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101.
Francisco J. Rubio Francisco J. Valero Jose Luis Suñer Vicente Mata 《Asian journal of control》2010,12(4):468-479
This paper addresses the solution of smooth trajectory planning for industrial robots in environments with obstacles using a direct method, creating the trajectory gradually as the robot moves. The presented method deals with the uncertainties associated with the lack of knowledge of kinematic properties of intermediate via‐points since they are generated as the algorithm evolves looking for the solution. Several cost functions are also proposed, which use the time that has been calculated to guide the robot motion. The method has been applied successfully to a PUMA 560 robot and four operational parameters (execution time, computational time, distance travelled and number of configurations) have been computed to study the properties and influence of each cost function on the trajectory obtained. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
102.
This article proposes an optimization–simulation model for planning the transport of supplies to large public infrastructure
works located in congested urban areas. The purpose is to minimize their impact on the environment and on private transportation
users on the local road network. To achieve this goal, the authors propose and solve an optimization problem for minimizing
the total system cost made up of operating costs for various alternatives for taking supplies to the worksite and the costs
supported by private vehicle users as a result of increased congestion due to the movement of heavy goods vehicles transporting
material to the worksite. The proposed optimization problem is a bi-level Math Program model. The upper level defines the
total cost of the system, which is minimized taking into account environmental constraints on atmospheric and noise pollution.
The lower level defines the optimization problem representing the private transportation user behavior, assuming they choose
the route that minimizes their total individual journey costs. Given the special characteristics of the problem, a heuristic
algorithm is proposed for finding optimum solutions. Both the model developed and the specific solution algorithm are applied
to the real case of building a new port at Laredo (Northern Spain). A series of interesting conclusions are obtained from
the corresponding sensitivity analysis. 相似文献
103.
Liquid recirculation in microfluidic channels by the interplay of capillary and centrifugal forces 总被引:1,自引:1,他引:0
Jose L. Garcia-Cordero Lourdes Basabe-Desmonts Jens Ducrée Antonio J. Ricco 《Microfluidics and nanofluidics》2010,9(4-5):695-703
We demonstrate a technique to recirculate liquids in a microfluidic channel by alternating predominance of centrifugal and capillary forces to rapidly bring the entire volume of a liquid sample to within one diffusion length, δ, of the surface, even for sample volumes hundreds of times the product of δ and the geometric device area. This is accomplished by repetitive, random sampling of an on-disc sample reservoir to form a thin fluid layer of thickness δ in a microchannel, maintaining contact for the diffusion time, then rapidly exchanging the fluid layer for a fresh aliquot by disc rotation and stoppage. With this technique, liquid volumes of microlitres to millilitres can be handled in many sizes of microfluidic channels, provided the channel wall with greatest surface area is hydrophilic. We present a theoretical model describing the balance of centrifugal and capillary forces in the device and validate the model experimentally. 相似文献
104.
Julia Clemente Jaime Ramírez Angélica de Antonio 《Expert systems with applications》2011,38(7):8066-8078
The advances in the educational field and the high complexity of student modeling have provoked it to be one of the aspects more investigated in Intelligent Tutoring Systems (ITSs). The Student Models (SMs) should not only represent the student’s knowledge, but rather they should reflect, as faithfully as possible, the student’s reasoning process. To facilitate this goal, in this article a new approach to student modeling is proposed that benefits from the advantages of Ontological Engineering, advancing in the pursue of a more granular and complete knowledge representation. It’s focused, mainly, on the SM cognitive diagnosis process, and we present a method providing a rich diagnosis about the student’s knowledge state – especially, about the state of learning objectives reached or not. The main goal is to achieve SMs with a good adaptability to the student’s features and a high flexibility for its integration in varied ITSs. 相似文献
105.
Antonio de la Oliva Ignacio Soto Albert Banchs Johannes Lessmann Christian Niephaus Telemaco MeliaAuthor vitae 《Computer Standards & Interfaces》2011,33(6):556-564
The IEEE 802.21 standard facilitates media independent handovers by providing higher layer mobility management functions with common service primitives for all technologies. Right after the base specification was published, several voices rose up in the working group advocating to broaden the scope of IEEE 802.21 beyond handovers. This paper aims at updating the reader with the main challenges and functionalities required to create a Media Independence Service Layer, through the analysis of scenarios which are being discussed within the working group: 1) Wireless Coexistence, and 2) Heterogeneous Wireless Multihop Backhaul Networks. 相似文献
106.
Jose A. Belloch Alberto Gonzalez F. J. Martínez-Zaldívar Antonio M. Vidal 《The Journal of supercomputing》2011,58(3):449-457
Massive convolution is the basic operation in multichannel acoustic signal processing. This field has experienced a major
development in recent years. One reason for this has been the increase in the number of sound sources used in playback applications
available to users. Another reason is the growing need to incorporate new effects and to improve the hearing experience. Massive
convolution requires high computing capacity. GPUs offer the possibility of parallelizing these operations. This allows us
to obtain the processing result in much shorter time and to free up CPU resources. One important aspect lies in the possibility
of overlapping the transfer of data from CPU to GPU and vice versa with the computation, in order to carry out real-time applications.
