Experimental and Numerical Investigation on Manufacturing-Induced Material Inhomogeneity in Hydrogenation Reactor Shell

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Song Huang ◽  
You Li ◽  
Xinyi Song ◽  
Hu Hui ◽  
Jiru Zhong
Keyword(s):  
Load Capacity ◽  
Strength Distribution ◽  
Data Driven ◽  
Material Strength ◽  
Manufacturing Processes ◽  
Material Inhomogeneity ◽  
Actual Material ◽  
Hydrogenation Reactor ◽  
Good Agreement

Abstract Hydrogenation reactor services as key equipment in chemical and energy industries. Manufacturing processes of hydrogenation reactor changes its performance before long-term service but impact of manufacturing residual influence remains unclear. In this work, actual material strength distribution (MSD) in hydrogenation reactor shell was investigated. First, a hydrogenation reactor shell made from 2.25Cr1Mo0.25V was dissected to measure MSD in thickness. Then, a numerical model was proposed to predict actual material strength in hydrogenation reactor shell. The model employs both data-driven and finite element techniques to simulate material evolution during manufacturing. Third, the predict results were discussed with respect to accuracy based on experiment result. Results exhibit good agreement between predicted value and experiment outcomes. At last, impact of manufacturing residual influence on load capacity of hydrogenation reactor shell was investigated. Results indicate that fit for service (FFS) evaluation of hydrogenation reactor based on heat treatment material properties is not conservative. This work will contribute to the accurate description of hydrogenation reactor's performance.

Some Principles of Brittle Material Design

1975 ◽  
Author(s):  
W. H. Dukes
Keyword(s):  
Statistical Methods ◽  
Stress Gradient ◽  
Statistical Treatment ◽  
Material Design ◽  
Strength Properties ◽  
Strength Distribution ◽  
Material Strength ◽  
Stress Distributions ◽  
Failure Loads ◽  
Actual Material

This paper presents the basic principles which must be followed in designing structures to utilize completely brittle materials to carry tensile loads or stresses in an efficient and reliable manner. Brittleness introduces a need for highly refined stress analysis methods. Brittleness also requires the statistical treatment of material strength because of sensitivity to microscopic flaws which are distributed statistically in size and shape. It proves, in fact, to be impractical to do this and still achieve the extremely low probabilities of failure expected of a primary structure. The use of statistical methods to describe the material strength properties should also be extended to the statistical treatment of loads applied to the component, because it is the overall probability of failure of the component which is significant. These methods must also be extended to cover such effects as nonuniform stress distributions, stress gradient and fatigue, and methods for doing this are suggested. Finally, the use of statistical methods raises problems in the verification of a design since the successful test of a small number of components is not likely to include material at the lower extremes of the strength distribution curve. The use of the proof test permits this problem to be circumvented by comparing component destruction test results with expected failure loads based on the actual material strength in each individual component.

Anthropologic Relationships among Prehistoric Northeastern Amerindians

1980 ◽  
Vol 1 (2) ◽  
pp. 145-159
Author(s):  
Edward F. Harris ◽  
Nicholas F. Bellantoni
Keyword(s):  
New York ◽  
Gene Flow ◽  
Material Culture ◽  
New England ◽  
Cultural Barriers ◽  
Group Differences ◽  
Phenetic Analysis ◽  
Trade Relationships ◽  
Good Agreement

Archaeologically defined inter-group differences in the Northeast subarea ate assessed with a phenetic analysis of published craniometric information. Spatial distinctions in the material culture are in good agreement with those defined by the cranial metrics. The fundamental dichotomy, between the Ontario Iroquois and the eastern grouping of New York and New England, suggests a long-term dissociation between these two groups relative to their ecologic adaptations, trade relationships, trait-list associations, and natural and cultural barriers to gene flow.

scholarly journals Semi-Analytical Solution to Assess CO2 Leakage in the Subsurface through Abandoned Wells

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2452
Author(s):  
Tian Qiao ◽  
Hussein Hoteit ◽  
Marwan Fahs
Keyword(s):  
Analytical Solution ◽  
Storage Site ◽  
Co2 Leakage ◽  
Transient Pressure ◽  
Flow Paths ◽  
Abandoned Wells ◽  
Diffusivity Equation ◽  
Carbon Dioxide Co2 ◽  
Good Agreement

Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts.

scholarly journals Modeling cesium migration through Opalinus clay: a benchmark for single- and multi-species sorption-diffusion models

2021 ◽  
Author(s):  
Jesús F. Águila ◽  
Vanessa Montoya ◽  
Javier Samper ◽  
Luis Montenegro ◽  
Georg Kosakowski ◽  
...  
Keyword(s):  
Time Discretization ◽  
Single Species ◽  
Opalinus Clay ◽  
Sorption Behavior ◽  
Diffusion Experiment ◽  
Modeling Tools ◽  
Cesium Sorption ◽  
Code Performance ◽  
Good Agreement

