Dome Displacement Research Articles

Rainfall-induced Gravity Movement of the Unzen-Fugendake Volcanic Dome Analysis combining Ground-Radar Interferometry and XRAIN Rainfall radar system

Lava domes created by volcanoes often cause pyroclastic and debris flows, which have a significant impact on the surrounding infrastructure and population and have been the subject of much research. However, because volcanic domes tend not to survive the eruptions that form them, the instability of domes that survive eruptions such as Unzen Fugendake in Japan is both a poorly understood process and a danger. Therefore, the present contribution aims to (1) Displacement and precipitation from 2018 to 2020 for lava domes at Unzen volcano and their relationship to earthquakes, and (2) Haar wavelet analysis to understand the response of displacement to precipitation. The method is based on dome displacement from the Unzen Ground Based Synthetic Aperture Radar system and 48-hour rainfall from the MP radar rain gauge system. As a result, the authors confirmed the following: (1) precipitation of 150 mm or more in 48 hours tends to increase the vertical fluctuation of the dome, and even rainfall of less than 100 mm per 48 hours has a similar effect when it is repeated in an intensive manner; (2) After precipitation, major dome displacement can take days or weeks to occur, and is not instantaneous like the dome collapses in Soufriere and Merapi.

Structural Characteristics of Hagia Sophia under Consideration of the Ribs Inside the Dome

In this study, an analytical model of Hagia Sophia, modeled by the shell and the ribs was prepared to clarify the structural characteristics of the main dome depending on the effect of displacements and stresses of the dome with and without 40 ribs. A tetrahedral secondary elements were adopted to mesh. As the results, in displacement, the maximum amount of displacement of dome with ribs is smaller than that without ribs. Therefore, ribs is effective to prevent the deformation. In the equivalent stress of dome with ribs is smaller than that without ribs. Therefore, ribs was effective for reducing the stress of the dome between the openings.

SU‐E‐J‐176: A Simple 4D MRI Technique for Radiation Therapy Planning

Purpose: 4D CT is routinely performed for radiation therapy planning when patient motion is a significant factor. As more benefits of using MRI become clearer in treatment planning, the feasibility of 4D MRI, however, has been questionable. The challenge of 4D MRI is the balance between satisfactory image quality and the speed to capture patient breathing cycle. So far, neither the image quality nor the speed has been satisfactory. Here, a simple MRI technique to do 4D MRI is introduced. Methods: 3T MRI (Philips Ingenia) was used for scanning. For monitoring breathing cycles, a regular respiratory belt was used. The breathing cycle was then divided into multiple phases. For each breathing phase, a predefined respiratory trigger time was set and the multi‐slice (30 slices) MRI scan was performed for each breathing phase. A single‐shot fast spin echo with partial k‐space filling was used with varied trigger time from 0 up to the length of breathing cycle. Results: As seen in Fig 1 (1 of 30 slices), the image quality for each breathing phase is quite good. The line profiles from the line ROI in Fig 1, which was placed over the liver dome, are shown in Fig 2 for a few different breathing phases. The position of the line was fixed across the breathing phases to see the displacement caused by breathing. This demonstrates the liver dome displacement (along the x axis) during breathing cycles. Conclusion: The 4D MRI for treatment planning can be done with satisfactory imaging quality and speed with a regular respiratory triggering technique, which can be directly implemented on most MRI devices without the need of extra device. However, since only a brief time‐window during each breathing cycle is used for acquisition, total acquisition time may be longer (∼30 min), and the improvement is undergoing.

