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排序方式: 共有185条查询结果,搜索用时 31 毫秒
11.
This article is about nonstationary nonlinear discrete-time deterministic and stochastic control systems with Borel state and control spaces, possibly noncompact control constraint sets, and unbounded costs. The control problem is to minimise an infinite-horizon total cost performance index. Using dynamic programming arguments we show that, under suitable assumptions, the optimal cost functions satisfy optimality equations, which in turn give a procedure to find optimal control policies. 相似文献
12.
In recent years, several extensions of tree automata have been considered. Most of them are related with the capability of testing equality or disequality of certain subterms of the term evaluated by the automaton. In particular, tree automata with global constraints are able to test equality and disequality of subterms depending on the state to which they are evaluated. The emptiness problem is known decidable for this kind of automata, but with a non-elementary time complexity, and the finiteness problem remains unknown. In this paper, we consider the particular case of tree automata with global constraints when the constraint is a conjunction of disequalities between states, and the disequality predicate is forced to be reflexive. This restriction is significant in the context of XML definitions with monadic key constraints. We prove that emptiness and finiteness are decidable in triple exponential time for this kind of automata. 相似文献
13.
Ramón Moreira Francisco Chenlo María D. Torres Adrián Romaní 《Food and Bioprocess Technology》2017,10(3):603-613
Thermo-rheological behaviour of chestnut flour doughs supplemented with kappa/iota-hybrid carrageenan (HC) (up to 2.0%, flour basis (f.b.)) and sodium chloride (1.8%, f.b.) was determined at both target (C1) and final (C5) mixing peaks. For this purpose, small amplitude oscillatory shear (0.01 to 100 Hz), creep–recovery (loading of 50 Pa for 60 s, 30 °C), temperature sweeps (from 30 up to 180 °C) and heating/cooling cycles (between 30 and 60 °C) were conducted on a controlled stress rheometer. Previously, the thermal-mixing behaviour at proposed mixing temperature (50 °C) was conducted on Mixolab® apparatus. Results showed that the dough stability (from 2.2 to 5.8 min) in mixing stage and starch heat resistance to dough processing were significantly improved at proposed mixing temperature, even in the absence of HC. No statistical differences in rheological properties were observed for doughs evaluated in C1; however, those analysed in C5 were significantly modified in the presence of HC, mainly in terms of viscous behaviour (from 52.1 × 106 to 39.1 × 106 Pa s). Creep–recovery data sets, successfully fitted using Burgers model, revealed that the elasticity (J r/J max from 73.3 to 87.6%) of doughs analysed in C5 improved with HC addition. Thermal tests showed that the starch transitions were significantly promoted and stabilized with HC addition. 相似文献
14.
Marco Dondero Adrián P. Cisilino José M. Carella J. Pablo Tomba 《International Journal of Heat and Mass Transfer》2011,54(17-18):3874-3881
This work introduces a numerical methodology for the computation of the effective thermal conductivity (ETC) of random micro-heterogeneous materials using representative volume elements and the Fast Multipole Boundary Element Method (FMBEM). The methodology is applied to solve two-dimensional foam-like materials consisting of random distributions of circular isolated holes. The computed ETC values are successfully used to predict the temperature fields of two materials with functionally graded ETCs. Numerical and analytical results are experimentally validated. The proposed methodology is flexible and versatile, as it is capable to account for both, the geometrical and topological details of the material microstructure. 相似文献
15.
New ways of achieving small, multiband, multifunctional, and standard solutions for mobile handset antennas are demanded in the current wireless market. A non‐resonant element of , a matching network, and a slotted ground plane are proposed to satisfy mobile market demands that require multiband operation and small antenna solutions. The main advantage of the proposed design is that with only one non‐resonant element of considerably small size (0.015λ, 900 MHz), the handset is capable of providing operation at mobile bands. 相似文献
16.
Patrik?LambertEmail author Adrià?De?Gispert Rafael?Banchs José?B.?Mari?o 《Language Resources and Evaluation》2005,39(4):267-285
The purpose of this paper is to provide guidelines for building a word alignment evaluation scheme. The notion of word alignment quality depends on the application: here we review standard scoring metrics for full text alignment and give explanations on how to use them better. We discuss strategies to build a reference corpus, and show that the ratio between ambiguous and unambiguous links in the reference has a great impact on scores measured with these metrics. In particular, automatically computed alignments with higher precision or higher recall can be favoured depending on the value of this ratio. Finally, we suggest a strategy to build a reference corpus particularly adapted to applications where recall plays a significant role, like in machine translation. The manually aligned corpus we built for the Spanish-English European Parliament corpus is also described. This corpus is freely available. 相似文献
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The Journal of Supercomputing - Modern GPUs can achieve high computing power at low cost, but still requires much time and effort. Tridiagonal system and scan solvers are one example of widely used... 相似文献
20.
Gutiérrez-Cruz Adrián Ruiz-Hernández Ali Roberto Vega-Clemente José Fernando Luna-Gazcón Daniela Guadalupe Campos-Delgado Jessica 《Journal of Materials Science》2022,57(31):14543-14578
Journal of Materials Science - As nanotechnology floods application areas like medicine, electronics, water remediation, space and textiles, just to name a few, some nanomaterials remain in the... 相似文献