Thus, a synthesis of 3D sound scenes could be achieved with only a peer-to-peer music streaming environment using a simple
GPU in your computer, while the CPU in the computer is being used for other tasks. Nowadays, these effects are obtained in
theaters or funfairs at a very high cost, requiring a large quantity of resources. Thus, our work focuses on two mains points:
to describe an efficient massive convolution implementation and to incorporate this task to real-time multichannel-sound applications. 相似文献
107.
Francisco Almeida Domingo Giménez Jose J. López-Espín 《The Journal of supercomputing》2011,58(3):292-301
This paper presents a parameterized shared-memory scheme for parameterized metaheuristics. The use of a parameterized metaheuristic
facilitates experimentation with different metaheuristics and hybridation/combinations to adapt them to the particular problem
we are working with. Due to the large number of experiments necessary for the metaheuristic selection and tuning, parallelism
should be used to reduce the execution time. To obtain parallel versions of the metaheuristics and to adapt them to the characteristics
of the parallel system, a unified parameterized shared-memory scheme is developed. Given a particular computational system
and fixed parameters for the sequential metaheuristic, the appropriate selection of parameters in the unified parallel scheme
eases the development of parallel efficient metaheuristics. 相似文献
108.
Time series prediction is a complex problem that consists of forecasting the future behavior of a set of data with the only
information of the previous data. The main problem is the fact that most of the time series that represent real phenomena
include local behaviors that cannot be modelled by global approaches. This work presents a new procedure able to find predictable
local behaviors, and thus, attaining a better level of total prediction. This new method is based on a division of the input
space into Voronoi regions by means of Evolution Strategies. Our method has been tested using different time series domains.
One of them that represents the water demand in a water tank, through a long period of time. The other two domains are well
known examples of chaotic time series (Mackey-Glass) and natural phenomenon time series (Sunspot). Results prove that, in
most of cases, the proposed algorithm obtain better results than other algorithms commonly used. 相似文献
109.
MELM-GRBF: A modified version of the extreme learning machine for generalized radial basis function neural networks 总被引:3,自引:0,他引:3
Francisco Fernández-NavarroAuthor Vitae César Hervás-MartínezAuthor VitaeJavier Sanchez-MonederoAuthor Vitae Pedro Antonio GutiérrezAuthor Vitae 《Neurocomputing》2011,74(16):2502-2510
In this paper, we propose a methodology for training a new model of artificial neural network called the generalized radial basis function (GRBF) neural network. This model is based on generalized Gaussian distribution, which parametrizes the Gaussian distribution by adding a new parameter τ. The generalized radial basis function allows different radial basis functions to be represented by updating the new parameter τ. For example, when GRBF takes a value of τ=2, it represents the standard Gaussian radial basis function. The model parameters are optimized through a modified version of the extreme learning machine (ELM) algorithm. In the methodology proposed (MELM-GRBF), the centers of each GRBF were taken randomly from the patterns of the training set and the radius and τ values were determined analytically, taking into account that the model must fulfil two constraints: locality and coverage. An thorough experimental study is presented to test its overall performance. Fifteen datasets were considered, including binary and multi-class problems, all of them taken from the UCI repository. The MELM-GRBF was compared to ELM with sigmoidal, hard-limit, triangular basis and radial basis functions in the hidden layer and to the ELM-RBF methodology proposed by Huang et al. (2004) [1]. The MELM-GRBF obtained better results in accuracy than the corresponding sigmoidal, hard-limit, triangular basis and radial basis functions for almost all datasets, producing the highest mean accuracy rank when compared with these other basis functions for all datasets. 相似文献
110.
Antonio Fernández-CaballeroAuthor Vitae María T. LópezAuthor Vitae Enrique J. CarmonaAuthor VitaeAna E. DelgadoAuthor Vitae 《Neurocomputing》2011,74(8):1175-1181
Certainly, one of the prominent ideas of Professor José Mira was that it is absolutely mandatory to specify the mechanisms and/or processes underlying each task and inference mentioned in an architecture in order to make operational that architecture. The conjecture of the last fifteen years of joint research has been that any bottom-up organization may be made operational using two biologically inspired methods called “algorithmic lateral inhibition”, a generalization of lateral inhibition anatomical circuits, and “accumulative computation”, a working memory related to the temporal evolution of the membrane potential. This paper is dedicated to the computational formulation of both methods. Finally, all of the works of our group related to this methodological approximation are mentioned and summarized, showing that all of them support the validity of this approximation. 相似文献