数模联合驱动的动态对抗自适应轴承故障诊断方法

针对现实工业场景下,故障数据样本稀缺,服役工况复杂导致的滚动轴承诊断准确率低下的问题,提出了一种数模联合驱动的动态对抗自适应轴承故障诊断方法。首先,提出用于快速产生具有明确时频域轴承故障特征的四自由度动力学仿真模型。随后,探讨了实测数据分布与动力学仿真信号之间的共性和差异性。最后,建立可以提取隐层域不变特征并自动对齐仿真源域数据、目标域待诊断数据分布的动态对抗自适应网络。设计滚动轴承故障诊断试验,探讨了由动力学模型产生带有标签信息的仿真信号、带标签信息的其他数据集实测信号与极少数带标签信息的待诊断实测信号构成的源域数据基础上,设定的3类任务中神经网络的诊断效果,完成了对大量无标签样本的分类识别。结果表明,仿真信号包含轴承故障的特征信息,可以对真实的轴承数据进行表征,并且所提出的动态对抗自适应网络相较于其他诊断方法能更准确实现轴承的故障诊断。同时,源域数据中包含极少数的带标签目标域数据可使得提出方法的识别准确率大幅提升。

美国国家半导体与浙江大学合作创办的模拟与数模混合集成电路联合实验室正式启用

美国国家半导体公司(National Semiconductor Corporation)(美国纽约证券交易所上市代号：NSM)一直非常重视中国市场。公司与浙江大学合作建立的模拟与数模混合集成电路联合实验室已经正式启用。据美国国家半导体表示，这是该公司与中国大学携手设立的首间模拟与数模混合集成电路实验室。

CDIO模式下综合实验平台的校内实习实训课程探讨

随着教学方式的不断改进、高校学生的不断增多,传统的校外实习和实训的短板愈加明显。为了改善这个问题,课题组从创新理念、优化方案及创新教学三个层面进行研究,分析了基于CDIO教育模式的校内实训机制、基于实习实训平台的自主实训设计、遵从电力安全规范的独立自主实训实操以及基于C-PMBOK项目管理模式的实训过程管理体系等,旨在建设动模—数模联合仿真的电气工程专业校内实习实训平台,为提高学生的动手能力以及提升实习课程质量提供新思路。

基于DAC1220与ADS1255的低漂移精密DAC设计

本文介绍了一种基于DAC1220与ADS1255的低漂移精密DAC设计。该设计以TI公司的20位∑-△型数模转换芯片DAC1220和24位∑-△型模数转换芯片ADS1255为核心,以基于ARM Cortex-M3内核的STM32系列处理器为控制器,通过高精度DAC和更高精度ADC芯片的联合转换及程序处理方式实现了20位精度的低漂移精密DAC设计。

Fuzzy Synthetic Evaluation of Water Quality of Naoli River Using Parameter Correlation Analysis

In order to improve the effectiveness of Fuzzy Synthetic Evaluation (FSE) models, a Parameter Correlation Analysis (PCA) was introduced into the FSE and a case study was carried out in the Naoli River in the Sanjiang Plain, Northeast China. The basic principle of the PCA is that the pairs of parameters which are highly correlated and linear with each other would contribute the same information to an assessment and one of them should be eliminated. The method of the PCA is that a correlation relationship among candidate parameters is examined before the FSE. If there is an apparent nonlinear or curvilinear relationship between two parameters, then both will be retained; if the correlation is significant (p<0.01), and the scatter plot suggests a linear relationship, then one of them will be deleted. However, which one will be deleted? For solving this problem, a sensitivity test was conducted and the higher sensitivity parameters remained. The results indicate that the original data should be preprocessed through the PCA for redundancy and variability. The study shows that introducing the PCA into the FSE can simplify the FSE calculation process greatly, while the results have not been changed much.

Numerical simulation of aluminum holding furnace with fluid-solid coupled heat transfer

To predict three-dimensional temperature distribution of molten aluminum and its influencing factors inside an industrial aluminum holding furnace,a fluid-solid coupled method was presented.The fluid-solid coupled mathematics models of aluminum holding furnace in the premixed combustion processing were established based on mass conservation,moment conservation,momentum conservation,energy conservation and chemistry species conservation.Computational results agree well with the test data of the typical condition.The maximum combustion temperature is 1 850 K.The average temperature of the molten aluminum is 1 158 K,and the maximum temperature difference is about 240 K.The average temperature increases 0.3 ℃ while the temperature of combustion air increases 1 ℃.The optimal excess air ratio is 1.25-1.30.

Combined Effect of Nutrient and Pest Managements on Substrate Utilization Pattern of Soil Microbial Population in Hybrid Rice Cropping System

A field experiment was conducted to study the combined effect of nutrient andpest managements on soil biomass phospholipid contents, functional biodiversity and substrateutilization patterns of soil microbial populations in hybrid rice cropping system. The mineral N, Pand K fertilizers (as urea, calcium superphosphate and KCl respectively) were incorporated at 100,25, and 100 kg ha^(-1), respectively, and the various pesticides were applied at the recommendedrates. The results of the experiment demonstrated a decline in the microbial abundance and soilmicrobial biomass phospholipid contents with the advancement of crop growth, and significant changesin substrate utilization pattern of soil microbial population studied were observed with differentmanagement practices and at different growth stages. The principal component analysis (PCA) usingall 95-carbon sources (BIOLOG plates) gave good differentiation among the treatments, indicatingthat they have different patterns of carbon utilization under different habitats. The data showedthat diversity in microbial community continuously changed with the progression in crop stage,particularly at physiological maturity (PM) stage that was evident from the utilization of differentcarbon sources at various crop stages.

