Energy Technology Data Exchange (ETDEWEB)
Miocchi, P.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Alessandrini, E. [Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Pasquato, M.; Lee, Y.-W. [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Vesperini, E. [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States)
2015-01-20
We present semi-analytical models and simplified N-body simulations with 10{sup 4} particles aimed at probing the role of dynamical friction (DF) in determining the radial distribution of blue straggler stars (BSSs) in globular clusters. The semi-analytical models show that DF (which is the only evolutionary mechanism at work) is responsible for the formation of a bimodal distribution with a dip progressively moving toward the external regions of the cluster. However, these models fail to reproduce the formation of the long-lived central peak observed in all dynamically evolved clusters. The results of N-body simulations confirm the formation of a sharp central peak, which remains as a stable feature over time regardless of the initial concentration of the system. In spite of noisy behavior, a bimodal distribution forms in many cases, with the size of the dip increasing as a function of time. In the most advanced stages, the distribution becomes monotonic. These results are in agreement with the observations. Also, the shape of the peak and the location of the minimum (which, in most of cases, is within 10 core radii) turn out to be consistent with observational results. For a more detailed and close comparison with observations, including a proper calibration of the timescales of the dynamical processes driving the evolution of the BSS spatial distribution, more realistic simulations will be necessary.
Miocchi, P; Lanzoni, B; Ferraro, F R; Dalessandro, E; Vesperini, E; Alessandrini, E; Lee, Y W
2014-01-01
We present semi-analytical models and simplified $N$-body simulations with $10^4$ and $10^5$ particles aimed at probing the role of dynamical friction (DF) in determining the radial distribution of Blue Straggler Stars (BSSs) in globular clusters. The semi-analytical models show that DF (which is the only evolutionary mechanism at work) is responsible for the formation of a bimodal distribution with a dip progressively moving toward the external regions of the cluster. However, these models fail to reproduce the formation of the long-lived central peak observed in all dynamically evolved clusters. The results of $N$-body simulations confirm the formation of a sharp central peak, which remains as a stable feature over the time regardless of the initial concentration of the system. In spite of a noisy behavior, a bimodal distribution forms in many cases, with the size of the dip increasing as a function of time. In the most advanced stages the distribution becomes monotonic. These results are in agreement with ...
Computer modelling of eddy current probes
International Nuclear Information System (INIS)
Computer programs have been developed for modelling impedance and transmit-receive eddy current probes in two-dimensional axis-symmetric configurations. These programs, which are based on analytic equations, simulate bobbin probes in infinitely long tubes and surface probes on plates. They calculate probe signal due to uniform variations in conductor thickness, resistivity and permeability. These signals depend on probe design and frequency. A finite element numerical program has been procured to calculate magnetic permeability in non-linear ferromagnetic materials. Permeability values from these calculations can be incorporated into the above analytic programs to predict signals from eddy current probes with permanent magnets in ferromagnetic tubes. These programs were used to test various probe designs for new testing applications. Measurements of magnetic permeability in magnetically biased ferromagnetic materials have been performed by superimposing experimental signals, from special laboratory ET probes, on impedance plane diagrams calculated using these programs. (author). 3 refs., 2 figs
Institute of Scientific and Technical Information of China (English)
MIN Yinghua; LI Zhongcheng
1999-01-01
Delay consideration has been a majorissue in design and test of high performance digital circuits. Theassumption of input signal change occurring only when all internal nodesare stable restricts the increase of clock frequency. It is no longertrue for wave pipelining circuits. However, previous logical delaymodels are based on the assumption. In addition, the stable time of arobust delay test generally depends on the longest sensitizable pathdelay. Thus, a new delay model is desirable. This paper explores thenecessity first. Then, Boolean process to analytically describe thelogical and timing behavior of a digital circuit is reviewed. Theconcept of sensitization is redefined precisely in this paper. Based onthe new concept of sensitization, an analytical delay model isintroduced. As a result, many untestable delay faults under thelogical delay model can be tested if the output waveforms can be sampledat more time points. The longest sensitizable path length is computedfor circuit design and delay test.
Model for resonant plasma probe.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue
2007-04-01
This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.
Analytical investigation into the resonance frequencies of a curling probe
Arshadi, Ali; Brinkmann, Ralf Peter
2016-08-01
The term ‘active plasma resonance spectroscopy’ (APRS) denotes a class of closely related plasma diagnostic methods which utilize the natural ability of plasmas to resonate on or near the electron plasma frequency {ω\\text{pe}} ; an electrical radio frequency signal (in the GHz range) is coupled into the plasma via an antenna or a probe, the spectral response is recorded and a mathematical model is employed to determine plasma parameters such as the plasma density and the electron temperature. The curling probe, recently invented by Liang et al (2011 Appl. Phys. Express 4 066101), is a novel realization of the APRS concept which has many practical advantages. In particular, it can be miniaturized and flatly embedded into the chamber wall, thus allowing the monitoring of plasma processes without contamination nor disturbance. Physically, the curling probe can be understood as a ‘coiled’ form of the hairpin probe (Stenzel 1976 Rev. Sci. Instrum. 47 603). Assuming that the spiralization of the probe has little electrical effect, this paper investigates the characteristcs of a ‘straightened’ curling probe by modeling it as an infinite slot-type resonator that is in direct contact with the plasma. The diffraction of an incident plane wave at the slot is calculated by solving the cold plasma model and Maxwell’s equations simultaneously. The resonance frequencies of the probe are derived and are found to be in good agreement with the numerical results of the probe inventors.
Analytical model for ramp compression
Xue, Quanxi; Jiang, Shaoen; Wang, Zhebin; Wang, Feng; Hu, Yun; Ding, Yongkun
2016-08-01
An analytical ramp compression model for condensed matter, which can provide explicit solutions for isentropic compression flow fields, is reported. A ramp compression experiment can be easily designed according to the capability of the loading source using this model. Specifically, important parameters, such as the maximum isentropic region width, material properties, profile of the pressure pulse, and the pressure pulse duration can be reasonably allocated or chosen. To demonstrate and study this model, laser-direct-driven ramp compression experiments and code simulation are performed successively, and the factors influencing the accuracy of the model are studied. The application and simulation show that this model can be used as guidance in the design of a ramp compression experiment. However, it is verified that further optimization work is required for a precise experimental design.
Analytical applications of near-infrared fluorescent probes
Patonay, Gabor; Tarazi, Leila A.; George, Abraham; Van Aken, Koen; Gorecki, Tadeusz; Strekowski, Lucjan
1997-05-01
By combining near-infrared (NIR) fluorophores and commercially available laser diodes, a promising technique emerges where visible probes are less effective due to background interference. The application of NIR fluorophores in fiber-optic probes for the determination of metal ions in the environment and for biological assays will be discussed. The spectral behavior of a new NIR fluorophore TG-170 in the presence of metal ions and the first synthesis and spectral characterization of a NIR dye KVA-22 substituted with a crown ether, a metal complexing functionality, will be presented.
