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Propeller Analysis
Published in James DeLaurier, Aircraft Design Concepts, 2022
Upon having confidence that an efficient propeller will result from these calculations, an initial estimate of ηestimated=0.8 may be made. Then the resulting value of Pdesign should be compared with the motor's power curve. If this value is above the motor's maximum power, then clearly, the aircraft is not capable of sustained flight. If properly selected, though, the design power Pdesign, will fall comfortably upon the left-hand side of the curve, as shown above. This gives a power margin for climbing and maximum speed.
Emerging Wide-Area Power Applications with Mission-Critical Data Delivery Requirements
Published in David Bakken, Krzysztof Iniewski, Smart Grids, 2017
The reactive power Qmeasured is collected at each bus at time instant ti Then, the inductive loading at each bus is incremented by a real-time simulation until the system becomes unstable. This is the estimated value Qcollapse. The difference is the reactive power margin at that time. When QVmargin crosses a defined threshold, the system is assessed as becoming unable to handle the reactive power demands. It is important that all measurements are taken at the same time to improve accuracy and to ensure that measurement artifacts are not causing artificial convergence issues. More sophisticated methods utilizing time-synchronized measurements have also been developed [27,28]. Once a system is assessed as becoming unstable, the information is provided to the operators, who can then adjust reactive power or generation dispatch to alleviate the situation.
mm-Waves in the Internet of Nano-Things
Published in Fadi Al-Turjman, Internet of Nano-Things and Wireless Body Area Networks (WBAN), 2019
Fadi Al-Turjman, Jehad Hamamreh
Despite the varying advantages offered by the mm-Waves, they suffer from a number of critical problems that must be resolved. There is a need to distinguish between different standards for broader market exploitation; the IEEE 802.15.3c is positioned to provide gigabit rates and longer operating range [12]. At these rates and ranges, it is a nontrivial task for millimeter -wave systems to provide sufficient power margin that assures a reliable communication link. Furthermore, delay spread across the communication channel is another limiting factor for high-speed transmissions.
Detection of DoS attacks exploiting SUBSCRIBE messages of the MQTT protocol
Published in International Journal of Computers and Applications, 2022
Dmitrii Dikii, Aleksey Tikhomirov
With the development of information technologies, new methods for information processing, transmitting, and storing are created and the existing methods improved. One of these technologies is the Internet of Things (IoT). Data processing tools, transmitting protocols, and algorithms are developed for the IoT technologies to operate effectively in limited calculating and energy resource conditions. For example, technologies exist that allow transmitting information from the autonomous sensor to the server at a distance more than 10 kilometers under favorable conditions through wireless connection [1,2]. Interoperable protocols of application layer as well as of the physical and data-link layers are developed [3]. The example of such a protocol is MQTT. This protocol, built on the ‘publisher-subscriber’ structure, has many advantages over the most common in the Internet client-server architecture. It is convenient for multicasting in conditions of limited electric power margin in a transmitting device. The service headers in this protocol’s messages are small which contribute to energy-conserving data transfer. Along with the advantages of this protocol, it has several disadvantages in the field of information security.
Distributed parameter-based voltage stability index for identification of critical lines and voltage stability margin in power system
Published in Cogent Engineering, 2018
The proposed index is also capable of measuring the reactive power margin of a line. Margin of reactive power can be measured by multiplying () with maximum reactive loading. Maximum reactive loading is the permissible loading at which index reaches near unity value. Case study for IEEE 30-bus test system is presented below.
Reliability evaluation of power systems with massive penetration of photovoltaic generation
Published in Journal of International Council on Electrical Engineering, 2019
Ryo Yamaguchi, Yoshiki Nakachi, S. C. Verma, Takao Tsuji, Tsutomu Oyama
This paper first proposes two indices, the power margins PMij and PMi, to evaluate the power systems in the viewpoint of capacity constraint. In this paper, power margin means available capacity. These indices exhibit power that can be supplied to another network before the loop switching operation.