一种基于条件度量迁移学习的机械故障诊断可解释方法

迁移学习技术可以减小源域和目标域特征之间的分布差异。然而,在跨设备场景下,现有研究往往难以衡量并缩小不同设备间数据的条件分布差异,导致模型在源域获得的知识不能很好地迁移到目标域。此外,在实际的故障诊断场景中,决策者通常需要理解模型为何将某些数据归类为特定故障类型。由于深度学习模型的复杂性,其往往被看作是“黑匣子”,难以解释其内部工作机制。为了克服上述缺点,提出一种基于条件度量迁移学习的可解释故障诊断方法。首先利用Hilbert包络谱分析将时域信号转为频域信号;其次搭建深度孪生卷积神经网络和分类器,从频域中提取源域和目标域数据中的高维特征并做分类训练;然后将可解释的条件核Bures度量嵌入到无监督学习的损失函数中,提高条件分布下的特征适配能力和模型可解释性;最后利用博弈论中的SHAP方法对模型诊断结果做基于包络谱的事后可解释分析。在3种设备的6种跨设备轴承故障诊断任务中开展试验,对所提方法和其他相关对比方法进行评估,结果表明提出的方法可以有效地提高跨设备机械故障诊断精度,达到了平均99.47%的诊断精度。并解释了哪些频率点对模型的决策起到关键作用。

n值R_(0)命题逻辑系统中公式的条件随机真度

基于条件概率的思想和赋值集的随机化方法,在n值R_(0)命题系统中提出公式的条件随机真度,证明条件随机真度的MP规则和HS规则。其次,引入公式间的条件随机相似度和条件随机伪距离,建立条件随机逻辑度量空间,进一步给出在条件Γ下的近似推理理论。

Lukasiewicz n值命题逻辑中公式的条件随机真度

基于条件概率的思想,利用赋值集的随机化方法,在Lukasiewicz n值命题逻辑系统中引入公式的条件随机真度,证明了条件随机真度的MP规则和HS规则。引入公式间的条件随机相似度和条件伪距离,建立了条件随机逻辑度量空间,推导出条件伪距离的若干性质,证明了条件随机逻辑度量空间中逻辑运算的连续性,初步研究了给定条件下的近似推理理论。

度量与控制金融风险的新方法

介绍了近年来被发达国家普遍采用的管理和控制金融风险的风险价值度量 (VaR)方法 ,阐述了VaR的概念、方法和功能 ,指出了VaR的缺陷。进一步介绍了近年才发展的具有一致性 (Coherent)的条件风险价值度量 (CVaR)的概念 ,阐述CVaR的优点和作用及在证券组合优化中的应用。

四值非全序逻辑系统中公式的条件随机真度

基于条件概率的思想,利用赋值集的随机化方法,在四值非全序逻辑系统中引入公式的条件随机真度,证明了条件随机真度的MP规则和HS规则.引入公式间的条件随机相似度和条件伪距离,建立了条件随机逻辑度量空间,推导出条件伪距离的若干性质,证明了条件随机逻辑度量空间中逻辑运算的连续性,并初步研究了给定条件下的近似推理理论.

三值乘积逻辑中公式的条件随机真度

基于条件概率的思想,利用赋值集的随机化方法,在三值乘积逻辑系统中引入公式的条件随机真度,证明了条件随机真度的MP规则和HS规则,引入公式间的条件相似度和条件伪距离,建立了条件逻辑度量空间,推导出条件伪距离的若干性质.

应用CoGVaR方法度量系统风险贡献

基于系统风险度量的角度,提出了一类新的条件风险度量——广义条件风险价值(CoGVaR).这类新的风险度量是条件分位数的自然广义化,它包括了经典的CoVaR.相较于经典的条件风险价值(CoVaR)和条件expectile(CoExpectile),它在实际中有着更好的应用价值,这一优势来源于它考虑了决策者的风险态度,而这一点目前为止并没有被其他工作关注过.使用加入状态变量的广义分位数回归方法,在道琼斯美国金融指数实例中给出了具体的计算结果,发现这类风险度量为系统风险贡献的度量提供了一种新的角度.除此之外,这一结果也显示了该风险度量能够通过使用更凸的负效用函数来更好地捕捉尾部风险.

n值逻辑系统中条件随机真度理论

在n值命题逻辑系统中命题的随机真度、随机逻辑度量空间的基础上,给出了修正的n值G¨odel命题逻辑系统中命题的条件真度、条件相似度的概念并讨论了其性质,建立了条件随机逻辑度量空间.