Analytic and preparative resources of scanning probe microscopy for nanotechnology
International Nuclear Information System (INIS)
Full text: The NTEGRA line of NT-MDT microscopes is the realization of the Probe NanoLaboratory (PNL) concept. PNL is a versatile complex, a bench top laboratory which opens a new era of scanning probe microscopy. Being a high level modern scanning probe microscope (SPM) it permits the sample surface investigations with highest resolution available nowadays. The system is able to run any of the 43 SPM techniques, has low intrinsic noises and due to integrated capacitive sensors the scanner non-linearity is also very low. User-friendly developed design solution allows customer easily modify configuration currently used by changing active parts and external devices. The self-recognition option is included so the auto adjustment is possible. PNL lays on the crossroad of scanning probe microscopy, optical microscopy, spectroscopy, and electron microscopy techniques. The high quality surface information about the object is greatly supplemented by spectral properties characterization, 3D physical properties reconstruction and automated high throughput screening that can be performed using PNL based systems. Full range of nano-lithographic techniques provides a broad spectrum possibility to modify the object surface deliberately. Thus unlike conventional SPM, the PNL based systems provide high score tools for large scale optical observations, chemical analysis, and spatial structure investigations. As to new developments on the scanning probe microscopy field the -AFAM (Atomic Force Acoustic Microscopy) mode should be especially mentioned. It provides the unique possibility to perform contrast imaging of the local hardness distribution on soft as well as on hard samples that is hardly possible using other techniques, such as Phase Imaging or Force Modulation. What is even more valuable, AFAM allows Young's modulus to be quantitatively determined at each point of the scan. The scientific market tendencies direct creation of a new generation of scientific instrumentation
Detection of double analytes by employing new luminescent lanthanide probe
Ma, Qianmin; Wang, Qianming
2015-11-01
The synthesis and spectroscopic features of 1,4-bis([1,10] phenanthroline-[5,6-d] imidazol-2-yl) benzene (BPIB) with its europium (III) complex have been described. Characteristic red emissions can be achieved upon the excitation at 369 nm. This compound exhibited ultraviolet absorption shifts as well as fluorescence emission quenching upon exposure to Cu2+ ions. Hence, it can be utilized as a responsive copper sensor in terms of double routes including naked-eye observation and fluorescent probing. In the case of anions, this sensor could be used for direct determination of F- in DMSO through fluorescence signal changes with satisfied results.
Analytical methods used at model facility
International Nuclear Information System (INIS)
A description of analytical methods used at the model LEU Fuel Fabrication Facility is presented. The methods include gravimetric uranium analysis, isotopic analysis, fluorimetric analysis, and emission spectroscopy
In Situ Scanning Probe Microscopy and New Perspectives in Analytical Chemistry
DEFF Research Database (Denmark)
Andersen, Jens Enevold Thaulov; Zhang, Jingdong; Chi, Qijin; Hansen, Allan Glargaard; Nielsen, Jens Ulrik; Friis, Esben P.; Ulstrup, Jens; Boisen, Anja; Jensenius, Henriette
1999-01-01
for molecular- and mesoscopic-scale analytical chemistry, are then reviewed. They are illustrated by metallic electro-crystallisation and -dissolution, and in situ STM spectroscopy of large redox molecules. The biophysically oriented analytical options of in situ atomic force microscopy, and......The resolution of scanning probe microscopies is unpresedented but the techniques are fraught with limitations as analytical tools. These limitations and their relationship to the physical mechanisms of image contrast are first discussed. Some new options based on in situ STM, which hold prospects...... analytical chemical perspectives for the new microcantilever sensor techniques are also discussed....
Analytical eigenstates for the quantum Rabi model
Zhong, Honghua; Lee, Chaohong
2013-01-01
We develop a method to find analytical solutions of the quantum Rabi model. The analytical solutions including symmetric, anti-symmetric and asymmetric ones are given in terms of the confluent Heun functions. In particular, both regular and exceptional solutions are given in a unified form. In addition, the analytical conditions for determining the energy spectrum are obtained. Our results show analytically that the Braak's conditions [Phys. Rev. Lett. \\textbf{107}, 100401 (2011)] are a type of sufficient conditions for determining the regular solutions.
Analytical modelling of soccer heading
Indian Academy of Sciences (India)
Zahari Taha; Mohd Hasnun Arif Hassan; Iskandar Hasanuddin
2015-08-01
Heading occur frequently in soccer games and studies have shown that repetitive heading of the soccer ball could result in degeneration of brain cells and lead to mild traumatic brain injury. This study proposes a two degree-of-freedom linear mathematical model to study the impact of the soccer ball on the brain. The model consists of a mass–spring–damper system, in which the skull, the brain and the soccer ball are modelled as a mass and the neck modelled as a spring–damper system. The proposed model was compared with previous dynamic model for soccer ball-to-head impact. Moreover, it was also validated against drop ball experiment on an instrumented dummy skull and also compared with head acceleration data from previous studies. Comparison shows that our proposed model is capable of describing both the skull and brain accelerations qualitatively and quantitatively. This study shows that a simple linear mathematical model can be useful in giving a preliminary insight on the kinematics of human skull and brain during a ball-to-head impact. The model can be used to investigate the important parameters during soccer heading that affect the brain displacement and acceleration, thus providing better understanding of the mechanics behind it.
Analytical model of internally coupled ears
DEFF Research Database (Denmark)
Vossen, Christine; Christensen-Dalsgaard, Jakob; Leo van Hemmen, J
2010-01-01
, data demonstrating an asymmetrical spatial pattern of membrane vibration. As the analytical calculations show, the internally coupled ears increase the directional response, appearing in large directional internal amplitude differences (iAD) and in large internal time differences (iTD). Numerical...... differences in the tympanic membrane vibrations. Both cues show strong directionality. The work presented herein sets out the derivation of a three dimensional analytical model of internally coupled ears that allows for calculation of a complete vibration profile of the membranes. The analytical model...... additionally provides the opportunity to incorporate the effect of the asymmetrically attached columella, which leads to the activation of higher membrane vibration modes. Incorporating this effect, the analytical model can explain measurements taken from the tympanic membrane of a living lizard, for example...
Bocquet, Franck; Nony, Laurent; Loppacher, Christian; Glatzel, Thilo
2008-01-01
An analytical model of the electrostatic force between the tip of a non-contact Atomic Force Microscope (nc-AFM) and the (001) surface of an ionic crystal is reported. The model is able to account for the atomic contrast of the local contact potential difference (CPD) observed while nc-AFM-based Kelvin Probe Force Microscopy (KPFM) experiments. With the goal in mind to put in evidence this short-range electrostatic force, the Madelung potential arising at the surface of the ionic crystal is p...
Analytical eigenstates for the quantum Rabi model
International Nuclear Information System (INIS)
We develop a method to find analytical solutions for the eigenstates of the quantum Rabi model. These include symmetric, anti-symmetric and asymmetric analytic solutions given in terms of the confluent Heun functions. Both regular and exceptional solutions are given in a unified form. In addition, the analytic conditions for determining the energy spectrum are obtained. Our results show that conditions proposed by Braak (2011 Phys. Rev. Lett. 107 100401) are a type of sufficiency condition for determining the regular solutions. The well-known Judd isolated exact solutions appear naturally as truncations of the confluent Heun functions. (paper)
An analytic uranium sources model
International Nuclear Information System (INIS)
This document presents a method for estimating uranium resources as a continuous function of extraction costs and describing the uncertainty in the resulting fit. The estimated functions provide convenient extrapolations of currently available data on uranium extraction cost and can be used to predict the effect of resource depletion on future uranium supply costs. As such, they are a useful input for economic models of the nuclear energy sector. The method described here pays careful attention to minimizing built-in biases in the fitting procedure and defines ways to describe the uncertainty in the resulting fits in order to render the procedure and its results useful to the widest possible variety of potential users. (author)
An improved model of Robinson equivalent circuit analytical model
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The Robinson equivalent circuit analytical model can be used only in calculating shielding effectiveness of enclosure with the same multi-holes in one wall, but cannot be used in different multi-holes in two walls. According to the practical requirement, this article uses Konefal’s and Farhana’s characteristic impedance of apertures to improve the equivalent circuit analytical model in different multi-holes in two walls. The improved equivalent circuit analytical model is more useful than Robinson equivalent circuit analytical model. In the article, all kinds of enclosures are simulated by TLM (Transmission-Line Matrix method) to prove that this improved model is feasible in multimode.
