Optimization of Building Rubbles in Flexible Pavement Using Experimental Approach and Mechanistic- Empirical Method

2015 ◽  
Vol 3 (2) ◽  
pp. 50-66
Author(s):  
Ahmed Ebrahim Abu El-Maaty Behiry
Keyword(s):  
Experimental Approach ◽  
Flexible Pavement ◽  
Empirical Method

scholarly journals Evaluation of Finite Element Software for Pavement Stress Analysis

2021 ◽  
Author(s):  
Huan Chen
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Concrete Slab ◽  
Flexible Pavement ◽  
Empirical Method ◽  
Future Trend ◽  
Traffic Load ◽  
Rigid Pavement ◽  
Finite Element Software ◽  
Pavement Engineering

Different approaches are usually taken when designing flexible and rigid pavement: the rigid concrete slab carries major portion of the traffic load; while for flexible pavement, external loads are distributed to the subgrade because of the relatively low modulus of elasticity of asphalt layer comparing to concrete in the case of rigid pavement. Pavement engineering has gone through major developments; the transition from Empirical Design Method to Mechanistic-Empirical Methods is becoming a near-future trend. The Mechanistic-Empirical Method has two components: (1) stress, strain and deflection are calculated based on analyzing mechanical characteristics of materials; (2) critical pavement distresses are quantitatively predicted by experimental calibrated equations. Hence, stress analysis has become an important role in pavement engineering. The most practical and widely used stress analysis method for flexible pavement is Burmister's Elastic Layered Theory; and for analyzing rigid pavement is Finite Element Method. KENSLABS and STAAD-III are both Finite Element software; KENSLABS is designed specifically for concrete pavement stress analysis, therefore it is more user-frielndly for pavement design; STAAD-III is more suitable for general plane and space structures. The project compares the use of both software for stress analysis in rigid pavement in term of simplicity and precision.

scholarly journals Evaluation of Finite Element Software for Pavement Stress Analysis

2021 ◽  
Author(s):  
Huan Chen
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Concrete Slab ◽  
Flexible Pavement ◽  
Empirical Method ◽  
Future Trend ◽  
Traffic Load ◽  
Rigid Pavement ◽  
Finite Element Software ◽  
Pavement Engineering

Different approaches are usually taken when designing flexible and rigid pavement: the rigid concrete slab carries major portion of the traffic load; while for flexible pavement, external loads are distributed to the subgrade because of the relatively low modulus of elasticity of asphalt layer comparing to concrete in the case of rigid pavement. Pavement engineering has gone through major developments; the transition from Empirical Design Method to Mechanistic-Empirical Methods is becoming a near-future trend. The Mechanistic-Empirical Method has two components: (1) stress, strain and deflection are calculated based on analyzing mechanical characteristics of materials; (2) critical pavement distresses are quantitatively predicted by experimental calibrated equations. Hence, stress analysis has become an important role in pavement engineering. The most practical and widely used stress analysis method for flexible pavement is Burmister's Elastic Layered Theory; and for analyzing rigid pavement is Finite Element Method. KENSLABS and STAAD-III are both Finite Element software; KENSLABS is designed specifically for concrete pavement stress analysis, therefore it is more user-frielndly for pavement design; STAAD-III is more suitable for general plane and space structures. The project compares the use of both software for stress analysis in rigid pavement in term of simplicity and precision.

scholarly journals Effect of variations in layer thickness and resilience modulus on flexible pavement performance

2021 ◽  
Vol 10 (8) ◽  
pp. e42610817466
Author(s):  
Thaís Ferrari Réus ◽  
Heliana Barbosa Fontenele
Keyword(s):  
Layer Thickness ◽  
Design Method ◽  
Flexible Pavement ◽  
Empirical Method ◽  
Performance Criteria ◽  
Pavement Performance ◽  
Layered System ◽  
State Highway ◽  
Pavement Performance Prediction ◽  
Resilience Modulus

