2,946 research outputs found
La gallina criolla colombiana
No full textPara la elaboración de este libro se utilizaron además varios trabajos y documentos históricos donde se destaca, el "Tratado de avicultura especies y razas", escrito Dürigen, B (1931). quien describe las características de la gran mayoría de las razas de gallinas, pero en forma amplia ya que detalla 117 razas incluyendo discusiones sobre la domésticación, el aspecto exterior y la formación de la raza, con una descripción de los aspectos históricos, relacionados con su origen y distribución, dicho autor asume la clasificación de la gallina doméstica como Gallus domesticus y le adiciona otra(s) palabra(s) por ejemplo Gallus domesticus barbatus turingiacus, posibilitando su identificación, sin embargo dicha forma de clasificar no está acorde con el "Código Internacional de Nomenclatura Zoológica" (1999), donde se debe aplicar el principio de nomenclatura binomial y según el artículo 5 el nombre científico de una especie es una combinación de dos nombres, la primera es el nombre genérico y el segundo es el nombre específico, por tal razón en el libro y acorde con el trabajo "Synopsis and classification of living organisms" , editado por Sybil P. Parker, se describe la especie como Gallus domesticus, y en este libro se propone una reorganización para identificar los tipos de gallina criolla, agregando la subespecie con el tercer nombre dado por Dürigen (1931) a las gallinas que describió, como un homenaje a su gran trabajo investigativo, en este mismo ejemplo quedaría Gallus domesticus L subespecie barbatus; el segundo libro se titula "Genética avícola" de Hutt, F.B (1960), donde se centra en las variaciones genéticas relacionadas con: la longitud de las plumas, la distribución de las plumas, la estructura de las plumas, el esqueleto axial, el esqueleto apendicular, la coloración de las aves y las mutaciones; el tercer texto se refiere a la tesis en zootecnia de Valencia Ll, N.F y Betancourth G, L.F (1991), "Origen, desarrollo y descripción de los tipos de gallina criolla existentes en varios municipios del Valle del Cauca", donde se describen I1 tipos de la gallina criolla, se realiza una descripción historica sobre la presencia de gallinas en America del Sur, demostrando su origen precolombino (Isla de Pascua) lo que permitió contextualizar; se destacan las investigaciones del chileno Wilhelm (1953 , 1957, 1963, 1965, 1966), quien describe y realiza varias investigaciones sobre la gallina americana, Gallus inauris (Castelloi, 1914); finalmente algunos documentos históricos sobre Cronistas de Indias y Viajeros, describen el objeto de estudio
Fra utilitas e salubritas: esempi maltesi di bonifiche con anfore
No full textThis study examines for the first time tree cases of inverted amphorae used like soils improvement under floors of domus in Melite at the Roman times. The finality of inverted amphorae is once again recognized, based on studies' experiences of authior, througt analysis of lithological soils characters. In the first book of this Collection (Itinera ,1, 1996) the author offered some technical factors for analysis of the possible function of this biulding method and now, using the same method, i.e. with regard to the natural state of land, their statis lift, etc., has been possible to understand the aim of amphorae structures in Roman age
ON THE STABILIZING AND DESTABILIZING EFFECTS OF DAMPING IN WOOD CUTTING MACHINES
No full textIn this paper an analytical investigation of the possibility of employing damping elements to prevent chatter instability in wood machining is presented. A simplified model of a two-degree-of-freedom machine for wood cutting is first established. Then, the stabilizing effect of damping on the initially unstable and undamped system is investigated. The influence of damping on flutter and divergence instability is analyzed separately following different approaches. Some simplified assumptions are made to facilitate the analysis and a set of explicit conditions ensuring stability is found. Since the studied system is nonconservative, not only the effect of damping on the initially unstable system is investigated, but also its effect on the initially stable system. In particular, a condition preventing the destabilization of the system is achieved through the eigenvalue sensitivity analysis. The results attained might ensure important productivity improvements in real wood machining application
Manipulability of a planar wire driven haptic device
