China
Africa
Explore chapters and articles related to this topic
Organizing with Unix
Published in Rafael A. Irizarry, Introduction to Data Science, 2019
Most Unix commands can be run with arguments. Arguments are typically defined by using a dash - or two dashes -- (depending on the command) followed by a letter or a word. An example of an argument is the -r behind rm. The r stands for recursive and the result is that files and directories are removed recursively, which means that if you type: rm -r directory-name
Integrated control of highway traffic flow
Published in Journal of Control and Decision, 2018
Yihang Zhang, Petros A. Ioannou
In this section, an integrated variable speed limit, ramp metering and lane change controller is proposed. The goal is to maintain the bottleneck flow at the maximum possible level and homogenise the traffic conditions in the overall controlled highway segment. Considering the fact that RM controllers have been widely deployed in the United States, we assume that the RM control command is determined before the VSL and design the VSL controller to coordinate with the RM and stabilise the traffic flow. Then, we introduce the ALINEA/Q ramp metering strategy to manage the on-ramp flows and the queue lengths on the ramps.
Travel time models for the rack-moving mobile robot system
Published in International Journal of Production Research, 2020
Kun Wang, Yiming Yang, Ruixue Li
AnyLogic software is used to simulate a command cycle of the RM machine in various scenarios of different layouts in RMMRs and to validate the accuracy of the analytical model. On the basis of the simulation flowchart of the command cycle of the RM machine, the simulation procedure using AnyLogic involves generation of the initial layout, creation of the picking order, and setting of parameters, variables, and functions.
Optimal periodic preventive maintenance policy for a system subject to failures/repairs which follow the non-homogeneous pure birth process
Published in Quality Technology & Quantitative Management, 2021
Yu-Hung Chien, Zhe George Zhang, Siping Su, Shey-Huei Sheu
Most periodic PM models for repairable systems have been studied by assuming that the failure process between two PMs follows a Non-homogeneous Poisson process (NHPP), which represents that the CM performed on each failure is the minimal repair type. ‘Minimal repair’ means that the state of the system after the repair is restored to the state prior to the failure (i.e., as-bad-as-old condition). In other words, after a minimal repair action, the system is operational, but the failure rate of the system remains unchanged. Although the minimal repair assumption makes the analysis more tractable (e.g., nice mathematical properties for the optimal solutions in maintenance optimization), it does have some limitations. For example, when a component in a complex (multi-component) system fails, other adjacent components may be negatively affected (or even damaged to a certain degree) due to the operating condition changes (pressure, temperature, or humidity) caused by this failure. This eventually results in system degradation, which increases the system failure rate. This means that the repair can be ‘worse-than-minimal-repair’ type. Such a realistic system behavior cannot be captured by using the NHPP to model the failure/repair process between the two consecutive PMs. Sheu et al. (2012a, 2012b, 2013a, 2013b, 2013c, 2014, 2016) considered a repairable system with a new repair type, called the Non-Homogeneous Pure Birth Process (NHPBP) which is a kind of ‘worse-than-minimal-repair’. They assumed the system is subject to shocks that arrive according to an NHPBP. As shocks occur the system has two types of failures: one that can be removed by a general repair (CM) and the other that can be removed only by an unplanned replacement (RM). Sheu et al. (2012a) considered an age replacement policy where a planned RM happens whenever an operating system reaches age T. Sheu et al. (2012b) studied a block replacement policy where an operating system is replaced preventively by a planned RM every T time units to reduce the chances of more expensive unplanned RMs. Sheu et al. (2013a, 2013b) further investigated the age replacement policy for a two-unit system. Sheu et al. (2013c) proposed a more general bivariate replacement policy (n, T) under which the system is replaced at planned life age T (planned RM), or at the nth type I failure or at any type II failure (unplanned RM), whichever occurs first. Sheu et al. (2014, 2016) determined the optimal number of CMs before RM and further proposed a modified two-variable block replacement policy. Based on the NHPBP repairable system that is proposed by Sheu et al. (2012a, 2012b; 2013a, 2013b, 2013c, 2014, 2016), Chien (2019b) focuses on deriving an optimal PM scheme for a system under the free-repair warranty.