International Nuclear Information System (INIS)
This paper presents a simple analytical theory for the velocity-dependent pump-probe laser spectroscopy of 87Rb and 85Rb atoms where the pump and the probe beams are circularly or linearly polarized. The analytical solutions of the line shapes of the velocity-selective optical pumping spectroscopy [G. Moon and H. R. Noh, Phys. Rev. A 78, 032506 (2008)] and saturated absorption spectroscopy [G. Moon and H. R. Noh, J. Opt. Soc. Am. B 25, 701 (2008); 27, 1741 (2010)] obtained in the previous reports, expressed as a sum of several Lorentzian functions, could be approximated as one (or in some cases, two) Lorentzian function(s). In particular, the contributions of the saturation and optical pumping effects could be discriminated explicitly in these simple analytical solutions, which is not possible in existing theories such as Nakayama's model. The simple analytical results for the saturation spectroscopy were compared with experimental results, and good agreement between them was observed.
Analytical model for Stirling cycle machine design
Energy Technology Data Exchange (ETDEWEB)
Formosa, F. [Laboratoire SYMME, Universite de Savoie, BP 80439, 74944 Annecy le Vieux Cedex (France); Despesse, G. [Laboratoire Capteurs Actionneurs et Recuperation d' Energie, CEA-LETI-MINATEC, Grenoble (France)
2010-10-15
In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined. (author)
Analytical model for Stirling cycle machine design
Formosa, Fabien; 10.1016/j.enconman.2010.02.010
2013-01-01
In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined.
Analytical model for Stirling cycle machine design
International Nuclear Information System (INIS)
In order to study further the promising free piston Stirling engine architecture, there is a need of an analytical thermodynamic model which could be used in a dynamical analysis for preliminary design. To aim at more realistic values, the models have to take into account the heat losses and irreversibilities on the engine. An analytical model which encompasses the critical flaws of the regenerator and furthermore the heat exchangers effectivenesses has been developed. This model has been validated using the whole range of the experimental data available from the General Motor GPU-3 Stirling engine prototype. The effects of the technological and operating parameters on Stirling engine performance have been investigated. In addition to the regenerator influence, the effect of the cooler effectiveness is underlined.
An analytical model of prominence mass motion
Routh, Swati; Bhat, Atul
2016-01-01
Solar Prominences are intriguing, but poorly understood magnetic structures of the solar corona. Convective motions in the photosphere and sub-photosphere may be responsible for generating the magnetic fields that support long-lived quiescent solar prominence. The dynamics of solar prominence has been the subject of a large number of studies. We develop a theoretical model using analytical approximations to analyze the nature of the dynamics of these quiescent solar prominences based on the K-S model.
Relativistic models of magnetars: Nonperturbative analytical approach
Yazadjiev, Stoytcho
2011-01-01
In the present paper we focus on building simple nonperturbative analytical relativistic models of magnetars. With this purpose in mind we first develop a method for generating exact interior solutions to the static and axisymmetric Einstein-Maxwell-hydrodynamic equations with anisotropic perfect fluid and with pure poloidal magnetic field. Then using an explicit exact solution we present a simple magnetar model and calculate some physically interesting quantities as the surface elipticity and the total energy of the magnetized star.
Analytic amplitude models for forward scattering
Kang, K.; Cudell, Jean-René; Ezhela, V. V.; Gauron, P.; Kuyanov, Yu. V.; Lugovsky, S. V.; Nicolescu, B.; Tkachenko, N. P.
2001-01-01
We report on fits of a large class of analytic amplitude models for forward scattering against the comprehensive data for all available reactions. To differentiate the goodness of the fits of many possible parametrizations to a large sample of data, we developed and used a set of quantitative indicators measuring statistical quality of the fits over and beyond the typical criterion of the $\\Chi^2 /dof$. These indicators favor models with a universal $ log^2 s$ Pomeron term, which enables one ...
A robust molecular probe for Ångstrom-scale analytics in liquids.
Nirmalraj, Peter; Thompson, Damien; Dimitrakopoulos, Christos; Gotsmann, Bernd; Dumcenco, Dumitru; Kis, Andras; Riel, Heike
2016-01-01
Traditionally, nanomaterial profiling using a single-molecule-terminated scanning probe is performed at the vacuum-solid interface often at a few Kelvin, but is not a notion immediately associated with liquid-solid interface at room temperature. Here, using a scanning tunnelling probe functionalized with a single C60 molecule stabilized in a high-density liquid, we resolve low-dimensional surface defects, atomic interfaces and capture Ångstrom-level bond-length variations in single-layer graphene and MoS2. Atom-by-atom controllable imaging contrast is demonstrated at room temperature and the electronic structure of the C60-metal probe complex within the encompassing liquid molecules is clarified using density functional theory. Our findings demonstrates that operating a robust single-molecular probe is not restricted to ultra-high vacuum and cryogenic settings. Hence the scope of high-precision analytics can be extended towards resolving sub-molecular features of organic elements and gauging ambient compatibility of emerging layered materials with atomic-scale sensitivity under experimentally less stringent conditions. PMID:27516157
Automated statistical modeling of analytical measurement systems
International Nuclear Information System (INIS)
The statistical modeling of analytical measurement systems at the Idaho Chemical Processing Plant (ICPP) has been completely automated through computer software. The statistical modeling of analytical measurement systems is one part of a complete quality control program used by the Remote Analytical Laboratory (RAL) at the ICPP. The quality control program is an integration of automated data input, measurement system calibration, database management, and statistical process control. The quality control program and statistical modeling program meet the guidelines set forth by the American Society for Testing Materials and American National Standards Institute. A statistical model is a set of mathematical equations describing any systematic bias inherent in a measurement system and the precision of a measurement system. A statistical model is developed from data generated from the analysis of control standards. Control standards are samples which are made up at precise known levels by an independent laboratory and submitted to the RAL. The RAL analysts who process control standards do not know the values of those control standards. The object behind statistical modeling is to describe real process samples in terms of their bias and precision and, to verify that a measurement system is operating satisfactorily. The processing of control standards gives us this ability
Conductivity bounds in probe brane models
Ikeda, Tatsuhiko N; Nakai, Yuichiro
2016-01-01
We discuss upper and lower bounds on the electrical conductivity of finite temperature strongly coupled quantum field theories, holographically dual to probe brane models, within linear response. In a probe limit where disorder is introduced entirely through an inhomogeneous background charge density, we find simple lower and upper bounds on the electrical conductivity in arbitrary dimensions. In field theories in two spatial dimensions, we show that both bounds persist even when disorder is included in the bulk metric. We discuss the challenges with finding sharp lower bounds on conductivity in three or more spatial dimensions when the metric is inhomogeneous.
Some analytical models of anisotropic strange stars
Murad, Mohammad Hassan
2016-01-01
Over the years of the concept of local isotropy has become a too stringent condition in modeling relativistic self-gravitating objects. Taking local anisotropy into consideration, in this work, some analytical models of relativistic anisotropic charged strange stars have been developed. The Einstein-Maxwell gravitational field equations have been solved with a particular form of one of the metric potentials. The radial pressure and the energy density have been assumed to follow the usual linear equation of state of strange quark matter, the MIT bag model.
SIMMER-III analytic thermophysical property model
International Nuclear Information System (INIS)
An analytic thermophysical property model using general function forms is developed for a reactor safety analysis code, SIMMER-III. The function forms are designed to represent correct behavior of properties of reactor-core materials over wide temperature ranges, especially for the thermal conductivity and the viscosity near the critical point. The most up-to-date and reliable sources for uranium dioxide, mixed-oxide fuel, stainless steel, and sodium available at present are used to determine parameters in the proposed functions. This model is also designed to be consistent with a SIMMER-III model on thermodynamic properties and equations of state for reactor-core materials. (author)
Vortex microscope: analytical model and experiment
Masajada, Jan; Popiołek-Masajada, Agnieszka; Szatkowski, Mateusz; Plociniczak, Łukasz
2015-11-01
We present the analytical model describing the Gaussian beam propagation through the off axis vortex lens and the set of axially positioned ideal lenses. The model is derived on the base of Fresnel diffraction integral. The model is extended to the case of vortex lens with any topological charge m. We have shown that the Gaussian beam propagation can be represented by function G which depends on four coefficients. When propagating from one lens to another the function holds its form but the coefficient changes.
