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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
The general-purpose operating systems can be classified into four types: the batch systems, timesharing systems, real-time systems, and distributed systems. A batch system is an early type of operating systems that runs similar jobs sorted by an operator as a batch through an operation console. A timesharing system is a type of multitasking operating systems that executes multiple jobs by automatically switching among them with predefined time slice. A real-time operating system is a type of special-purpose operating systems that is designed for dealing with highly time-constraint events of I/Os and processes for control systems. A distributed operating system is a type of operating systems that supports networking, communication, and file sharing among multiple computers via a network protocol [Sloane, 1993; Tanenbaum, 1994].
Mixed-Signal Integrated Systems: Limitations and Challenges
Published in Tertulien Ndjountche, CMOS Analog Integrated Circuits, 2017
The functional description is realized by an analog circuit and a digital circuit, which can be designed and verified using various computer-aided design programs such Cadence, Synopsys, and Mentor Graphics tools. When the data processing in the digital domain may require processors or microcontrollers, the design of a real-time operating system (RTOS), application software and device driver is necessary. Besides allowing a modular and scalable programming approach, the desirable features of an RTOS include the ability to provide basic support for task scheduling, resource management, inter-task and input-output communication such that the processor functionality is available to application software in an optimized and predictable way. Stateflow is an interactive design and simulation tool that can be used to describe complex logic, such as an RTOS, in a form that can easily be coded using C/C++ language or assembler.
Software Design Considerations for Real-Time DSP Systems
Published in Gillian M. Davis, Noise Reduction in Speech Applications, 2018
There are various reasons for a multitasking DSP to suspend. A task may be blocked due to resource access control. A task may be waiting to synchronize execution with some other task. The task may be held waiting for some reason (I/O completion and jitter control). There may be no budget or job to execute (this is a form of bandwidth control). The RTOS maintains different queues for tasks suspended or blocked for different reasons (e.g., a queue for tasks waiting for each resource). The RTOS may also keep a number of task-ready queues. In fixed priority scheduling, there will be a queue for each priority. Rather than simply admitting the tasks to the CPU, the RTOS scheduler makes a decision based on the task state and priority.
Predicting the effects of task jitter in digital control systems
Published in Australian Journal of Electrical and Electronics Engineering, 2022
Long Tran, P. J. Radcliffe, Liuping Wang
Simulation of jitter can be very fast and help to overcome the testing time limitations when using real hardware. TrueTime Simulink toolbox (Cervin et al. 2003) can be an excellent tool to simulate a real-time operating system and then jitter patterns can be observed. But there is no guaranty that those jitter patterns are the same as ones in a real hardware platform. The effect of task jitter on a motor speed controller was investigated by (Tran, Radcliffe, and Wang 2017) where a novel method to simulate sampling jitter in the simulation was presented. There was an excellent match between simulation and real hardware. Results Figure 1 from show some patterns of task jitter resulted in significant increases in overshoot. It was observed that applying random task jitter did not always uncover these extreme cases. Some analysis method were proposed such as JitterBug (Cervin et al. 2003) and Jitter Margin (Behnam and Isovic 2007) to evaluate average and worst-case performance. While the JitterBug tool is limited at the evaluation of average performance, the tool Jitter Margin ignores the jitter in the sampling task hence it will not be practical. It was concluded that very large numbers of simulation runs may be required to uncover these extreme events. Testing a real system to uncover such behaviour may not be practical especially with slow systems such as thermal controllers. This work suggested that jitter RMS would not predict rare and extreme behaviour.
Enhancements to the New TREAT Automatic Reactor Control System (ARCS)
Published in Nuclear Technology, 2021
Benjamin Allen Baker, Kurt D. Fielding, Jacob E. Hansen, Tanner Ellsworth
When TREAT was restarted, ARCS ran on several Intel 8086 CPU boards and was written in an assembly code from the 1980s. A decision was made to replace the ARCS system with a modern software and hardware platform. The system was upgraded to several PXI chassis running a real-time operating system that executes the LabVIEW code. In addition, the code was set up in a way that a majority of code could be run without hardware and input/output, making it possible to run the code on a desktop computer for simulation purposes. This program is called pocket ARCS or PARCS, and a lighter and faster version is called small ARCS. ARCS is composed of many nodes with specific purposes. The control node is responsible for commanding the control of the transient rods, the monitor node plays a data acquisition and supervisory role, the simulator node performs simulation of the core and rods, and the program timer node provides digital signals to external systems. The reactor operates in four modes: full simulation, partial simulation, actual transient, and rod drop. The full simulation mode performs a transient while simulating the reactor core and rods. The partial simulation mode simulates the reactor core but moves the transient rods while the reactor is shut down. The actual transient and rod drop modes are self-explanatory. For an extensive overview of the entire ARCS system and theory, the reader is directed to Ref. 6.
Special issue on ‘smart computing and communication’ in International Journal of Parallel, Emergent and Distributed Systems
Published in International Journal of Parallel, Emergent and Distributed Systems, 2020
Big data generates urgent needs for a large amount of data retrieval in the distributed systems like clouds. To fill this gap, the eighth article studies the usage of fog computing to efficiently manage the Internet service and resources. The cost and resources can be reduced and the billing can be attained through a calculation of the utilised resources. The ninth article presents a research on the total amount of literature in the treatment of cardiovascular diseases by traditional Chinese medicine is on the rise. The tenth article proposes the distributed dynamic cuckoo filter system based on Redis cluster and an efficient hash indexing structure – dynamic cuckoo filter was presented. The eleventh article presents a new attributes recognition model using Feature Nets that can improve emotion recognition performance and generalisation capabilities. Meanwhile, in order to accelerate the big data process, the twelfth article studies a new NMF-based mixed data analysis algorithm with maximum overall coverage constraints introduced in traditional NMF. The thirteenth article studies an unsupervised tool for automatically reverse the format of the industrial protocol from network trace that applies an extended voting expert algorithm to infer the boundaries of industrial protocol fields. The fourteenth article gives the new design of the real-time operating system scheduling mechanism based on time deterministic cyclic scheduling for live multimedia tasks processing in the real-time hyper-physical system.