A Thermo-Hydro-Mechanical True Triaxial Cell for Evaluation of the Impact of Anisotropy on Thermally Induced Volume Changes in Soils

2012 ◽  
Vol 35 (2) ◽  
pp. 103803 ◽  
Author(s):  
L. D. Suits ◽  
T. C. Sheahan ◽  
Charles James Russell Coccia ◽  
John S. McCartney
Keyword(s):  
Volume Changes ◽  
True Triaxial ◽  
Thermally Induced ◽  
Triaxial Cell ◽  
The Impact

The impact of prostate volume changes during external-beam irradiation in consequence of HDR brachytherapy in prostate cancer treatment

2009 ◽  
Vol 185 (6) ◽  
pp. 397-403 ◽  
Author(s):  
Markus Karl Alfred Herrmann ◽  
Tammo Gsänger ◽  
Arne Strauss ◽  
Tereza Kertesz ◽  
Hendrik A. Wolff ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Treatment ◽  
Prostate Volume ◽  
External Beam ◽  
Hdr Brachytherapy ◽  
Beam Irradiation ◽  
Volume Changes ◽  
Prostate Cancer Treatment ◽  
External Beam Irradiation ◽  
The Impact

Experimental Study of Capillary Radiant Cooling System with Parameters Changing

2013 ◽  
Vol 300-301 ◽  
pp. 1048-1053 ◽  
Author(s):  
Yong Hong Wang
Keyword(s):  
Room Temperature ◽  
Cooling System ◽  
Cooling Capacity ◽  
Test Methods ◽  
Radiation Response ◽  
Volume Changes ◽  
Indoor Temperature ◽  
Radiant Cooling ◽  
Radiation Laboratory ◽  
The Impact

In this paper, the test methods of radiation laboratory and data analysis in detail were introduced. The impact of the capillary system with different parameters changing, such as water temperature or water flow the capillary cooling capacity changes, and the capillary cooling system when the initial radiation response time were specificially studied. Under different parameters while cooling capillary volume changes associated with the indoor temperature can be seen under certain conditions, the capillary cooling capacity and room temperature has a linear relationship.

scholarly journals Thermally Induced Mechanical Response of Metal Foam During Laser Forming

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Tizian Bucher ◽  
Adelaide Young ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Y. Lawrence Yao
Keyword(s):  
Temperature Gradient ◽  
Mechanical Response ◽  
Metal Foam ◽  
Mechanical Performance ◽  
Image Correlation ◽  
Laser Forming ◽  
Experimental Proof ◽  
Thermally Induced ◽  
The Impact ◽  
Different Levels

To date, metal foam products have rarely made it past the prototype stage. The reason is that few methods exist to manufacture metal foam into the shapes required in engineering applications. Laser forming is currently the only method with a high geometrical flexibility that is able to shape arbitrarily sized parts. However, the process is still poorly understood when used on metal foam, and many issues regarding the foam's mechanical response have not yet been addressed. In this study, the mechanical behavior of metal foam during laser forming was characterized by measuring its strain response via digital image correlation (DIC). The resulting data were used to verify whether the temperature gradient mechanism (TGM), well established in solid sheet metal forming, is valid for metal foam, as has always been assumed without experimental proof. Additionally, the behavior of metal foam at large bending angles was studied, and the impact of laser-induced imperfections on its mechanical performance was investigated. The mechanical response was numerically simulated using models with different levels of geometrical approximation. It was shown that bending is primarily caused by compression-induced shortening, achieved via cell crushing near the laser irradiated surface. Since this mechanism differs from the traditional TGM, where bending is caused by plastic compressive strains near the laser irradiated surface, a modified temperature gradient mechanism (MTGM) was proposed. The densification occurring in MTGM locally alters the material properties of the metal foam, limiting the maximum achievable bending angle, without significantly impacting its mechanical performance.

Active monitoring of hydraulic fracture propagation: an experimental and numerical study

2011 ◽  
Vol 51 (1) ◽  
pp. 479 ◽  
Author(s):  
Amin Nabipour ◽  
Brian Evans ◽  
Mohammad Sarmadivaleh
Keyword(s):  
Hydraulic Fracturing ◽  
Real Time ◽  
Hydraulic Fracture ◽  
Numerical Study ◽  
Fluid Pressure ◽  
Active Monitoring ◽  
Fracture Width ◽  
True Triaxial ◽  
Transmitted Waves ◽  
Triaxial Cell

