Apatite fission track analysis: geological thermal history analysis based on a three-dimensional random process of linear radiation damage

1990 ◽  
Vol 332 (1627) ◽  
pp. 419-438 ◽  
Keyword(s):  
Random Process ◽  
Three Dimensional ◽  
Temperature History ◽  
Apatite Crystal ◽  
Maximum Temperature ◽  
Geological Time ◽  
Full Likelihood ◽  
History Analysis ◽  
History Of ◽  
Uplift And Erosion

Spontaneous fission of uranium atoms over geological time creates a random process of linearly shaped features (fission tracks) inside an apatite crystal. The theoretical distributions associated with this process are governed by the elapsed time and temperature history, but other factors are also reflected in empirical measurements as consequences of sampling by plane section and chemical etching. These include geometrical biases leading to over-representation of long tracks, the shape and orientation of host features when sampling totally confined tracks, and ‘gaps’ in heavily annealed tracks. We study the estimation of geological parameters in the presence of these factors using measurements on both confined tracks and projected semi-tracks. Of particular interest is a history of sedimentation, uplift and erosion giving rise to a twocomponent mixture of tracks in which the parameters reflect the current temperature, the maximum temperature and the timing of uplift. A full likelihood analysis based on all measured densities, lengths and orientations is feasible, but because some geometrical biases and measurement limitations are only partly understood it seems preferable to use conditional likelihoods given numbers and orientations of confined tracks

Optimization of Laser Hardening Processes for Industrial Parts With Complex Geometry via Predictive Modeling

2009 ◽  
Author(s):  
Neil S. Bailey ◽  
Yung C. Shin
Keyword(s):  
Phase Transformation ◽  
Thermal Model ◽  
Complex Geometry ◽  
Solid Phase ◽  
Three Dimensional ◽  
Laser Hardening ◽  
Temperature History ◽  
Temperature Phase ◽  
Laser Systems ◽  
History Of

A predictive laser hardening model for industrial parts with complex geometric features has been developed and used for optimization of hardening processes. A transient three-dimensional thermal model is combined with a three-dimensional kinetic model for steel phase transformation and solved in order to predict the temperature history and solid phase history of the workpiece while considering latent heat of phase transformation. Further, back-tempering is also added to the model to determine the phase transformation during multitrack laser hardening. The integrated model is designed to accurately predict temperature, phase distributions and hardness inside complex geometric domains. The laser hardening parameters for two industrial workpieces are optimized for two different industrial laser systems using this model. Experimental results confirm the validity of predicted results.

An X-ray Diffraction Method for the Determination of Temperatures in Coke Reactions

1984 ◽  
Vol 28 ◽  
pp. 383-388 ◽  
Author(s):  
Jack L. Johnson ◽  
Seymour Katz
Keyword(s):  
Diffraction Method ◽  
Temperature History ◽  
Maximum Temperature ◽  
Slag Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Potential Source ◽  
History Of ◽  
Extract Information

Information about the conditions and reactions in a foundry cupola is essential to understand the thermochemistry of a cupola and thus improve its efficiency. A potential source of such information is coke taken from inside an operating cupola. In the region of the cupola that extends from the melt zone to the taphole, coke is directly involved in important chemical processes such as combustion, gasification, slag formation, iron sulfurization, carbon pickup, and oxide reduction. Coke is also suspected of being involved in the transport of silicon to the liquid iron. Each of these processes produces characteristic physical and/or chemical changes in the coke, making it possible to extract information about the processes from an examination of coke pieces taken from within an operating cupola. A program to study such coke samples is in progress. To effectively interpret these data it is necessary to know the temperature history of the coke being examined, especially the maximum temperature attained by the coke piece in the cupola.