Vector refinement equation and subdivision schemes in Lp spaces

In this paper we will first prove that the nontrivial L p solutions of the vector refinement equation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p without assumption of the stability of the solutions. Then we obtain a characterization of the convergence of the subdivision scheme in terms of the mask. This gives a complete answer to the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes.

A Local Ensemble Transform Kalman Filter Data Assimilation System for the Global FSU Atmospheric Model

Data assimilation is the process by which measurements and model predictions are combined to obtain an accurate representation of the state of the modeled system. We implemented a data assimilation scheme called LETKF （local ensemble transform Kalman filter） with FSUGSM （Florida State University Global Spectral Model） and made an experiment to evaluate the initial condition generated to numerical weather prediction to FSUGSM model. The LETKF analysis carries out independently at each grid point with the use of ＂local＂ observations. An ensemble of estimates in state space represents uncertainty. The FSUGSM is a multilevel （27 vertical levels） spectral primitive equation model, where the variables are expanded horizontally in a truncated series of spherical harmonic functions （at resolution T63） and a transform technique is applied to calculate the physical processes in real space The assimilation cycle runs on the period 01/01/2001 to 31/01/2001 at （00, 06, 12 and 18 GMT） for each day. We examined the atmospheric fields during the period and the OMF （observation-minus-forecast） and the OMA （observation-minus-analysis） statistics to verify the analysis quality comparing with forecasts and observations. The analyses present stability and show suitable to initiate the weather predictions.

Evaluation and Driving Force Analysis of Marine Sustainable Development based on the Grey Relational Model and Path Analysis

With the rapid development of the marine economy,the demand for marine resources development and the pressure on marine environmental protection are gradually increasing.It is critical to evaluate and analyze the driving forces of marine sustainable development in order to promote the coordinated development of the marine economy,resources and environment.Taking Jiangsu Province of China as an example,this paper constructs an evaluation index system for marine sustainable development from the three aspects of marine economy,resources and environment,and calculates the weight of the variation coefficient for each indicator.Based on the grey relational model,the average value of the relational degree,calculated by the average value method of correlation coefficients and the weighting method,is then used to evaluate the status of marine sustainable development in this province.The comprehensive index model is used to analyze the dynamic trend of the evolution of marine sustainable development.The driving forces of marine sustainable development are analyzed by the path analysis method combined with the average values of the grey relational degree for each indicator.This analysis found that the marine sustainable development in 2016 and 2012 was good,the situation in 2007 was bad,and the remaining years were intermediate.Compared with the previous years,the optimal conditions of 2008 and 2012 were obvious.The main driving factors of marine sustainable development are cargo throughput of coastal ports,economic losses caused by storm surges in coastal areas,the area of marine nature reserves in coastal areas,coastal wind power generation capacity,and marine biodiversity.

Coupled 3D discrete-continuum numerical modeling of pile penetration in sand

A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand.A self-developed non-circular particle numerical simulation program was used which considered sand near the pile as interacted particles using a discrete element method;the sand away from the pile was simulated as a continuous medium exhibiting linear elastic behaviors.The domain analyzed was divided into two zones.Contact forces at the interface between the two zones were obtained from a discrete zone and applied to the continuum boundaries as nodal forces,while the interface velocities were obtained from the continuum zone and applied to the discrete boundaries.We show that the coupled discrete-continuum simulation can give a microscopic description of the pile penetration process without losing the discrete nature of the zone concerned,and may significantly improve computational efficiency.

Coupling mechanism of mathematical models for sediment transport based on characteristic theory

This paper aims to explore the coupling mechanism between flow movement, sediment transport and riverbed evolution in currently widely used mathematical models for sediment transport. Based on characteristic theory, analytic forms of eigenvalues,eigenvectors and characteristic relationships of total-sediment transport model, bed-load transport model and suspenedload transport model were derived, respectively. The singular perturbation technology was implemented to obtain the asymptotic solutions to different families of eigenvalues. The results indicate that, interactions between motion variables were explicitly coupled in the characteristics of total-sediment transport model and bed-load transport model. Further qualitative and quantitative analysis demonstrates that high sediment transport intensity and significant riverbed change will inevitably affect the property of flow movement. In the process of deposition, sediment-laden flow will move faster when sediment transport intensity becomes stronger. In contrast, the wave of flow will propagate at slower speed as erosion intensity becomes stronger.For most existing suspended-load transport models, however, the characteristics are decoupled as the interactions between motion variables cannot be integrally illustrated in eigenvalues, eigenvectors and characteristic relationship.

The nonparametric estimation of long memory spatio-temporal random field models

This paper considers the local linear estimation of a multivariate regression function and its derivatives for a stationary long memory(long range dependent) nonparametric spatio-temporal regression model.Under some mild regularity assumptions, the pointwise strong convergence, the uniform weak consistency with convergence rates and the joint asymptotic distribution of the estimators are established. A simulation study is carried out to illustrate the performance of the proposed estimators.

Time-varying latent model for longitudinal data with informative observation and terminal event times

Longitudinal data often occur in follow-up studies, and in many situations, there may exist informative observation times and a dependent terminal event such as death that stops the follow-up. We propose a semiparametric mixed effect model with time-varying latent effects in the analysis of longitudinal data with informative observation times and a dependent terminal event. Estimating equation approaches are developed for parameter estimation, and asymptotic properties of the resulting estimators are established. The finite sample behavior of the proposed estimators is evaluated through simulation studies, and an application to a bladder cancer study is provided.