AbstractSophisticated modeling of the migration of sorbing radionuclides in compacted claystones is needed for supporting the safety analysis of deep geological repositories for radioactive waste, which requires robust modeling tools/codes. Here, a benchmark related to a long term laboratory scale diffusion experiment of cesium, a moderately sorbing radionuclide, through Opalinus clay is presented. The benchmark was performed with the following codes: CORE2DV5, Flotran, COMSOL Multiphysics, OpenGeoSys-GEM, MCOTAC and PHREEQC v.3. The migration setup was solved with two different conceptual models, i) a single-species model by using a look-up table for a cesium sorption isotherm and ii) a multi-species diffusion model including a complex mechanistic cesium sorption model. The calculations were performed for three different cesium boundary concentrations (10−3, 10−5, 10−7 mol / L) to investigate the models/codes capabilities taking into account the nonlinear sorption behavior of cesium. Generally, good agreement for both single- and multi-species benchmark concepts could be achieved, however, some discrepancies have been identified, especially near the boundaries, where code specific spatial (and time) discretization had to be improved to achieve better agreement at the expense of longer computation times. In addition, the benchmark exercise yielded useful information on code performance, setup options, input and output data management, and post processing options. Finally, the comparison of single-species and multi-species model concepts showed that the single-species approach yielded generally earlier breakthrough, because this approach accounts neither for cation exchange of Cs+ with K+ and Na+, nor K+ and Na+ diffusion in the pore water.

scholarly journals Comparison of numerical and standard sarnat grading using the NICHD and SIBEN methods

2021 ◽  
Author(s):  
Brian H. Walsh ◽  
Chelsea Munster ◽  
Hoda El-Shibiny ◽  
Edward Yang ◽  
Terrie E. Inder ◽  
...  
Keyword(s):  
Predictive Ability ◽  
Roc Curves ◽  
Cerebral Injury ◽  
Neonatal Encephalopathy ◽  
Minimum Threshold ◽  
Term Outcome ◽  
Long Term Outcome ◽  
Grading Systems ◽  
Good Agreement

Abstract Objective The NICHD and SIBEN assessments are adapted from the Sarnat grade, and used to determine severity of neonatal encephalopathy (NE). We compare NICHD and SIBEN methods, and their ability to define a minimum threshold associated with significant cerebral injury. Study design Between 2016 and 2019, 145 infants with NE (77-mild; 65-moderate; 3-severe) were included. NICHD and SIBEN grade and numerical scores were assigned. Kappa scores described agreement between methods, and ROC curves their ability to predict MR injury. Results Good agreement existed between grading systems (K = 0.86). SIBEN defined more infants as moderate, and less as mild, than NICHD (p < 0.001). Both numerical scores were superior to standard grades in predicting MR injury. Conclusion Despite good agreement between methods, SIBEN defines more infants as moderate NE. Both numerical scores were superior to standard grade, and comparable to each other, in defining a minimum threshold for cerebral injury. Further assessment contrasting their predictive ability for long-term outcome is required.

scholarly journals The Rate of Mutation and the Homozygous and Heterozygous Mutational Effects for Competitive Viability: A Long-Term Experiment With Drosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 681-693 ◽  
Author(s):  
David Chavarrías ◽  
Carlos López-Fanjul ◽  
Aurora García-Dorado
Keyword(s):  
Drosophila Melanogaster ◽  
Minimum Distance ◽  
Deleterious Mutations ◽  
Regression Estimate ◽  
Term Experiment ◽  
Degree Of Dominance ◽  
Long Term Experiment ◽  
Rate Of Decline ◽  
Good Agreement

Abstract The effect of 250 generations of mutation accumulation (MA) on the second chromosome competitive viability of Drosophila melanogaster was analyzed both in homozygous and heterozygous conditions. We used full-sib MA lines, where selection hampers the accumulation of severely deleterious mutations but is ineffective against mildly deleterious ones. A large control population was simultaneously evaluated. Competitive viability scores, unaffected by the expression of mutations in heterozygosis, were obtained relative to a Cy/L2 genotype. The rate of decline in mean ΔM ≈ 0.1% was small. However, that of increase in variance ΔV ≈ 0.08 × 10-3 was similar to the values obtained in previous experiments when severely deleterious mutations were excluded. The corresponding estimates of the mutation rate λ ≥ 0.01 and the average effect of mutations E(s) ≤ 0.08 are in good agreement with Bateman-Mukai and minimum distance estimates for noncompetitive viability obtained from the same MA lines after 105 generations. Thus, competitive and noncompetitive viability show similar mutational properties. The regression estimate of the degree of dominance for mild-to-moderate deleterious mutations was ∼0.3, suggesting that the pertinent value for new unselected mutations should be somewhat smaller.

