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F L Black 《Human biology; an international record of research》1991,63(6):763-774
Previous attempts to classify South American Indian tribes according to genetic characteristics have failed to yield a hierarchical system of relationships. This can be explained by the facts that (1) tribal populations did not evolve through sequential fissions but through frequent fusions of groups with diverse histories and (2) allele frequencies have been held at nearly common values by intertribal migration or balancing selection. A valid model must allow for fusion and mixed populations as well as for fission; factor analysis or newer methods of fuzzy mathematics permit this. The effects of migration and balancing can be made more manageable by partitioning them according to the limited time periods recorded by haplotypes. An initial attempt using factor analysis and HLA haplotype data on 19 rain forest tribes revealed two overlapping clusters that are largely but not neatly separated by the lower Amazon River. Several tribes, especially in the west, were excluded from these clusters. 相似文献
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笔者在研究新疆准噶尔盆地西北缘百38井克拉玛依组粉组合时,运用模糊数学的方法进行了孢粉分带,本文介绍了进行孢粉分带所选用的数学公式,用BASIC语言所编制的计算程序以及使用方法。 相似文献
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David W. Roberts 《Plant Ecology》1989,83(1-2):71-80
Fuzzy systems vegetation theory is a comprehensive framework for the expression of vegetation theory and conceptual models, as well as the development of vegetation analyses. It is applicable to vegetation/environment relations, vegetation dynamics, and the effects of environmental dynamics on vegetation composition. Fuzzy systems vegetation theory is a fuzzy set generalization of dynamical systems theory and incorporates a formal logic and mathematics. This paper presents the elements of fuzzy systems vegetation theory and discusses the relationship of the fuzzy systems theory to the geometric concepts generally employed in vegetation theory. 相似文献
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T Yamakawa 《Journal of biotechnology》1992,24(1):1-32
This paper describes a fuzzy sets method which is very useful for handling uncertainties and essential for knowledge acquisition of a human expert. Kinetics of a reactor is often complex and not trivial to describe by mathematical equations. Reactor control by traditional control technology is therefore difficult. A novel technology is presented. In the following a fuzzy inference (approximate reasoning) is used for decision making in analogy to human thinking, facilitating a more sophisticated control. Readers of this paper do not need any advanced mathematics beyond the four basic operations in arithmetic (+, -, x, divided by) and using the maximum and minimum values. This fuzzy inference is introduced to construct a fuzzy logic controller which is suitable for a nonlinear, multivariable and time variant system applied to a bioreactor. 相似文献
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Raymond R. Tan 《The International Journal of Life Cycle Assessment》2008,13(7):585-592
Background, aim, and scope Analysis of uncertainties plays a vital role in the interpretation of life cycle assessment findings. Some of these uncertainties
arise from parametric data variability in life cycle inventory analysis. For instance, the efficiencies of manufacturing processes
may vary among different industrial sites or geographic regions; or, in the case of new and unproven technologies, it is possible
that prospective performance levels can only be estimated. Although such data variability is usually treated using a probabilistic
framework, some recent work on the use of fuzzy sets or possibility theory has appeared in the literature. The latter school
of thought is based on the notion that not all data variability can be properly described in terms of frequency of occurrence.
In many cases, it is necessary to model the uncertainty associated with the subjective degree of plausibility of parameter
values. Fuzzy set theory is appropriate for such uncertainties. However, the computations required for handling fuzzy quantities
has not been fully integrated with the formal matrix-based life cycle inventory analysis (LCI) described by Heijungs and Suh
(2002).
Materials and methods This paper integrates computations with fuzzy numbers into the matrix-based LCI computational model described in the literature.
The approach uses fuzzy numbers to propagate the data variability in LCI calculations, and results in fuzzy distributions
of the inventory results. The approach is developed based on similarities with the fuzzy economic input–output (EIO) model
proposed by Buckley (Eur J Oper Res 39:54–60, 1989).
Results The matrix-based fuzzy LCI model is illustrated using three simple case studies. The first case shows how fuzzy inventory
results arise in simple systems with variability in industrial efficiency and emissions data. The second case study illustrates
how the model applies for life cycle systems with co-products, and thus requires the inclusion of displaced processes. The
third case study demonstrates the use of the method in the context of comparing different carbon sequestration technologies.