Gas Pressure Profile Prediction from Variable Strain Rate Deformation Paths in AA5083 Bulge Forming

Two approaches to gas pressure profile prediction for bulge forming of AA5083 sheet under Quick Plastic Forming (QPF) conditions at 450 °C were investigated. The first was based on an algorithm internal to ABAQUS™ wherein the gas pressure results from maintaining a constant effective target strain rate at the dome pole. In the second, the nonlinear long wavelength stability analysis was combined with a single creep mechanism material model that accounts for hardening/softening. A series of stability curves, which denote combinations of strain and strain rate for unmitigated thinning and, ultimately, rupture of an AA5083 bar, were computed. These are based on a parameter that characterizes an assumed geometric non-uniformity, η. The associated uniaxial strains and strain rates were expressed in terms of von Mises effective strains and strains rates, and pressure profiles were computed. An ancillary approach to variable strain rate path prediction based on a thinning factor was used to suggest a suitable value of η in the stability analysis for a reasonable thinning level at the end of forming. Key advantages and disadvantages of both approaches to pressure profile prediction are examined relative to bulge forming time and thinning at a 50-mm dome displacement.

Mechanisms of the inspiratory action of the diaphragm during isolated contraction

The lung-expanding action of the diaphragm is primarily related to the descent of the dome produced by the shortening of the muscle fibers. However, when the phrenic nerves in dogs are selectively stimulated at functional residual capacity, the muscle insertions into the lower ribs also move caudally. This rib motion should enhance the descent of the dome and increase the fall in pleural pressure (DeltaPpl). To quantify the role of this mechanism in determining DeltaPpl during isolated diaphragm contraction and to evaluate the volume dependence of this role, radiopaque markers were attached to muscle bundles in the midcostal region of the muscle in six animals, and the three-dimensional location of the markers during relaxation at different lung volumes and during phrenic nerve stimulation at the same lung volumes was measured using computed tomography. From these data, accurate measurements of muscle length, dome displacement, and lower rib displacement were obtained. The values of dome displacement were then corrected for lower rib displacement, and the values of DeltaPpl corresponding to the corrected dome displacements were obtained using the measured relationship between DeltaPpl and dome displacement. The measurements showed that phrenic stimulation at all lung volumes causes a caudal displacement of the lower ribs and that this displacement, taken alone, contributes approximately 25% of the DeltaPpl produced by the diaphragm. To the extent that this lower rib displacement is itself caused by DeltaPpl, the lung-expanding action of the diaphragm during isolated contraction may therefore be viewed as a self-facilitating phenomenon.

Force and Displacement Preferences for an Alternative Keyboard

Over the past several years, much attention has been given to repetitive strain injuries (RSI's) in the office environment. Perhaps the most common and widely publicized of these RSI's is carpal tunnel syndrome (CTS). CTS is an insidious, progressive RSI that affects millions of typists every year. The effects of CTS are far reaching. In the office, CTS reduces worker job satisfaction and productivity which may ultimately affect the company's bottom line. U.S. businesses spend in excess of $10 billion each year to combat the CTS problem. The AID-CTS keyboard (commercially referred to as the OrbiTouch by Keybowl, Inc.) is an alphanumeric input system that is developed to combat CTS and numerous other upper extremity disabilities. It is designed to offer all typists a more comfortable means of typing and navigation. The purpose of the current study was to determine what combination of dome force and dome displacement were most acceptable to the user. A study was conducted to evaluate different dome forces and different dome displacements using a variable force joystick to establish the most appropriate range of acceptable force and displacement characteristics. The study resulted in an optimum force and displacement that minimizes arm and wrist movements while maximizing user comfort.

The theory of a piezoelectric plastic film transducer for earphones

The author is concerned with the theory of a domed piezoelectric plastic film which can be used as a combined diaphragm and transducer element in an earphone. In his model the diaphragm is held in a dome shape by a pressure, P, applied to one side. It is shown that the centre of the dome is displaced from the perimeter plane by a distance which varies as P1/3 at high pressures. At low pressures the displacement depends on the state of the diaphragm before pressure is applied. An electric field applied across the film thickness changes the dome displacement through the piezoelectric effect. For large P and small electric fields the change of displacement is linearly proportional to the field and varies as P-1/3. As P to 0 the behaviour is more complicated.