多尺度模糊熵及其在滚动轴承故障诊断中的应用

提出了一种新的时间序列复杂性度量的方法——多尺度模糊熵(multiscale fuzzy entropy,简称MFE)。多尺度模糊熵是基于模糊熵而定义的。模糊熵作为样本熵的改进,是对时间序列复杂性和无规则程度的度量,而多尺度模糊熵则在模糊熵的基础上引入了尺度因子,是对时间序列在不同尺度因子下复杂性的量度。与样本熵、模糊熵和分形维数等其他表征复杂性的非线性动力学方法相比,多尺度模糊熵包含更多时间模式信息。论文首先介绍了模糊熵和多尺度模糊熵的概念,并将其应用于滚动轴承振动信号复杂性的量度,由此提出了一种基于多尺度模糊熵和支持向量机的滚动轴承故障诊断方法。试验数据分析表明,新提出的方法能有效地提取故障特征,实现故障类型的诊断。     

近似熵在声发射信号处理中的应用

为研究在载荷作用下,结构裂纹声发射信号的变化特征,提出了将一种最近新发展起来的度量序列复杂性的统计方法--近似熵引入到结构裂纹声发射信号的研究中.介绍了近似熵的概念及性质,并对仿真声发射信号和预制裂纹钢管在静载下的声发射实验信号进行了近似熵计算分析,结果表明,近似熵在表征信号的复杂性方面有明显的效果,从而为声发射信号分析提供了一种很有效的新方法.     

基于近似熵的语音端点检测

提高语音信号端点检测的正确率一直是语音识别领域的一个重要课题,特别是提高在各种实际噪声环境下语音端点检测的正确率更为重要,而传统的基于能量与过零率的方法在噪声环境下不能有效地工作。近似熵是一种新的度量序列复杂性的方法,它具有较强的抗干扰能力。从信号复杂性的角度提出了一种基于近似熵的带噪语音端点检测方法,证明了通过给定一个合理的阈值可以有效地进行语音端点检测。在不同类型噪声及不同信噪比环境下进行实验,结果表明,对语音信号起点和终点的检测性能均要比传统基于能量的方法要好,即使是在较低的信噪比下,该方法仍能够比较准确地检测出语音的起止端点。     

基于插值多尺度熵与模糊C-均值的滚动轴承故障诊断

多尺度熵是一种有效的衡量时间序列复杂性的方法。为了克服多尺度熵粗粒化过程遗漏特征信息的问题,提出了一种基于三次样条插值时间序列的插值多尺度熵算法。该方法首先通过三次样条插值时间序列代替原粗粒化过程,再计算各个尺度下的样本熵。通过分析仿真信号将提出的方法与原多尺度熵方法进行对比,结果表明了方法的有效性和优越性。在此基础上,提出一种基于插值多尺度熵与模糊C-均值的滚动轴承故障诊断方法。最后,将提出的故障诊断方法应用于滚动轴承的试验数据分析。结果表明,所提出的方法比基于MSE的故障诊断方法识别率更高。     

多重分形近似熵与减法FCM聚类的研究及应用

提出了一种基于多重分形与近似熵相结合的信号特征量提取方法,应用于齿轮箱的故障信号诊断中。针对齿轮箱的故障信号的复杂性,先用减法聚类对提取到的信号特征量进行处理,得到初始聚类中心,然后再用模糊C均值聚类(FCM)作进一步处理,实现齿轮箱故障的自动诊断和识别。多重分形谱提取的特征量如谱宽,可以表示信号的波动程度,而近似熵可以表示信号的复杂程度。两者结合可以得到更加准确的齿轮箱故障信号模式。减法聚类可以有效解决FCM容易陷入局部最优的问题,还可以提高收敛速度。提取的特征参数作为聚类分析的数据,通过计算数据点与聚类中心的隶属度判定所属类型,实现齿轮箱故障类型聚类以及模式识别。通过风力发电机齿轮箱故障诊断实验,证明该方法的可行性和有效性。为齿轮箱故障诊断提供了一种新的有效途径。     