Long-term performance of prestressed concrete continuous box girders in the natural environment

2020 ◽  
Vol 47 (7) ◽  
pp. 856-864
Author(s):  
Guohui Cao ◽  
Wang Zhang ◽  
Jiaxing Hu ◽  
Xirong Peng
Keyword(s):  
Prestressed Concrete ◽  
Load Test ◽  
Time Dependent ◽  
Material Strength ◽  
Practical Calculation ◽  
Box Girders ◽  
Load Types ◽  
In The Beginning ◽  
Support Reactions

A long-term load test performed for 470 days on two two-span prestressed concrete (PC) continuous box girders is reported in this paper. Load types were selected as the test variates, and structural responses such as support reactions, deflections, and concrete strains were monitored. Simultaneously, affiliated experiments such as material strength, creep, and shrinkage tests were conducted to investigate the time-dependent performances of the materials. Data obtained from these tests showed that deflections, strains, and support reactions develop rapidly in the beginning and stabilize afterward; the reactions of mid- and end-supports decline and rise over time, respectively. Time-dependent patterns of deflections and support reactions were analyzed on the basis of an effective modulus method, and a practical calculation method for long-term deflections considering reaction redistributions was proposed. The effects of the service environment on the performance of PC girders were evaluated through an incremental analysis method.

Geothermal modeling of soil or mine tailings with concurrent freezing and deposition

1998 ◽  
Vol 35 (2) ◽  
pp. 234-250 ◽  
Author(s):  
JF (Derick) Nixon ◽  
Nick Holl
Keyword(s):  
Snow Cover ◽  
Mine Tailings ◽  
Frozen Soil ◽  
Freezing And Thawing ◽  
Frozen Ground ◽  
Geothermal Model ◽  
Winter Time ◽  
Upper Boundary ◽  
Good Agreement

A geothermal model is described that simulates simultaneous deposition, freezing, and thawing of mine tailings or sequentially placed layers of embankment soil. When layers of soil or mine tailings are placed during winter subfreezing conditions, frozen layers are formed in the soil profile that may persist with time. The following summer, warmer soil placement may not be sufficient to thaw out layers from the preceding winter. Remnant frozen soil layers may persist for many years or decades. The analysis is unique, as it involves a moving upper boundary and different surface snow cover functions applied in winter time. The model is calibrated based on two uranium mines in northern Saskatchewan. The Rabbit Lake scenario involves tailings growth to a height of 120 m over a period of 24 years. At Key Lake, tailings increase in height at a rate of 1.3 m/year. Good agreement between the observed position of frozen layers and those predicted by the model is obtained. Long-term predictions indicate that from 80 to 200 years would be required to thaw out the frozen layers formed during placement, assuming 1992 placement conditions continue. Deposition rates of 1.5-3 m/year give the largest amounts of frozen ground. The amount of frozen ground is sensitive to the assumed snow cover function during winter.Key words: geothermal, model, tailings, freezing, deposition.

Experimental analysis of the automated process of sanding aircraft surfaces

2014 ◽  
Vol 118 (1199) ◽  
pp. 53-64
Author(s):  
B. Giublin ◽  
J. A. Vieira ◽  
T. G. Vieira ◽  
L. G. Trabasso ◽  
C. A. Martins
Keyword(s):  
Load Capacity ◽  
Manufacturing Processes ◽  
Robotic Cell ◽  
Research Project ◽  
Average Value ◽  
Aluminum Metal ◽  
Structural Assembly ◽  
Riveting Process ◽  
High Load Capacity ◽  
Operating Method

Abstract ITA and EMBRAER are currently executing the research project Automation of Aircraft Structural Assembly (AASA) whose goal is to implement a robotic cell for automating the riveting process of aeronautical structures. The proposal described herein complements the AASA project, adds other manufacturing processes, namely sanding and polishing of aircraft surfaces. To implement the additional processes AASA project resources and facilities were used (robots and metrology systems) and devices designed and /or acquired to allow sharing of these resources. Among these, an Automatic Tooling Support for AERonautics structures (ATS_AER) was designed and built; also, a robot tool changer with high load capacity was acquired. The outcome of this research project is the evaluation of the feasibility of automating the processes of sanding and polishing metal surfaces in the aircraft manufacture using robots. The operating method adopted for surface treatment employed the ‘U’ type trajectory optimised to be run by a KUKA robot KR 500. The sanding process has been applied to aluminum metal sheet specimen sized 2•18ft2 (0•20m2) and used commercial 600 and 800 sandpaper. The automated sanding process yielded an average value of RA 0•48 ± 0•08 which is 25% more efficient when compared to the traditional, manual process whose average value of RA is 0•75 ± 0•51.

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