Effect of AlP master alloy on grain refinement of primary silicon in eutectic Al-Si alloys

To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon‘s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys.     

MODELING OF FREE JUMPS DOWNSTREAM SYMMETRIC AND ASYMMETRIC EXPANSIONS： THEORITICAL ANALYSIS AND METHOD OF STOCHASTIC GRADIENT BOOSTING

The general computational approach of Stochastic Gradient Boosting(SGB) is seen as one of the most powerful methods in predictive data mining.Its applications include regression analysis,classification problems with/without continuous categorical predictors.The present theoretical and experimental study aims to model the free hydraulic jump created through rectangular Channels Downstream(DS) symmetric and asymmetric expansions using SGB.A theoretical model for prediction of the depth ratio of jumps is devel...     

近源地震的特性及其对RC柱延性的影响

介绍了近源地震的特点,研究了RC柱在近源地震时的延性特性.计算结果表明,近源地震的垂直地面运动的幅值和频率成分对柱的延性和拟加速度响应有很大影响,对位于近源地震区域的建筑物的抗震设计有必要考虑垂直地面荷载.     

冷弯薄壁型钢压弯构件的稳定性计算

本文对原《薄壁型钢结构技术规范》(TJ 18-75)中有关偏心受压构件稳定性计算的规定作了评述和讨论,并就现行《冷弯薄壁型钢结构技术规范》(aBJ 18-87)采用相关公式计算压弯构件稳定性的依据及有关问题作了较为详尽的说明。     

冷弯薄壁型钢结构的概率极限状态设计法

本文介绍现行《冷弯薄壁型钢结构技术规范》(GBJ 18-87)所采用的基于概率理论的极限状态设计方法,其中包括(?)次(?)阶矩概率法的基本原理,可靠指标的计算模式,参数,薄钢结构的抗力参数及设计表达式等。同时,对新、旧薄钢规范的设计方法作了简要的比较。     

无粘结预应力井式梁板悬挂技术夹层升板结构

本文介绍一种新的结构体系——无粘结预应力井式梁板、悬挂技术夹层升板结构。井式梁板中靠近柱子的主梁为无粘结预应力连续双梁,次梁为非预应力连续梁,技术夹层为厚8厘米的钢筋混凝土平板,用钢吊杆悬挂于井式梁的交点下,并与井式梁楼板一同提升。 本文主要结合具体工程——无锡第一棉纺织厂介绍这一体系的设计和施工方法。     

压电振动发电机的研究现状与发展趋势

综述了国内外压电振动发电机的技术发展,阐述了压电发电机工作原理,系统介绍了压电材料与压电换能元件结构形式,重点报道了能量转换接口电路及共振频率调整策略的研究现状。举例说明了压电振动发电机的应用领域,并针对目前研究中存在的问题对压电振动发电机发展趋势进行了预测。随着低功耗微电子技术与微机械加工技术的发展,压电振动发电机在各种MEMS产品、无线传感器网络及低功耗电子设备中的应用将逐渐实用化、普及化。     

Effect of Silver Content on Microstructure and Properties of Brass/steel Induction Brazing Joint Using Ag-Cu-Zn-Sn Filler Metal

The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study.The influence of Ag content on the microstructure and properties were analyzed by means of optical microscopy,scanning electron microscopy and electron probe microanalysis.Defect free joint was achieved using Ag-Cu-Zn-Sn filler metal.The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution.The increase of Ag content and the cooling rate both led to the increase of the needle like eutectic structure.The tensile strength decreased with the increase of Ag content.The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa.All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.