Hydraulic fracturing is known as one of the most common stimulation techniques performed in oil and gas wells for maximising hydrocarbon production. It is a complex procedure due to numerous influencing factors associated with it. As a result, hydraulic fracturing monitoring techniques are used to determine the real-time extent of the induced fracture and to prevent unwanted events. Although the well-known method of monitoring is the microseismic method, active monitoring of a hydraulic fracture has shown capable of providing useful information about the fracture properties in both laboratory conditions and field operations. In this study, the focus is on laboratory experiment of hydraulic fracturing using a true-triaxial cell capable of simulating field conditions required for hydraulic fracturing. By injecting high-pressure fluid, a hydraulic fracture was induced inside a 20 cm cube of cement. Using a pair of ultrasonic transducers, transmission data were recorded before and during the test. Both cases of an open and closed hydraulic fracture were investigated. Then, using a discrete particle scheme, seismic monitoring of the hydraulic fracture was numerically modelled for a hexagonally packed sample and compared with the lab results. The results show good agreements with data in the literature. As the hydraulic fracture crosses the transducers line, signal dispersion was observed in the compressional wave data. A decrease was observed in both the amplitude and velocity of the waves. This can be used as an indicator of the hydraulic fracture width. As the fracture closes by reducing fluid pressure, a sensible increase occurred in the amplitude of the transmitted waves while the travel time showed no detectable variations. The numerical model produced similar results. As the modelled hydraulic fracture reached the source-receiver line, both amplitude and velocity of the transmitted waves decreased. This provides hope for the future real-time ability to monitor the growth of induced fractures during the fraccing operation. At present, however, it still needs improvements to be calibrated with experimental results.

An Experimental Examination of the Effect of Interface Cooling on Thermal Wear Mechanisms in Carbon Graphite

2005 ◽  
Author(s):  
Daryl S. Schneider ◽  
Lyndon S. Stephens
Keyword(s):  
Heat Sink ◽  
Elevated Temperatures ◽  
Frictional Heating ◽  
Operating Conditions ◽  
Stable Operation ◽  
Mechanical Seal ◽  
Premature Failure ◽  
Thermally Induced ◽  
Wear Rates ◽  
The Impact

Premature failure of mechanical seal components is often a result of the elevated temperatures at the sealing interface that arise due to frictional heating. The Heat Sink Mechanical Seal (HSS) is a new approach to interface cooling in which a micro heat sink is constructed within millimeters of the sealing interface. Coolant circulated through the highly structured pin fin region carries away the generated heat. This work investigates the impact of interface cooling on carbon wear rates for a tungsten carbide (WC) and carbon graphite material pair. Experiments are performed using a thrust washer rotary tribometer to simulate a mechanical seal operating in dry running conditions within and in excess of the PV limit for the material pair (17.5 MPa*m/s or 500,000 psi*ft/min). Results show stable operation of sealing components in harsh operating conditions as well as the potential to reduce the occurrence of thermally induced wear and failure.

Three-year longitudinal population-based volumetric MRI study in first-episode schizophrenia spectrum patients

2013 ◽  
Vol 44 (8) ◽  
pp. 1591-1604 ◽  
Author(s):  
R. Roiz-Santiáñez ◽  
R. Ayesa-Arriola ◽  
D. Tordesillas-Gutiérrez ◽  
V. Ortiz-García de la Foz ◽  
R. Pérez-Iglesias ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Brain Volume ◽  
Early Years ◽  
Control Group ◽  
Antipsychotic Treatment ◽  
Brain Abnormalities ◽  
Volume Changes ◽  
Schizophrenia Spectrum ◽  
The Impact

BackgroundSchizophrenia is a chronic brain disorder associated with structural brain abnormalities already present at the onset of the illness. Whether these brain abnormalities might progress over time is still under debate.MethodThe aim of this study was to investigate likely progressive brain volume changes in schizophrenia during the first 3 years after initiating antipsychotic treatment. The study included 109 patients with a schizophrenia spectrum disorder and a control group of 76 healthy subjects. Subjects received detailed clinical and cognitive assessment and structural magnetic resonance imaging (MRI) at regular time points during a 3-year follow-up period. The effects of brain changes on cognitive and clinical variables were examined along with the impact of potential confounding factors.ResultsOverall, patients and healthy controls exhibited a similar pattern of brain volume changes. However, patients showed a significant lower progressive decrease in the volume of the caudate nucleus than control subjects (F1,307.2 = 2.12, p = 0.035), with healthy subjects showing a greater reduction than patients during the follow-up period. Clinical and cognitive outcomes were not associated with progressive brain volume changes during the early years of the illness.ConclusionsBrain volume abnormalities that have been consistently observed at the onset of non-affective psychosis may not inevitably progress, at least over the first years of the illness. Taking together with clinical and cognitive longitudinal data, our findings, showing a lack of brain deterioration in a substantial number of individuals, suggest a less pessimistic and more reassuring perception of the illness.

The Studies of Rock Damage Softening Statistical Constitutive Model under True Triaxial Stress State

2014 ◽  
Vol 580-583 ◽  
pp. 312-315
Author(s):  
Hui Mei Zhang ◽  
Xiang Miao Xie ◽  
Geng She Yang
Keyword(s):  
Constitutive Model ◽  
Strain Curve ◽  
Stress Path ◽  
Complex Stress ◽  
Model Parameters ◽  
Stress Strain ◽  
Deformation And Failure ◽  
True Triaxial ◽  
Complex Stress Path ◽  
The Impact

From the feature of rock micro-unit failure obeys Poisson random distribution, the damage softening statistical constitutive of was established under true triaxial confinement based on D-P criterion, so the impact of the intermediate principal stress on rock deformation and failure was considered in theory, and the actual engineering rock complex stress path evolution was reflected more realistically. Furthermore, according to the geometrical conditions of stress-strain relationship, the theoretical relationship between constitutive model parameters and the stress-strain curve characteristic parameters during the process of rock softening and deforming, which enhance the adaptability of the model. Finally, the rationality of the model verified by the measured data.

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