Analytical model of the pulse tube engine
International Nuclear Information System (INIS)
The pulse tube engine represents the thermodynamic inversion of the pulse tube refrigerator used in cryogenic cooling applications. It has a high potential to be used as a prime mover for the conversion of low grade waste heat into mechanical or electrical energy. This paper describes an analytical analysis of the pulse tube engine based on a zero-dimensional model. During compression and expansion, the engine components are considered as isothermal with characteristic temperatures. At the piston's dead centers, a thermal relaxation model is used to switch between these temperatures. Analytical relations for the pV–work developed by the pulse tube engine and its efficiency are derived. The irreversible nature of the pulse tube engine is studied by calculating the entropy production in the components. Furthermore, the thermodynamic cycle is investigated analytically under variation of design features and operating conditions. The results are compared to prior numerical studies. The minimal temperature ratio above which the engine provides a work output is derived analytically and compared to experimental observations. Fundamental characteristics and application limitations of the pulse tube engine are disclosed. An upper limit for the efficiency of the pulse tube engine is derived theoretically and confirmed experimentally as well as through numerically calculations. - Highlights: • An analytical expression for the pV-work of the pulse tube engine is derived. • The irreversible nature of the pulse tube engine is shown mathematically. • The temperature ratio above which the engine operates is calculated and measured. • An upper limit for the pulse tube engine's efficiency is derived
Application of an analytical phase transformation model
Institute of Scientific and Technical Information of China (English)
LIU Feng; WANG Hai-feng; YANG Chang-lin; CHEN Zheng; YANG Wei; YANG Gen-cang
2006-01-01
Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic.
Analysis of Kelvin Probe Operational Models
Popescu, Eugeniu M.
2011-01-01
We present a study of several models on which Kelvin Probe instruments with flat and spherical tips rely for operation and for the determination of the contact potential difference. Using covariance analysis, we have investigated the precision limits of each model as imposed by the Cramer-Rao bound. Where the situation demanded, we have evaluated the bias introduced by the method in the estimation of the contact potential difference.
SIMMER-III Analytic Thermophysical Property Model
守田 幸路; 飛田 吉春; 近藤 悟; E.A.Fischer
1999-01-01
An analytic thermophysical property model using general function forms is developed for a reactor safety analysis code, SIMMER-III. The function forms arc designed to represent correct behavior of properties of reactor-core materials over wide temperature ranges, especially for the thermal conductivity and the viscosity near the critical point. The most up-to-date and reliable sources for uranium dioxide, mixed-oxide fuel, stainless stee1, and sodium available at present are used to determine...
Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes
International Nuclear Information System (INIS)
Infrared-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro analysis in the clinical laboratory and for non-invasive diagnostics. In general, the analysis of biofluids such as whole blood, urine, microdialysates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of infrared silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-infrared spectroscopy could revolutionize analytical tools in the clinical chemistry laboratory, and an example is given. Infrared diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathology in particular cannot be left out using mid-infrared fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain analysis of biopsy samples from bog mummified corpses, and recent results on the chemistry of dermis and hair samples are reported. Another field of application, for which results are reported, is food analysis and bio-reactor monitoring
Analytical model of parallel thermoelectric generator
International Nuclear Information System (INIS)
Highlights: → A novel theoretical model of parallel TEG was developed. → Approximate equations of output power, current of parallel TEG were derived. → How contact effect reduces the output power of parallel TEG was investigated. → An experimental platform was built to verify the model. → The theoretical values are basically consistent with the experimental results. -- Abstract: The paper studied the performances of parallel thermoelectric generator (TEG) by theoretical analysis and experimental test. An analytical model of parallel TEG was developed by theoretical analysis and calculation, based on thermodynamics theory, semiconductor thermoelectric theory and law of conservation of energy. Approximate expressions of output power and current of parallel TEG were deduced by the analytical model. An experimental system was built to verify the model. The results indicate that only when all of the thermoelectric modules (TE modules) in the parallel TEG have the same inherent parameters and working conditions, the parallel properties of the TEG are the same as that of common DC power. The existence of contact resistance is just like the increase of the TE module's internal resistance, which leads to the deceases of output power. The thermal contact resistance reduces the output power by reducing the temperature difference between the two sides of the thermocouples. The results derived from the model are basically consistent with the experimental results, the model is suitable for the performance researching and designing of parallel TEG.
Probing inflation models with gravitational waves
Domcke, Valerie
2016-01-01
A direct detection of primordial gravitational waves is the ultimate probe for any inflation model. While current CMB bounds predict the generic scale-invariant gravitational wave spectrum from slow-roll inflation to be below the reach of upcoming gravitational wave interferometers, this prospect may dramatically change if the inflaton is a pseudoscalar. In this case, a coupling to any abelian gauge field leads to a tachyonic instability for the latter and hence to a new source of gravitational waves, directly related to the dynamics of inflation. In this contribution we discuss how this setup enables the upcoming gravitational wave interferometers advanced LIGO/VIRGO and eLISA to probe the microphysics of inflation, distinguishing between different universality classes of single-field slow-roll inflation models. We find that the prime candidate for an early detection is a Starobinsky-like model.
Organizational Models for Big Data and Analytics
Directory of Open Access Journals (Sweden)
Robert L. Grossman
2014-04-01
Full Text Available In this article, we introduce a framework for determining how analytics capability should be distributed within an organization. Our framework stresses the importance of building a critical mass of analytics staff, centralizing or decentralizing the analytics staff to support business processes, and establishing an analytics governance structure to ensure that analytics processes are supported by the organization as a whole.
Analytical performance modeling for computer systems
Tay, Y C
2013-01-01
This book is an introduction to analytical performance modeling for computer systems, i.e., writing equations to describe their performance behavior. It is accessible to readers who have taken college-level courses in calculus and probability, networking and operating systems. This is not a training manual for becoming an expert performance analyst. Rather, the objective is to help the reader construct simple models for analyzing and understanding the systems that they are interested in.Describing a complicated system abstractly with mathematical equations requires a careful choice of assumpti
An analytical model for interactive failures
International Nuclear Information System (INIS)
In some systems, failures of certain components can interact with each other, and accelerate the failure rates of these components. These failures are defined as interactive failure. Interactive failure is a prevalent cause of failure associated with complex systems, particularly in mechanical systems. The failure risk of an asset will be underestimated if the interactive effect is ignored. When failure risk is assessed, interactive failures of an asset need to be considered. However, the literature is silent on previous research work in this field. This paper introduces the concepts of interactive failure, develops an analytical model to analyse this type of failure quantitatively, and verifies the model using case studies and experiments
Analytical models of relativistic accretion disks
Zhuravlev, Viacheslav V
2015-01-01
We present not a literature review but a description, as detailed and consistent as possible, of two analytic models of disk accretion onto a rotating black hole: a standard relativistic disk and a twisted relativistic disk. Although one of these models is much older than the other, both are of topical current interest for black hole studies. The way the exposition is presented, the reader with only a limited knowledge of general relativity and relativistic hydrodynamics can --- with little or no use of additional sources -- gain good insight into many technical details lacking in the original papers.
An Improved Analytic Model for Microdosimeter Response
Shinn, Judy L.; Wilson, John W.; Xapsos, Michael A.
2001-01-01
An analytic model used to predict energy deposition fluctuations in a microvolume by ions through direct events is improved to include indirect delta ray events. The new model can now account for the increase in flux at low lineal energy when the ions are of very high energy. Good agreement is obtained between the calculated results and available data for laboratory ion beams. Comparison of GCR (galactic cosmic ray) flux between Shuttle TEPC (tissue equivalent proportional counter) flight data and current calculations draws a different assessment of developmental work required for the GCR transport code (HZETRN) than previously concluded.
