不同饵料、密度和池底对锯缘青蟹大眼幼体蜕皮变态的影响

实验观察了不同饵料、池底、密度对锯缘青蟹大眼幼体蜕皮变态率和残杀率的影响.实验结果表明:投喂裸腹蚤时,大眼幼体蜕皮变态率最高,3种池底大眼幼体蜕皮变态率平均为 78.1%,残杀率最低平均为 11.4%;海泥池底大眼幼体蜕皮变态率最高,投喂3种饵料的大眼幼体蜕皮变态率平均为84.8%,残杀率最低平均为7.6%;裸腹蚤是青蟹大眼幼体培育适宜的饵料,而海泥则是大眼幼体变态适宜的池底.不同培育密度对青蟹大眼幼体蜕皮变态率和残杀率的实验结果表明:当大眼幼体的培育密度为3 尾/dm3 时,其蜕皮变态率最高,而残杀率与大眼幼体培育密度的关系不明确. 【英文摘要】 Effects of different dietary,densities and substrata on metamorphosis rate and cannibalistic rate from protozoea 1 (PZ1) to postlarvae 1(PL1) stages of Scylla serrata megalopae were studied in two separate experiments.In the first experiment,three dietary:Monia mongolica,minced meat of Ruditapes philippinaram which filted through mesh and haima 0 shrimp stuff and three substrata:sea mud,sand and cement were investigated.It showed that the metamorphosis rate of megalopae was higher when it was fed Monia mong...国家海洋 863 项目“锯缘青蟹大规模人工育苗技术”(2002AA603013)资

RFRTOS: A Real-time OS Based on Linux

为满足国内工控、嵌入式、多媒体等领域的需要,我们基于红旗Linux开发了RFRTOS实时操作系统.在该系统中,作者主要承担了如下三方面的工作：Linux的时钟粒度很粗糙（10ms）,难以满足实时应用的需求.RFRTOS改变了标准Linux时钟中断的固定频率模式,通过重新设定使得时钟得以微秒（μS）为单位在任何需要的时候产生中断,并提供了标准Linux核心时钟并行运行的一个细粒度的实时核心时钟处理系统.对于SMP的支持,我们设计并实现了由用户指定CPU的实时多处理器静态调度算法;CPU预留资源的主要变化是在系统初始化时,为每个CPU创建一个强制定时器.另外,在RFRTOS中,为了改进标准Linux核心不可抢占性和防止优先级反转,我们通过中断处理线程化、互斥锁机制的改进、每次中断返回都判断是否需要重新调度等方式实现了可抢占核心和对PIP协议的支持.目前,RFRTOS已经通过测试,并作为产品投入市场销售.In real-time system, the correctness of the system depends not only on the logical result of the computation, but also on the time at which the results are produced. In hard real-time system, failure to meet deadline is considered to be a fatal fault. In soft real-time system, a few misses of soft deadlines do no serious harm, and only the system's overall performance becomes poorer and poorer when more and more jobs with soft deadlines complete late. Along with the development of compute sciences, embedded real-time system needs some services provided only in general OS. At the same time, some applications in the desktop environment also need real-time support. In order to support more sophisticated services in real-time OS, and satisfy the need of embedded system and processing control fields etc., we developed RFRTOS real-time OS based on Redflag Linux OS. In this system, I mainly undertake the following task: First, Linux's temporal granulariry is unacceptable for real-time system(lOms). Instead of using fixed rate timer interrupt, RFRTOS provides a microsecond resolution real-time timer queue running with standard Linux's timer queue concurrently. The test result shows that RFRTOS narrows timer deviation from 10ms to 30μ S (3/1000),while the overhead is less than 10μS. Second, although Linux supports SCHED_RR and SCHED_FIFO real-time scheduling policy according to POSIX standard, all these are insufficient for real-time system. In order to provide timely, guaranteed and enforced access to system resource, resouce reservation and other improved features are added in RFRTOS. As real-time scheduling test shows, a process always consumes CPU time as much as possible(C/T>>l) under stardard Linux. But in RFRTOS, the deviation of process run time is under 23 μS(include timer responsing and processing time, scheduling time etc.). Finally, RFRTOS supports static multiprocessor scheduling algorithm by which users specify a processor to execute their task. The main change in resource reservation is that an enforce-timer is created for every CPU. In addition, in order to resolve the non-preemptibility of Linux kernel and support PIP, we implement the IRQ thread, improve the spinlocks to mutex, and check for reschedule on return from every interrupt. Now, RFRTOS has passed the testing, and it has been put into market as a product

