Models Of Physical Effects Research Articles

Application of uncertainty quantification techniques in the framework of process safety studies: Advanced dispersion simulations

AbstractIn the framework of process safety studies, consequence assessment of accidental scenarios is a crucial step affecting the eventual risk profile associated with the facilities under analysis. Conventional models used for consequence assessment are based on integral models, and may not be adequate to cope with the dynamic evolution of accidental scenarios and their three‐dimensional features. On the other hand, consequence assessment models based on computational fluid dynamics (CFD) approaches are promising to cope with complex scenarios and environments, but setting the simulation introduces relevant uncertainties associated with both the input data, assumptions, and with the modelling of physical effects involved. In the present study, uncertainty quantification (UQ) techniques are applied to support advanced safety studies based on CFD simulations of hazardous gas dispersion. Firstly, the accidental scenarios are characterized by defining release scenarios and conditions and quantifying source terms using integral models. At the same time, input meteorological data are gathered. This enables the development of high‐fidelity CFD simulations of gas dispersion based on different input sets and eventually the implementation of UQ techniques. The generalized polynomial chaos (gPC) expansion is employed to obtain hazardous gas concentration based on the variation of wind direction and speed. The present method is applied for the analysis of a real plant featuring a complex layout. The results show the advantages of the present approach by quantifying the influence of meteorological conditions and providing indications for supporting the development of protection systems and emergency measures.

Thermomechanics Modeling and Visualization of Physical Effects to Improve Cryopreservation by Vitrification

Thermomechanics Modeling and Visualization of Physical Effects to Improve Cryopreservation by Vitrification

Theory of Edge Effects and Conductance for Applications in Graphene-Based Nanoantennas

In this paper, we present a theory of edge effects in graphene for its applications to nanoantennas in the THz, infrared, and visible frequency ranges. The novelty of the presented model is reflected in its self-consistency, which is reached due to the formulation in terms of dynamical conductance instead of ordinary surface conductivity. The physical model of edge effects is based on using the concept of the Dirac fermion and the Kubo approach. In contrast with earlier well-known and widely used models, the surface conductance becomes non-homogeneous and non-local. The numerical simulations of the spatial behavior of the surface conductance were performed in a wide range of values, known from the literature, for the graphene ribbon widths and electrochemical potential. It is shown that if the length exceeds 800 nm, our model agrees with the classical Drude conductivity model with a relatively high degree of accuracy. For rather short lengths, the conductance exhibits a new type of spatial oscillations, which are not present in the ordinary conductivity model. These oscillations modify the form of effective boundary conditions and integral equations for electromagnetic field at the surface of graphene-based antenna. The developed theory opens a new way for realizing electrically controlled nanoantennas by changing the electrochemical potential via gate voltage. The obtained results may be applicable for the design of different carbon-based nanodevices in modern quantum technologies.

Brief overview and demonstration of some commercial off-the-shelf modeling tools

This paper is intended to lead the special session on “Modeling and Simulation of Physical Effects in Sound Reproduction.” To begin, a brief overview of linear systems theory is presented to set the stage for demonstrating some tools that use impulse responses and convolution to generate various “effects.” This will be followed by a brief overview and demonstration of some commercially available modeling tools, ranging from the emulation of amplifiers and microphones, to reverberation and microphone placement. Some examples of the modeling of electromechanical instruments will be shown as well, including the Hammond organ and the Leslie rotating speaker.

The Development of Frequency Multipliers for Terahertz Remote Sensing System

This paper summarizes the development of novel Schottky-diode-based terahertz frequency multipliers. The basic structure and manufacturing process of planar Schottky barrier diodes (SBDs) are reviewed, along with other diode structures that have been proposed in the literature. A numerical modeling method for the novel diodes in the context of terahertz frequency multipliers is presented, which includes 3D electromagnetic (EM) modeling, electro-thermal modeling and modeling of physical non-ideal effects. Furthermore, a general design methodology for developing terahertz frequency multipliers is introduced, involving a sub-division design method (SDM), a global design method (GDM) and a half-sub-division and half-global design method (HS-HGDM). These methods are summarized and compared for 110 GHz and 220 GHz frequency multipliers in the context of communication and imaging applications. Laboratory measurements of these multipliers show good agreement with numerical simulations. Finally, several classic terahertz remote sensing systems are reviewed, and a 220 GHz remote sensing system established using novel frequency multipliers for security inspection purposes is presented along with associated imaging results.

