电子剪切散斑技术在木材无损检测中的应用

复合板材及木制品等表面或内部的缺陷对材料性能有很大影响,如何快速准确地对其进行无损检测,并判断缺陷的位置大小是很有意义的.针对松木板试件,通过预置表面和内部隐藏缺陷来近似模拟实际缺陷情况,提出一种基于剪切散斑干涉技术的木材无损检测技术新方法,实现了对松木试件的无损检测.在表面缺陷的检测中讨论了剪切量对结果的影响,利用像素标定的方法,得到直径为6、5、3mm的缺陷信息;在内部隐藏缺陷检测中,借助热加载技术同时引入相移技术使剪切散斑检测技术不仅具有非接触、全场实时检测等特点,而且完成对内部隐藏近表面缺陷的定量无损检测.整个检测过程光路简单,实时快速,实验结果与实际情况符合较好.     

Improved Computational Model of Grid Cells Based on Column Structure

To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian-like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real-time positioning results are modified.     

完备局部凸凹计数模式及其旋转不变纹理分类

局部凸凹模式是新近提出的一种有效纹理描述子,但对旋转纹理图像描述不足。针对局部凸凹模式算法的此缺陷,提出了局部凸凹计数模式进行旋转不变纹理描述。局部凸凹计数模式统计纹理的局部凸或凹模式数目,而抛弃了局部凸凹模式的结构信息。在纹理图像发生平面内旋转情况下,局部凸凹计数模式所提取的纹理特征具有不变性。另外,为了增强局部凸凹计数模式的性能,提出了完备局部凸凹计数模式算法。完备局部凸凹计数模式不仅统计了局部凸或凹模式数目,还对局部纹理的凸或凹强度进行了描述,中心像素所包含的鉴别信息也统计在完备局部凸凹模式算法中。二个纹理数据库和一个掌纹数据库上的试验充分表明完备局部凸凹计数模式是一种有效的旋转不变纹理特征提取算法。     

Fault diagnosis of internal combustion engines using visual dot patterns of acoustic and vibration signals

An investigation of the fault diagnosis technique in internal combustion engines based on the visual dot pattern of acoustic and vibration signals is presented in this paper. Acoustic emissions and vibration signals are well known as being able to be used for monitoring the conditions of rotating machineries. Most of the conventional methods for fault diagnosis using acoustic and vibration signals are primarily based on observing the amplitude differences in the time or frequency domain. Unfortunately, the signals caused by damaged elements, such as those buried in broadband background noise or from smearing problems arising in practical applications, particularly at low revolution, are not always available. In the present study, a visual dot pattern technique is proposed to identify the acoustic emission and vibration signals for fault diagnosis in an internal combustion engine and drive axle shaft. Experiments are carried out to evaluate the proposed system for fault diagnosis under various fault conditions. The experimental results indicate that the proposed technique is effective in the fault diagnosis of an internal combustion engine and drive axle shaft.     

Preparation and characterization of superhydrophobic silica-based surfaces by using polypropylene glycol and tetraethoxysilane precursors

Preparation of superhydrophobic silica-based surfaces via sol-gel process by adding polypropylene glycol (PPG) polymer into the precursor solution has been developed. Surface roughness of the films was obtained by removing the organic polymer at 500 °C and then the hydrophobic groups bonded onto the films were obtained by chemical reaction with hexamethyldisilazane (HMDS). Physical properties of the as-prepared films were analyzed by contact angle measurements, scanning electron microscopy (SEM), UV-VIS scanning spectrophotometer and Fourier transform infrared (FT-IR) spectrophotometer. The experimental parameters were varied by the type of silane species, the weight ratio of PPG solution to precursor solution, the hydrolysis time of the precursor solution, the molecular weight of PPG, the casting temperature and the evaporation temperature. The phase separation of the PPG polymer rich domain occurred on the substrates at a lower temperature. The result showed that the contact angles of the films prepared at 5 °C were greater than 150° when the weight ratio of PPG solution to precursor solution was 5. In addition, the transmittance of the films was greater than 80% simultaneously.     

消失模铸钢件表面局部合金化研究

在泡沫模表面涂覆富钒涂层 ,利用液态铸钢浇铸时的高温和液态钢水的作用 ,使涂层被烧结成合金层 ,同时 ,涂层中的钒渗入铸钢基体组织中 ,形成渗钒层。结果表明 ,该工艺可以使钒渗入到铸钢基体中达 15 0 0～2 0 0 0 μm ,烧结层和渗钒层均为α (Fe ,V)单相组织 ,基体为铁素体和珠光体 ,渗钒层显微硬度与基体硬度相当 ,当涂层粉体粒度 <4 7μm时可得到理想的合金化渗层。涂层粉体粒度越小 ,钒原子在涂层中的扩散越容易 ,渗钒层中钒含量越高 ,渗钒层越厚。     

PATTERN RECOGNITION APLLIED TO STABILITY OF FILLED Ti_2Ni PHASES

Pattern recognition method is used for the investigation of stability,region of filled Ti_2Niphases in multi-dimensional bond-parameter space.The filling of C,N and O atoms intoT_6 octahedra consisting of atoms of earhy-transition elements makes the expansion of thestability region of Ti_2Ni phase,and the relative stability of AI_2Cu and MoSi_2 type com-pounds decreases after the introduction of non-metallic elements such as C,N and O.     

用于树脂砂造型的木模结构设计及制作工艺

从木模起模和木模强度等方面入手，阐述了树脂砂木模结构的设计、木模结构简化的方法。提出了木模的选材及制作工艺     

精密铸造硅溶胶模壳的制造工艺

介绍用石蜡-硬脂酸低温模料，生产铸件的熔模和用精密铸造硅溶胶，作为制壳粘结刑，制造铸件的模壳的工艺要求。主要研究熔模制造工艺、硅溶胶模壳工艺和焙烧工艺。五年多来的生产实践充分证明精密铸造硅溶胶模壳制造工艺是成熟的。为生产合格模壳和精密铸件提供了技术保障。     

消失模铸造成型用PLC控制装置研制

本文采用可编程控制器(PIG)为主要控制元件，研制出一台成型控制装置。对控制系统的硬件和软件构成、控制方式及特点作了介绍。最后利用该控制装置制作出表面光洁的优质泡沫模样。