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排序方式: 共有1323条查询结果,搜索用时 31 毫秒
31.
Dissipative particle dynamics simulations for fibre suspensions in newtonian and viscoelastic fluids
Duc Duong-Hong Nhan Phan-Thien Khoon Seng Yeo Gilles Ausias 《Computer Methods in Applied Mechanics and Engineering》2010,199(23-24):1593-1602
A versatile model of fibre suspensions in Newtonian and viscoelastic fluids has been developed using dissipative particle dynamics method. The viscoelastic fluid is modelled by linear chains with linear connector spring force (the Oldroyd-B model), which is known to be a reasonable model for the so-called Boger fluid (a dilute suspension of polymer in a highly viscous solvent). The numerical results are in excellent agreement with the analytical results of the Oldroyd-B model in simple shear flow. An effective meso-scale model of fibre in DPD is proposed and then incorporated with simple Newtonian fluid and our Boger fluid to enable entirely study rheological properties of fibre suspensions in both Newtonian and viscoelastic solvents. The numerical results are well compared with available experimental data and other numerical models. 相似文献
32.
33.
This paper describes a process for mashing heterogeneous data sources based on the Multi-data source Fusion Approach (MFA) (Nachouki and Quafafou, 2008 [52]). The aim of MFA is to facilitate the fusion of heterogeneous data sources in dynamic contexts such as the Web. Data sources are either static or active: static data sources can be structured or semi-structured (e.g. XML documents or databases), whereas active sources are services (e.g. Web services). Our main objective is to combine (Web) data sources with a minimal effort required from the user. This objective is crucial because the mashing process implies easy and fast integration of data sources. We suppose that the user is not expert in this field but he/she understands the meaning of data being integrated. In this paper, we consider two important aspects of the Web mashing process. The first one concerns the information extraction from the Web. The results of this process are the static data sources that are used later together with services in order to create a new result/application. The second one concerns the problem of semantic reconciliation of data sources. This step consists to generate the Conflicts data source in order to improve the problem of rewriting semantic queries into sub-queries (not addressed in this paper) over data sources. We give the design of our system MDSManager. We show this process through a real-life application. 相似文献
34.
The last generation of infrared imaging aircraft seekers and trackers uses pattern recognition algorithms to find and keep
a lock on an aircraft in the presence of decoy flares. These algorithms identify targets, based on the features of the various
objects in the missile’s field of view. Because modern both aircrafts and missiles fly faster than sound, speed of operation
of the target identifier is critical. In this article, we propose a target recognition system that respects this time constraint.
It is based on an artificial neural network implemented in hardware, as a set of parallel processors on a commercially available
silicon chip called a ZISC, for zero instruction set computer. This chip would be integrated in the infrared missile seeker
and tracker. We describe the characteristics of the images that the image processing module of this seeker and tracker extracts
from the infrared video frames and show how to construct from these translation and rotation invariant features that can be
used as input to the neural network. We determine the individual discriminating power of these features by constructing their
histograms, which allows us to eliminate some as not being useful for our purpose. Finally, by testing our system on real
data, we show that it has a 90% success rate in aircraft-flare identification, and a processing time that during this time,
the aircrafts and missiles will have traveled only a few millimeters. Most of the images on which the neural network makes
its mistakes are seen to be hard to recognize even by a human expert. 相似文献
35.
Region merging methods consist of improving an initial segmentation by merging some pairs of neighboring regions. In a graph,
merging two regions, separated by a set of vertices, is not straightforward. The perfect fusion graphs defined in J. Cousty
et al. (J. Math. Imaging Vis. 30:(1):87–104, 2008) verify all the basic properties required by region merging algorithms as used in image segmentation. Unfortunately, the
graphs which are the most frequently used in image analysis (namely, those induced by the direct and the indirect adjacency
relations) are not perfect fusion graphs. The perfect fusion grid, introduced in the above mentioned reference, is an adjacency
relation on ℤ
d
which can be used in image analysis, which indeed induces perfect fusion graphs and which is “between” the graphs induced
by the direct and the indirect adjacencies. One of the main results of this paper is that the perfect fusion grid is the only
such graph whatever the dimension d.
