Genetic differences in clinical and environmental strains of Vibrio parahaemolyticus have been wi... more Genetic differences in clinical and environmental strains of Vibrio parahaemolyticus have been widely used as criteria in identifying pathogenic isolates. However, few studies have been carried out to assess the differences in biochemical characteristics of V. parahaemolyticus isolates from human and environmental sources. We compared the biochemical profiles obtained by the characterization of V. parahaemolyticus isolates from human infections and the marine environment using the API 20E system. Environmental and clinical isolates showed significant differences in the gelatin and arabinose tests. Additionally, clinical isolates were correctly identified according to the API 20E profile using 0.85% NaCl diluent, but they presented nonspecific profiles with 2% NaCl diluent. In contrast, use of 2% NaCl diluent facilitated correct identification of the environmental isolates. Clinical isolates showed significant differences in up to five biochemical tests with respect to the API 20E database. The API 20E system is widely used in routine identification of bacteria in clinical laboratories, and this discrepancy in an important number of biochemical tests may lead to misidentification of V. parahaemolyticus infection.
ABSTRACT This work Studies the effect of boron on the density of a 409Nb ferritic stainless steel... more ABSTRACT This work Studies the effect of boron on the density of a 409Nb ferritic stainless steel obtained by powder metallurg during the process of sintering. The purpose of adding boron is to promote the formation of a liquid phase during sintering at temperatures below 1200 degrees C. The boron contents varied from 0.0 to 1.5%wt. Specimens were compacted at 700MPa, and sintering was made at 1075 and 1150 degrees C during 60 minutes under a hydrogen atmosphere, using a heating rate of 20 degrees C/min. Density values were determined by the Archimedes method, and the samples were analyzed using scanning electron microscopy. This work shows the dependence of the steel density and morphology of the microstructure as a function of boron content and the temperature of sintering.
Phase locked loop (PLL) algorithms for grid synchronization are a very important part of the cont... more Phase locked loop (PLL) algorithms for grid synchronization are a very important part of the control in most of the grid-connected power converters applications. The performance of the PLL should not be much affected under distorted grid conditions: the presence of harmonics, unbalance, noise, etc in the inputs should not distort PLL measurements. This paper presents an optimized design approach of PLLs, both for single-phase and three-phase systems. The loop filter of the PLL sets its dynamic response; the loop filter should be tuned in order to achieve a correct tradeoff between transient response and harmonics/noise cancellation. This paper proposes the use of notch filters inside the loop in order to optimize the PLL performance; this approach is suitable both for single-phase and three-phase PLLs. Another novel interesting proposal of this paper is the implementation of the digitally controlled oscillator (DCO): the digital model of a sinusoidal oscillator is implemented, instead trigonometric functions. This reduces the needed digital resources without reducing the performance. This approach is specially useful for DSP-based control of power converters. The proposed PLLs have been implemented and tested in a fixed point DSP (TI TMS320LF2407) and also in a floating point microprocessor (PowerPC of the dSpace DS1103). The systems have been tested with different distorted inputs in order to check the validity of the design approaches and good results have been obtained.
The design of synchronous multiphase DC-DC converters for automobile applications is now a very a... more The design of synchronous multiphase DC-DC converters for automobile applications is now a very active field, because the automotive industry forecast that future power demands inside a car will oscillate between 2.5 kW and 3.5kW, keeping a dual system of 42/14V batteries. The design of controllers for the optimal behavior of such converters is a very delicate task. In this paper, an optimized fuzzy control algorithm has been developed to control a synchronous multiphase converter of 1.6kW. First, the fuzzy control algorithm is designed and verified, together with a non linear model of the converter power stage, by means of Matlab and Simulink. Then, the fuzzy controller hardware is developed through Xilinx System Generator for Simulink, and implemented in a Spartan 3 FPGA to achieve a real-time controller
Reference generation is very important in the control of power line conditioners. This paper pres... more Reference generation is very important in the control of power line conditioners. This paper presents some algorithms both for single-phase and three-phase systems very suitable for reference generation and digital implementation. The key of the proposed algorithm is the implementation and tuning of Moving Average FIR filters (MVAs). Thanks to the rapid step-response and good harmonic/noise cancellation of MVAs, proposed
ABSTRACT Harmonic detection is very important in the control of active power filters (APFs). This... more ABSTRACT Harmonic detection is very important in the control of active power filters (APFs). This paper presents a technique for harmonic identification, based on moving average filters (MVAs) and heterodyning, very suitable for digital implementation. The approach of fundamental component identification is contributed both for single-phase and three-phase voltage/current systems. Selective harmonic identification is also feasible. Due to the rapid step-response, good harmonic/noise cancellation of MVAs, and good frequency adaptation of the proposed algorithms, they have a very good performance compared with other alternatives. Experimental results of digital implementation in a rapid prototyping platform (dSpace DS1103), including an APF prototype are contributed proving the theoretical approaches. Details and experimental results of FPGA implementation, a clear trend in the field of digital control, are also contributed.
