Carlos Andrés Ramos Paja  Alfonso Romero Nevado  Robert Giral Castillón  Luis Martinez‐Salamero  Carlos Ignacio Sanchez Saenz 《International Journal of Circuit Theory and Applications》2011,39(5):475-499

A fuel cell‐based power systems emulator designed to test devices and loads intended to interact with real prototypes is presented. The emulator uses a digital processing device and electrical power systems, evaluating the impact of using either switching or linear power stages in the emulator capabilities. A real fuel cell prototype is emulated using a parameterized physical fuel cell model, which is computed online by a digital device. Also, several power stages not previously used specifically for this application, with different efficiencies and performances, were developed and analysed. One of the power stages was based on a two‐inductor step‐down DC/DC converter for a switching power stage instead of the classical buck structure that is more prone to duty cycle saturation in transients at low output voltages. The other ones used high‐power operational amplifiers for a linear power stage and linear regulators for a scalable linear power stage. Finally, the emulation system and the power stages were evaluated and validated using experimental data of a real fuel cell prototype. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

    

A. G. Martinez‐Lopez  A. Cerdeira  J. C. Tinoco  J. Alvarado  W. Y. Padron  C. Mendoza  J.‐P. Raskin 《International Journal of Numerical Modelling》2015,28(4):465-478

These last years, the triple‐gate fin field‐effect transistor (FinFET) has appeared as attractive candidate to pursue the complementary metal‐oxide semiconductor technology roadmap for digital and analog applications. However, the development of analog applications requires models that properly describe the static and RF behaviors as well as the extrinsic parameters related to the three‐dimensional FinFET architecture, in order to establish adequate design strategies. We demonstrate the feasibility of the compact model developed for symmetric doped double‐gate metal‐oxide‐semiconductor field‐effect transistor (symmetric doped double‐gate MOSFET) to reproduce the experimental dc and RF behaviors for 40‐nm technology node Silicon‐on‐Insulator triple‐gate FinFETs. Extrinsic gate capacitances and access extrinsic resistances have been included in order to properly predict the transistor small‐signal behavior, the current gain, and the maximum available power gain cut‐off frequencies. Finally, the improvement of the FinFET RF characteristics by the reduction of the parasitics is addressed. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

    

Ivan Maza  Fernando Caballero  Jesus Capitan  J.R. Martinez‐de‐Dios  Anibal Ollero 《野外机器人技术杂志》2011,28(3):303-328

This paper presents the architecture developed in the framework of the AWARE project for the autonomous distributed cooperation between unmanned aerial vehicles (UAVs), wireless sensor/actuator networks, and ground camera networks. One of the main goals was the demonstration of useful actuation capabilities involving multiple ground and aerial robots in the context of civil applications. A novel characteristic is the demonstration in field experiments of the transportation and deployment of the same load with single/multiple autonomous aerial vehicles. The architecture is endowed with different modules that solve the usual problems that arise during the execution of multipurpose missions, such as task allocation, conflict resolution, task decomposition, and sensor data fusion. The approach had to satisfy two main requirements: robustness for operation in disaster management scenarios and easy integration of different autonomous vehicles. The former specification led to a distributed design, and the latter was tackled by imposing several requirements on the execution capabilities of the vehicles to be integrated in the platform. The full approach was validated in field experiments with different autonomous helicopters equipped with heterogeneous devices onboard, such as visual/infrared cameras and instruments to transport loads and to deploy sensors. Four different missions are presented in this paper: sensor deployment and fire confirmation with UAVs, surveillance with multiple UAVs, tracking of firemen with ground and aerial sensors/cameras, and load transportation with multiple UAVs. © 2011 Wiley Periodicals, Inc.  相似文献   

    

Hamsici  O.C. Martinez  A.M. 《IEEE transactions on pattern analysis and machine intelligence》2009,31(11):1985-1999

Shape analysis requires invariance under translation, scale, and rotation. Translation and scale invariance can be realized by normalizing shape vectors with respect to their mean and norm. This maps the shape feature vectors onto the surface of a hypersphere. After normalization, the shape vectors can be made rotational invariant by modeling the resulting data using complex scalar-rotation invariant distributions defined on the complex hypersphere, e.g., using the complex Bingham distribution. However, the use of these distributions is hampered by the difficulty in estimating their parameters and the nonlinear nature of their formulation. In the present paper, we show how a set of kernel functions that we refer to as rotation invariant kernels can be used to convert the original nonlinear problem into a linear one. As their name implies, these kernels are defined to provide the much needed rotation invariance property allowing one to bypass the difficulty of working with complex spherical distributions. The resulting approach provides an easy, fast mechanism for 2D & 3D shape analysis. Extensive validation using a variety of shape modeling and classification problems demonstrates the accuracy of this proposed approach.  相似文献   