Analytical solutions for the Rabi model
Yu, Lixian; Liang, Qifeng; Chen, Gang; Jia, Suotang
2012-01-01
The Rabi model that describes the fundamental interaction between a two-level system with a quantized harmonic oscillator is one of the simplest and most ubiquitous models in modern physics. However, this model has not been solved exactly because it is hard to find a second conserved quantity besides the energy. Here we present a unitary transformation to map this unsolvable Rabi model into a solvable Jaynes-Cummings-like model by choosing a proper variation parameter. As a result, the analytical energy spectrums and wavefunctions including both the ground and the excited states can be obtained easily. Moreover, these explicit results agree well with the direct numerical simulations in a wide range of the experimental parameters. In addition, based on our obtained energy spectrums, the recent experimental observation of Bloch-Siegert in the circuit quantum electrodynamics with the ultrastrong coupling can be explained perfectly. Our results have the potential application in the solid-state quantum information...
Analytic Models of Plausible Gravitational Lens Potentials
Energy Technology Data Exchange (ETDEWEB)
Baltz, Edward A.; Marshall, Phil; Oguri, Masamune
2007-05-04
Gravitational lenses on galaxy scales are plausibly modeled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasizing that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential.We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modeled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.
An analytical model for climatic predictions
International Nuclear Information System (INIS)
A climatic model based upon analytical expressions is presented. This model is capable of making long-range predictions of heat energy variations on regional or global scales. These variations can then be transformed into corresponding variations of some other key climatic parameters since weather and climatic changes are basically driven by differential heating and cooling around the earth. On the basis of the mathematical expressions upon which the model is based, it is shown that the global heat energy structure (and hence the associated climatic system) are characterized by zonally as well as latitudinally propagating fluctuations at frequencies downward of 0.5 day-1. We have calculated the propagation speeds for those particular frequencies that are well documented in the literature. The calculated speeds are in excellent agreement with the measured speeds. (author). 13 refs
Analytical modeling of the steady radiative shock
Boireau, L.; Bouquet, S.; Michaut, C.; Clique, C.
2006-06-01
In a paper dated 2000 [1], a fully analytical theory of the radiative shock has been presented. This early model had been used to design [2] radiative shock experiments at the Laboratory for the Use of Intense Lasers (LULI) [3 5]. It became obvious from numerical simulations [6, 7] that this model had to be improved in order to accurately recover experiments. In this communication, we present a new theory in which the ionization rates in the unshocked (bar{Z_1}) and shocked (bar{Z_2} neq bar{Z_1}) material, respectively, are included. Associated changes in excitation energy are also taken into account. We study the influence of these effects on the compression and temperature in the shocked medium.
A simplified analytical model for pool swell
International Nuclear Information System (INIS)
Vapour suppression pool is being used in the containment of PHWR's to limit the pressure and temperature build-up in the containment following a LOCA. The discharge of high pressure water due to LOCA flashes into steam in the drywell, causes a rapid pressure build-up and forces an air-steam mixture into the suppression pool via the vent system. The containment and the pool internal structures need to withstand the hydrodynamic loading due to jet impingement and general motion of the pool water during the water clearing phase from the vents, the loads associated with pool swell in the subsequent air-clearing phase and those due to chugging - the oscillatory condensation of steam - apart from the general thermodynamic loading due to the mass and energy releases from the LOCA. This paper presents a simplified analytical model for pool swell assuming that the bubble is spherical in shape and it migrates vertically. (orig./HP)
Modeling Biodegradation and Reactive Transport: Analytical and Numerical Models
Energy Technology Data Exchange (ETDEWEB)
Sun, Y; Glascoe, L
2005-06-09
The computational modeling of the biodegradation of contaminated groundwater systems accounting for biochemical reactions coupled to contaminant transport is a valuable tool for both the field engineer/planner with limited computational resources and the expert computational researcher less constrained by time and computer power. There exists several analytical and numerical computer models that have been and are being developed to cover the practical needs put forth by users to fulfill this spectrum of computational demands. Generally, analytical models provide rapid and convenient screening tools running on very limited computational power, while numerical models can provide more detailed information with consequent requirements of greater computational time and effort. While these analytical and numerical computer models can provide accurate and adequate information to produce defensible remediation strategies, decisions based on inadequate modeling output or on over-analysis can have costly and risky consequences. In this chapter we consider both analytical and numerical modeling approaches to biodegradation and reactive transport. Both approaches are discussed and analyzed in terms of achieving bioremediation goals, recognizing that there is always a tradeoff between computational cost and the resolution of simulated systems.
Lower bounds in the quantum cell probe model
Sen, Pranab; Venkatesh, S.
2001-01-01
We introduce a new model for studying quantum data structure problems -- the "quantum cell probe model". We prove a lower bound for the static predecessor problem in the address-only version of this model where we allow quantum parallelism only over the `address lines' of the queries. The address-only quantum cell probe model subsumes the classical cell probe model, and many quantum query algorithms like Grover's algorithm fall into this framework. Our lower bound improves the previous known ...
Probing Dark Energy models with neutrons
Pignol, Guillaume
2015-07-01
There is a deep connection between cosmology — the science of the infinitely large — and particle physics — the science of the infinitely small. This connection is particularly manifest in neutron particle physics. Basic properties of the neutron — its Electric Dipole Moment and its lifetime — are intertwined with baryogenesis and nucleosynthesis in the early Universe. I will cover this topic in the first part, that will also serve as an introduction (or rather a quick recap) of neutron physics and Big Bang cosmology. Then, the rest of the paper will be devoted to a new idea: using neutrons to probe models of Dark Energy. In the second part, I will present the chameleon theory: a light scalar field accounting for the late accelerated expansion of the Universe, which interacts with matter in such a way that it does not mediate a fifth force between macroscopic bodies. However, neutrons can alleviate the chameleon mechanism and reveal the presence of the scalar field with properly designed experiments. In the third part, I will describe a recent experiment performed with a neutron interferometer at the Institut Laue Langevin that sets already interesting constraints on the chameleon theory. Last, the chameleon field can be probed by measuring the quantum states of neutrons bouncing over a mirror. In the fourth part, I will present the status and prospects of the GRANIT experiment at the ILL.
Analytic Models of High-Temperature Hohlraums
International Nuclear Information System (INIS)
A unified set of high-temperature-hohlraum models has been developed. For a simple hohlraum, Ps = (As+(1minusαW)AW+AH)σTR4 + (4Vσ/c)(dTRr/dt) where PS is the total power radiated by the source, As is the source area, AW is the area of the cavity wall excluding the source and holes in the wall, AH is the area of the holes, σ is the Stefan-Boltzmann constant, TR is the radiation brightness temperature, V is the hohlraum volume, and c is the speed of light. The wall albedo αW triplebond (TW/TR)4 where TW is the brightness temperature of area AW. The net power radiated by the source PN = PS-ASσTR4, which suggests that for laser-driven hohlraums the conversion efficiency ηCE be defined as PN/PLASER. The characteristic time required to change TR4 in response to a change in PN is 4V/C((lminusαW)AW+AH). Using this model, TR, αW, and ηCE can be expressed in terms of quantities directly measurable in a hohlraum experiment. For a steady-state hohlraum that encloses a convex capsule, PN = {(1minusαW)AW+AH+((1minus C)(AS+AWαW)AC/AT= )}σTRC4 where αC is the capsule albedo, AC is the capsule area, AT triplebond (AS+AW+AH), and TRC is the brightness temperature of the radiation that drives the capsule. According to this relation, the capsule-coupling efficiency of the baseline National-Ignition-Facility (NIF) hohlraum is 15% higher than predicted by previous analytic expressions. A model of a hohlraum that encloses a z pinch is also presented
Analytic Ballistic Performance Model of Whipple Shields
Miller, J. E.; Bjorkman, M. D.; Christiansen, E. L.; Ryan, S. J.