PROBLEM SOL PROBLEM SOLVING ME VING METHODS FOR SYN THODS FOR SYNTHESIS OF PH THESIS OF PHYSICAL PRINCIPLES OF MECHATRONIC MODULE OPERATIONS IN INTELLIGENT ROBOTIC SYSTEMS

The scientific paper investigates the methods for solving problems of synthesis of physical principles of operation of mechatronic modules of intelligent robotic systems are considered. In addition, it deals with the specifics of the process of synthesis of the physical principles of the operation ofmechatronic modules using predicate models, list models and information matrices of physical and technical effects. It shows the interpretation of the components of the model of the system for the synthesis of the physical principles of operation of mechatronic modules of intelligent robotic systems and automatic control and the features of the synthesis algorithm for the physical principles of operation of mechatronic modules of intelligent robotic systems based on list models of physical and technical effects are considered.

Development of a Physical Model of Thermovoltaic Effects in the Thin Films of Zinc Oxide Doped with Transition Metals

A model of the thermovoltaic effect emergence in ZnO/ZnO<Me> (Me = Cu, Fe), sandwich structures has been developed in the article. The samples were made by the sol-gel method. When they were uniformly heated in a laboratory furnace in the temperature range of 200–300 °C, there an electromotive force (EMF) of −7~10 mV, not associated with the Seebeck effect, emerged. The developed physical mechanisms of the effect emergence consist of the following well-known fact: iron and copper coexist in zinc oxide in two states, namely, Fe2+ and Fe3+ (donor), and Cu2+ and Cu+ (acceptor). During the heating of the ZnO/ZnO–Me system, the concentration of charge carriers in the layers will increase, while in the upper layer its value will be larger because of the presence of electrically active impurities. At room temperatures, Coulomb forces retain an electron that is located on the Fe2+ ion, as well as a hole on Cu2+ ion, and the main states undergo ionization. However, as the temperature increases, the carrier concentration can reach a critical level, when they can screen the ion charge (the Debye screening radius decreases to the Bohr radius of the impurity). In this case, an abrupt collective endothermic process of ionization of multivalent impurities takes place, accompanied by the appearance of a concentration gradient of free carriers in the sample, and accordingly, the emergence of an electromotive force. Quantitative calculations of the critical temperature, at which the onset of EMF generation is observed, performed within the framework of the developed models.

Coda wave interferometry during the heating of deep geothermal reservoir rocks

Coda wave interferometry (CWI) is a high-resolution technique that aims at tracking small changes in a diffusive medium from the time correlation of seismic waveforms. CWI has been widely used in recent years to monitor the fine-scale evolution of fault zones and more recently of deep reservoirs. However, to provide a quantitative interpretation of the reservoir, direct modeling of physical effects like the influence of temperature on seismic wave scattering is required to investigate temperature effects from measurements of velocity changes. Here, we propose to quantify the impact of thermo-elastic deformation on CWI measurements by comparing experimental results obtained from a previous study on Westerly Granite to a numerical approach based on two combined codes (SPECFEM2D and Code_Aster) for modeling wave propagation in complex media during thermo-elastic deformation. We obtain two major results. First, we show that multiple reflections on the boundaries of our simplified numerical sample reproduce well the wave scattering properties of the experimental granitic sample characterized by a complex mineral assembly and a large set of microcracks. We based our comparison on the wave diffusion model that describes both the experimental and numerical samples (similarity in energy density function and mean free path). We also show that both samples share a similar thermo-elastic behavior, but only after the second heating and cooling cycle. Second, the stretching technique used for CWI measurements on both samples reveals reversible time shifts correlated with the thermo-elastic deformation of the sample. However, the influence of thermo-elastic deformation is different between our numerical proxy and the experimental sample. We discuss the role of irreversible deformation (e.g., microcracking) for the observed discrepancy by introducing temperature dependence of elastic moduli in the model. These results suggest that there are open perspectives to monitor thermal strain in geothermal reservoirs using CWI.

