China
Africa
Explore chapters and articles related to this topic
Lighting
Published in Stephen A. Roosa, Steve Doty, Wayne C. Turner, Energy Management Handbook, 2020
Eric A. Woodroof, Stan Walerczyk, Fred Hauber
Time clocks can be used to control lights when their operation is based on a fixed operating schedule. Time clocks are available in electronic or mechanical styles. However, periodic checks are needed to ensure that the time clock is controlling the system properly. After a power loss, electronic timers without battery backups can get off schedule, cycling on and off improperly. It requires a great deal of maintenance time to reset isolated time clocks if many are installed.
Time Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Both types of time measurements are referenced to the frequency of a periodic event that repeats at a constant rate. For example, this periodic event could be the swings of a pendulum. We could agree to establish a base unit of time interval by defining the second as one complete swing, or cycle, of the pendulum. Now that we have defined the second, we can measure longer time intervals, such as minutes, hours, and days, by simply counting the swings of the pendulum. This process is how a time scale is formed. A time scale is simply an agreed upon way to order events and keep time. It is formed by measuring and establishing a base time unit (the second) and then counting elapsed seconds to establish longer time intervals. A device that measures and counts time intervals to mark the passage of time is called a clock. Let’s continue our discussion by looking at the evolution of clocks and timekeeping.
Clock Synchronization in Distributed Systems Using NTP and PTP
Published in Richard Zurawski, Industrial Communication Technology Handbook, 2017
Reinhard Exel, Thilo Sauter, Paolo Ferrari, Stefano Rinaldi
A clock can be considered an instrument to measure, keep, and indicate time. Practically, all clocks are built as a two-part device: An oscillating device for defining a reference time interval (e.g., a second or fraction thereof) and a counter device, which accumulates the number of time intervals and provides a time indication. Mechanical oscillators, such as a pendulum or balance wheel, have been widely used for timekeeping until the invention of electronic oscillators. Quartz-crystal oscillators are today the most widely used oscillators, thanks to their low price, ruggedness, and low power consumption. Atomic clocks provide a much better stability than Quartz oscillators or any mechanical oscillator. They exploit the quantum effect, where the transition between two energy levels in an atom requires exactly a certain amount of energy to emit a photon. As the frequency of the emitted photon and its energy are connected by the Planck’s constant, the atomic resonance can be exploited to create a well-defined frequency. Due to the stability of the quantum transition, the SI unit second was defined in 1967 as the duration of 9,192,631,770 periods of the radiation of the two hyperfine levels of the ground state of the cesium-133 atom [2].
COVID-19 affected remote workers: a temporal analysis of information system development during the pandemic
Published in Journal of Decision Systems, 2022
Mairead O Connor, Kieran Conboy, Denis Dennehy
Since Taylorism, the ticking clock has been used as a resource which can be used to manage an organisation through the utilisation of schedules and deadlines. In organisations, time is predominately measured objectively (Shipp & Cole, 2015). However, it may be the subjective and intuitive aspect of time which garners most interesting information about how time relates to the organisation (Lord et al., 2015). Worryingly, effective management is impeded by this reliance on the dominant clock time (Adam, 1995). Traditional time management techniques focus on improving timing issues around temporal characteristics such as duration, planning, and synchronisation. Time management practices are often cited as a critical success factor for project performance (Shipp & Cole, 2015). While organisations regularly place huge emphasis on improving time management practices, they focus on improving the objective aspects of time. This leads to the overlooking of important temporal characteristics which can contribute to the improvement of time management. Furthermore, while organisations are focusing attention on how individuals use and manage time, they further neglect any understanding about how individuals think about time (Shipp & Cole, 2015).
Timing Synchronization System on RF-Driven Neutral Beam Injection System
Published in Fusion Science and Technology, 2022
Y. Li, C. D. Hu, Y. Z. Zhao, Q. L. Cui, X. L. Shu, Y. H. Xie, W. Liu
The time synchronization of the microsecond plant control system mainly needs to complete the following parts: configuring the master and slave devices, configuring the network communication function between the master and slave devices, and keeping the slave device in sync with the master device. The master device takes its own clock as the network time reference, and the slave devices receive the time reference sent by the master device in the synchronous network, corrects the time of its own system through this time reference, and completes the time synchronization. The clock synchronization test displayed by an oscilloscope is shown in Fig. 2. According to the test, we can draw the following conclusions: the master and slave clocks are not synchronized at the beginning of the experiment. After a period of correction, the two clocks can be kept basically in sync with nanosecond accuracy. This unit uses PTP as the timing principle for clock and time synchronization.
Time and freestyle piling: a subjective approach to 3D printing
Published in Digital Creativity, 2019
Yet since the introduction of the concept of standardized time in the late nineteenth century, our perception of time has been objectified by the ever-changing form of the clock. Clocks that are as small as grains of sand now punctuate the microprocessors of digital machines (e.g. computers, ‘smart’ phones, microwaves, etc.) that exist virtually everywhere across the world. These clocks count with extreme precision in order to sequence the transfer of ‘bits’ of information and ensure that our digital machines respond to us precisely when we expect them to. In computer science terms, such synchronicity is called ‘real-time computing.’ To be real-time, a computer must have ‘a system that performs its functions and responds to external, asynchronous events within a predictable (or deterministic) amount of time’ (Furht et al. 1991, 1). The clocks in computer microprocessors are responsible for maintaining such technological determinism.