Jet:progress in performance and understanding

In 1990 JET operated with a number of technical improvements which led to advances in performance and permitted the carrying out of experiments specifically aimed at improving physics understanding of selected topics relevant to the "NEXT STEP". The new facilities include beryllium antenna screens, a prototype lower hybrid current drive system, and modification of the NI system to enable the injection of He-3 and He-4. Continued investigation of the hot-ion H-mode produced a value of n(D)(0)tau-E(T)(i)(0) = 9 x 10(20)m-3s keV, which is near conditions required for Q(DT) = 1, while a new peaked density profile H-mode was developed with only slightly lower performance. Progress towards steady state operation has been made by achieving ELMy H-modes under certain operating conditions, while maintaining good tau-E values. Experimental simulation of He ash transport indicates effective removal of alpha-particles from the plasma core for both L and H mode plasmas. Detailed analyses of particle and energy transport have helped establish a firmer link between particle and energy transport, and have suggested a connection between reduced energy transport and reversed shear. Numerical and analytic studies of divertor physics carried out for the pumped divertor phase of JET have helped clarify the key parameters governing impurity retention, and an intensive model validation effort has begun. Experimental simulation of alpha-particle effects with beta-fast up to 8% have shown that the slowing down processes are classical, and have given no evidence of deleterious collective effects.

GOTOBLAS一般矩阵乘法高效实现机制的研究

对GOTOBLAS库(GOTO)的实现机制,尤其是其中的一般矩阵乘法部分的实现进行了分析.结合近年来的一些研究成果,讨论了如何高效地实现矩阵相乘操作,把存储层次对程序性能的影响提高到计算模型的高度.对比实验表明,GOTO库的性能远远高于没有考虑存储层次的一般BLAS库.证明了GOTO库性能上的优越性和将存储层次引入计算模型的必要性.

高效XML验证技术的实现

XML解析器是分析、处理XML文档的基础软件。对XML解析器的高效验证技术进行了研究,实现了支持StAX接口的验证型解析器OnceStAXParser2.0。该解析器采用了多项性能优化措施,包括属性验证的高效实现、元素验证自动机的优化、基于统计的预测算法等。性能测试表明,在进行验证的条件下,OnceStAXParser2.0具有出色的解析性能。

高效DOM实现的技术研究

DOM是目前为止唯一成为W3C正式标准的XML解析模型。本文充分考虑了DOM模型的特点,设计并实现了一个高性能的支持DOM的XML解析器OnceDOMParser。为了提高DOM实现的性能,我们采用用户堆提高对象管理的效率,减少对象在JVM中创建的数量,并采取了数据的延迟装载策略。OnceDOMParser经过了严格的XML兼容性测试和DOM API兼容性测试,多方面的性能测试表明OnceDOMParser性能优越,其平均吞吐量比目前最流行的XML解析器Xerces高43.7%左右。