Horizons and Ergoregions in Superfluids

Ripplons—gravity-capillary waves on the free surface of a liquid or at the interfaces between two superfluids—are the most favorable excitations for simulation of the general-relativistic effects related to horizons and ergoregions. The white-hole horizon for the “relativistic” ripplons at the surface of the shallow liquid is easily simulated using the kitchen-bath hydraulic jump. The same white-hole horizon is observed in quantum liquid—superfluid ⁴He. The ergoregion for the “non-relativistic” ripplons is generated in the experiments with two sliding ³He superfluids. The common property experienced by all these ripplons is the Miles instability inside the ergoregion or horizon. Because of the universality of the Miles instability, one may expect that it could take place inside the horizon of the astrophysical black holes, if there is a preferred reference frame which comes from the trans-Planckian physics. If this is the case, the black hole would evapotate much faster than due to the Hawking radiation. Hawking radiation from the artificial black hole in terms of the quantum tunneling of phonons and ripplons is also discussed.      

一种基于量化改动的二值图像水印改进方法

在基于单位块内黑白像素比率的二值图像水印算法的基础上。提出了一种改进的量化水印方案。算法在以合适的量化步长保证水印嵌入的稳健性，并大大提高了可嵌入水印的有效块数，同时使得水印改动的像素个数在一个量化步长以内，从而使得水印系统的容量、稳健性以及视觉失真等指标达到一个有效的折中。另外执行算法时无须记录水印嵌入的位置信息，保证了盲提取的要求。实验结果证明了这种用于二值图像水印算法的有效性和改进性。     

基于改进几何哈希法的矢量图形检索

针对图形文件以矢量方式记录几何实体的特点,提出了一种基于改进几何哈希法的图形检索算法。与图像的对应处理方式相比,该算法充分利用图形的矢量信息,以实体基准点和实体的准确几何形式描述几何实体;在检索过程中,每个图形实体仅有基准点参与排序和查询,哈希表数据组织形式简单,查询速度快;通过验证图形实体属性,保证了查询结果的准确性。最后以矢量图形文件为图例,验证了方法的有效性。     

一种生成卵形曲线的方法

利用几何变换的方法解决了卵形曲线的生成问题。以椭圆作为变换的初始曲线,按照所给条件对其使行变换。讨论了该曲线的形成过程,创建了相应的数学方程。分析了方程中各参数的意义及所表达的曲线的特性,并根据所建的数学方程进行编程、验证,结果表明,所绘出的图形与分析完全吻合。     

一种基于Gr(o)bner基和有向图的几何约束求解方法

方程组规模大和约束一致性分析方法的欠缺影响基于Grobner基的代数法在约束求解中的应用。针对应用有向图进行约束分解产生的强连通分量不饱和问题，提出进行强连通分量内变量匹配，以消去自由实体，从而使强连通分量趋于饱和，方程组得以简化。并以此为基础提出基于Grobner基进行约束一致性判别的方法。以含有冗余约束的三角形为例阐述了约束一致性分析和求解的过程。     

基于几何特性的三次均匀B样条曲线构造描述

基于B样条曲线是分段的Bézier曲线段的集合这一数学特性,通过剖析三次均匀B样条曲线的数学表达及其几何意义,由曲线的几何特性给出了各曲线段Bézier点的几何表示。每段B样条曲线段(三次Bézier曲线段)对应的4个Bézier特征顶点,可以导出该曲线段的B样条基函数。依此为基础,描述了三次均匀B样条曲线构造的原理和过程,并给出了不同曲线段数情况下曲线特征构造和插值构造的相关公式。     

基于语义激活的智能图形处理系统

全面分析了目前知识处理系统所存在的弊病,提出了下一代语义激活系统,探讨了新一代知识系统所应提供的服务;并将之运用于图形处理系统,阐明了图形数据从统一表示到有效存储、建模、再现和检索等一系列智能处理过程;进而提出了图形信息的语义表示和智能推理模型.     

Design and Application of Quality Control Strategies at the Operational Level of a Production Process Chain

This paper presents strategies for an automated control of distortion at the operational level of a production process chain, as well as first steps towards a combined implementation in heat‐treatment processes. In order to minimise the loss of production due to quality defects, the first quality control loop will be implemented on an in‐process level. The second control loop within the reach of operational control includes the feedback of post‐process measurements of quality features. As such, the post‐process control loop optimises the set‐values of the in‐process control loop.     

Advanced cold rolled steels for automotive applications

Advanced multiphase steels offer a great potential for bodies‐in‐white through their combination of formability and achievable component strength levels. They are first choice for strength and crash‐relevant parts of challenging geometry. The intensive development of high‐strength multiphase steels by ThyssenKrupp has led to hot dip galvanizing concepts with an outstanding forming potential. Hot rolled, hot dip galvanized complex phase steels are currently produced in addition to cold rolled DP and RA steels. New continuously annealed grades with tensile strength levels of up to 1000 MPa in combination with sufficient ductility for applications mainly in the field of structural automobile elements make use of the classic advantages of microalloying as well as the principles of DP and TRIP steels. Further improvement of properties will be reached by the new class of high manganese alloyed steels.     

60Si2Mn弹簧圆钢机械性能不合原因及改进措施

鄂钢电炉炼钢厂在生产60Si2Mn弹簧圆钢时,发生较为严重的机械性能不合,主要表现为延伸率及断面收缩率低,试样呈脆性断口,断口及低倍试样中发现有白点缺陷.经分析,造成60Si2Mn弹簧圆钢机械性能不合的主要原因为钢中氢含量高,在工艺中提出改进措施,以改进其机械性能,提高产品质量.