2015-01-01
The dual-wall, Whipple shield is the shield of choice for lightweight, long-duration flight. The shield uses an initial sacrificial wall to initiate fragmentation and melt an impacting threat that expands over a void before hitting a subsequent shield wall of a critical component. The key parameters to this type of shield are the rear wall and its mass which stops the debris, as well as the minimum shock wave strength generated by the threat particle impact of the sacrificial wall and the amount of room that is available for expansion. Ensuring the shock wave strength is sufficiently high to achieve large scale fragmentation/melt of the threat particle enables the expansion of the threat and reduces the momentum flux of the debris on the rear wall. Three key factors in the shock wave strength achieved are the thickness of the sacrificial wall relative to the characteristic dimension of the impacting particle, the density and material cohesion contrast of the sacrificial wall relative to the threat particle and the impact speed. The mass of the rear wall and the sacrificial wall are desirable to minimize for launch costs making it important to have an understanding of the effects of density contrast and impact speed. An analytic model is developed here, to describe the influence of these three key factors. In addition this paper develops a description of a fourth key parameter related to fragmentation and its role in establishing the onset of projectile expansion.
Atmospheric Probe Model: Construction and Wind Tunnel Tests
Vogel, Jerald M.
1998-01-01
The material contained in this document represents a summary of the results of a low speed wind tunnel test program to determine the performance of an atmospheric probe at low speed. The probe configuration tested consists of a 2/3 scale model constructed from a combination of hard maple wood and aluminum stock. The model design includes approximately 130 surface static pressure taps. Additional hardware incorporated in the baseline model provides a mechanism for simulating external and internal trailing edge split flaps for probe flow control. Test matrix parameters include probe side slip angle, external/internal split flap deflection angle, and trip strip applications. Test output database includes surface pressure distributions on both inner and outer annular wings and probe center line velocity distributions from forward probe to aft probe locations.
CO2-Leaking Well - Analytical Modeling
Wertz, F.; Audigane, P.; Bouc, O.
2009-04-01
The long-term integrity of CO2 storage in geological system relies highly on local trapping mechanisms but also on the absence/control of any kind of outlets. Indeed numerous pathways (faults, wells, rock heterogeneities…) exist that can lead stored gas back to the surface. Thus, such leakage risks must be assessed and quantified if possible. In France, BRGM is inquired for evaluating safety criteria and developing a methodology for qualifying potential geological storage sites. This implies in particular to study the leakage scenario, here through a water-filled well as a worth scenario case. In order to determine the kinds of impacts leaking CO2 can have; knowing the velocity and flow rate of uprising CO2 is a necessity. That is why a better knowledge of CO2 in storage conditions and its behaviour with the environment is required. The following study aims at characterising the CO2 flowing into the well and then rising up in a water column over the vertical dimension. An analytical model was built that describes: - In a first step, the CO2 flow between the reservoir and the inside of the well, depending on quality and thickness of different seals, which determines the flow rate through the well. - In a second step, the CO2 uprising through an open and water filled well, however in steady state, which excludes a priori the characterisation of periodic or chaotic behaviours such as geyser formation. The objective is to give numerous orders of magnitude concerning CO2 thermodynamic properties while rising up: specific enthalpy, density, viscosity, velocity, flow, gas volume fraction and expansion, pressure and temperature gradient. Dissolution is partially taken into account, however without kinetic. The strength of this model is to compute analytically - easily and instantaneously - the 1-dimensional rising velocity of CO2 in a water column as a function of the CO2 density, interfacial tension and initial volume fraction. Characteristic speeds - the ones given by
Bocquet, Franck; Loppacher, Christian; Glatzel, Thilo
2008-01-01
An analytical model of the electrostatic force between the tip of a non-contact Atomic Force Microscope (nc-AFM) and the (001) surface of an ionic crystal is reported. The model is able to account for the atomic contrast of the local contact potential difference (CPD) observed while nc-AFM-based Kelvin Probe Force Microscopy (KPFM) experiments. With the goal in mind to put in evidence this short-range electrostatic force, the Madelung potential arising at the surface of the ionic crystal is primarily derived. The expression of the force which is deduced can be split into two major contributions: the first stands for the coupling between the microscopic structure of the tip apex and the capacitor formed between the tip, the ionic crystal and the counter-electrode; the second term depicts the influence of the Madelung surface potential on the mesoscopic part of the tip, independently from its microscopic structure. These short-range electrostatic forces are in the range of ten pico-Newtons. When explicitly cons...
Probe Error Modeling Research Based on Bayesian Network
Institute of Scientific and Technical Information of China (English)
Wu Huaiqiang; Xing Zilong; Zhang Jian; Yan Yan
2015-01-01
Probe calibration is carried out under specific conditions; most of the error caused by the change of speed parameter has not been corrected. In order to reduce the measuring error influence on measurement accuracy, this article analyzes the relationship between speed parameter and probe error, and use Bayesian network to establish the model of probe error. Model takes account of prior knowledge and sample data, with the updating of data, which can reflect the change of the errors of the probe and constantly revised modeling results.
A nuclear analytical model for uranium zirconium hydride reactor core
International Nuclear Information System (INIS)
The nuclear analytical model and codes for the uranium zirconium hydride reactor are outlined. The criticality and control rods effeciency of abroad TRIGA reactor are obtained using this model and codes. The results are satisfactory
Analysis of Power Switching Losses Accounting Probe Modeling
Ammous, Kaiçar; Morel, Hervé; Ammous, Anis
2010-01-01
This paper focuses on the errors affecting the estimation of power switching losses in power semiconductor devices based on integration of the voltage by current product. It is shown that the measured waveforms are not simply delayed by the probes, but some overshoots and distortions are due to the probes, which may not easily be corrected. These effects are the source of errors, particularly in fast transients. This paper shows analyses of simulation and measurements, including probe models.
Analytical solution of a model for complex food webs
Camacho Castro, Juan; Guimerà, Roger; Amaral, Luís A. Nunes
2002-01-01
We investigate numerically and analytically a recently proposed model for food webs [Nature {\\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain analytical expressions for several quantities with ecological interest, in particular the probability distributions for the number of prey and the number of predators. We find that these distributions have fast-decaying exponential and Gaussian tails, respectively. We also find that our analytical expressi...
Liquid contact resonance AFM: analytical models, experiments, and limitations
Parlak, Zehra; Tu, Qing; Zauscher, Stefan
2014-11-01
Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces.
Liquid contact resonance AFM: analytical models, experiments, and limitations
International Nuclear Information System (INIS)
Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces. (paper)
Analytical modeling of masonry infilled steel frames
International Nuclear Information System (INIS)
A comprehensive program is underway at the Oak Ridge Y-12 Plant to evaluate the seismic capacity of unreinforced hollow clay tile infilled steel frames. This program has three major parts. First, preliminary numerical analyses are conducted to predict behavior, initial cracking loads, ultimate capacity loads, and to identify important parameters. Second, in-situ and laboratory tests are performed to obtain constitutive parameters and confirm predicted behavior. Finally, the analytical techniques are refined based on experimental results. This paper summarizes the findings of the preliminary numerical analyses. A review of current analytical methods was conducted and a subset of these methods was applied to known experimental results. Parametric studies were used to find the sensitivity of the behavior to various parameters. Both in-plane and out-of-plane loads were examined. Two types of out-of-plane behavior were examined, the inertial forces resulting from the mass of the infill panel and the out-of-plane forces resulting from interstory drift. Cracking loads were estimated using linear elastic analysis and an elliptical failure criterion. Calculated natural frequencies were correlated with low amplitude vibration testing. Ultimate behavior under inertial loads was estimated using a modified yield line procedure accounting for membrane stresses. The initial stiffness and ultimate capacity under in-plane loadings were predicted using finite element analyses. Results were compared to experimental data and to failure loads obtained using plastic collapse theory
In Situ Scanning Probe Microscopy and New Perspectives in Analytical Chemistry
DEFF Research Database (Denmark)
Andersen, Jens Enevold Thaulov; Zhang, Jingdong; Chi, Qijin;
1999-01-01
for molecular- and mesoscopic-scale analytical chemistry, are then reviewed. They are illustrated by metallic electro-crystallisation and -dissolution, and in situ STM spectroscopy of large redox molecules. The biophysically oriented analytical options of in situ atomic force microscopy, and...