Effect of Ingress on Turbine Discs

2015 ◽  
Author(s):  
GeonHwan Cho ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Three Dimensional ◽  
Temperature History ◽  
Infrared Sensors ◽  
Rotating Disc ◽  
Hot Gas ◽  
Mainstream Flow ◽  
History Of ◽  
Thermal Buffering ◽  
Adiabatic Effectiveness ◽  
Semi Empirical

The ingress of hot gas through the rim seal of a gas turbine depends on the pressure difference between the mainstream flow in the turbine annulus and that in the wheel-space radially inward of the seal. This paper describes experimental measurements which quantify the effect of ingress on both the stator and rotor discs in a wheel-space pressurised by sealing flow. Infrared sensors were developed and calibrated to accurately measure the temperature history of the rotating disc surface during a transient experiment, leading to an adiabatic effectiveness. The performance of four generic (though engine-representative) single- and double-clearance seals was assessed in terms of the variation of adiabatic effectiveness with sealing flow rate. The measurements identify a so-called thermal buffering effect, where the boundary layer on the rotor protects the disc from the effects of ingress. It was shown that the effectiveness on the rotor was significantly higher than the equivalent stator effectiveness for all rim seals tested. Although the ingress through the rim seal is a consequence of an unsteady, three-dimensional flow field, and the cause-effect relationship between pressure and the sealing effectiveness is complex, the time-averaged experimental data is shown to be successfully predicted by relatively simple semi-empirical models, which are described in a separate paper. Of particular interest to the designer, significant ingress can enter the wheel-space before its effect is sensed by the rotor.

Effect of Ingress on Turbine Disks

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
GeonHwan Cho ◽  
Carl M. Sangan ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Three Dimensional ◽  
Rotating Disk ◽  
Disk Surface ◽  
Temperature History ◽  
Ir Sensors ◽  
History Of ◽  
Turbine Disks ◽  
Thermal Buffering ◽  
Adiabatic Effectiveness ◽  
Semi Empirical

The ingress of hot gas through the rim seal of a gas turbine depends on the pressure difference between the mainstream flow in the turbine annulus and that in the wheel-space radially inward of the seal. This paper describes experimental measurements which quantify the effect of ingress on both the stator and rotor disks in a wheel-space pressurized by sealing flow. Infrared (IR) sensors were developed and calibrated to accurately measure the temperature history of the rotating disk surface during a transient experiment, leading to an adiabatic effectiveness. The performance of four generic (though engine-representative) single- and double-clearance seals was assessed in terms of the variation of adiabatic effectiveness with sealing flow rate. The measurements identify a so-called thermal buffering effect, where the boundary layer on the rotor protects the disk from the effects of ingress. It was shown that the effectiveness on the rotor was significantly higher than the equivalent stator effectiveness for all rim seals tested. Although the ingress through the rim seal is a consequence of an unsteady, three-dimensional flow field, and the cause–effect relationship between pressure and the sealing effectiveness is complex, the time-averaged experimental data are shown to be successfully predicted by relatively simple semi-empirical models, which are described in a separate paper. Of particular interest to the designer, significant ingress can enter the wheel-space before its effect is sensed by the rotor.

Sea Urchins and Circuses: The Modernist Natural Histories of Jean Painlevé and Alexander Calder

2018 ◽  
Vol 13 (2) ◽  
pp. 187-211
Author(s):  
Patricia E. Chu
Keyword(s):  
New Media ◽  
Sea Urchins ◽  
Life Sciences ◽  
Three Dimensional ◽  
Machine Age ◽  
Avant Garde ◽  
History Of ◽  
And Performance ◽  
The One ◽  
Natural Historian

The Paris avant-garde milieu from which both Cirque Calder/Calder's Circus and Painlevé’s early films emerged was a cultural intersection of art and the twentieth-century life sciences. In turning to the style of current scientific journals, the Paris surrealists can be understood as engaging the (life) sciences not simply as a provider of normative categories of materiality to be dismissed, but as a companion in apprehending the “reality” of a world beneath the surface just as real as the one visible to the naked eye. I will focus in this essay on two modernist practices in new media in the context of the history of the life sciences: Jean Painlevé’s (1902–1989) science films and Alexander Calder's (1898–1976) work in three-dimensional moving art and performance—the Circus. In analyzing Painlevé’s work, I discuss it as exemplary of a moment when life sciences and avant-garde technical methods and philosophies created each other rather than being classified as separate categories of epistemological work. In moving from Painlevé’s films to Alexander Calder's Circus, Painlevé’s cinematography remains at the forefront; I use his film of one of Calder's performances of the Circus, a collaboration the men had taken two decades to complete. Painlevé’s depiction allows us to see the elements of Calder's work that mark it as akin to Painlevé’s own interest in a modern experimental organicism as central to the so-called machine-age. Calder's work can be understood as similarly developing an avant-garde practice along the line between the bestiary of the natural historian and the bestiary of the modern life scientist.

