scholarly journals Investigation on the low-freauency noise physical models and the defects' characterization of the PbS infrared dectector

2011 ◽  
Vol 60 (10) ◽  
pp. 107202
Author(s):  
Chen Wen-Hao ◽  
Du Lei ◽  
Yin Xue-Song ◽  
Kang Li ◽  
Wang Fang ◽  
...  
Keyword(s):  
Physical Models

Radiological Characterization of the Nuclear Waste Streams of the Belgian Nuclear Research Centre SCK•CEN

2007 ◽  
Author(s):  
Patrick Maris ◽  
Rene´ Cornelissen ◽  
Michel Bruggeman
Keyword(s):  
Nuclear Research ◽  
Physical Models ◽  
Research Centre ◽  
Waste Streams ◽  
Activity Ratios ◽  
Disposal Option ◽  
The Many ◽  
Non Destructive ◽  
Radiological Characterization

The radiological characterization of nuclear wastes of a research centre is difficult seen the many different processes that generate waste. Since these wastes may contain radionuclides relevant for the disposal option, the nuclide content and activity have to be known. Considering the fact that some wastes are generated only in minor quantities, complex approaches, involving sampling and successive analysis are not justified. Basic physical models can generally be applied to estimate activity ratios, from which the radionuclide inventory can be determined by non-destructive assay on waste-packages. This article discusses waste streams at the Belgian Nuclear Research Centre SCK•CEN and explains how nuclide inventories and activity are determined. The physical models, used to derive activity ratios, and other simple approaches are discussed.

scholarly journals Porosity Characterization of Thermal Barrier Coatings by Ultrasound with Genetic Algorithm Backpropagation Neural Network

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Shuxiao Zhang ◽  
Gaolong Lv ◽  
Shifeng Guo ◽  
Yanhui Zhang ◽  
Wei Feng
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Thermal Barrier Coatings ◽  
Amplitude Spectrum ◽  
Physical Models ◽  
Average Error ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
The Time Domain

Porosity is considered as one of the most important indicators for the characterization of the comprehensive performance of thermal barrier coatings (TBCs). In this study, the ultrasonic technique and the artificial neural network optimized with the genetic algorithm (GA_BPNN) are combined to develop an intelligent method for automatic detection and accurate prediction of TBCs’s porosity. A series of physical models of plasma-sprayed ZrO2 coating are established with a thickness of 288 μm and porosity varying from 5.71% to 26.59%, and the ultrasonic reflection coefficient amplitude spectrum (URCAS) is constructed based on the time-domain numerical simulation signal. The characteristic features f 1 , f 2 , A max , Δ A of the URCAS, which are highly dependent on porosity, are extracted as input data to train the GA_BPNN model for predicting the unknown porosity. The average error of the prediction results is 1.45%, which suggests that the proposed method can achieve accurate detection and quantitative characterization of the porosity of TBCs with complex pore morphology.

Characterization of Microwave Power FETs Based on Physical Models

1991 ◽  
Author(s):  
Christopher M. Snowden ◽  
Renato R. Pantoja
Keyword(s):  
Microwave Power ◽  
Physical Models

scholarly journals Emirates Mars Mission Characterization of Mars Atmosphere Dynamics and Processes

2021 ◽  
Vol 217 (8) ◽  
Author(s):  
Hessa Almatroushi ◽  
Hoor AlMazmi ◽  
Noora AlMheiri ◽  
Mariam AlShamsi ◽  
Eman AlTunaiji ◽  
...  
Keyword(s):  
Physical Models ◽  
Lower Atmosphere ◽  
Imaging Data ◽  
Science Data ◽  
Mars Atmosphere ◽  
Mars Mission ◽  
Atmospheric Escape ◽  
Infrared Wavelengths ◽  
Circulation Dynamics

AbstractThe Emirates Mars Mission (EMM) – Hope Probe – was developed to understand Mars atmospheric circulation, dynamics, and processes through characterization of the Mars atmosphere layers and its interconnections enabled by a unique high-altitude (19,970 km periapse and 42,650 km apoapse) low inclination orbit that will offer an unprecedented local and seasonal time coverage over most of the planet. EMM has three scientific objectives to (A) characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability, (B) correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere, and (C) characterize the spatial structure and variability of key constituents in the Martian exosphere. The EMM data products include a variety of spectral and imaging data from three scientific instruments measuring Mars at visible, ultraviolet, and infrared wavelengths and contemporaneously and globally sampled on both diurnal and seasonal timescale. Here, we describe our strategies for addressing each objective with these data in addition to the complementary science data, tools, and physical models that will facilitate our understanding. The results will also fill a unique role by providing diagnostics of the physical processes driving atmospheric structure and dynamics, the connections between the lower and upper atmospheres, and the influences of these on atmospheric escape.

Characterization of operational vibrations of highway bridges Via Lidar

2021 ◽  
Author(s):  
Adriana Trias
Keyword(s):  
Physical Model ◽  
Natural Frequencies ◽  
Highway Bridges ◽  
Physical Models ◽  
Highway Bridge ◽  
Steel Girder ◽  
Use Of Data ◽  
Steel Girder Bridge ◽  
Girder Bridge

<p>During the examination of data obtained from scanning an operational steel girder bridge, local ripples were noted in horizontal elements that were expected to be planar in nature (such as girder flanges). It was hypothesized that these ripples are a result of the bridge vibrating under truck traffic. The objective of this paper is to examine this hypothesis through the use of data obtained from an operating highway bridge together with the use of numerical and physical models. After analyzing the data, by estimating the distance between the peak of these ripples (and translating this into time using the data acquisition metrics) the frequency of the vibrating object can be estimated. For the operating bridge and physical model employed in this research, the natural frequencies were estimated within 2% to 10% and 0,22% to 5%, respectively.</p>

scholarly journals Comparison of GA-Optimized Viscoelastic Models for the Characterization of Compression Behavior of Warp-Knitted Spacer Fabrics