An analytic performance model of disk arrays and its application
Lee, Edward K.; Katz, Randy H.
1991-01-01
As disk arrays become widely used, tools for understanding and analyzing their performance become increasingly important. In particular, performance models can be invaluable in both configuring and designing disk arrays. Accurate analytic performance models are desirable over other types of models because they can be quickly evaluated, are applicable under a wide range of system and workload parameters, and can be manipulated by a range of mathematical techniques. Unfortunately, analytical performance models of disk arrays are difficult to formulate due to the presence of queuing and fork-join synchronization; a disk array request is broken up into independent disk requests which must all complete to satisfy the original request. We develop, validate, and apply an analytic performance model for disk arrays. We derive simple equations for approximating their utilization, response time, and throughput. We then validate the analytic model via simulation and investigate the accuracy of each approximation used in deriving the analytical model. Finally, we apply the analytical model to derive an equation for the optimal unit of data striping in disk arrays.
Feedbacks Between Numerical and Analytical Models in Hydrogeology
Zlotnik, V. A.; Cardenas, M. B.; Toundykov, D.; Cohn, S.
2012-12-01
Hydrogeology is a relatively young discipline which combines elements of Earth science and engineering. Mature fundamental disciplines (e.g., physics, chemistry, fluid mechanics) have centuries-long history of mathematical modeling even prior to discovery of Darcy's law. Thus, in hydrogeology, relatively few classic analytical models (such those by Theis, Polubarinova-Kochina, Philip, Toth, Henry, Dagan, Neuman) were developed by the early 1970's. The advent of computers and practical demands refocused mathematical models towards numerical techniques. With more diverse but less mathematically-oriented training, most hydrogeologists shifted from analytical methods to use of standardized computational software. Spatial variability in internal properties and external boundary conditions and geometry, and the added complexity of chemical and biological processes will remain major challenges for analytical modeling. Possibly, analytical techniques will play a subordinate role to numerical approaches in many applications. On the other hand, the rise of analytical element modeling of groundwater flow is a strong alternative to numerical models when data demand and computational efficiency is considered. The hallmark of analytical models - transparency and accuracy - will remain indispensable for scientific exploration of complex phenomena and for benchmarking numerical models. Therefore, there will always be feedbacks and complementarities between numerical and analytical techniques, as well as a certain ideological schism among various views to modeling. We illustrate the idea of feedbacks by reviewing evolution of Joszef Toth's analytical model of gravity driven flow systems. Toth's (1963) approach was to reduce the flow domain to a rectangle which allowed for closed-form solution of the governing equations. Succeeding numerical finite-element models by Freeze and Witherspoon (1966-1968) explored the effects of geometry and heterogeneity on regional groundwater flow
Monte Carlo modeling of ultrasound probes for image guided radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Bazalova-Carter, Magdalena, E-mail: bazalova@uvic.ca [Department of Radiation Oncology, Stanford University, Stanford, California 94305 and Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2 (Canada); Schlosser, Jeffrey [SoniTrack Systems, Inc., Palo Alto, California 94304 (United States); Chen, Josephine [Department of Radiation Oncology, UCSF, San Francisco, California 94143 (United States); Hristov, Dimitre [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States)
2015-10-15
Purpose: To build Monte Carlo (MC) models of two ultrasound (US) probes and to quantify the effect of beam attenuation due to the US probes for radiation therapy delivered under real-time US image guidance. Methods: MC models of two Philips US probes, an X6-1 matrix-array transducer and a C5-2 curved-array transducer, were built based on their megavoltage (MV) CT images acquired in a Tomotherapy machine with a 3.5 MV beam in the EGSnrc, BEAMnrc, and DOSXYZnrc codes. Mass densities in the probes were assigned based on an electron density calibration phantom consisting of cylinders with mass densities between 0.2 and 8.0 g/cm{sup 3}. Beam attenuation due to the US probes in horizontal (for both probes) and vertical (for the X6-1 probe) orientation was measured in a solid water phantom for 6 and 15 MV (15 × 15) cm{sup 2} beams with a 2D ionization chamber array and radiographic films at 5 cm depth. The MC models of the US probes were validated by comparison of the measured dose distributions and dose distributions predicted by MC. Attenuation of depth dose in the (15 × 15) cm{sup 2} beams and small circular beams due to the presence of the probes was assessed by means of MC simulations. Results: The 3.5 MV CT number to mass density calibration curve was found to be linear with R{sup 2} > 0.99. The maximum mass densities in the X6-1 and C5-2 probes were found to be 4.8 and 5.2 g/cm{sup 3}, respectively. Dose profile differences between MC simulations and measurements of less than 3% for US probes in horizontal orientation were found, with the exception of the penumbra region. The largest 6% dose difference was observed in dose profiles of the X6-1 probe placed in vertical orientation, which was attributed to inadequate modeling of the probe cable. Gamma analysis of the simulated and measured doses showed that over 96% of measurement points passed the 3%/3 mm criteria for both probes placed in horizontal orientation and for the X6-1 probe in vertical orientation. The
Analytical dynamic modeling of fast trilayer polypyrrole bending actuators
International Nuclear Information System (INIS)
Analytical modeling of conjugated polymer actuators with complicated electro-chemo-mechanical dynamics is an interesting area for research, due to the wide range of applications including biomimetic robots and biomedical devices. Although there have been extensive reports on modeling the electrochemical dynamics of polypyrrole (PPy) bending actuators, mechanical dynamics modeling of the actuators remains unexplored. PPy actuators can operate with low voltage while producing large displacement in comparison to robotic joints, they do not have friction or backlash, but they suffer from some disadvantages such as creep and hysteresis. In this paper, a complete analytical dynamic model for fast trilayer polypyrrole bending actuators has been proposed and named the analytical multi-domain dynamic actuator (AMDDA) model. First an electrical admittance model of the actuator will be obtained based on a distributed RC line; subsequently a proper mechanical dynamic model will be derived, based on Hamilton's principle. The purposed modeling approach will be validated based on recently published experimental results
Institute of Scientific and Technical Information of China (English)
吴金辉; 王登攀; 张惠芳; 肖志宏; 高锦岳
2003-01-01
We propose a new four-level atomic model for achieving light amplification at a short wavelength, where direct incoherent pumping into the top level is avoided by the advantage of coherent pumping. In this model, the lower level of the probe transition is an excited state but not the usual ground state. By analytical as well as numerical calculations, we find that the probe gain, either with or without population inversion, which depends on the relation between spontaneous decay rates γ42 and γ21, can be achieved with proper parameters. We note that the Raman scattering gain always plays an important role in achieving the probe amplification.
International Nuclear Information System (INIS)
The controlled removal of material conducted with the tip of an atomic force microscope (AFM) probe is a technique that has started gaining increased attention in recent years within the micro and nano manufacturing research community. The attractive characteristics of this process are that it is relatively simple to implement and low-cost compared with vacuum-based lithography techniques for micro and nano fabrication. However, similarly to any machining process, the resulting surface finish of features cut with an AFM probe can be critical. In this context, the focus of the paper is on the development and validation of a novel analytical model for predicting the floor surface roughness induced by AFM probe-based machining when generating cavities composed of linear parallel grooves. In addition to kinematic parameters, the proposed model takes into account the minimum chip thickness and elastic recovery associated with each phase present within the microstructure of a workpiece. The implementation of the model was carried out and its performance tested when processing a dual phase brass alloy using an AFM nano-indentation probe. A relatively good agreement was achieved between the analytical and experimental results with an average prediction error of 21% when assessing the arithmetic average roughness, Ra. (paper)
Analytic Models for the Mechanical Structure of the Solar Core
Kennedy, Dallas C.; Bludman, Sidney A.
1998-01-01
All stars exhibit universal central behavior in terms of new homology variables (u,w). In terms of these variables, we obtain simple analytic fits to numerical standard solar models for the core and radiative zones of the ZAMS and present Suns, with a few global parameters. With these analytic fits, different theoretical models of the solar core, neutrino fluxes, and helioseismic observations can be parametrized and compared.