AN EFFICIENT SENSITIVITY CALCULATION OF TILTED APERTURES FOR PRECLINICAL MULTI-PINHOLE SPECT

Sensitivity performance is one of the key issues in multi-pinhole collimator design for small animal pinhole Single photon emission computed tomography (SPECT). Currently, there are two approaches in predicting sensitivity performance: analytical formula and Monte Carlo (MC) simulation. Analytical formula offers fast computation, while MC simulation provides better modeling of various physical effects and generates more accurate sensitivity prediction. Tilted pinhole apertures become popular in modern system design, because they can avoid projection overlapping and increase field-of-view (FOV) compared to traditional multiple pinholes. However, conventional analytical formula for sensitivity prediction cannot be directly applied to tilted apertures. In this research, we present a modified analytical formula to predict the sensitivity performance by considering tilted and translated pinhole apertures in a multi-pinhole collimation design. The modification is based on a construction of a virtual object plane which is parallel to the aperture plane in the tilted pinhole. Since the new formula is derived in the vector domain, it can be readily integrated to computer-aided-design software to greatly simplify the collimator design optimization. The results show that the modified formula generates sensitivity prediction similar to that from the MC simulation for a multi-pinhole system with tilted pinholes. When larger tilted pinholes are used to increase FOV, the formula can also accurately generate sensitivity prediction with a slightly reduced peak value. For a tilted pinhole aperture up to 40°, the simulation results indicate that the conventional analytical formula may overestimate as much as 25% sensitivity.

Modeling of physical effects governing the behavior of the activity coefficients of an electrolyte

A model describing the interaction of hydrated ions in an electrolyte is proposed. The approach developed is capable of allowing one to calculate the action of the main physical factors and explain the nature of the curves for the activity coefficients based on this. The results of simulation are tested on a large number of experimental data.

Complex Flexible Aerospace Vehicles Simulation and Control System Design

New results in the field of the automaton of the aerospace flight control system design are presented in this paper. The concept of a universal program for research of dynamic properties, calculation of comprehensive mathematical models, and simulation of the flight motion and synthesis of smart control laws for different types of the flexible aerospace constructions (launchers and missiles) is considered. The special attention to creation of mathematical models of different physical phenomenon of aerospace vehicles is given. The basis of the program is the structure, which allows carrying out of the analysis of dynamic characteristics, simulation, and visual information representation. The software package is supplied with the library of program modules. These modules are designed on the base of mathematical models of separate vehicle elements and different physical effects, such as flexibility, sloshing, sluggishness of engines, local angle of attack values, etc. Selection of different sets of the mathematical models and program modules allows investigating different constructions for known and prospective vehicles. The interface of the program enables changing parameters of the vehicle in a wide range, to simulate flight at any trajectory and to output results of the analysis in a digital or graphical form. For synthesis of control laws, provides the usage of the smart control approach.

Software Package for Simulation and Control System Design for a Nonrigid Space Vehicle

New results in the field of automation of the space flight control system design are presented in this paper. The concept of a universal program for research of dynamic properties, calculation of comprehensive mathematical models, simulation of the flight motion and synthesis of smart control laws for different types of flexible aerospace constructions (launchers and missiles) is considered. Special attention is given to creation of mathematical models of different physical phenomena in aerospace vehicles. The basis of the program is a block that enables the analysis of dynamic characteristics, simulation, and the visual representation of information. The software package is supplied with a library of program modules. These modules are designed on the base of mathematical models of separate vehicle elements and different physical effects, such as flexibility, sloshing, sluggishness of engines, local angle of attack values, etc. Selection of different sets of mathematical models and program modules allows investigating different constructions for known and prospective vehicles. The interface of the program enables changing parameters of the vehicle in a wide range, simulate flight at any trajectory and output results of the analysis in a numerical or graphical form. For synthesis of control laws the smart control approach is used.