2018 ◽  
Vol 18 (3) ◽  
pp. 209-215
Author(s):  
Masih Yousefpour ◽  
Mohammad Saleh Ahmadi ◽  
Pedram Payvandy
Keyword(s):  
Genetic Algorithm ◽  
Physical Modeling ◽  
Viscoelastic Properties ◽  
Physical Models ◽  
Burger Model ◽  
Compression Behavior ◽  
Viscoelastic Models ◽  
Fabric Structure ◽  
Spacer Fabrics

Abstract Nowadays, Warp-Knitted Spacer Fabrics (WKSF) have been widely used for many technical applications. Compressional behavior of WKSF is one of their important properties. Physical modeling is one of the solutions to predict these properties for engineered designing of WKSF. In this study, four common physical models are introduced and compared in order to simulate compressional behavior of polyester WKSF. Genetic Algorithm (GA) was applied to optimize each model parameter. The results showed that the Burger model has the highest adoption with 0.2 percent Mean Absolut Error (MAE). The effect of thickness, outer fabric structure and spacer monofilament density on viscoelastic properties of the samples were also studied.

scholarly journals Reflectance Spectra Analysis Algorithms for the Characterization of Deposits and Condensed Traces on Surfaces

2022 ◽  
Author(s):  
Ran Aharoni ◽  
Asaf Zuck ◽  
David Peri ◽  
Shai Kendler
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Physical Models ◽  
Health Concern ◽  
Spectra Analysis ◽  
Material Classification ◽  
Pure Compounds ◽  
Secondary Evaporation ◽  
Industrial Compounds

Identification of particulate matter and liquid spills contaminations is essential for many applications, such as forensics, agriculture, security, and environmental protection. For example, toxic industrial compounds deposition in the form of aerosols, or other residual contaminations, pose a secondary, long-lasting health concern due to resuspension and secondary evaporation. This chapter explores several approaches for employing diffuse reflectance spectroscopy in the mid-IR and SWIR to identify particles and films of materials in field conditions. Since the behavior of thin films and particles is more complex compared to absorption spectroscopy of pure compounds, due to the interactions with background materials, the use of physical models combined with statistically-based algorithms for material classification, provides a reliable and practical solution and will be presented.

Experimental Characterization of Airflow Within a Clean HEPA Filter Used for the Containment of Radioactive Contamination in Nuclear Facilities

2016 ◽  
Author(s):  
Alilou Youssef ◽  
Bourrous Soleiman ◽  
Thomas Dominique ◽  
Bardin-Monnier Nathalie ◽  
Nérisson Philippe ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Efficiency ◽  
Filter Design ◽  
Physical Models ◽  
Airflow Rate ◽  
Nuclear Facilities ◽  
Airborne Contamination ◽  
Pleated Filters ◽  
The Impact

In hazardous industrial activities such as in nuclear facilities, High Efficiency Particulate Air filters (HEPA filters) are essential to ensure the containment of airborne contamination. Most of the filters used in ventilation networks are pleated, in order to offer a larger surface of filtration. For industrial risks likely to lead to an important release of particles (e.g. fire), predicting the evolution of the pressure drop of pleated filters is very important, in order to anticipate any dysfunction, failure or breaking of these devices. Pressure drop variations are linked to airflow rate variations and to clogging process of the medium by airborne particles. Thus, the airflow pattern in a pleat channel is essential for optimizing the filter design and enhancing its lifetime. Particles are transported by the airflow and deposited at the filter surface; hence, the geometry of the dust cake (shape and location) is partially determined knowing the velocity streamlines. The present paper focuses on the characterization of airflows in a clean HEPA filter. The difficulty to perform fine measurement on a real scale filter led us to develop an experimental device, consisting in the reproduction of a single pleat, identical to a real pleat constituting industrial filters. The small dimension of the pleat makes the velocity measurement difficult to establish. That is why μ-PIV method has been adapted to measure the velocity field inside the filter for different filtration velocities at the first moments of the experiment, in order to avoid the impact of clogging by particles used to seed the flow. These particles are DEHS droplets 0.01 < St < 0.05. In the future, these well-characterized airflows will be the basis for CFD computation of particle transport and deposition inside the pleats. Ultimately, the aim is to develop or upgrade physical models predicting the pressure drop evolution of pleated filters, during clogging process in accidental situations.

scholarly journals Experimental and numerical characterization of the interface between concrete masonry block and mortar

2020 ◽  
Vol 13 (3) ◽  
pp. 578-592
Author(s):  
R. D. PASQUANTONIO ◽  
G. A. PARSEKIAN ◽  
F. S. FONSECA ◽  
N. G.SHRIVE
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Physical Models ◽  
The Finite Element Method ◽  
Numerical Characterization ◽  
Tension Tests ◽  
Analytical Research ◽  
The Finite Element Model

Abstract Masonry is a construction system that has been used since the beginning of civilization and is still used throughout the world. The finite element method is a recent development that allows complex problems, including structural masonry problems, to be solved. A vast amount of literature exists on finite element modeling, using software such as ABAQUS, to represent experimental masonry models. Based on this established pattern, an experimental and analytical research program was designed and implemented. Thus, a set of tests was conducted to determine the compressive and tensile strengths of the masonry components, i.e., block, mortar, and grout. Bond wrench tests, diagonal tension tests, and horizontal joint shear tests were conducted to characterize the interface between the blocks and the mortar. A finite element model was then developed to represent the physical models and the general conclusion is that the finite element model was able to represent reasonably well the physical models.

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