research and implementation on improving kernel premempablity of linux

随着开放源码的Linux应用逐渐普及,改进Linux的性能,使其适用于实时领域成为一个极具潜力的发展方向.在参考了与此相关的研究的基础上,该文对改善Linux核心可抢占性的方法提出了3个改进措施:中断管理进程化、改进互斥锁的机制和增加互斥锁协议支持,并在Linux 2.2系列的核心上加以实现.试验证明,这些改进达到了减少系统的抢占粒度,提高调度精度的目的

priority inheritance protocol of non-exclusive mutex and its implementation under linux

对于系统中的同步和互斥算法中，支持优先级继承协议的互斥锁在提高实时系统调度精度，增强系统的行为可预见性方面起到较为关键的作用.但较早的优先级继承算法和实现并未考虑到非独占锁，如读锁的优先级继承的问题，本文提出一种基于读锁的优先级继承协议，并给出了关于该协议的分析，在此基础上，基于Linux实现了该算法

research of process management of linux

1引言Linux作为一个多任务的操作系统,支持分时处理,由于其良好的性能,完善的设计,在服务器、台式机、嵌入实时等领域得到了广泛的应用.在操作系统的几个关键设计中,如内存管理、中断管理、进程、文件系统、进程通信等方面都有独到的特点,而作为操作系统的关键部分之一--进程管理方面,Linux作了较为周密的考虑,系统的高效、稳定很大一部分来自于进程管理的严整规划

基于TPM虚拟单调计数器的电子钱包方案的分析和扩展

针对一种基于虚拟单调计数器的电子钱包方案存在的不足,对其进行了扩展,原方案商品原子性无法得到满足,且不能够防止货币消失的问题,即其货币原子性只能得到部分满足。在原方案的基础上,将货物的交换过程考虑进来,扩展后的方案既满足货币原子性,又满足商品原子性,同时能够为顾客提供隐私保护

design and implementation of real-time scheduling in linux

作为一个分时系统,Linux的设计目标为提高吞吐率和平均响应时间,因此采取了基于时间片的调度策略,显然这种机制无法保证实时任务得到及时响应和调度.为了改进Linux操作系统的实时性能,探讨了基于Linux的实时操作系统RFRTOS中的实时调度机制.实验验证,所做改进有效地提高了Linux的调度精度,满足了软实时方面的需求

Linux互斥锁机制的研究及改进

1 引言随着Linux操作系统的成功,改进Linux的设计和性能,使其应用于实时领域吸引了许多研究人员和开发人员的注意力,Linux的实时化已有多种方案,如RTAI,RTLinux为代表的硬实时化,KuRT、ART Linux等的软实时化方案。硬实时化方案主要在中断处理、调度和时钟管理方面进行了改进工作,中断处理方面,RTAI提出的中断虚拟层减少了由于中断屏蔽而引起的调度延迟,硬实时化方案同时提供了一个具有进程管理、中断管理等基本核心服务的实时核心为实时任务服务,而原核心对于该实时核心来说是一个i-dl

a fine-grain timer scheme for real-time in linux

时钟精度直接影响到任务能否被及时响应和调度,作为一个分时系统,Linux 的10ms周期性时钟粒度是必要而且合适的.但是实时系统一般都要求微秒级的响应精度,显然Linux的时钟粒度过于粗糙.然而简单地提高时钟频率意味着时钟中断的相应处理过程将占用过多的处理器时间,从而使得整个系统的有效利用率急剧下降.为了改进Linux的实时性能,讨论了基于Linux的实时操作系统RFRTOS中的时钟粒度细化方案.实验结果显示所做改进以不大的代价有效地提高了Linux的时钟精度

用于升降机平层锁定的变杆长RSSR机构研究

在SS型施工升降机平层锁定机构中,开发了一种可变杆长的空间RSSR机构,通过串联平面正弦机构实现升降机平层锁定。该机构可依据升降机吊笼开门角度的大小,通过调整RSSR机构的杆长,保证吊笼门在不同的开门角度下,其正弦机构输出构件的位移量基本保持不变,实现平层机构的可靠工作。介绍了该装置的结构,建立了该组合机构的运动模型,给出了相关的设计计算过程,并结合实例进行了说明。研究工作为同类产品的开发提供可靠参考