An empirical model of collective electrostatic effects for laser-beam channeling in long-scale-length relativistic plasmas

This work investigates the capability of ultraintense lasers with irradiance from 1018 to 1021 W cm−2 to produce highly energetic electron beams from a Gaussian focus in a low-density plasma. A simple particle simulation code including a physical model of collective electrostatic effects in relativistic plasmas has been developed. Without electrostatic fields, free electrons escape from the Gaussian focal region of a 10-ps petawatt laser pulse very quickly, well before the laser field reaches its maximum amplitude. However, it has been demonstrated that the electrostatic field generated by the electron flow is able to strongly modify the range and direction of the laser-generated MeV electrons by allowing trapped electrons to experience much higher laser-intensity peaks along their trajectories. This modeling predicts some collimation but not enough to meet the requirements of fast ignition.

Verilog-A Modeling of Radiation-Induced Mismatch Enhancement

Physical model of TID effects is embedded into BSIM3v3 model implemented using Verilog-A. Radiation-induced mismatch enhancement due to the combined action of technology variations and electrical bias difference is demonstrated by simulation. It is shown that the total ionizing dose degradation of circuit components under inequivalent electric field conditions could lead to mismatch of internal circuit parameters, which results in a change to circuit output mismatch parameters.

Theory and Software Package for Simulation and Smart Control Design for Complex Flexible Aerospace Vehicles

AbstractNew results in the field of the automaton of the aerospace flight control system design are presented in this paper. The concept of a universal program for research of dynamic properties, calculation of comprehensive mathematical models, and simulation of the flight motion and synthesis of smart control laws for different types of the flexible aerospace constructions (launchers and missiles) is considered. The special attention to creation of mathematical models of different physical phenomenon of aerospace vehicles is given. The basis of the program is the structure, which allows carrying out of the analysis of dynamic characteristics, simulation, and visual information representation. The software package is supplied with the library of program modules. These modules are designed on the base of mathematical models of separate vehicle elements and different physical effects, such as flexibility, sloshing, sluggishness of engines, local angle of attack values, etc. Selection of different sets of the mathematical models and program modules allows investigating different constructions for known and prospective vehicles. The interface of the program enables changing parameters of the vehicle in a wide range, to simulate flight at any trajectory and to output results of the analysis in a digital or graphical form. For synthesis of control laws, provides the usage of the smart control approach.

Use of a Plume-Modeling Study To Reduce the Risk of H2S Release in an Exploration Well

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper IPTC 13636, ’The Use of a Plume Modelling Study to Reduce the Risk of H2S Release in an Exploration Well to as Low as Reasonably Practicable (ALARP),’ by J.G. Mcllroy, SPE, Petroleum Development Oman, originally prepared for the 2009 International Petroleum Technology Conference, Doha, Qatar, 7-9 December. With the increasing likelihood of exploration wells being near population centers, a blueprint for the evaluation of the risk of an uncontrolled release of gas reaching such a settlement needs to be quantified. The full-length paper reviews a case study from Oman in which a plume-(gas cloud) modeling study was completed to determine the level of hydrogen sulfide (H2S) away from an exploration well. Introduction Within Petroleum Development Oman’s (PDO’s) Block 6 license, the South Oman salt basin has been widely explored. The discovery of oil-bearing carbonates encased in salt (referred to as “stringers”) led to deeper drilling and more-challenging technical issues, including increasing pressures and the presence of H2S. The well under consideration was notable as the first stringer well to be close to a significant population center. The full-length paper includes background information, key study elements, results, and identified risk-mitigation actions required to reduce the risk to as low as reasonably practicable (ALARP). Modeling PDO has been involved in drilling operations in onshore Oman for more than 40 years and has a very high success rate in terms of wells drilled safely. This overpressure stringer well represents another well drilled to a target within the salt, and as such is “business as usual” from an exploration perspective, but the presence of the nearby settlement requires a more-complete approach to risk analysis. This called for modeling of physical effects (toxic dispersion) of an unconstrained flow from a well. The blowout frequency and probability of blowout type are based on reviews of reports compiled for previous clients. This led to a review of the existing PDO operational Bow-Tie (or risk and outcome) analysis to assess the adequacy of controls (existing and planned) to reduce risk to tolerable and ALARP. The following key steps were followed in this study. An assessment of the likelihood of an uncontrolled H2S release (blowout) occurring. This was based on available global statistics. Computer modeling of near- and far-field H2S concentrations that would result from several release scenarios, which used software from the Energy Resources Conservation Board (ERCB) of Calgary, Canada, and software developed by Shell (for consequence and risk modeling). The Shell dispersion-modeling results were considered more appropriate for the relatively near-field-concentration calculations. It provided more input control than the ERCB software because it allowed entering a large number of parameters including process conditions. This also includes the estimates of the probabilities of the blowout types (with drillpipe and without drillpipe) and the estimate of fluid type.

