1,126 research outputs found
Natural and semisynthetic analogues of manadoperoxide B reveal new structural requirements for trypanocidal activity
No full textChemical analysis of the Indonesian sponge Plakortis cfr. lita afforded two new analogues of the potent trypanocidal agent manadoperoxide B (1), namely 12-isomanadoperoxide B (2) and manadoperoxidic acid B (3). These compounds were isolated along with a new short chain dicarboxylate monoester (4), bearing some interesting relationships with the polyketide endoperoxides found in this sponge. Some semi-synthetic analogues of manadoperoxide B (6-8) were prepared and evaluated for antitrypanosomal activity and cytotoxicity. These studies revealed crucial structure-activity relationships that should be taken into account in the design of optimized and simplified endoperoxyketal trypanocidal agents
Stima di velocità e posizione per motori sincroni a magneti permanenti mediante osservatore di back-EMF
No full textCritical Surveys Covering the Year 2006: Total Synthesis of Natural Products
No full textComunicazione Orale su Invito
Stima di velocità e posizione per motori sincroni a magneti permanenti mediante osservatore di back-EMF
No full textRecreational drug discovery: natural products as lead structures for the synthesis of smart drugs
No full textOver the past decade, there has been a growing transition in recreational drugs from natural materials (marijuana, hashish, opium), natural products (morphine, cocaine), or their simple derivatives (heroin), to synthetic agents more potent than natural prototypes, sometimes less harmful in the short term, or that combine properties from different classes of recreational prototypes. These agents have been named smart drugs, and have become popular both for personal consumption and for collective intoxication in rave parties. The reasons for this transition are various, but mainly regulatory and commercial. New analogues of known illegal intoxicants are invisible to most forensic detection techniques, while the alleged natural status and the lack of avert acute toxicity make them appealing to a wide range of users. On the other hand, the advent of internet has made it possible the quick dispersal of information among users and the on-line purchase of these agents and/or the precursors for their synthesis. Unlike their natural products chemotypes (ephedrine, mescaline, cathinone, psilocybin, THC), most new drugs of abuse are largely unfamiliar to the organic chemistry community as well as to the health care providers. To raise awareness in the growing plague of smart drugs we have surveyed, in a medicinal chemistry fashion, their development from natural products leads, their current methods of production, and the role that clandestine home laboratories and underground chemists have played in the surge of popularity of these drugs
Speed and Position Estimation for PM Synchronous Motor with Back-EMF Observer
No full textThis paper presents a sensorless scheme for PM synchronous motors, based on back-EMF observer. It provides full analytical description of the back-EMF observer, and the calculation of the position estimation error, taking into account the variation of the electrical parameters of the motor, i.e. stator resistance and synchronous inductance, and the variation of the feeding voltage. The knowledge of such characteristics could be used to improve the performance and the robustness of the sensorless drive by a specific real-time compensation mechanism. Verifications and comparisons are carried out in three steps: a) a time-continuous simulation model (using Matlab-Simulink) is developed to confirm the analytical results; b) a real time simulator of the sensorless drive is used, to evaluate the influence of the time-discrete implementation; c) an experimental BSP based implementation is used to compare actual results
Speed and Position Estimation for PM Synchronous Motor with Back-Emf Observer
No full textThis paper presents a sensorless scheme for PM synchronous motors, based on back-EMF observer. It provides full analytical description of the back-EMF observer, and the calculation of the position estimation error, taking into account the variation of the electrical parameters of the motor, i.e. stator resistance and synchronous inductance, and the variation of the feeding voltage. The knowledge of such characteristics could be used to improve the performance and the robustness of the sensorless drive by a specific real-time compensation mechanism. Verifications and comparisons are carried out in three steps: a) a time-continuous simulation model (using Matlab-Simulink) is developed to confirm the analytical results; b) a real time simulator of the sensorless drive is used, to evaluate the influence of the time-discrete implementation; c) an experimental DSP based implementation is used to compare actual results
Speed and Position Estimation for PM Synchronous Motor using self-compensated Back-EMF Observers
No full textPrecise motion control requires high-accuracy and highbandwidth feedback speed information, often calculated by direct measurement of the rotor position available through the incremental encoder equipping the drive. The resolution of the encoder heavily affects the cost of the drive and the accuracy and bandwidth of the calculated speed. The limitations introduced by a low resolution encoder can be partially reduced by a proper speed calculation (or estimation) algorithm, that therefore plays a key role in modern drive systems. In this paper a comparative analysis of state of-art speed measurement and estimation algorithms suitable for low-resolution incremental encoder equipped drives is presented, aiming at highlighting the specific feature of each one, both from the performance point of view, and from the computational requirements needed for actual implementation. The paper proposes itself as a guide for engineers in the complex choice of the best solution for each application
Ignored wakes. Dialogue with Luis Scafati
No full textEsta entrevista a Luis Scafati se realizó con el fin de generar fuentes para una historiografía por venir, de conocer, desde la mirada crítica y nunca conformista del artista, tanto las cuestiones que atraviesan su obras y su manera de fundir las imágenes y las palabras, como sus reflexiones sobre la teoría y sobre las formas de producción artística en la actualidad.This interview to Luis Scafati was carried out in order to generate sources for a future historiography, to know, from the critic and never-conformist view of the artist, the questions that are involved in his works and how he joins images and words as well as his reflections on the theory and forms of artistic production in the present time.Facultad de Bellas Arte
Extended Torque-Speed Sensor-Less Control of Interior Permanent Magnet Synchronous Motors
No full textIn this paper a sensor-less speed controller for an Interior permanent magnet synchronous motor is presented. It allows to fully exploit the torque-speed characteristic of the motor, also in the flux-weakening region. It is based on the estimation of a generalized back-EMF space vector by means of a Luenberger state and disturbance observer. The estimated rotor-magnet position and speed are then employed inside an optimised vector control scheme of direct and quadrature motor currents trajectories. Test results are presented, in order to verify the performance and demonstrate the effectiveness of the proposed solution
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