Solanum tuberosum sp. andigena

As part of the rhizosphere microbiota, actinomycetes interact with their host by releasing metabolites that positively influence their host’ growth. The main objective of this study was to evaluate the plant growth-promoting capacity of actinomycetes isolated from the rhizosphere of potato crops collected in the city of San Jeronimo, Andahuaylas, Peru. Forty-nine actinomycetes strains were isolated and screened for their capacity to solubilize phosphates, fix atmospheric nitrogen, produce indole acetic acid (IAA) and produce siderophores. Out of the total number of isolates, 33 (63.27%) solubilized phosphates, 42 (87.72%) fixed atmospheric nitrogen, 10 (20.41%) produced IAA and 18 (24.49%) were siderophore producers; strains AND 13 and AND 16 being the top performers. AND 13 was identified by 16S RNAr gene amplification as Streptomyces sp. The results indicate that actinomycetes can be considered as potential PGPR organisms and could be included in biofertilization programs of potato crops as an alternative to agrochemicals

The Isoconditioning Loci of Planar Three-DOF Parallel Manipulators

The subject of this paper is a special class of parallel manipulators. First, we analyze a family of three-degree-of-freedom manipulators. Two Jacobian matrices appear in the kinematic relations between the joint-rate and the Cartesian-velocity vectors, which are called the "inverse kinematics" and the "direct kinematics" matrices. The singular configurations of these matrices are studied. The isotropic configurations are then studied based on the characteristic length of this manipulator. The isoconditioning loci of all Jacobian matrices are computed to define a global performance index to compare the different working modes