A Calibration Procedure for Compressor Simulation Models using Evolutionary Algorithm

Comprehensive models are widely adopted to predict the performance of compressors due to their low computational cost and acceptable prediction capability. In general, the accuracy of such models depends strongly on the correct adjustment of some parameters that are of difficult to determine both analytically and experimentally. However, due to the nonlinearities of the compressor model, the tuning of such parameters affects many output variables and hence can be very challenging and time consuming. In this paper, we consider this procedure of adjustment of parameters as a multiple objective optimization problem that can be solved by using an elitist non-dominated sorting genetic algorithm (NSGA-II). The parameters of two simulation models are adjusted following this new procedure. In the first model the suction muffler was neglected and a mass-spring-damper system was adopted to predict the suction valve dynamics. The second model solves the suction valve dynamics by the finite element method and the flow in the suction muffler with the finite volume method. In both models the clearance volume and parameters associated with the suction valve were chosen to be adjusted while the deviations between predictions and measurements for the mass flow rate, indicated power, and suction valve dynamics were defined as the objective functions to be minimized

Study of in vitro and in vivo extraction of kavalactones of pharmaceutical form containing ground plant drug (Piper methysticum G. Forster)

An evaluation of the extraction of pharmacological markers (kavalactones) of the plant species Piper methysticum (kava-kava) was conducted. Capsules containing ground kava-kava were submitted to an in vitro method using a controlled dissolution system where the extractive mediums were a solution of 0.1M HCl, phosphate buffered solution (pH = 6.8) and distilled water, at 30 and 60 min, and in vivo that was based on the pylorus ligation method in rats. In the in vitro system starting from 6 capsules (3 g) containing the kava-kava powder, the following extractive concentrations of kavalactones were obtained: HCl (30 min.) = 0.93% (27.9 mg), HCl (60 min.) = 1.1% (33 mg), buff. (30 min) = 2.8% (84 mg), buff. (60 min.) = 0.7% (21 mg), water (30 min.) = 0.71% (21.3 mg) and water (60 min.) = 2.6% (78 mg), while in the in vivo method, 1 and 2 h after administration of 500 mg of the kava-kava powder through gavage, the extractive concentrations of total kavalactones were: 1h = 1.31% (6.55 mg) and 2h = 1.41 % (7.05 mg). In the in vitro system a slight difference was observed among the solutions, which were not statistically significant, and the same occurred with the in vivo experiment, although at the time of 2 h after administration it proved more effective in the extraction of kavalactones by the gastric juice, but below the dose recommended for therapeutic use.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Study of in vitro and in vivo extraction of kavalactones of pharmaceutical form containing ground plant drug (Piper methysticum G. Forster)

An evaluation of the extraction of pharmacological markers (kavalactones) of the plant species Piper methysticum (kava-kava) was conducted. Capsules containing ground kava-kava were submitted to an in vitro method using a controlled dissolution system where the extractive mediums were a solution of 0.1M HCl, phosphate buffered solution (pH = 6.8) and distilled water, at 30 and 60 min, and in vivo that was based on the pylorus ligation method in rats. In the in vitro system starting from 6 capsules (3 g) containing the kava-kava powder, the following extractive concentrations of kavalactones were obtained: HCl (30 min.) = 0.93% (27.9 mg), HCl (60 min.) = 1.1% (33 mg), buff. (30 min) = 2.8% (84 mg), buff. (60 min.) = 0.7% (21 mg), water (30 min.) = 0.71% (21.3 mg) and water (60 min.) = 2.6% (78 mg), while in the in vivo method, 1 and 2 h after administration of 500 mg of the kava-kava powder through gavage, the extractive concentrations of total kavalactones were: 1h = 1.31% (6.55 mg) and 2h = 1.41 % (7.05 mg). In the in vitro system a slight difference was observed among the solutions, which were not statistically significant, and the same occurred with the in vivo experiment, although at the time of 2 h after administration it proved more effective in the extraction of kavalactones by the gastric juice, but below the dose recommended for therapeutic use.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

