Energy-efficient Hardware Accelerators for the SA-DCT and Its Inverse

The explosive growth of the mobile multimedia industry has accentuated the need for efficient VLSI implementations of the associated computationally demanding signal processing algorithms. In particular, the short battery life caused by excessive power consumption of mobile devices has become the biggest obstacle facing truly mobile multimedia. We propose novel hardware accelerator architectures for two of the most computationally demanding algorithms of the MPEG-4 video compression standard––the forward and inverse shape adaptive discrete cosine transforms (SA-DCT/IDCT). These accelerators have been designed using general low-energy design philosophies at the algorithmic/architectural abstraction levels. The themes of these philosophies are avoiding waste and trading area/performance for power and energy gains. Each core has been synthesised targeting TSMC 0.09 μm TCBN90LP technology, and the experimental results presented in this paper show that the proposed cores improve upon the prior art.

任意形状散射体模型的建立和修正

文中提供了一种对任意形状导体散射体的原始数据进行分析修正,并最终形成可计算模型的方法。散射体的几何数据,通常包括重叠、空洞和相交等错误,它们必须在计算前予以修正。该文在AutoCAD环境,及其二次开发工具支持下,完成了自动检测,半自动地数据修正,最终得到了可计算的表面或实体模型。给出了计算实例以说明该方法的有效性。     

基于VRML的三维几何体建模算法研究

由于虚拟现实建模语言(VRML)的繁杂性,用其直接构造三维几何体较为困难,我们根据VRML97规范中定制的几类三维几何体,分别予以算法实现,从而提高基于VRML创建三维虚拟场景的效率。本文主要讨论基于VRML进行三维几何体建模中的主要算法,最后展示了利用建模算法完成的一个三维场景建模实例。1     

Ultra-fine pitch palladium-coated copper wire bonding: Effect of bonding parameters

Copper (Cu) wire bonding has become a mainstream IC assembly solution due to its significant cost savings over gold wire. However, concerns on corrosion susceptibility and package reliability have driven the industry to develop alternative materials. In recent years, palladium-coated copper (PdCu) wire has become widely used as it is believed to improve reliability. In this paper, we experimented with 0.6 ml PdCu and bare Cu wires. Palladium distribution and grain structure of the PdCu Free Air Ball (FAB) were investigated. It was observed that Electronic Flame Off (EFO) current and the cover gas type have a significant effect on palladium distribution in the FAB. The FAB hardness was measured and correlated to palladium distribution and grain structure. First bond process responses were characterized. The impact of palladium on wire bondability and wire bond intermetallic using a high temperature storage test was studied.     

Hierarchical Implicit Shape Modeling

In this paper, a new hierarchical approach for object detection is proposed. Object detection methods based on Implicit Shape Model (ISM) efficiently handle deformable objects, occlusions and clutters. The structure of each object in ISM is defined by a spring like graph. We introduce hierarchical ISM in which structure of each object is defined by a hierarchical star graph. Hierarchical ISM has two layers. In the first layer, a set of local ISMs are used to model object parts. In the second layer, structure of parts with respect to the object center is modeled by global ISM. In the proposed approach, the obtained parts for each object category have high discriminative ability. Therefore, our approach does not require a verification stage. We applied the proposed approach to some datasets and compared the performance of our algorithm to comparable methods. The results show that our method has a superior performance.     

舵面形状对铰链力矩的影响分析

为研究舵面形状对铰链力矩的影响,运用CFD技术模拟某无翼式布局弹箭在不同马赫数下的尾舵受力分布情况,分别对尾舵前缘根弦、后缘梢弦与后缘根弦进行小面积的裁剪,得到三组弹身-尾舵组合体,分别对各组合体进行数值模拟,得到各组合体在不同马赫数下的舵面压心、铰链力矩以及全弹气动特性系数。结果表明,裁剪尾舵前缘使舵面压心更分散; 裁剪尾舵后缘使舵面压心更集中,有利于铰链轴的设计,可有效减小铰链力矩; 裁剪尾舵对全弹的气动特性有微小的影响。     

Influence of pad shape on self-alignment in electronic packaging

Anisotropic self-alignment of the noncircular pads is investigated to reduce the misalignment in electronic packaging, and the effects of the direction and length ratio of the noncircular pads are analyzed. The restoring forces of circular and noncircular pads are calculated numerically using the surface evolver and are compared with the experimental data. The restoring force in the minor-axis direction of the noncircular pad becomes largest followed by the circular pad and the major-axis direction of the noncircular pad. Directionality increases with the length ratio, which implies that more accurate alignment can be achieved in the specific direction.     

YAG激光输出波形的时域整形技术

该文以实验为基础,结合理论分析,叙述了能够对YAG脉冲激光器的输出波形进行有效的时域整形的技术--慢调Q腔倒空方法。     

激光快速成形过程中熔池形态的演化

采用高速摄影技术对激光快速成形过程中液态熔池的形成及其演化过程进行了实时观察。结果发现,以一定速度向前运动的激光束辐照基材时,基材表面开始熔化并形成液态熔池,经过一个较短的时间间隔(约1．0 s)后熔池深度增大至一定值,熔池长度则围绕一恒定值波动。以恒定送粉率向熔池中连续送进金属粉末时,熔池的长度和宽度逐渐减小,熔池寿命缩短。同时熔池后沿不断抬高即熔覆层厚度不断增加,最大熔深处熔池自由表面法向和激光束轴线之间的夹角由几度逐渐增大到20°～30°左右。熔池自由表面发生周期性的变化,实验观察到熔池后沿有周期性的“岛状凸起”出现和消失现象。数值计算结果证实这主要是熔池中熔体在表面张力梯度下引起的强制对流作用的结果。     

PBGA焊点热疲劳寿命的正交试验及回归分析

通过对ＰＢＧＡ焊点形态参数与焊点热疲劳寿命的正交试验,利用大型统计分析软件进行多元线性回归分析,建立起ＰＢＧＡ焊点高度固定,芯片在上焊点高度不固定及芯片在下焊 度不固定三种不同工作条件下形态参数与热疲劳寿命之间的回归多项表式,即ＰＢＧＡ焊点形参数与热疲劳寿命的关系表达式。