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排序方式: 共有833条查询结果,搜索用时 31 毫秒
1.
This paper presents an innovative solution to model distributed adaptive systems in biomedical environments. We present an original TCBR-HMM (Text Case Based Reasoning-Hidden Markov Model) for biomedical text classification based on document content. The main goal is to propose a more effective classifier than current methods in this environment where the model needs to be adapted to new documents in an iterative learning frame. To demonstrate its achievement, we include a set of experiments, which have been performed on OSHUMED corpus. Our classifier is compared with Naive Bayes and SVM techniques, commonly used in text classification tasks. The results suggest that the TCBR-HMM Model is indeed more suitable for document classification. The model is empirically and statistically comparable to the SVM classifier and outperforms it in terms of time efficiency. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(56):23772-23786
As the PEMFC is a complex multi-physics device whose reliability and durability depend on the thermal-mechanical-electrical and chemical parameters. In this paper, theoretical and numerical studies is proposed to optimize the fuel cell performance using multiphysics model and design of experiments. 3D finite element analysis including a fully coupling of thermal-electrical-mechanical model is proposed to predict the electrical resistance of fuel cell. As the mechanical parameters (bending radius of the bipolar plate, thickness of the GDL and clamping pressure) remain uncertain, the design of experiments procedure is used to optimize the fuel cell behavior under several conditions. 相似文献
3.
4.
介绍了VRS与数字测深集成技术的测量原理,探讨了测量作业方法与影响测量精度的因素,及在苏州东南环桥隧工程穿越独墅湖段水下地形图测绘中的应用与体会,结合工程实例对测量精度进行了尝试性的验证,阐述了该方法成图周期短、成果准确可靠、效率高等特点. 相似文献
5.
Under frequency load shedding is an effective approach to maintain or restore the steady-state operation of the
power system when frequency accidents occur. An improved under frequency load shedding strategy based on
dynamic power flow tracking is proposed. The expression of the kinetic energy theorem in power system is derived
and combined with the power flow tracing method to analyze the relation between system energy distribution
and its frequency. The power system frequency influencing factors are then constructed and applied to find the
reasons of frequency decline and to quantify the contributions of the mechanical power of the generators, the load
power and the transmission losses for the frequency deviation. Finally, considering a variety of unbalanced power
scenarios in the system, the modified load shedding strategy is designed. Based on the results of dynamic power
flow tracing, the strategy can choose the suitable load node to control, and the defined load frequency contribution
indicator is utilized to determine the load shedding amount which each control object undertakes. The proposed
methodology is verified by the fault scenarios when the generator sets mistakenly cut off and the trip of important
tie-lines in the IEEE 39-bus system. Compared with the conventional strategies, the proposed strategy is more selective,
can reduce the blackout range, and improve the effect of stable frequency recovery. 相似文献
6.
7.
This paper addresses the dynamics of a class of discrete-time switched nonlinear systems with time-varying delays and uncertainties and subject to perturbations. It is assumed that the nominal switched nonlinear system is robustly uniformly exponentially stable. It is revealed that there exists a maximal Lipschitz constant, if perturbation satisfies a Lipschitz condition with any Lipschitz constant less than the maximum, then the perturbed system can preserve the stability property of the nominal system. In situations where the perturbations are known, it is proved that there exists an upper bound of coefficient such that the perturbed system remains exponentially stable provided that the perturbation is scaled by any coefficient bounded by the upper bound. A numerical example is provided to illustrate the proposed theoretical results. 相似文献
8.
YUVAL SHAHAR 《人工智能实验与理论杂志》2013,25(1):123-144
Temporal interpolation is the task of bridging gaps between time-oriented concepts in a context-sensitive manner. It is a subtask important for solving the temporal-abstraction task-abstraction of interval-based, higher-level concepts from time-stamped data. We present a knowledge-based approach to the temporal-interpolation task and discuss in detail the precise knowledge required by that approach, its theoretical foundations, and the implications of the approach. The temporal-interpolation computational mechanism we discuss relies, among other knowledge types, on a temporal-persistence model. The temporal-persistence model employs local temporal-persistence functions that are temporally bidirectional (i.e. extend a belief measure in a predicate both into the future and into the past) and global, maximal-gap temporal-persistence functions that bridge gaps between interval-based predicates. We investigate the quantitative and qualitative properties implied by both types of persistence functions. We have implemented our approach in the RÉSUMÉ program and evaluated it in several different medical and engineering domains. We discuss the implications of our conceptual and computational methodology for acquisition, maintenance, reuse, and sharing of temporal-abstraction knowledge. 相似文献
9.
Power system emergency control is one key defense strategy in contingencies for protecting the system from cascading blackout. Under Frequency Load Shedding (UFLS) is one such strategy to ensure system stability by shedding load to retrieve balance between power supply and demand. Novel UFLS scheme design and a scheme optimization approach are proposed in this paper to find the optimal load-shedding schemes for different network partition resulted from contingencies. To obtain all possible UFLS schemes for a certain area, a candidate scheme set design algorithm based on value assigning of scheme parameters is proposed and then a relatively complete candidate scheme set is constructed. Considering network splitting caused by protection, several subsystems may exist from the reconstruction of independent network areas. The concept of homological area is defined and a graph-based method is used to analyse system topology change. Then, a multi-attribute decision-making (MADM) algorithm is introduced for order preference by similarity to an ideal solution (TOPSIS) for global optimizing candidate schemes. Optimal schemes for an area in both isolated area and homological area cases can be derived from all feasible UFLS schemes by MADM method. Simulation results demonstrate that the UFLS schemes can effectively restore system frequency in different network topologies. 相似文献
10.
《Ergonomics》2012,55(11):1345-1360
In this study we investigate the behaviour and the performance of experimental subjects, who had to solve a series of tasks of ‘strategic thinking’ under a stress and a non-stress condition. No significant differences between the conditions could be found with respect to performance and improvement of performance within the series of tasks, but the experimental subjects exhibited under the different conditions different forms of behaviour. Unexpectedly the Ss working under the stress-condition exhibited a more ‘analytical’ behaviour and increased their workload, instead of decreasing it. Additionally they exhibited a tendency for measures with salient effects and proved to be better in finding the right points of main effort. The results are discussed with respect to a general theory of action regulation. 相似文献