Discussion These simple case studies illustrate the important features of the model, including possible computational issues that can
arise with larger and more complex life cycle systems.
Conclusions A fuzzy matrix-based LCI model has been proposed. The model extends the conventional matrix-based LCI model to allow for computations
with parametric data variability represented as fuzzy numbers. This approach is an alternative or complementary approach to
interval analysis, probabilistic or Monte Carlo techniques.
Recommendations and perspectives Potential further work in this area includes extension of the fuzzy model to EIO-LCA models and to life cycle impact assessment
(LCIA); development of hybrid fuzzy-probabilistic approaches; and integration with life cycle-based optimization or decision
analysis. Additional theoretical work is needed for modeling correlations of the variability of parameters using interacting
or correlated fuzzy numbers, which remains an unresolved computational issue. Furthermore, integration of the fuzzy model
into LCA software can also be investigated. 相似文献
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一种天敌控制多种害虫作用的模糊数学评价方法 总被引:3,自引:1,他引:2
从生物防治的基本思想出发,利用模糊数学和生态经济的原理,探讨天敌的作用,建立了一种天敌控制多种害虫的模糊数学评判方法,文中给出了一种天敌对害虫的影响率和影响强度、一种天敌对害虫影响的大小以及天敌对害虫的控制能力,并进行了控制分析。 相似文献
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Stochastic Petri nets (SPNs) have been widely used to model randomness which is an inherent feature of biological systems. However, for many biological systems, some kinetic parameters may be uncertain due to incomplete, vague or missing kinetic data (often called fuzzy uncertainty), or naturally vary, e.g., between different individuals, experimental conditions, etc. (often called variability), which has prevented a wider application of SPNs that require accurate parameters. Considering the strength of fuzzy sets to deal with uncertain information, we apply a specific type of stochastic Petri nets, fuzzy stochastic Petri nets (FSPNs), to model and analyze biological systems with uncertain kinetic parameters. FSPNs combine SPNs and fuzzy sets, thereby taking into account both randomness and fuzziness of biological systems. For a biological system, SPNs model the randomness, while fuzzy sets model kinetic parameters with fuzzy uncertainty or variability by associating each parameter with a fuzzy number instead of a crisp real value. We introduce a simulation-based analysis method for FSPNs to explore the uncertainties of outputs resulting from the uncertainties associated with input parameters, which works equally well for bounded and unbounded models. We illustrate our approach using a yeast polarization model having an infinite state space, which shows the appropriateness of FSPNs in combination with simulation-based analysis for modeling and analyzing biological systems with uncertain information. 相似文献
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应用模糊数学对 7个平菇品种进行模糊判决 ,结果表明 :在权重偏重于生物学效率的凸模糊判决中平菇 17- 2为首选。而在权重相等的模糊判决中平菇 99号为首选。对平菇 99号进行综合评判的结果为某类菇农对该品种很喜欢。 相似文献
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The hydrophobic core, when subjected to analysis based on the fuzzy oil drop model, appears to be a universal structural component of proteins irrespective of their secondary, supersecondary, and tertiary conformations. A study has been performed on a set of nonhomologous proteins representing a variety of CATH categories. The presence of a well-ordered hydrophobic core has been confirmed in each case, regardless of the protein’s biological function, chain length or source organism. In light of fuzzy oil drop (FOD) analysis, various supersecondary forms seem to share a common structural factor in the form of a hydrophobic core, emerging either as part of the whole protein or a specific domain. The variable status of individual folds with respect to the FOD model reflects their propensity for conformational changes, frequently associated with biological function. Such flexibility is expressed as variable stability of the hydrophobic core, along with specific encoding of potential conformational changes which depend on the properties of helices and β-folds. 相似文献
