5 resultados para MIPS
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
为了在龙芯2E处理器上建立稳定的Java运行环境,丰富龙芯平台的上层软件库,以Kaffe这款开源Java虚拟机为移植对象,分析了其运行机制,确定了其代码结构中平台相关的3个主要模块:SysCallMethod、Trampoline和JTT,并结合龙芯2E处理器的特点,给出了相关模块的修改方案.最后用第三方的测试标准对移植后的虚拟机进行了测试,表明了移植的有效性.
Resumo:
随着计算机芯片的速度不断提升,器件的门限电压越来越低,因此单粒子翻转的瞬时故障越来越容易发生。特别是在太空环境中的计算机系统,在宇宙射线的影响下,瞬时故障更为频繁,系统可靠性面临更突出的考验。 为了提高计算机系统的可靠性,一般有硬件冗余容错和软件冗余容错两种方法。相对硬件容错而言,软件容错的优点是价格便宜,性价比高,配置灵活等,缺点是会带来额外的时间和空间开销,而且给程序员带来编写额外的容错代码的工作量。近来出现了一些基于编译的软件容错方法,可在编译的过程中自动加入冗余容错逻辑,但是这类编译容错方法仍然会带来显著的时间空间开销。如何在保持容错能力的同时尽量降低时空开销,是有待继续研究的问题。 本文在编译容错方向上进行了进一步研究和实现,提出利用源代码中的变量信息对冗余容错逻辑进行了剪裁,在保证容错能力的同时降低了时空开销,对内存和寄存器中的数据进行保护。具体内容有: 1. 提出了一个容错编译环境SCC的设计蓝图,构建了一个容错编译工具的远 景目标。 2. 提出了一种指令级的编译容错检测方法VarBIFT ,提供检测瞬时故障的能力。平均只利用0.0069倍的时间损耗和0.3620倍的空间损耗就将发生瞬时故障时,程序正确执行和检测到故障的概率总和平均从39.1%提升到76.9%, 3. 提出了一种指令级的编译容错恢复方法VarRIFT ,提供从瞬时故障中恢复正确数据的能力。平均只增加0.043倍的时间损耗和0.69倍的空间损耗就将发生瞬时故障时,程序仍然正确执行的概率平均从44.8%提升到了78.7%。 4. 基于开源编译器LCC,实现了上述两个编译容错方法VarBIFT 和VarRIFT 。在容错方法的实现中只修改了跟具体CPU指令相独立的中间逻辑,所以这两个实现能够方便得移植到SPARC、MIPS等其他CPU架构上。 5. 开发了一个故障注入工具,并用它测试了上述两个编译容错方法VarBIFT和VarRIFT 的容错能力。
Resumo:
Java虚拟机作为Java运行环境的核心,已成为现代计算机平台不可缺少的组成部分。Java虚拟机和平台间的兼容性直接决定了上层Java程序的运行的稳定性。龙芯2E是由中科院计算机研究所自主研发的高性能微处理器。由于采用MIPS指令集,现有Java虚拟机对龙芯的支持并不理想,这极大地限制了龙芯平台的上层应用。 针对这一问题,本文对现有虚拟机进行了分析,选择了移植性较强的Kaffe虚拟机作为移植对象,力求在龙芯2E上建立一个稳定的Java运行环境。以此为目的,本文整理了龙芯2E相关的内容,包括龙芯2E的指令集特点,龙芯下参数传递的方式,龙芯下函数栈的组织等等;研究了Java虚拟机规范中,一般Java虚拟机的体系结构;分析了Kaffe虚拟机的代码结构,确定了移植需要修改的三个主要模块:本地代码调用接口,Trampoline技术和JIT3引擎;给出了移植方案。其中,JIT3引擎作为整个虚拟机的核心,是整个移植工作的重点。本文对其编译过程,寄存器分配策略,Java栈的组织方式,以及标签,常量池等平台相关机制进行了深入的分析。在此基础上,修改了Java栈向本地栈的映射方式,实现了标签机制中平台相关部分的代码,重新描述了寄存器信息并重新实现了本地汇编指令。 针对Java虚拟机调试困难的问题,本文总结了龙芯平台下Kaffe虚拟机的调试方法。在调试过程中发现了Kaffe原有代码中的编码错误,并给出了修改方案。 最后采用第三方的评测工具对移植后的虚拟机进行测试,验证了移植的有效性。
Resumo:
Three nitrophenol isomer-imprinted polymers were prepared under the same conditions using 4-vinylpyridine as a functional monomer. Different recognition capacities for template molecules were observed for the three polymers. Another imprinting system with stronger acidity than nitrophenol isomers, 2-hydroxybenzoic acid (salicylic acid) and 4-hydroxybenzoic acid, was imprinted using 4-vinylpyridine or acrylamide as functional monomer respectively. Both 4-hydroxybenzoic acid-imprinted polymers using the two monomers showed recognition ability for the template molecule. However, when acrylamide was chosen as functional monomer, the salicylic acid-imprinted polymer showed very weak recognition for the template molecule, whereas strong recognition ability of the resultant polymer for salicylic acid was observed with 4-vinylpyridine as functional monomer. It seems that the structure and acidity of template molecules is responsible for the difference in recognition, by influencing the formation and strength of interaction between template molecule and functional monomer during the imprinting process. An understanding of the mechanism of molecular imprinting and molecular recognition of MIPs will help to predict the selectivity of MIPs on the basis of template molecule properties. Copyright (C) 2003 John Wiley Sons, Ltd.
Resumo:
We initially report an electrochemical sensing platform based on molecularly imprinted polymers (MIPs) at functionalized Indium Tin Oxide Electrodes (ITO). In this research, aminopropyl-derivatized organosilane aminopropyltriethoxysilane (APTES), which plays the role of functional monomers for template recognition, was firstly self-assembled on an ITO electrode and then dopamine-imprinted sol was spin-coated on the modified surface. APTES which can interact with template dopamine (DA) through hydrogen bonds brought more binding sites located closely to the surface of the ITO electrode, thus made the prepared sensor more sensitive for DA detection. Potential scanning is presented to extract DA from the modified film, thus DA can rapidly and completely leach out. The affinity and selectivity of the resulting biomimetic sensor were characterized using cyclic voltammetry (CV). It exhibited an increased affinity for DA over that of structurally related molecules, the anodic current for DA oxidation depended on the concentration of DA in the linear range from 2 x 10(-6) M to 0.8 x 10(-3) M with a correlation coefficient of 0.9927.In contrast, DA-templated film prepared under identical conditions on a bare ITO showed obviously lower response toward dopamine in solution.