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Design of drainage canals, pumps and structures
Published in Willem F. Vlotman, Lambert K. Smedema, David W. Rycroft, Modern Land Drainage, 2020
Willem F. Vlotman, Lambert K. Smedema, David W. Rycroft
The normal tidal movement of the sea level, resulting from the mutual attraction between the moon and the earth and the rotation of the earth, generally conforms to a sinusoidal type of curve as shown in Figure 13.13 with two high and two low levels within each lunar day (semi-diurnal tide). Diurnal tides with one high and one low tide per lunar day, however, also occur. The lunar day is longer than a calendar day (24 hours and 50 minutes), resulting in the about one-hour daily shift in the time of occurrence of the highest and lowest levels. The sun also has an influence. At full and at new moon the forces exerted by the moon and the sun on the earth reinforce each other, generating the largest tidal range. This situation is termed spring tide (Figure 13.13). At half moon the forces oppose each other, resulting in the smallest tidal range in a lunar cycle, termed neap tide.
Solar and Lunar Effects on Built Environment
Published in Masanori Shukuya, Bio-Climatology for Built Environment, 2019
According to the apparent solar time described in section 4.1, one day is the period from the time when the Sun is on the meridian, due south, and appears again next time on the meridian on the following day. It is called one solar day. As can be seen in Fig. 4.11, there is one other day called lunar day. Its length is from when point P on the Earth faces the Moon exactly on the meridian, due south, and to when it faces again exactly the Moon. It is obviously longer than one solar day because the Moon moves a bit while one solar day lasts. The Moon revolves once taking 29.53 days as was shown in Fig. 4.8. Provided that one solar day is defined as 24 hours, then one lunar day is 24.89 hours. When the line drawn between point P and the centre of the Earth exactly overlaps the line between point P and the Moon, the gravitational force exerted by the Moon at point P is the largest and when the two lines are perpendicular to each other, it becomes the smallest. This is why high and low tides appear twice, respectively, for the period of one lunar day.
Active Filters
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
With the development of aerospace exploration, design considerations for extreme environments have attracted attentions [21]. The extreme environments, such as temperature, radiation, pressure, and vibration, will preclude the use of conventional ICs that are designed for operation, actuation, and movement under terrestrial ambient conditions. The extreme temperature conditions (+120°C at lunar day and −180°C at lunar night) on the lunar surface can easily invalidate conventional electronic components and systems for control, sensing, and communication. This is problematic, since the development of modular, expandable, and reconfigurable human and robotics systems for lunar missions requires electronic components and integrated packaged electronics modules that can operate robustly without external thermal control. Designing robust electronic systems for over 300°C (cyclic) temperature variations has never been attempted, until recently [22,23].
Mineral Processing and Metal Extraction on the Lunar Surface - Challenges and Opportunities
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Matthew Shaw, Matthew Humbert, Geoffrey Brooks, Akbar Rhamdhani, Alan Duffy, Mark Pownceby
The synodic period on the Moon, a lunar day, is 29.53 (Earth) days or 708.72 hours (Reese, Chang and Dupuy 1989). This results in two Earth weeks of constant access to sunlight and an equal time with no access to sunlight. The illumination on the lunar surface during the day averages 1361 W/m2 (Kaczmarzyk, Gawronski and Piatkowski 2018) which varies throughout the year and decreases based on the angle of incidence. This is the same flux that hits the upper atmosphere of Earth, however, on the Moon this solar flux is not attenuated by the atmosphere and weather phenomenon.