Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm²) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.     

Similarity retrieval of iconic image database

The perception of spatial relationships among objects in a picture is one of the important selection criteria to discriminate and retrieve the images in an iconic image database system. The data structure called 2D string, proposed by Chang et al., is adopted to represent symbolic pictures. The 2D string preserves the objects' spatial knowledge embedded in images. Since spatial relationship is a fuzzy concept, the capability of similarity retrieval for the retrieval by subpicture is essential. In this paper, similarity measure based on 2D string longest common subsequence is defined. The algorithm for similarity retrieval is also proposed. Similarity retrieval provides the iconic image database with the distinguishing function different from a conventional database.     

MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization.

Image segmentation is an indispensable process in the visualization of human tissues, particularly during clinical analysis of magnetic resonance (MR) images. Unfortunately, MR images always contain a significant amount of noise caused by operator performance, equipment, and the environment, which can lead to serious inaccuracies with segmentation. A robust segmentation technique based on an extension to the traditional fuzzy c-means (FCM) clustering algorithm is proposed in this paper. A neighborhood attraction, which is dependent on the relative location and features of neighboring pixels, is shown to improve the segmentation performance dramatically. The degree of attraction is optimized by a neural-network model. Simulated and real brain MR images with different noise levels are segmented to demonstrate the superiority of the proposed technique compared to other FCM-based methods. This segmentation method is a key component of an MR image-based classification system for brain tumors, currently being developed. Index Terms-Improved fuzzy c-means clustering (IFCM), magnetic resonance imaging (MRI), neighborhood attraction, segmentation.     

化学还原法制备纳米铜粉的研究

本文采用KBH4在液相中化学还原CuSO4,并加入KOH和络合剂EDTA ,制得了纳米级的纯净的铜粉 ,通过调整反应物的浓度 ,可以消除Cu2 O等杂质。制备的纳米铜粉还存在一定程度的团聚 ,需试验加入分散剂来改善。     

Improve the quality of vaginal delivery]

Between 1990 and 1992, external sphincter repair was performed in 20 patients rendered faecally incontinent after earlier fistula surgery. All were improved, 13 (65%) achieving Grade 1 or 2 continence. Postoperative ultrasound was useful in explaining the sub-optimal outcome of 3 patients who still had defects. Clinical outcome in female patients was better than in male patients. Clinical outcome was not related to the results of preoperative manometry, the site of external sphincter damage, the use of a stoma, or the occurrence of wound complications. External sphincter repair for faecal incontinence after fistula surgery achieves good results in the majority of patients.     

Study on Hot Deformation Cracks of Steel D2 Using Procesing Map

ＳｔｕｄｙｏｎＨｏｔＤｅｆｏｒｍａｔｉｏｎＣｒａｃｋｓｏｆＳｔｅｅｌＤ２ＵｓｉｎｇＰｒｏｃｅｓｉｎｇＭａｐＧａｏＳｈａｎ，ＬｉｕＸｉａｎｇｈｕａ，ＷａｎｇＧｕｏｄｏｎｇＡＢＳＴＲＡＣＴＴｈｅｈｏｔｄｅｆｏｒｍａｔｉｏｎｂｅｈａｖｉｏｒｓｏｆｓｔｅｅｌ...     

硼／铝复合材料管构件的界面特性EI

主要研究带钛合金连接头硼／铝复合材料管构件中Ｂ－Ａｌ－Ｔｉ间的界面结构与性质。研究表明，在复合工艺条件下，硼－铝界面附近没有检测到任何铝－硼化合物，而钛－铝间形成ＴｉＡｌ有序金属间化合物相。实验证明，硼／铝复合材料与铝合金端环之间采用的固结方法是有效的，且可按照受载类型随意调整斜面搭接长度，达到承受不同载荷的目的。     

面向对象中文窗口开发环境：C—VISION

Ｃ－ＶＩＳＩＯＮ中文窗口系统综合采用了面向对象与窗口环境设计的程序方法，彻底更新了在微机上进行中文窗口设计的编程思想，同时作为一个基础系统，为软件设计节约了大量的人力和时间，实现了微机程序的共享。     

整体式预热器U型管蒸汽发生器数学模型及动态模拟

本文针对整体式预热器Ｕ型管蒸汽发生器建立了热工数学模型并进行了动态模拟。该模型是一个２５阶、非线性、可移动边界模型。包括：一、二次侧的质量与能量平衡方程以及确定二次侧下降段流量的动量守恒方程。对所建立的模型利用Ｇｅａｒ方法作了蒸汽阀门开度阶跃１０％的瞬态模拟，所得结果和国外所公布的结果吻合得很好。由此可见。本文所建立的模型可以为这种蒸汽发生器的设计、运行、控制提供理论依据。