Background Dielectric elastomer (DE) transducers permit to efectively develop large-deformation, energy-efcient, and compliant mechatronic devices. By arranging many DE elements in an array-like confguration, a soft actuator/sensor system capable of cooperative features can be obtained. When many DE elements are densely packed onto a common elastic membrane, spatial coupling efects introduce electro-mechanical interactions among neighbors, which strongly afect the system actuation and sensing performance. To efectively design cooperative DE systems, those coupling efects must be systematically characterized and understood frst. Objective As a frst step towards the development of complex cooperative DE systems, in this work we present a systematic characterization of the spatial electro-mechanical interactions in a 1-by-3 array of silicone DEs. More specifcally, we investigate how the force and capacitance characteristics of each DE in the array change when its neighbors are subject to diferent types of mechanical or electrical loads. Force and capacitance are chosen for this investigation, since those quantities are directly tied to the DE actuation and sensing behaviors, respectively. Methods An electro-mechanical characterization procedure is implemented through a novel experimental setup, which is specifcally developed for testing soft DE arrays. The setup allows to investigate how the force and capacitance characteristics of each DE are afected by static deformations and/or electrical voltages applied to its nearby elements. Diferent combinations of electro-mechanical loads and DE neighbors are considered in an extensive experimental campaign. Results The conducted investigation shows the existence of strong electro-mechanical coupling efects among the diferent array elements. The interaction intensity depends on multiple parameters, such as the distance between active DEs or the amount of deformation/voltage applied to the neighbors, and provides essential information for the design of array actuators. In some cases, such coupling efects may lead to changes in force up to 9% compared to the reference confguration. A further coupling is also observed in the DE capacitive response, and opens up the possibility of implementing advanced and/or distributed self-sensing strategies in future applications. Conclusion By means of the conducted experiments, we clearly show that the actuation and sensing characteristics of each DE in the array are strongly infuenced by the electro-mechanical loading state of its neighbors. The coupling efects may signifcantly afect the overall cooperative system performance, if not properly accounted for during the design. In future works, the obtained results will allow developing cooperative DE systems which are robust to, and possibly take advantage of, such spatial coupling efects

Multivariate Curve Resolution Of Ph Gradient Flow Injection Mixture Analysis With Correction Of The Schlieren Effect.

Multivariate curve resolution using alternating least squares (MCR-ALS) was used to quantify ascorbic (AA) and acetylsalicylic (ASA) acids in four pharmaceutical samples using a flow injection analysis (FIA) system with pH gradient and a diode array (DAD) spectrometer as a detector. Four different pharmaceutical drugs were analyzed, giving a data array of dimensions 51 x 291 x 61, corresponding respectively to number of samples, FIA times and spectral wavelengths. MCR-ALS was applied to these large data sets using different constraints to have optimal resolution and optimal quantitative estimations of the two analytes (AA and ASA). Since both analytes give an acid-basic pair of species contributing to the UV recorded signal, at least four components sholuld be proposed to model AA and ASA in synthetic mixture samples. Moreover, one additional component was needed to resolve accurately the Schlieren effect and another additional component was also needed to model the presence of possible interferences (like caffeine) in the commercial drugs tablets, giving therefore a total number of 6 independent components needed. The best quantification relative errors were around 2% compared to the reference values obtained by HPLC and by the oxidation-reduction titrimetric method, for ASA and AA respectively. In this work, the application of MCR-ALS allowed for the first time the full resolution of the FIA diffusion profile due to the Schlieren effect as an independent signal contribution, suggesting that the proposed MCR-ALS method allows for its accurate correction in FIA-DAD systems.133774-8

RANGO DE HOGAR Y USO DE HÁBITAT DEL FRUTERO VERDINEGRO PIPREOLA RIEFFERII EN BOSQUES MONTANOS FRAGMENTADOS AL NORTE DE PERÚ

Resumen ∙ La fragmentación del hábitat ha causado la extinción local de muchas especies y mayormente de aquellas con poblaciones pequeñas. Sin embargo, ciertas características del paisaje permiten que algunas especies logren persistir a pesar del impacto en sus hábitats. Desde 2016 a 2019, estudiamos el rango de hogar y el uso de hábitat en función de la densidad poblacional del frutero verdinegro Pipreola riefferii (estimada mediante puntos de conteo) en bosques de niebla fragmentados en el norte de Perú. Usando radiotelemetría (10 individuos en 7 paisajes) estimamos que la media del rango de hogar para el frutero verdinegro basada en 95% densidad de Kernel (KDE) fue 3,72 ± 1,70 ha, y de 100% Polígono Mínimo Convexo (MCP) fue 1,85 ± 0,84 ha. La densidad del frutero verdinegro en bosque primario fue igual que en fragmentos, y significativamente más alta que en zonas de bosques en regeneración o silvopastoriles. Al mismo tiempo, la densidad en el bosque estuvo correlacionada negativamente con la cobertura del dosel medida con densitometría esférica. Concluimos que el frutero verdinegro puede persistir en paisajes fragmentados porque posee rangos de hogar pequeños y se encuentra en lugares con aperturas del dosel parcialmente abierto. Recomendamos el mantenimiento de bosque en regeneración u otras formas de hábitat sucesionales con abundancia de arbustos para mejorar la conectividad poblacional y la persistencia del frutero verdinegro en fragmentos aislados