相似文献
Gilles BertrandEmail: |
36.
Tegawendé F. Bissyandé Laurent Réveillère Julia L. Lawall Gilles Muller 《Automated Software Engineering》2016,23(1):3-41
The Linux kernel does not export a stable, well-defined kernel interface, complicating the development of kernel-level services, such as device drivers and file systems. While there does exist a set of functions that are exported to external modules, this set of functions frequently changes, and the functions have implicit, ill-documented preconditions. No specific debugging support is provided. We present Diagnosys, an approach to automatically constructing a debugging interface for the Linux kernel. First, a designated kernel maintainer uses Diagnosys to identify constraints on the use of the exported functions. Based on this information, developers of kernel services can then use Diagnosys to generate a debugging interface specialized to their code. When a service including this interface is tested, it records information about potential problems. This information is preserved following a kernel crash or hang. Our experiments show that the generated debugging interface provides useful log information and incurs a low performance penalty. 相似文献
37.
Transfer of learning in virtual environments: a new challenge? 总被引:1,自引:0,他引:1
The aim of all education is to apply what we learn in different contexts and to recognise and extend this learning to new
situations. Virtual learning environments can be used to build skills. Recent research in cognitive psychology and education
has shown that acquisitions are linked to the initial context. This provides a challenge for virtual reality in education
or training. A brief overview of transfer issues highlights five main ideas: (1) the type of transfer enables the virtual
environment (VE) to be classified according to what is learned; (2) the transfer process can create conditions within the
VE to facilitate transfer of learning; (3) specific features of VR must match and comply with transfer of learning; (4) transfer
can be used to assess a VE’s effectiveness; and (5) future research on transfer of learning must examine the singular context
of learning. This paper discusses how new perspectives in cognitive psychology influence and promote transfer of learning
through the use of VEs. 相似文献
38.
This paper describes a new approach of heterogeneous data source fusion. Data sources are either static or active: static data sources can be structured or semi-structured, whereas active sources are services. In order to develop data sources fusion systems in dynamic contexts, we need to study all issues raised by the matching paradigms. This challenging problem becomes crucial with the dominating role of the internet. Classical approaches of data integration, based on schemas mediation, are not suitable to the World Wide Web (WWW) environment where data is frequently modified or deleted. Therefore, we develop a loosely integrated approach that takes into consideration both conflict management and semantic rules which must be enriched in order to integrate new data sources. Moreover, we introduce an XML-based Multi-data source Fusion Language (MFL) that aims to define and retrieve conflicting data from multiple data sources. The system, which is developed according to this approach, is called MDSManager (Multi-Data Source Manager). The benefit of the proposed framework is shown through a real world application based on web data sources fusion which is dedicated to online markets indices tracking. Finally, we give an evaluation of our MFL language. The results show that our language improves significantly the XQuery language especially considering its expressiveness power and its performances. 相似文献
39.
This paper presents a new bio-inspired algorithm (FClust) that dynamically creates and visualizes groups of data. This algorithm uses the concepts of a flock of agents that move together in a complex manner with simple local rules. Each agent represents one data. The agents move together in a 2D environment with the aim of creating homogeneous groups of data. These groups are visualized in real time, and help the domain expert to understand the underlying structure of the data set, like for example a realistic number of classes, clusters of similar data, isolated data. We also present several extensions of this algorithm, which reduce its computational cost, and make use of a 3D display. This algorithm is then tested on artificial and real-world data, and a heuristic algorithm is used to evaluate the relevance of the obtained partitioning. 相似文献
40.
The purpose of this paper is relative to the determination of the multiplication factor Mfor an optimum behaviour of the avalanche photodetector. Two types of avalanche photodetector s are compared: a silicon structure n + πpπp + Read diode and a GaAlAs heterostructure. Calculating the Noise Equivalent Power (nep)of the whole system, the law Si(f) =2q IphoMx is used, where the parameter x is determined experimentally in both avalanche photodetectors. The exponent x (between 2 and 4) dominates in the nep expression and the ideal nep for the avalanche photodetector system is obtained when x equals 2. 相似文献