Ln命题演算中的一种新程度化方法

将Lukasiewiczn值逻辑系统Ln中的矛盾式概念程度化,引入了矛盾度的概念,并且讨论了公式的矛盾度的若干重要性质,进而用矛盾度定义了公式之间的差异度函数ρ',证明了ρ'是一个伪度量,从而在F(S)上建立了逻辑度量空间(F(S),ρ').     

Climate trade-off between black carbon and carbon dioxide emissions

There are various difficulties involved with comparing the effects of short-lived and long-lived atmospheric species on climate. Global warming potentials (GWPs) can be computed for pulse emissions of short-lived species. However, if the focus is on the long-term effect of a pulse emission occurring today, GWPs do not factor in the fact that if a radiative forcing is applied for a short period, the climate system has time to relax back to equilibrium. The concept of global temperature change potential (GTP) at a time horizon for an emission pulse has been proposed to circumvent this problem. Here we show how GTPs can be used to compare black carbon (BC) and CO₂ emissions and the methodology is illustrated with two concrete examples. In particular we discuss a trade-off situation where a decrease in BC emissions is associated with a fuel penalty and therefore an additional CO₂ emission. A parameter—which depends on the BC radiative effects, the BC emission reduction and the additional CO₂ emission—is defined and can be compared to a critical parameter to assess whether or not the BC emission reduction wins over the fuel penalty for various time horizons. We show how this concept can be generalised to compare the climate effects of carbon dioxide against a set of short-lived species and to account for differences in climate efficacy. Finally, the need for additional research is discussed in the light of current uncertainties.     

A Histogram Matching Approach for assessment of flow regime alteration: application to environmental flow optimization

In this paper we present a Histogram Matching Approach (HMA) for assessment of the flow regime alteration. The HMA uses the degree of histogram dissimilarity as a metric for impact assessment, which is based on the quadratic‐form distance between the frequency vectors of the pre‐ and post‐impact histograms weighted by a specified similarity matrix. The HMA is coupled with an aggregated multiobjective optimization genetic algorithm and applied to a case study on the Kaoping diversion weir (Taiwan) for determining the optimal environmental flow scheme that balances the ecosystem and human needs objectives. Two key issues are addressed in this study. First, we compare the performances of the HMA and existing Range of Variability Approach (RVA). Second, we employ three types of similarity function to investigate their effect on the outcomes of the HMA. The results reveal that the HMA consistently outperforms the RVA in preserving the natural flow variability regardless of what type of similarity function is used. No single type of similarity function can be found that would simultaneously best preserve the natural patterns of 32 Indicators of Hydrologic Alteration (IHA). For the situations where the water‐supply reliability is of critical concern, the pulse similarity is recommended because it would assure the smallest water‐supply deficit. If, however, minor degradation in the water‐supply reliability may be overlooked, the linear similarity is suggested because it would generally result in the post‐impact flows that most satisfactorily resemble to the natural flow regime. Copyright © 2008 John Wiley & Sons, Ltd.     

Tuning Parameter Tolerance Design: Foundations, Methods, and Measures

In this paper, a novel technique is presented to solve tolerance design problems. To achieve the desired performance tolerance, the technique uses a subtle, but significant, change in the design: the addition of a tuning parameter in place of an increase in component precision. Statistical models are used to develop a framework for the tuning parameter design method. Also developed is a new, dimensionless design metric which ranks candidate tuning parameters. A step-by-step method is developed for the application of tuning parameters using this metric. The step-by-step tuning parameter design method is applied to a heavy-duty manual stapler as a clarifying example.     

广义Bayes法在裂隙岩体渗透系数随机反演中的应用

工程中由于存在各种随机因素,采用确定性的渗流分析方法进行渗透系数的反演必然会导致结果的不确定性.本文基于渗流场的随机有限元分析方法,结合变尺度优化算法和广义Bayes法,建立了一种渗透系数的随机反演方法,推导了详细的计算公式.该方法不仅考虑量测水头、渗透系数的随机性,还考虑了边界水头的随机性,不仅可以获得渗透系数的均值反演结果,还可以得到标准差的反演结果.最后将该法应用于重力坝坝基渗流算例分析中,以渗流有限元正分析计算结果作为"假想"的实测点水头值,通过随机反演,同时获得渗透系数均值与标准差的反演结果,将输入信息与反演结果对比分析,验证了渗透系数和标准差反演结果的正确性.     

凸度量空间内广义渐近拟非扩张映射不动点的迭代

在凸度量空间中，引入一类比渐近拟非扩张映射更加广泛的广义渐近拟非扩张型映射，并在完备凸度量空间给出修改的Ishikawa迭代序列收敛于广义渐近拟非扩张型映射不动点的充要条件。     

用软件实现回溯方式的维特比译码

本文在分析维特比译码原理的基础上，提出了用软件编程实现回溯方式的维特比译码的设计和处理技巧。     

Stochastic back analysis of permeability coefficient using generalized Bayesian method

Owing to the fact that the conventional deterministic back analysis of the permeability coefficient cannot reflect the uncertainties of parameters, including the hydraulic head at the boundary, the permeability coefficient and measured hydraulic head, a stochastic back analysis taking consideration of uncertainties of parameters was performed using the generalized Bayesian method. Based on the stochastic finite element method （SFEM） for a seepage field, the variable metric algorithm and the generalized Bayesian method, formulas for stochastic back analysis of the permeability coefficient were derived. A case study of seepage analysis of a sluice foundation was performed to illustrate the proposed method. The results indicate that, with the generalized Bayesian method that considers the uncertainties of measured hydraulic head, the permeability coefficient and the hydraulic head at the boundary, both the mean and standard deviation of the permeability coefficient can be obtained and the standard deviation is less than that obtained by the conventional Bayesian method. Therefore, the present method is valid and applicable.     

最大对齐度算法在多模态图像配准中正负像无关性分析

基于对齐度的配准是一种重要的多模态图像配准方法,其中的图像预处理是关键.在对红外热像仪图像和可见光图像进行配准的过程中,首先进行图像预处理,其中一个环节是将红外热像仪图像取负像,这样可使之与相应的可见光灰度图像比较相近.实验结果表明,对齐度配准算法与正负像无关,即可见光图像与相应的红外热像仪图像正像和负像的对齐度配准结...     

海洋工程用电缆标准IEEE1580导体概述

依据美国海洋工程用电缆标准IEEE 1580对导体规定的描述,介绍了美标电缆导体的AWG线规知识、AWG线规与公制的转换、导体结构以及相关的技术参数等,以期对电缆的制造者及使用者提供参考.