碳纤维复合材料拉伸损伤声发射信号MC-ApEn分析

采用滑动移除近似熵(MC-ApEn)分析碳纤维环氧树脂复合材料拉伸损伤过程中产生的声发射信号。从信号的无序性、复杂性及动力学平衡角度描述基体开裂、纤维/基体脱胶及纤维断裂三种典型声发射信号的近似熵谱特征并给出相应解释。用MC-ApEn分析载荷、计数、声发射能量与时间的相关曲线。由不同趋势间过渡引起的近似熵突变发现,拉伸断裂过程被两结构突变时间点划分为三个不同阶段,并据其演进特点推荐复合材料拉伸失效的临界载荷。     

基于非线性几何不变量的轴承故障诊断方法研究

针对轴承传动本身具有非线性而在传统故障诊断中又被忽略掉的问题，提出了基于分形和混沌等非线性几何不变量的轴承故障诊断方法。该方法对测得的轴承振动时间序列去噪以后进行相空间重构，然后计算重构信号的分形维数、Lypunove指数、K熵、关联距离熵等多个几何不变量，并以此作为轴承故障诊断特征量，输入到径向基神经网络，对轴承故障进行模式识别。实验结果表明该方法能有效区别轴承各种故障状态，且为旋转机械的故障诊断提供了一种新方法。     

基于混沌和二维近似熵的滚动轴承故障诊断

针对滚动轴承故障的特征频率处于较低频带,容易被噪声淹没而难于直接检测的问题,提出了在衡量二维时间序列复杂性方面具有普遍意义的二维近似熵,及基于混沌和二维近似熵的滚动轴承故障诊断方法。该方法利用混沌振子对微弱周期信号的敏感性,可以直接检测低频段内滚动轴承微弱的故障特征频率。同时,以二维近似熵作为测度,能够从二维角度全面地量化振子的相变规律,从而客观、准确地识别振子状态并确定故障类型。对滚动轴承内、外圈故障的诊断实例验证了该方法的有效性。     

排列熵算法参数的优化确定方法研究

由于排列熵算法能够有效放大时间序列的微弱变化,且计算简单、实时性好,已在信号突变检测方面显示出良好的应用前景,但是排列熵算法中嵌入维数和延迟时间等参数的确定仍依赖于经验和尝试,该问题已成为排列熵算法走向工程应用的瓶颈问题。根据排列熵算法的原理,提出了基于重构时间序列最佳相空间来确定模型参数的方法。根据相空间重构的两种观点,介绍了延迟时间与嵌入维数独立确定和联合确定两种方法的基本理论,然后利用仿真信号和滚动轴承全寿命数据对两种算法进行了检验和对比。结果表明,模型参数的独立确定方法比联合确定方法对信号的异常检测更好。     

移动荷载作用下结构损伤的近似熵分析

当移动荷载接近或远离结构损伤部位时,结构的振动响应的幅值和非线性特征会发生变化,可以从中提取有关结构损伤的信息;近似熵可以表达一个时间序列的复杂性和内在模式。用移动荷载作用于结构上,对其振动响应数据进行近似熵计算,提取其非线性特征值,进而用神经网络进行结构损伤模式识别。通过一个移动荷载作用下简支梁的计算实例考察了这一方法的有效性。移动荷载的作用,使得损伤造成的结构非线性特征更加显著;研究、计算与实测案例表明近似熵能够有效地表征信号的非线性程度,而且对噪声干扰的敏感度低,可以作为神经网络模式识别的特征向量。     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

＂Three Transformations＂ and Standardization

During his inspection in Henan Province in May, Chinese President Xi Jinping stressed to ＂push forward the transformation from China Speed to China Quality, from Made in China to Created in China, and from Chinese Products to Chinese Brand＂. The ＂Three Transformations＂ are the specific requirements and goal of China＇s national development in the context that market should play a decisive role in the allocation of resources.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.     

SAC Delegation Visits AENOR and Signs Cooperation Agreements

正SAC Administrator Tian Shihong led the Chinese delegation to visit the Spanish Association for Standardization and Certification(AENOR)on September 15,2014.Mrs.Begona Cristeto,the Vice-Minister of Industry,Energy and Tourism of Spain,and Mr.Avelino Brito,the President and CEO of AENOR greeted the delegation.The two sides had a deep and friendly discussion on strengthening the cooperation between China and Spain in the standardization field and promoting the standardization work to support the development of economy and trade in the two countries.