Computed Tomography and Magnetic Resonance Imaging-aided Diagnosis of Primary Essential Cutis Verticis Gyrata: A Case Report with 5-year Follow-up and Review of the Literature

2019 ◽  
Vol 15 (9) ◽  
pp. 906-910
Author(s):  
Hongzhang Zhu ◽  
Shi-Ting Feng ◽  
Xingqi Zhang ◽  
Zunfu Ke ◽  
Ruixi Zeng ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Three Dimensional ◽  
Stable Condition ◽  
Resonance Imaging ◽  
Mri Findings ◽  
Cutis Verticis Gyrata ◽  
Essential Form ◽  
History Of ◽  
Magnetic Resonance Imaging Mri

Background: Cutis Verticis Gyrata (CVG) is a rare skin disease caused by overgrowth of the scalp, presenting as cerebriform folds and wrinkles. CVG can be classified into two forms: primary (essential and non-essential) and secondary. The primary non-essential form is often associated with neurological and ophthalmological abnormalities, while the primary essential form occurs without associated comorbidities. Discussion: We report on a rare case of primary essential CVG with a 4-year history of normal-colored scalp skin mass in the parietal-occipital region without symptom in a 34-year-old male patient, retrospectively summarizing his pathological and Computer Tomography (CT) and magnetic resonance imaging (MRI) findings. The major clinical observations on the CT and MR sectional images include a thickened dermis and excessive growth of the scalp, forming the characteristic scalp folds. With the help of CT and MRI Three-dimensional (3D) reconstruction techniques, the characteristic skin changes could be displayed intuitively, providing more evidence for a diagnosis of CVG. At the 5-year followup, there were no obvious changes in the lesion. Conclusion: Based on our observations, we propose that not all patients with primary essential CVG need surgical intervention, and continuous clinical observation should be an appropriate therapy for those in stable condition.

scholarly journals POSSIBILITY OF FORMING A LARGE DCC IN ULTRA-RELATIVISTIC HEAVY-ION COLLISIONS

2000 ◽  
Vol 15 (15) ◽  
pp. 2269-2288
Author(s):  
SANATAN DIGAL ◽  
RAJARSHI RAY ◽  
SUPRATIM SENGUPTA ◽  
AJIT M. SRIVASTAVA
Keyword(s):  
Three Dimensional ◽  
Thermal Fluctuations ◽  
Heavy Ion ◽  
High Energy ◽  
Chiral Condensate ◽  
Relativistic Heavy Ion Collisions ◽  
Maximum Temperature ◽  
Chiral Field ◽  
Heavy Nuclei ◽  
True Vacuum

We demonstrate the possibility of forming a single, large domain of disoriented chiral condensate (DCC) in a heavy-ion collision. In our scenario, rapid initial heating of the parton system provides a driving force for the chiral field, moving it away from the true vacuum and forcing it to go to the opposite point on the vacuum manifold. This converts the entire hot region into a single DCC domain. Subsequent rolling down of the chiral field to its true vacuum will then lead to emission of a large number of (approximately) coherent pions. The requirement of suppression of thermal fluctuations to maintain the (approximate) coherence of such a large DCC domain, favors three-dimensional expansion of the plasma over the longitudinal expansion even at very early stages of evolution. This also constrains the maximum temperature of the system to lie within a window. We roughly estimate this window to be about 200–400 MeV. These results lead us to predict that extremely high energy collisions of very small nuclei (possibly hadrons) are better suited for observing signatures of a large DCC. Another possibility is to focus on peripheral collisions of heavy nuclei.

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