CVaR风险度量下贝叶斯估计的渐近性研究

在金融数学中,风险度量是用来确定一个资产或资产组的储备数量(传统货币)。这个储备的目的是为了金融机构承担可能的风险。本文探讨风险度量应用于贝叶斯估计研究现状的基础上,给出了CVaR风险度量下的贝叶斯估计,并证明了该估计的强相合性和渐近正态性,同时通过数值模拟给实际应用提供了参考值。

对我国期货市场波动性的分阶段实证研究

波动性是经济和金融研究的热点问题。本文首先采用无条件波动度量方法对我国三大期货市场1997年—2004年的波动性进行了估计,发现第一阶段97年—02年期货价格总体呈下跌趋势,三大市场整体波动性不大,较高的波动性都出现在期货价格下跌时期,较低的波动性都出现在期货价格上涨时期;第二阶段03年—04年三大市场波动性显著提高,总体价格呈上升趋势,较高的波动性都出现在期货价格上涨时期,而较低的波动性都出现在期货价格下跌时期;本文进一步采用条件波动模型对我国三大期货市场两个阶段收益率与波动性的相关关系及波动性的杠杆效应进行了研究,结果表明铜期货收益率与波动性显著相关,大豆期货收益率与波动性不显著相关;我国三大期货市场均存在杠杆效应,并且两个阶段波动性的杠杆效应相反,其中铜期货市场的杠杆效应更显著。

我国期货市场波动性的非对称效应实证研究

波动的非对称性一直是金融市场波动性研究的一个重要方面.首先采用无条件波动度量方法对我国三大货市场四个主要品种1997年-2005年的波动性进行了估计,发现三大期货市场波动性呈现明显的阶段性和非对称性特征;然后根据无条件波动估计结果,对总样本进行了阶段性划分,进一步采用条件波动EGARCH模型对期货市场总体和两个不同阶段波动性的非对称效应进行了研究,结果发现小麦期货市场总体具有显著的非对称效应,而大豆、铜、铝期货市场总体不具显著的非对称效应,但分阶段后则呈现显著的非对称效应,并且两个阶段波动的非对称效应相反.

Adsorption mechanism of different coal ranks under variable temperature and pressure conditions

Variable temperature and pressure adsorption tests were conducted on four coal samples with different coal ranks, under simulated temperatures and pressures corresponding to coal reservoirs at different depths. The regularity of the variation in the amounts of adsorption by coals under variable temperature and pressure and 30 ℃ isothermal conditions are compared and the adsorption characteristics of coal under the composite effect of temperature and pressure were obtained. The adsorption test and data processing method of coal under variable temperature and pressure are presented and the effect of the mechanism of temperature and pressure on the adsorption capacity of coal has been studied. The research results are of significant importance in the investigation of coalbed methane storage mechanism and for the prediction of the amounts of coalbed methane at various depths.

The characteristics of rill development and their effects on runoff and sediment yield under different slope gradients

Rill formation is the predominant erosion process in slope land in the Loess Plateau, China. This study was conducted to investigate rill erosion characteristics and their effects on runoff and sediment yielding processes under different slope gradients at a rate of 10°, 15°, 20° and 25° with rainfall intensity of 1.5 mm min-1 in a laboratory setting. Results revealed that mean rill depth and rill density has a positive interrelation to the slope gradient. To the contrary, width-depth ratio and distance of the longest rill to the top of the slope negatively related to slope gradient. All these suggested that increasing slope steepness could enhance rill headward erosion, vertical erosion and the fragmentation of the slope surface. Furthermore,total erosion tended to approach a stable maximum value with increasing slope, which implied that there is probably a threshold slope gradient where soil erosion begins to weaken. At the same time, the correlation analysis showed that there was a close connection between slope gradient and the variousindices of soil erosion: the correlation coefficients of slope gradient with maximal rill depth, number of rills and the distance of the longest rill from the top of the slope were 0.98, 0.97 and-0.98, respectively,indicating that slope gradient is the major factor of affecting the development of rills. Furthermore,runoff was not sensitive to slope gradient and rill formation in this study. Sediment concentration,however, is positively related to slope gradient and rill formation, the sediment concentrations increased rapidly after rill initiation, especially. These results may be essential for soil loss prediction.

On some projectively flat polynomial (α,β)-metrics

In this paper, we consider some polynomial （a,fl）-metrics, and discuss the sufficient and necessary conditions for a Finsler metric in the form F=α＋α1β＋α2β^2/α＋α4β^4/α^3 to be projectively flat, where ai 0=1,2,4） are constants with a1≠0, a is a Riemannian metric and β is a 1-form. By analyzing the geodesic coefficients and the divisibility of certain polynomials, we obtain that there are only five projectively flat cases for metrics of this type. This gives a classification for such kind of Finsler metrics.

