编码协作系统准循环重复累积码的联合设计与性能分析

重复累积(RA)码是一种特殊结构的低密度奇偶校验(LDPC)码,不仅具有LDPC码的优点,还能实现差分编码。针对LDPC编码协作系统编码复杂度高、时延长的问题,该文引入准循环RA(QC-RA)码,推导出信源节点和中继节点采用的QC-RA码对应的联合校验矩阵,基于公差构造方法设计该联合校验矩阵,并证明该方法设计的联合校验矩阵不存在围长为girth-4, girth-6的短环。理论分析和仿真结果表明,同等条件下该系统比相应点对点系统具有更优异的误码率性能。仿真结果同时表明,与采用一般构造QC-RA码或基于Z型构造QC-RA码相比,采用基于公差构造的联合设计QC-RA码的多信源多中继协作均可获得更高的编码增益。     

Colourless distributed combustion effects on a pre-mixed coke oven gas flame

Fuels consisting of high hydrogen concentration can be consumed under colourless distributed combustion (CDC) to suppress flashback tendency in premixed conditions. Higher NO_X challenges can also be overcome through CDC. For those purposes, coke oven gas was consumed under CDC within the scope of this study. To achieve CDC, ${\mathrm{N}}_2$ or ${\mathrm{CO}}_2$ diluents were introduced into the oxidizer so that oxygen concentration in the oxidizer would be decreased from 21% O₂ to its lean blow-off limits. Excess air ratios were determined as λ = 1.2 and λ = 1.5 along with a thermal power of 10 kW under premixed conditions. A commercial computational fluid dynamics code was used to predict temperature distribution and ${\mathrm{NO}}_X$, CO, and ${\mathrm{CO}}_2$ emissions. 162-step reactions created with GRI-Mech 3.0 chemical kinetics was integrated to the eddy dissipation concept combustion model. The temperature and ${\mathrm{NO}}_X$ profiles predicted were compared with the experimental results. Consistency was achieved at ~95% for temperature profiles, and almost 100% for ${\mathrm{NO}}_X$ profiles between the measured and the predicted ones. According to the results, it is concluded that a more homogeneous temperature distribution with the ~21% decrease in the maximum temperature was observed, and there was about 96% decrease in ${\mathrm{NO}}_X$ level. It was also demonstrated that using ${\mathrm{CO}}_2$ as a diluent is more effective in terms of temperature distribution over the combustor and ${\mathrm{NO}}_X$ reduction, while dilution with ${\mathrm{N}}_2$ is more effective in terms about 70% in decrease on CO.     

Review: Investigation of Partially Pre-mixed Charge Ignitions (PPCI) Engine Mode

This paper embraces the key points of unpolluted internally combusted engine emissions. Core objective is focused on the recent effort to improve compression ignition(CI) and spark ignition(SI) engine to have fuel-efficient and minimized pollutant emissions. There are many advanced internal combustion engines to overcome the challenges of conventional compression ignition engines of the high level of particulate matter(PM) and oxides of nitrogen emission. One of the latest options on which many ...     

J2ME技术研究及开发实例

随着Java技术的不断发展，出现了针对嵌入式设备及消费类电器的J22ME技术，它适用于双向网络连接且硬件资源有限的设备，如手机或双向寻呼机。首先系统地介绍了J22ME的发展史、体系结构和主要功能，然后结合一个五子棋的开发实例，详细描述了J22ME在Motomla系列手机A6288上的开发过程。     

基于对象的 OpenXML 复合文件去重方法研究

现有的重复数据删除技术大部分是基于变长分块（content defined chunking ,CDC）算法的,不考虑不同文件类型的内容特征。这种方法以一种随机的方式确定分块边界并应用于所有文件类型,已经证明其非常适合于文本和简单内容,而不适合非结构化数据构成的复合文件。分析了 OpenXML 标准的复合文件属性,给出了对象提取的基本方法,并提出基于对象分布和对象结构的去重粒度确定算法。目的是对于非结构化数据构成的复合文件,有效地检测不同文件中和同一文件不同位置的相同对象,在文件物理布局改变时也能够有效去重。通过对典型的非结构化数据集合的模拟实验表明,在综合情况下,对象重复数据删除比 CDC 方法提高了10％左右的非结构化数据的去重率。     

一种IEC 61850通用数据类数据库信息模型的建模方法

提供了基于IEC 61850通用数据类的数据库信息模型及其接口的设计方法,该方法适用于变电站站控层设备。将数据库模型分为信息模型、设备模型和应用模型3层架构,其中信息模型和设备模型分别基于IEC 61850变电站配置文件(SCD)和IEC 61970公共信息模型(CIM)文件创建,标准的信息模型和设备模型实现了模型的复用。在IEC 61850通用数据类的基础上,设计了信息模型关系型数据库表结构及其接口的实现方法,能够直接导入变电站配置模型,自动生成数据库,并以IEC 61850数据对象引用为检索方式设计了数据库访问接口,简化了变电站工程实施流程。     

不等端弯矩作用下薄壁梁临界弯矩的计算分析

薄壁梁的弯扭屈曲分析是一个较为复杂的问题,在荷载作用下沿梁的弯矩为非均匀分布时,其屈曲方程的求解较为困难.根据梁柱杆端变形增量相关方程和改进后的CDC法,将薄壁梁的弯扭模型等效为拉弯模型,顺利的算出不等端弯矩作用下薄壁梁的临界弯矩,并提出建议公式.经计算与数值解比较,结果令人满意.     

基于CDC3207G的汽车仪表盘CAN通信模块设计

针对车载仪表复杂化的通信控制要求,介绍了德国Micronas公司专用汽车仪表芯片CDC3207G,提出了基于此芯片的CAN通信模块硬件接口电路及相关软件的设计方案,结果证明,该方案不仅可以方便地加入实时操作系统支持和移植应用层高级协议,还可以有效发挥ARM核心微处理器的低功耗、高效率的特点.     

铬基复合金刚石镀铬CDC活塞环在柴油机上的应用

本介绍了铬基复合金刚石镀铬CDC活塞环,国产化CDC活塞环批产应用于柴油机,标志着自主研发CDC技术取得突破性进展。