A pavement mechanistic-empirical analysis is based on a pre-designed structure checked for required performance criteria. In case the latter are not met, this structure is modified and reprocessed. In this context, analyzing the effect of variations in project parameters on pavement performance prediction subsidizes a better understanding of results provided by computer programs. The objective of this study is to assess the effect of layer thickness and resilience modulus variations on flexible pavement performance. To do so, performance was estimated for the 20th project year through Elastic Layered System Model 5 (ELSYM5) software and American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical method (ME). Using multiple regression models for result adjustment and through statistical assessments on regression coefficients calculated, it can be concluded that pavement lifespan consumption, predicted by simulations on ELSYM5, is sensitive to variations in coating and subbase thickness and in subgrade resilience modulus. For AASHTO ME method, predicted values for distresses were significantly sensitive to variations in coating, base and subbase thickness, and in base and subgrade resilience modulus. Comparing both approaches, it is concluded that ELSYM5 can be a viable alternative to the application of a ME pavement design method.

Quantification of Silica Uptake by Alveolar Macrophages - An Emperical Scanning Electron Microprobe Method

1982 ◽  
Vol 40 ◽  
pp. 332-333
Author(s):  
V. V. Damiano ◽  
R. P. Daniele ◽  
H. T. Tucker ◽  
J. H. Dauber
Keyword(s):  
Quantitative Analysis ◽  
Alveolar Macrophages ◽  
Bulk Sample ◽  
Silica Particles ◽  
Empirical Method ◽  
Phagocytic Cells ◽  
Calibration Standards ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Scanning Electron

An important example of intracellular particles is encountered in silicosis where alveolar macrophages ingest inspired silica particles. The quantitation of the silica uptake by these cells may be a potentially useful method for monitoring silica exposure. Accurate quantitative analysis of ingested silica by phagocytic cells is difficult because the particles are frequently small, irregularly shaped and cannot be visualized within the cells. Semiquantitative methods which make use of particles of known size, shape and composition as calibration standards may be the most direct and simplest approach to undertake. The present paper describes an empirical method in which glass microspheres were used as a model to show how the ratio of the silicon Kα peak X-ray intensity from the microspheres to that of a bulk sample of the same composition correlated to the mass of the microsphere contained within the cell. Irregular shaped silica particles were also analyzed and a calibration curve was generated from these data.

Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

1975 ◽  
Vol 33 ◽  
pp. 664-665
Author(s):  
Mircea Fotino
Keyword(s):  
Experimental Approach ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Biological Research ◽  
Specimen Thickness ◽  
Resolution Limit ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

Malfunctional Reorganization in the Developing Limbo-Prefrontal System in Animals: Implications for Human Psychoses?

2001 ◽  
Vol 12 (1) ◽  
pp. 8-14
Author(s):  
Gertraud Teuchert-Noodt ◽  
Ralf R. Dawirs
Keyword(s):  
Prefrontal Cortex ◽  
Mental Disorders ◽  
Dentate Gyrus ◽  
Cognitive Functions ◽  
Experimental Approach ◽  
Regulatory Mechanisms ◽  
Hippocampal Dentate Gyrus ◽  
Non Invasive ◽  
Invasive Method ◽  
Activity Dependent

Abstract: Neuroplasticity research in connection with mental disorders has recently bridged the gap between basic neurobiology and applied neuropsychology. A non-invasive method in the gerbil (Meriones unguiculus) - the restricted versus enriched breading and the systemically applied single methamphetamine dose - offers an experimental approach to investigate psychoses. Acts of intervening affirm an activity dependent malfunctional reorganization in the prefrontal cortex and in the hippocampal dentate gyrus and reveal the dopamine position as being critical for the disruption of interactions between the areas concerned. From the extent of plasticity effects the probability and risk of psycho-cognitive development may be derived. Advance may be expected from insights into regulatory mechanisms of neurogenesis in the hippocampal dentate gyrus which is obviously to meet the necessary requirements to promote psycho-cognitive functions/malfunctions via the limbo-prefrontal circuit.

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