No full textThis paper presents a planar 4 wire driven 3 D.o.F. mechanism. For a planar haptic interface, this device could provide planar forces and moment feedback to the human operator. The particular end-effector geometric configuration overcomes manipulability problems arising from other recent planar wire haptic interfaces. Moreover, an explicit forward kinematic pose solution is obtained by introducing a modified wire configuration. Complete kinematic and manipulability analyses are presente
SYNTHESIS AND EXPERIMENTAL VALIDATION OF A DELAYED REFERENCE CONTROLLER FOR ACTIVE VIBRATION SUPPRESSION IN MECHANICAL SYSTEMS
No full textThis paper introduces a non-time-based control scheme for active Position and vibration control of two-degree-of-freedom systems by applying it to the path-tracking and swing control of a system composed of a trolley and a simple pendulum. The basic idea behind such a scheme is to make the path reference of the trolley a function of the time and of a time delay. This latter which is affected by the measured oscillation, is calculated on-the-fly in order to reduce the swing phenomenon. The effectiveness of the proposed control scheme, which may have application to the control of overhead cranes, is proved experimentally
Novel Self-capacitance Sensor to Measure Textile Moisture Content
No full textMoisture content is an important property that is measured in textiles to regulate both the drying processes and the parameters of fabric manufacturing equipment. Currently commercialized sensors are bulky and too expensive for many industrial uses. The purpose of this study is to develop and test a novel low-cost and compact moisture sensor for textiles that is based, for the first time, on self-capacitance technology. The sensor is made up of a single-plate capacitor on a printed circuit board, connected to a capacitance-to-digital conversion circuit. The main challenge is to adapt a board, which was originally developed for proximity and touch applications, for moisture measurements. Three sensor layouts with different configurations of the electrodes are tested, coupled with diverse overlays and cables. The impedance analysis shows that electrodes designed with trace loops led to lower capacitance when compared to pad and hatch grids. Then, the performance of the sensor has been experimentally evaluated using four textiles: cotton, polycotton, wool and polyester. The results show good repeatability and resolution in the entire moisture range tested, from 5% till 70% using total-dry weight as reference point. Regression models are presented for each fabric type, with an excellent approximation confirmed by R-square values between 0.945 and 0.996. Finally, an analysis of both temperature and air humidity effects on the sensor measurement is discussed. The linear response at low and high humidity, with temperature as predominant factor, allows the usage of the sensor also in harsh environments
DELAYED-REFERENCE CONTROL OF A TWO MASS ELASTIC SYSTEM
No full textAn innovative non-time-based control scheme for path tracking and vibration control of a two-mass system is introduced in this paper. The basic idea of the scheme, called delayed reference control (DRC), is to make the path reference of the system be a function of an action reference parameter which depends both on time and a variable which plays the role of a time delay. By suitably computing the value of the delay on the basis of the vibration measured, such vibration can be actively suppressed while an independent position regulator ensures an accurate tracking of the desired path. The DRC scheme is therefore suitable for those applications, in particular in the robotic field, where a pre-defined path through space must be followed precisely while the time taken to carry out the task is not a primary concern. In this paper the stability of the system is investigated, and numerical results are provided to assess the performance of the proposed method, compared to that of an optimal linear quadratic regulator
Thrombin inhibition by the highly selective 'reversible suicide substrate' N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-azalysine p-nitrophenyl ester
No full textThrombin is the last enzyme in the blood coagulation cascade. All pharmacological aspects support the use of thrombin inhibitors as antithrombotic agents. Here, we review the unusual inhibition behavior of the highly selective,reversible suicide substrate' N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-azalysinep-nitrophenyl ester (EOC-D-Phe-Pro-azaLys-ONp) targeted to the active center of human alpha-thrombin. Eoc-D-Phe-Pro-azaLys-ONp is an acylating agent, but its hydrolysis product 1(N-ethoxycarbonyl-D-phenylatanyl-L-prolyl)-2(4-aminobutyl)hydrazine behaves as a highly selective human alpha-thrombin competitive inhibitor
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