    

Ignacio J. Blanco  M. Amparo Vila  Carmen Martinez‐Cruz 《国际智能系统杂志》2008,23(4):419-445

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Christopher J. Martinez  Wei-Ming Lin  Parimal Patel 《Journal of Network and Computer Applications》2007,30(4):1397-1427

Hashing algorithms have been widely adopted to provide a fast address lookup process which involves a search through a large database to find a record associated with a given key. Modern examples include address lookup in network routers for a forwarding outgoing link, rule-matching in intrusion detection systems comparing incoming packets with a large database, etc. Hashing algorithms involve transforming a key inside each target data to a hash value hoping that the hashing would render the database a uniform distribution with respect to this new hash value. When the database are already key-wise uniformly distributed, any regular hashing algorithm would easily lead to perfectly uniform distribution after the hashing. On the other hand, if records in the database are instead not uniformly distributed, then different hashing functions would lead to different performance. This paper addresses the cases when such distribution follows a natural negative linear distribution, a partial negative linear distribution, or an exponential distribution which are found to closely approximate many real-life database distributions. For each of these distributions, we derive a general formula for calculating the distribution variance produced by any given non-overlapping bit-grouping XOR hashing function. Such a distribution variance from the hashing directly translates to performance variations in searching. Through this, the best XOR hashing function can be easily determined for any given key size and any given hashing target size.  相似文献   

    

O.A. Sbodio    E.J. Tercero    R. Coutaz    E. Martinez 《Journal of food science》2002,67(3):1097-1102

ABSTRACT: :
To evaluate the relationship between the factors affecting coagulation, the hot wire method was used for direct measurements of the renneting milk process as well as a central composite design with 3 factors: rennet concentration (x₁), renneting pH (x₂), and temperature (x₃). Second-order models for maximum voltage (Y₁), time at maximum voltage (Y₂), and coagulation time (Y₃) were employed to generate response surface contours. Optimum conditions for cutting time were found with x₁= 0.0278 R.U./mL milk, x₂= 6.60, and x₃= 35 °C, for which the responses were Y₁= 2854 ± 171 μV, Y₂, = 14.08 ± 3.04 min, and Y₃= 7.16 ± 1.12 min. No significant differences (p > 0.01) were found between the 3 responses obtained in the experiment and the ones predicted by the models. The use of the objective and non-destructive monitoring of curd formation and the response surface methodology can be recommended to optimize milk coagulation.  相似文献   

    

Lígia Ribeiro Salgueiro  Eugnia Pinto  Maria Jos Gonalves  Inês Costa  Ana Palmeira  Carlos Cavaleiro  Cidlia Pina‐Vaz  Accio Gonalves Rodrigues  Jos Martinez‐de‐Oliveira 《Flavour and Fragrance Journal》2006,21(5):749-753

The antifungal activity of Thymus capitellatus oils on Candida, Aspergillus and dermatophyte strains were studied. The essential oils were obtained from the aerial parts of the plants by water distillation and analysed by GC and GC–MS. Three chemotypes were characterized: 1,8‐cineole (47.5%), 1,8‐cineole/borneol (28.8% and 19.5%, respectively) and 1,8‐cineole/linalyl acetate/linalool (27.5%, 20.0% and 17.0%, respectively). The minimal inhibitory concentration (MIC) determined according to the NCCLS protocols (M27‐A and M38‐P) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity of the oils against Candida (seven clinical isolates and three ATCC type strains), Aspergillus (five clinical isolates, two CECT and two ATCC type strains) and five dermatophyte clinical fungi strains. The oils exhibited antifungal activity for the dermatophyte strains, with MIC values of 0.32–1.25 µl/ml; the chemotype 1,8‐cineole/linalyl acetate/linalool proved to be more active. The highest antifungal activity of this oil can be associated with the contribution of the linalyl acetate. In the other hand, all samples showed low activity against Candida and Aspergillus strains. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

    

Juan Francisco Alcala‐Diaz  Oriol Rangel‐Zuñiga  Javier Delgado‐Lista  Elena M. Yubero‐Serrano  Javier Lopez‐Moreno  Francisco Jose Tinahones  Jose M. Ordovas  Marta Garaulet  Pablo Perez‐Martinez 《Molecular nutrition & food research》2015,59(12):2556-2564

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Stephanie E. Martinez  Neal M. Davies 《Molecular nutrition & food research》2015,59(9):1674-1689

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