Genetic differences in clinical and environmental strains of Vibrio parahaemolyticus have been wi... more Genetic differences in clinical and environmental strains of Vibrio parahaemolyticus have been widely used as criteria in identifying pathogenic isolates. However, few studies have been carried out to assess the differences in biochemical characteristics of V. parahaemolyticus isolates from human and environmental sources. We compared the biochemical profiles obtained by the characterization of V. parahaemolyticus isolates from human infections and the marine environment using the API 20E system. Environmental and clinical isolates showed significant differences in the gelatin and arabinose tests. Additionally, clinical isolates were correctly identified according to the API 20E profile using 0.85% NaCl diluent, but they presented nonspecific profiles with 2% NaCl diluent. In contrast, use of 2% NaCl diluent facilitated correct identification of the environmental isolates. Clinical isolates showed significant differences in up to five biochemical tests with respect to the API 20E database. The API 20E system is widely used in routine identification of bacteria in clinical laboratories, and this discrepancy in an important number of biochemical tests may lead to misidentification of V. parahaemolyticus infection.
ABSTRACT This work Studies the effect of boron on the density of a 409Nb ferritic stainless steel... more ABSTRACT This work Studies the effect of boron on the density of a 409Nb ferritic stainless steel obtained by powder metallurg during the process of sintering. The purpose of adding boron is to promote the formation of a liquid phase during sintering at temperatures below 1200 degrees C. The boron contents varied from 0.0 to 1.5%wt. Specimens were compacted at 700MPa, and sintering was made at 1075 and 1150 degrees C during 60 minutes under a hydrogen atmosphere, using a heating rate of 20 degrees C/min. Density values were determined by the Archimedes method, and the samples were analyzed using scanning electron microscopy. This work shows the dependence of the steel density and morphology of the microstructure as a function of boron content and the temperature of sintering.
Phase locked loop (PLL) algorithms for grid synchronization are a very important part of the cont... more Phase locked loop (PLL) algorithms for grid synchronization are a very important part of the control in most of the grid-connected power converters applications. The performance of the PLL should not be much affected under distorted grid conditions: the presence of harmonics, unbalance, noise, etc in the inputs should not distort PLL measurements. This paper presents an optimized design approach of PLLs, both for single-phase and three-phase systems. The loop filter of the PLL sets its dynamic response; the loop filter should be tuned in order to achieve a correct tradeoff between transient response and harmonics/noise cancellation. This paper proposes the use of notch filters inside the loop in order to optimize the PLL performance; this approach is suitable both for single-phase and three-phase PLLs. Another novel interesting proposal of this paper is the implementation of the digitally controlled oscillator (DCO): the digital model of a sinusoidal oscillator is implemented, instead trigonometric functions. This reduces the needed digital resources without reducing the performance. This approach is specially useful for DSP-based control of power converters. The proposed PLLs have been implemented and tested in a fixed point DSP (TI TMS320LF2407) and also in a floating point microprocessor (PowerPC of the dSpace DS1103). The systems have been tested with different distorted inputs in order to check the validity of the design approaches and good results have been obtained.
The design of synchronous multiphase DC-DC converters for automobile applications is now a very a... more The design of synchronous multiphase DC-DC converters for automobile applications is now a very active field, because the automotive industry forecast that future power demands inside a car will oscillate between 2.5 kW and 3.5kW, keeping a dual system of 42/14V batteries. The design of controllers for the optimal behavior of such converters is a very delicate task. In this paper, an optimized fuzzy control algorithm has been developed to control a synchronous multiphase converter of 1.6kW. First, the fuzzy control algorithm is designed and verified, together with a non linear model of the converter power stage, by means of Matlab and Simulink. Then, the fuzzy controller hardware is developed through Xilinx System Generator for Simulink, and implemented in a Spartan 3 FPGA to achieve a real-time controller
Reference generation is very important in the control of power line conditioners. This paper pres... more Reference generation is very important in the control of power line conditioners. This paper presents some algorithms both for single-phase and three-phase systems very suitable for reference generation and digital implementation. The key of the proposed algorithm is the implementation and tuning of Moving Average FIR filters (MVAs). Thanks to the rapid step-response and good harmonic/noise cancellation of MVAs, proposed
ABSTRACT Harmonic detection is very important in the control of active power filters (APFs). This... more ABSTRACT Harmonic detection is very important in the control of active power filters (APFs). This paper presents a technique for harmonic identification, based on moving average filters (MVAs) and heterodyning, very suitable for digital implementation. The approach of fundamental component identification is contributed both for single-phase and three-phase voltage/current systems. Selective harmonic identification is also feasible. Due to the rapid step-response, good harmonic/noise cancellation of MVAs, and good frequency adaptation of the proposed algorithms, they have a very good performance compared with other alternatives. Experimental results of digital implementation in a rapid prototyping platform (dSpace DS1103), including an APF prototype are contributed proving the theoretical approaches. Details and experimental results of FPGA implementation, a clear trend in the field of digital control, are also contributed.
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Papers by Oscar Jacobo