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This paper describes an initial but fundamental attempt to lay some groundwork for a fuzzy-set-based paradigm for sensory analysis and to demonstrate how fuzzy set and neural network techniques may lead to a natural way for sensory data interpretation. Sensory scales are described as fuzzy sets, sensory attributes as fuzzy variables, and sensory responses as sample membership grades. Multi-judge responses are formulated as a fuzzy membership vector or fuzzy histogram of response, which gives an overall panel response free of the unverifiable assumptions implied in conventional approaches. Neural networks are used to provide an effective tool for modeling and analysis of sensory responses in their naturally fuzzy and complex forms. A maximum method of defuzzification is proposed to give a crisp grade of the majority opinion. Two applications in meat quality evaluation are used to demonstrate the use of the paradigm and procedure. It is hoped that this work will bring up some new ideas and generate interest in research on application of fuzzy sets and neural networks in sensory analysis. 相似文献
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This paper proposed a max–min-entropy-based fuzzy partition method for fuzzy model based estimation of human operator functional state (OFS). The optimal number of fuzzy partitions for each I/O variable of fuzzy model is determined by using the entropy criterion. The fuzzy models were constructed by using Wang–Mendel method. The OFS estimation results showed the practical usefulness of the proposed fuzzy modeling approach. 相似文献
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正确评估海涂湿地生态服务价值有助于加强人们保护海涂湿地的意识,为海涂湿地围垦生态补偿标准的制定提供依据。视价格"便宜"、"适中"和"昂贵"为模糊集,基于CVM法区间型数据建立了传统模糊统计模型、赋权模糊统计模型和三相划分模型,并以此评价了杭州湾国家湿地公园单位面积年生态系统服务价值。结果显示:3种方法得到的单价分别为10.28、10.38、9.76元m~(-2)a~(-1),三者一致程度较高,与国内沿海湿地价值比较接近。分析了"生态价值"概念客观上的"模糊性"引致模糊数学模型的合理性;采用"橄榄球"式赋权建立赋权模糊统计模型以克服传统模糊统计模型中对区间数据均匀赋权的不合理性,结果在隶属度函数的光滑性和拟合度上好于后者;第三,三相划分模型拟合出3个模糊集的隶属度函数,可以比较相同价格在不同模糊集中隶属度差异。建立的模型对于基于CVM法的生态资源价值评估具有借鉴意义。 相似文献
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Nonlinear modeling and adaptive monitoring with fuzzy and multivariate statistical methods in biological wastewater treatment plants 总被引:9,自引:0,他引:9
A new approach to nonlinear modeling and adaptive monitoring using fuzzy principal component regression (FPCR) is proposed and then applied to a real wastewater treatment plant (WWTP) data set. First, principal component analysis (PCA) is used to reduce the dimensionality of data and to remove collinearity. Second, the adaptive credibilistic fuzzy-c-means method is used to appropriately monitor diverse operating conditions based on the PCA score values. Then a new adaptive discrimination monitoring method is proposed to distinguish between a large process change and a simple fault. Third, a FPCR method is proposed, where the Takagi-Sugeno-Kang (TSK) fuzzy model is employed to model the relation between the PCA score values and the target output to avoid the over-fitting problem with original variables. Here, the rule bases, the centers and the widths of TSK fuzzy model are found by heuristic methods. The proposed FPCR method is applied to predict the output variable, the reduction of chemical oxygen demand in the full-scale WWTP. The result shows that it has the ability to model the nonlinear process and multiple operating conditions and is able to identify various operating regions and discriminate between a sustained fault and a simple fault (or abnormalities) occurring within the process data. 相似文献
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A quantitative biomechanical model describes the tissue transformation during healing of a transverse osteotomy of a sheep metatarsal. The model predicts bridging of the bone ends through cartilage, followed by the growth of a callus cuff, and finally, the resorption of callus after ossification of the interfragmentary gap. We suggest bone density or the modulus of elasticity do not sufficiently characterize healing tissue for predictive purposes. In addition to the stimulus reflected by strain energy density we introduce a new osteogenic factor based upon stress gradients and which predicts areas of a high osteogenic capacity. Our model distinguishes three basic types of tissue, namely bone, cartilage and fibrous tissue. A fuzzy controller is proposed to model the tissue reaction. A set of fuzzy rules derived from medical knowledge has been implemented to describe tissue transformation such as intramembraneous or chondral ossification, atrophy or destruction. Fuzzy logic is able to model tissue transformation processes within the numerical simulation of remodeling processes. This approach improves the simulation tools and affords the potential to optimize planning of animal experiments and conduct parametric studies. 相似文献