398 research outputs found
Alternatives to monism and dualism: seeking yang substance with yin mode in Heshanggong's commentary on the Daodejing
This project is a close study and translation of Heshanggong's Commentary on the Daodejing. The text, attributed to the "Old Man by the River" (Heshanggong) and dating from the Eastern Han (25-220 CE), remains one of the most historically influential readings of the Daoist classic the Daodejing. However, in modern times it has received little attention, being dismissed as a superstitious interpretation of the original. This dissertation seeks to amend contemporary scholarship and address the underlying theoretical categories responsible for this situation. These problems largely originate from a common scholarly view of Chinese civilization as foundationally monistic. Because of this bias, any hints of transcendence found in the commentary are read as later "religious" distortions of the original "philosophical" holism of the Daodejing. Rather than engaging with debates over whether Daoism is monistic or dualistic, philosophical or religious, this dissertation shifts focus away from those Western constructs. It instead draws on different binaries found within the commentator's own writings. In particular, the categories of yin and yang become central to a native reading of this tradition. Furthermore, I argue that Heshanggong's approach rests on subdividing both yin and yang into a causal relationship of mode and substance. I use this fourfold conceptual framework to analyze the key themes of the commentary, including cosmology, body, and state. So doing reveals the novelty of Heshanggong's responses to a range of conceptual and historical issues in Early China (6th century BCE-3rd century CE). First, the mode-substance reading of yin-yang challenges depictions of early Daoism as having a solely "correlative cosmos": uncreated, relativistic, and perfectly united through spontaneous resonance. Instead, it suggests a single cosmic substance originating from a first cause, the yin mode of the Way (that includes stillness, emptiness, darkness, and softness). Second, this means that contrary to the often-asserted historical split between monistic "philosophical" Daoism and dualistic "religious" Daoism, one finds a continuous tradition that seeks Heavenly spirit (yang substance) through stillness (yin mode). By excising monism and dualism from the discussion, a greater awareness of historical progression and cosmological nuance appears
Dynamics of Water Entry
The hydrodynamics associated with water-entry of spheres can be highly
variable with respect to the material and kinematic properties of the sphere.
This series of five fluid dynamics videos illustrates several subtle but
interesting variations. The first series of videos contrasts the nature of
impact between a hydrophilic and hydrophobic sphere, and illustrates how
surface coating can affect whether or not an air cavity is formed. The second
video series illustrates how spin and surface treatments can alter the splash
and cavity formation following water entry. The spinning sphere causes a wedge
of fluid to be drawn into the cavity due to the no-slip condition and follows a
curved trajectory. The non-spinning sphere has two distinct surface treatments
on the left and right hemispheres: the left hemisphere is hydrophobic and the
right hemisphere is hydrophilic . Interestingly, the cavity formation for the
half-and-half sphere has many similarities to that of the spinning sphere
especially when viewed from above. The third video series compares two
millimetric nylon spheres impacting at slightly different impact speeds (Uo =
40 and 45 cm/s); the faster sphere fully penetrates the free surface, forming a
cavity, whereas the slower sphere does not. The fourth series shows the
instability of an elongated water-entry cavity formed by a millimetric steel
sphere with a hydrophobic coating impacting at Uo = 600 cm/s. The elongated
cavity forms multiple pinch-off points along its decent. Finally, a millimetric
steel sphere with a hydrophobic coating breaks the free surface with an impact
speed of Uo = 350 cm/s. The cavity pinches-off below the surface, generating a
Worthington jet that pinches into droplets owing to the Rayleigh-Plateau
instability.Comment: American Physical Society Division of Fluid Dynamics Gallery of Fluid
Motion Video Entry Replaced previous version because abstract had LaTex
markup and was too lon
Quantitative Flow Field Imaging about a Hydrophobic Sphere Impacting on a Free Surface
This fluid dynamics video shows the impact of a hydrophobic sphere impacting
a water surface. The sphere has a mass ratio of m* = 1.15, a wetting angle of
110 degrees, a diameter of 9.5 mm, and impacts the surface with a Froude number
of Fr = 9.2. The first sequence shows an impact of a sphere on the free surface
illustrating the formation of the splash crown and air cavity. The cavity grows
both in the axial and radial direction until it eventually collapses at a point
roughly half of the distance from the free surface to the sphere, which is
known as the pinch-off point. The second set of videos shows a sphere impacting
the free surface under the same conditions using Particle Image Velocimetry
(PIV) to quantify the flow field. A laser sheet illuminates the mid-plane of
the sphere, and the fluid is seeded with particles whose motion is captured by
a high-speed video camera. Velocity fields are then calculated from the images.
The video sequences from left to right depict the radial velocity, the axial
velocity, and the vorticity respectively in the flow field. The color bar on
the far left indicates the magnitude of the velocity and vorticity. All videos
were taken at 2610 fps and the PIV data was processed using a 16 x 16 window
with a 50% overlap.Comment: American Physical Society Division of Fluid Dynamics 2008 Annual
Meeting Replaced previous version because abstract had LaTex markup and was
too long, missing periods on middle initial of first two name
Drop on a Bent Fibre
Inspired by the huge droplets attached on cypress tree leaf tips after rain,
we find that a bent fibre can hold significantly more water in the corner than
a horizontally placed fibre (typically up to three times or more). The maximum
volume of the liquid that can be trapped is remarkably affected by the bending
angle of the fibre and surface tension of the liquid. We experimentally find
the optimal included angle () that holds the most water.
Analytical and semi-empirical models are developed to explain these
counter-intuitive experimental observations and predict the optimal angle. The
data and models could be useful for designing microfluidic and fog harvesting
devices
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