Theory and Software for Simulation of Complex Flexible Aerospace Vehicles and Smart Control

AbstractThe concept of a universal program for research into dynamic properties, calculation of comprehensive mathematical models, simulation of the flight motion and synthesis of smart control laws for different types of the flexible aerospace constructions (launchers and missiles) is considered. The basis of the program is the structure, which allows carrying out of the analysis of dynamic characteristics, simulation, and visual information representation. The software package is supplied with the library of program modules. These modules are designed on the base of mathematical models of separate vehicle elements and different physical effects, such as flexibility, sloshing, sluggishness of engines, local angle of attack values, etc. Selection of different sets of the mathematical models and program modules allows investigating different constructions for known and prospective vehicles. The interface of the program enables changing parameters of the vehicle in a wide range, to simulate flight at any trajectory and to output results of the analysis in a digital or graphical form. For synthesis of control laws, provides the usage of the smart control approach.

Bayesian statistical reconstruction for low-dose X-ray computed tomography using an adaptive-weighting nonlocal prior

How to reduce the radiation dose delivered to the patients has always been a important concern since the introduction of computed tomography (CT). Though clinically desired, low-dose CT images can be severely degraded by the excessive quantum noise under extremely low X-ray dose circumstances. Bayesian statistical reconstructions outperform the traditional filtered back-projection (FBP) reconstructions by accurately expressing the system models of physical effects and the statistical character of the measurement data. This work aims to improve the image quality of low-dose CT images using a novel AW nonlocal ( adaptive-weighting nonlocal) prior statistical reconstruction approach. Compared to traditional local priors, the proposed prior can adaptively and selectively exploit the global image information. It imposes an effective resolution-preserving and noise-removing regularization for reconstructions. Experimentation validates that the reconstructions using the proposed prior have excellent performance for X-ray CT with low-dose scans.

Physical Model of Field Enhancement and Edge Effects of FinFET Charge-Trapping NAND Flash Devices

The physical model for field enhancement (FE) and the edge effects of body-tied FinFET charge-trapping NAND Flash devices are extensively studied in this paper. First, analytical equations are derived to provide insight to the FE effect for FinFET devices, and these analytical results are validated by 3-D TCAD simulation and experimental verification. Next, complicated programming and erasing characteristics and transconductance and subthreshold slope (gm/SS) behaviors are completely explained by the nonuniform injection behavior along various corner edges in FinFET. FE allows high program and erase speed and larger memory window. On the other hand, the edge effect complicates the device DC I-V, as well as programming and erasing characteristics, and these must be taken into account in memory circuit design.

Simulation of imaging atmospheric Cherenkov telescopes with CORSIKA and sim_ telarray

Imaging atmospheric Cherenkov telescopes (IACTs) have resulted in a break-through in very-high energy (VHE) gamma-ray astrophysics. While early IACT installations faced the problem of detecting any sources at all, current instruments are able to see many sources, often over more than two orders of magnitude in energy. As instruments and analysis methods have matured, the requirements for calibration and modelling of physical and instrumental effects have increased. In this article, a set of Monte Carlo simulation tools is described that attempts to include all relevant effects for IACTs in great detail but aims to achieve this in an efficient and flexible way. These tools were originally developed for the HEGRA IACT system and later adapted for the H.E.S.S. experiment. Their inherent flexibility to describe quite arbitrary IACT systems makes them also an ideal tool for evaluating the potential of future installations. It is in use for design studies of CTA and other projects.