RTLinux实时调度算法的改进与实现

为提高RTLinux的实时调度性能,分析了RTLinux的工作原理,针对其现有调度算法的不足,提出了改进的最小裕度优先算法,有效减少了颠簸现象,提高了算法性能.深入分析了RTLinux下ILLF调度器的实现,提高了CPU的使用率,增强了系统调度性能,并通过程序验证和调度器仿真,验证了算法的可行性和有效性.     

视频图像在三维模型中的渲染

视频监控是大型安防工作中最重要的一个环节,传统的视频监控系统展示给用户的只是独立的二维平面图像,图像脱离环境,整体性不足,为了解决该问题,提出了将视频图像渲染显示于三维模型的思路.研究了纹理映射技术并结合视频图像渲染的特殊性分析研究了Z缓冲算法、Shadow map算法,根据实际应用提出Extend Shadow map算法以实现将视频图像与三维场景无缝贴合.实验结果表明,视频图像渲染显示于三维模型中所体现的优越性.     

分布式嵌入式系统实时调度的建模

针对RBTPN模型在建模分布式嵌入式系统实时调度时的不足,提出了一种新的扩展时间Petri网模型。该模型通过在需要处理器资源的变迁上引入变迁速率因子,得到具有相同优先级变迁的运行速率函数,从而在分布式嵌入式系统的调度建模中,在单个处理器上结合了固定优先级可抢先调度和轮转调度。随后给出了该模型可达图的构造方法,以便可以得到调度序列的各种性质。     

不同植被类型对土壤微生物量碳氮及土壤呼吸的影响

对四种植被类型下土壤微生物量碳、氮、土壤呼吸速率以及代谢熵的研究,结果表明,土壤微生物量碳、氮以及土壤呼吸在四种植被类型间差异显著,而土壤微生物代谢熵之间差异不明显.且不同植被演替阶段土壤微生物量碳、氮从初级阶段到次生林阶段逐步增大,从次生林到成熟林阶段明显减小;土壤呼吸随着植被的正向演替,呼吸速率逐渐增强;四种植被类型间土壤微生物代谢熵在次生林中最低,为0.44 mgg-1 h-1,万熟林地中最高,为1.01 mgg-1 h-1,表明土壤微生物对土壤碳的利用效率次生林较高,成熟林地较低.     

永磁直线同步电机电流检测系统设计

直线驱动系统由于机械结构简单而获得广泛应用.本文提出一种基于磁场平衡式霍尔电流传感器的永磁直线同步电机的电流检测系统及其实现方案.分析了电流检测系统的基本原理、电流信号的处理以及电流的过流保护的功能.实验结果验证了电流检测系统的有效性.     

利用80C196MC PTS 实现异步串行通信

异步串行通讯在单片机通讯中占据了相当重要的地位,因此大多教单片机都配备了UART来支持异步通讯.当单片机不支持UART时,利用别的方法实现异步串行通信就显得非常有意义.本文在分析异步串行通信规范的基础上,总结了实现异步串行通信的条件.然后深入讨论了80C196MC外设事务服务器实现异步串行通信的机理和时序.最后就异步串行通信编程实现中的一些要点和难点进行了分析.     

碳量子点的生物应用:成像、载药与毒性

碳量子点作为一种新型的纳米材料,具有荧光性能优异、尺寸小、毒性低等诸多优势,因而具有良好的应用前景,尤其在生物医学领域有突出的应用价值,近年来引起了科研者们的广泛关注。在介绍碳量子点光学性质的基础上,重点综述了碳量子点在生物成像、诊疗剂应用及碳量子点生物毒性等方面的最新研究进展,并探讨了碳量子点未来的发展方向和前景。     

Cigarette smoking and the colorectal adenoma-carcinoma sequence: a hypothesis to explain the paradox

As recognized precursor lesions to colorectal cancer, colorectal adenomatous polyps have been studied to enhance knowledge of colorectal cancer etiology. Although most of the known risk factors for colorectal cancer are also associated with the occurrence of colorectal adenomas, cigarette smoking has had a strong, consistent relationship with colorectal adenomas but is generally not associated with colorectal cancer. The explanation for this paradox is unknown. With data collected in 1986-1988 during a large case-control study based on colonoscopy results in New York City, New York, the authors investigated the possibility that the paradox may arise because subjects with colorectal adenomas were included in the control group of cancer case-control studies. The authors found a statistically significant increased risk between heavy cigarette smoking (smokers with > or = 40 pack-years of smoking) and risk of adenoma (odds ratio (OR) = 1.61, 95% confidence interval (CI) 1.06-2.44). They saw no increased colorectal cancer risk from heavy cigarette smoking (OR = 1.02, 95% CI 0.52-1.99) using a "manufactured" control group to simulate a typical unscreened, population-based control group. When the authors compared these colorectal cancer cases with an adenoma-free control group examined by colonoscopy in a polytomous model with several case groups (newly diagnosed adenomas, carcinoma in situ, intramucosal carcinoma, and colorectal cancer), they found that the risk for 20-39 pack-years of smoking was elevated, although not statistically significant, and was similar for all four case groups. The risk for the highest smoking category (> or = 40 pack-years) was more strongly elevated in all four case groups, although it was statistically significant for only the newly diagnosed adenoma and the carcinoma in situ cases (adenomas, OR = 1.59, 95% CI 1.05-2.42; carcinoma in situ, OR = 2.05, 95% CI 1.01-4.15; intramucosal carcinoma, OR = 1.30, 95% CI 0.61-2.77; and colorectal cancer, OR = 1.30, 95% CI 0.64-2.65). While the authors' study is weakened by the lack of statistical significance concerning risk for colorectal cancer, these data offer some support for the hypothesis that the association between cigarette smoking and risk of colorectal cancer may have been masked by inclusion in the control group of subjects with adenomas. They also suggest that the major effect of smoking on the colorectal adenoma-carcinoma sequence occurs in the earlier stages of the formation of adenoma and the development of carcinoma in situ.     

反馈线性化在液压型风力发电机组功率追踪中的应用

以液压型风力发电机组为研究对象,为使功率追踪的过程平稳,研究机组的最佳功率追踪控制方法.本文利用反馈线性化方法解决系统非线性问题,以液压系统压力为控制输出,设计最佳功率追踪控制器,并提出一种反馈线性化方法的工程应用解决方案,即结合传统PID控制解决反馈线性化工程应用中依赖模型参数精度的问题.依托30 k VA液压型风力发电机组半物理仿真实验台进行仿真和实验研究,验证了该方法的可行性,为机组进一步研究奠定理论与实验基础.