Forming regularity and relation between composition and property of B_2O_3-BaO-ZnO glass

B2O3-BaO-ZnO glass was prepared by using conventional melt quenching technology. The forming regularity and the relationship between the composition and the property of B2O3BaOZnO glass were investigated. The results show that the composition range for forming B2O3BaOZnO glass is very wide, but the content of B2O3 has a limit within mole fraction of 25%75%. When the content of B2O3 is over the limit, the melt will be divided into two phases with different compositions and structures, whereas too low content of B2O3 will result in the crystallization of the melt during the cooling process. The thermal expansion coefficient, the transition temperature and the resistivity of the glass at room temperature are （510）×10 -6℃ -1, 480620℃ and （1.53.0）×10 10Ω·m, respectively.

Projectively flat Asanov Finsler metric

In this work, we study the Asanov Finsler metric F=α（β^2/α^2＋gβ/α＋1）^1/2exp{（G/2）arctan[β/（hα）＋G/2]}, where α=（αijy^iy^i）^1/2 is a Riemannian metric and β=by^i is a 1-fom, g∈（-2,2）, h=（1-g^2/4）^1/2, G=g/h. We give the necessary and sufficient condition for Asanov metric to be locally projectively flat, i.e., α is projectively flat and ,Sis parallel with respect to α. Moreover, we proved that the Douglas tensor of Asanov Finsler metric vanishes if and only if β is parallel with respect to α.

The effect of operating conditions on acylation of 2-methylnaphthalene in a microchannel reactor

Acylation of 2-methylnaphthalene(2-MN) is a very important reaction in organic synthesis,and the effiency of the continuous reactor is more than one of the batch reactor.Considering that the Friedel–Crafts acylation is a rapid exothermic reaction,in this study,we perform the acylation of 2-MN in a stainless steel microchannel flow reactor,which is characterized by high mass and heat transfer rates.The effect of reactant ratio,mixing temperature,reaction temperature,and reaction time on product yield and selectivity were investigated.Under the optimal conditions,2-methyl-6-propionylnaphthalene(2,6-MPN) was obtained in 85.8% yield with 87.5% selectivity.Compared with the conventional batch system,the continuous flow microchannel reactor provides a more efficient method for the synthesis of 2,6-MPN.

Effect of loading rates on the characteristics of thermal damage for mudstone under different temperatures

The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temperature furnace MTS652.02.The mechanical properties of mudstone with various loading rates are studied under different temperature conditions.The results show that when temperature increases from room temperature to 400℃ and loading rate is less than 0.03 mm/s,the peak strength of mudstone specimen decreases as loading rate increases,while the various peak strengths show significant differences when loading rate exceeds 0.03 mm/s.At room temperature,the elastic modulus decreases at the first time and then increases with loading rate rising.When the temperature is between200 and 400℃,the elastic modulus presents a decreasing trend with increasing loading rate.With increasing the loading rate,the number of fragments in mudstone becomes larger and even the powder is observed in mudstone with higher loading rate.Under high loading rate,the failure mode of mudstone specimens under different temperatures is mainly conical damage.

Novel technology on preparation of double-layered pellets for sulfur and arsenic-bearing gold concentrates

Double-layered pellet （DLP） roasting is a novel pretreatment method for sulfur and arsenic-bearing gold concentrates. In this process, preparation of DLPs is a fundamental step which is required to produce DLPs with favorable mechanical strength and thermal stability. Studies were carried out to investigate the affecting factors and conditions on the preparation and properties of DLPs. The results show that moisture content has significant influence on DLPs preparation. With the increase of moisture content in the range of no more than 9.8%, drop resistance and compressive strength of green DLPs are raised and the pelletizing dynamics is improved accordingly. The optimum conditions are determined as moisture content of 9.8%, coating time of 14-16 min, drying temperature 〈80 ℃and drying gas velocity 〈1.2 m/s. When DLPs prepared under these conditions are roasted at 600 ℃ for 1 h, favorable removal and solidifying rates can be obtained, in which the removal rates of arsenic and sulfur are 94.38% and 82.55%, and the solidifying rates of arsenic and sulfur reach 99.62% and 99.79%, respectively. These results promise industrial application of DLP roasting.

Slant Submanifolds of an Almost Hyperbolic Contact Metric Manifolds

In the present paper, we introduce the notion of slant submanifolds of an almost hyperbolic contact metric manifolds. We have obtained some results on slant submanifolds of an almost hyperbolic contact metric manifolds. We have given a necessary and sufficient condition for a slant submanifold of an almost hyperbolic contact metric manifolds.