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81.
The continuous time Bayesian network (CTBN) enables reasoning about complex systems by representing the system as a factored, finite-state, continuous-time Markov process. Inference over the model incorporates evidence, given as state observations through time. The time dimension introduces several new types of evidence that are not found with static models. In this work, we present a comprehensive look at the types of evidence in CTBNs. Moreover, we define and extend inference to reason under uncertainty in the presence of uncertain evidence, as well as negative evidence, concepts extended to static models but not yet introduced into the CTBN model. 相似文献
82.
Variable elimination (VE) and join tree propagation (JTP) are two alternatives to inference in Bayesian networks (BNs). VE, which can be viewed as one-way propagation in a join tree, answers each query against the BN meaning that computation can be repeated. On the other hand, answering a single query with JTP involves two-way propagation, of which some computation may remain unused. In this paper, we propose marginal tree inference (MTI) as a new approach to exact inference in discrete BNs. MTI seeks to avoid recomputation, while at the same time ensuring that no constructed probability information remains unused. Thereby, MTI stakes out middle ground between VE and JTP. The usefulness of MTI is demonstrated in multiple probabilistic reasoning sessions. 相似文献
83.
针对NPC三电平逆变器故障诊断问题,提出一种基于极限学习机与规则推理的二级故障诊断方法。分析了依据输出电流诊断故障的可区分性,以及故障模式的分类。然后对输出电流提取故障特征,并采用极限学习机完成故障初级分类。对于初级分类结果为电流不可区分故障情况,再根据桥臂电压信息运用规则推理法实现故障二级精确诊断。诊断实验表明,该方法能够实现NPC三电平的多模式故障诊断,且故障诊断方法简单、定位精确、快速、鲁棒性强。 相似文献
84.
85.
The fine-tuning of the enzymatic hydrolysis of proteins may provide a pool of peptides with predefined molar mass distributions. However, the complex mixture of molecules (peptides and amino acids) that results after the proteolysis of cheese whey turns unfeasible the assessment of individual species. In this work, a hybrid kinetic model for the proteolysis of whey by alcalase, multipoint-immobilized on agarose, is presented, which takes into account the influence of pH (8.0-10.4) and temperature (40-55 degrees C) on the activity of the enzyme. Five ranges of peptides' molar mass have their reaction rates predicted by neural networks (NNs). The output of NNs trained for constant pH and temperatures was interpolated, instead of including these variables in the input vector of a larger NN. Thus, the model complexity was reduced. Coupled to differential mass balances, this hybrid model can be employed for the online inference of peptides' molar mass distributions. Experimental kinetic assays were carried out using a pH-stat, in a laboratory-scale (0.03 L) batch reactor. The neural-kinetic model was integrated to a supervisory system of a bench-scale continually stirred tank reactor (0.5 L), providing accurate predictions during validation tests. 相似文献
86.
87.
A. Guilloux 《Mathematical Methods of Statistics》2007,16(3):202-216
In a population of individuals, where the random variable (r.v.) σ denotes the birth time and X the lifetime, we consider the case, where an individual can be observed only if its life-line
(σ, X) = {(σ + y, y), 0 ≤ y ≤ X} intersects a given Borel set S in ℝ × ℝ+. Denoting by σ
S and X
S the birth time and lifetime for the observed individuals, we point out that the distribution function (d.f.) F
S of the r.v. X
S suffers from a selection bias in the sense that F
S = ∝ w d F/μ
S, where w and μ
S depend only on the distribution of σ and on F, the d.f. of X. Assuming in addition that the r.v. X
S is randomly right-censored as soon as the individual is selected, we construct a productlimit estimator
for the d.f. F
S and a nonparametric estimator ŵ for the weight function w. We prove a consistency result for ŵ and a weak convergence result for
. We establish in addition an exponential bound for
.
相似文献
88.
This paper is concerned with the rate of convergence of the distribution of the maximum likelihood estimators of the arrival
and the service rates in a GI/G/1 queueing system.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
89.
A new optoelectronic fuzzy inference system is proposed for processing a large number of fuzzy rules in parallel. The proposed system using spatial light modulator implements various membership functions as well as max–min inference. It has the features of easy implementation and large data processing capability. The membership function decomposition method is used to save space bandwidth and accommodate multiple-input fuzzy inference. 相似文献
90.
研究高中生如何解元素推断题能加深对化学问题解决的认识。用整群随机抽样法,以海南省某中学高二和高三年级各一个班的学生为被试,以改编的高考元素推断题为工具,用NVivo分析学生解题的书面报告,发现元素的解法和顺序有多种类型。这种多样性由不同的问题表征方式和解决策略引起。对课程与教学的启示:采用科学表征,并促进学生科学表征建构;重视问题解决的算法,矫正启发法造成的偏差。 相似文献