Analytical modelling of Thirty Meter Telescope optics polarization
Anche, Ramya M.; Anupama, G. C.; Reddy, Krishna; Sen, Asoke; Sankarasubramanian, K.; Ramaprakash, A. N.; Sengupta, Sujan; Skidmore, Warren; Atwood, Jenny; Tirupathi, Sivarani; Pandey, Shashi Bhushan
2015-06-01
The polarization introduced due to Thirty Meter Telescope (TMT) optics is calculated using an analytical model. Mueller matrices are also generated for each optical element using Zemax, based on which the instrumental polarization due to the entire system at the focal plane is estimated and compared with the analytical model. This study is significant in the estimation of the telescope sensitivity and also has great implications for future instruments.
A Unified Channel Charges Expression for Analytic MOSFET Modeling
Hugues Murray; Patrick Martin
2012-01-01
Based on a 1D Poissons equation resolution, we present an analytic model of inversion charges allowing calculation of the drain current and transconductance in the Metal Oxide Semiconductor Field Effect Transistor. The drain current and transconductance are described by analytical functions including mobility corrections and short channel effects (CLM, DIBL). The comparison with the Pao-Sah integral shows excellent accuracy of the model in all inversion modes from strong to weak inversion in ...
Analytical Model for Fictitious Crack Propagation in Concrete Beams
DEFF Research Database (Denmark)
Ulfkjær, J. P.; Krenk, Steen; Brincker, Rune
1995-01-01
are modeled by beam theory. The state of stress in the elastic layer is assumed to depend bilinearly on local elongation corresponding to a linear softening relation for the fictitious crack. Results from the analytical model are compared with results from a more detailed model based on numerical......An analytical model for load-displacement curves of concrete beams is presented. The load-displacement curve is obtained by combining two simple models. The fracture is modeled by a fictitious crack in an elastic layer around the midsection of the beam. Outside the elastic layer the deformations...... methods for different beam sizes. The analytical model is shown to be in agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. It is shown that the point on the load-displacement curve where the fictitious crack starts to develop and the point where...
Experimental and analytical generic space station dynamic models
Belvin, W. K.; Edighoffer, H. H.
1986-01-01
A dynamic model used for verification of analytical and experimental methods is documented. The model consists of five substructures to simulate the multibody, low frequency nature of large space structures. Design considerations which led to a fundamental vibration frequency of less than one Hz are described. Finite element analysis used to predict the vibration modes and frequencies of the experimental model is presented. In addition, modeling of cable suspension effects using prestressed vibration analysis is described. Details of the expermental and analytical models are included to permit replication of the study. Results of the modal vibration tests and analysis are presented in a separate document.
An analytical model and verification for MEMS Pirani gauges
International Nuclear Information System (INIS)
A new analytical model for the design of micromachined Pirani gauges operating in constant current mode is presented. This model expresses the pressure range as a closed-form analytical function of the design variables such as geometry and biasing. Furthermore, it yields simplified expressions for other performance parameters such as the sensitivity, output swing and power consumption. A Pirani gauge has been designed according to the presented model and has been fabricated and characterized in order to verify the validity of the model. The measurements match the theory closely. The model will be useful to designers who need to trade off performance against the costs of chip area and biasing power.
Analytical Modeling of Partially Shaded Photovoltaic Systems
Directory of Open Access Journals (Sweden)
Mohammadmehdi Seyedmahmoudian
2013-01-01
Full Text Available As of today, the considerable influence of select environmental variables, especially irradiance intensity, must still be accounted for whenever discussing the performance of a solar system. Therefore, an extensive, dependable modeling method is required in investigating the most suitable Maximum Power Point Tracking (MPPT method under different conditions. Following these requirements, MATLAB-programmed modeling and simulation of photovoltaic systems is presented here, by focusing on the effects of partial shading on the output of the photovoltaic (PV systems. End results prove the reliability of the proposed model in replicating the aforementioned output characteristics in the prescribed setting. The proposed model is chosen because it can, conveniently, simulate the behavior of different ranges of PV systems from a single PV module through the multidimensional PV structure.
Analytical Modeling of Partially Shaded Photovoltaic Systems
Mohammadmehdi Seyedmahmoudian; Saad Mekhilef; Rasoul Rahmani; Rubiyah Yusof; Ehsan Taslimi Renani
2013-01-01
As of today, the considerable influence of select environmental variables, especially irradiance intensity, must still be accounted for whenever discussing the performance of a solar system. Therefore, an extensive, dependable modeling method is required in investigating the most suitable Maximum Power Point Tracking (MPPT) method under different conditions. Following these requirements, MATLAB-programmed modeling and simulation of photovoltaic systems is presented here, by focusing on the ef...
Simulation-analytic model of a distributed informational system
International Nuclear Information System (INIS)
A model for the choice of effective connection channels between elements of a distributed homomorphous network has been described. This model combines simulation and analytical approaches in its architecture. Arguments for using such complex models, examples of some simulation results for a system with distributed topology have been given and summarized conclusions have been made
Analytical Model for Hook Anchor Pull-Out
DEFF Research Database (Denmark)
Brincker, Rune; Ulfkjær, J. P.; Adamsen, P.;
1995-01-01
A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assume that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...
Analytical Model for Hook Anchor Pull-out
DEFF Research Database (Denmark)
Brincker, Rune; Ulfkjær, J. P.; Adamsen, P.;
A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assumed that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...
The US Army HazMin probe model
International Nuclear Information System (INIS)
In 1987, the US Department of Defense (DOD) established a goal of reducing the quantity of hazardous waste generated by DOD facilities by 50%. To help achieve this goal, the US Army Production Base Modernization Activity (PBMA) has contracted with the Pacific Northwest Laboratory (PNL) to develop decision support software to be used in the Army-wide hazardous waste minimization (HazMin) program. The resulting waste minimization prioritization software has been named the Project Opportunity and Benefit Evaluation (PROBE) model. PROBE can be used to evaluate both waste stream and project priorities. PROBE operates on any IBM-compatible personal computer hardware with at least 640K of memory and 5 megabytes of available hard disk space. PROBE was developed under the direction of PBMA, which retains unlimited rights to the Federal version of PROBE. PBMA encourages other DOD services and other Federal agencies to use PROBE to assist in their own waste minimization programs. PNL is also considering developing a copyrighted version of PROBE for the commercial market. PROBE was written using FoxPro 2.0 application development software, and runs as an executable file from either MS-DOS or Windows. The software can be loaded onto a single high-capacity floppy disk in a compressed format and can be transferred onto hard disk, ready to operate, via a simple start-up routine
Meta-analytic structural equation modelling
Jak, Suzanne
2015-01-01
This book explains how to employ MASEM, the combination of meta-analysis (MA) and structural equation modelling (SEM). It shows how by using MASEM, a single model can be tested to explain the relationships between a set of variables in several studies. This book gives an introduction to MASEM, with a focus on the state of the art approach: the two stage approach of Cheung and Cheung & Chan. Both, the fixed and the random approach to MASEM are illustrated with two applications to real data. All steps that have to be taken to perform the analyses are discussed extensively. All data and syntax files are available online, so that readers can imitate all analyses. By using SEM for meta-analysis, this book shows how to benefit from all available information from all available studies, even if few or none of the studies report about all relationships that feature in the full model of interest.
Directory of Open Access Journals (Sweden)
Sagar Singh
2016-03-01
Full Text Available Single-unit recording neural probes have significant advantages towards improving signal-to-noise ratio and specificity for signal acquisition in brain-to-computer interface devices. Long-term effectiveness is unfortunately limited by the chronic injury response, which has been linked to the mechanical mismatch between rigid probes and compliant brain tissue. Small, flexible microelectrodes may overcome this limitation, but insertion of these probes without buckling requires supporting elements such as a stiff coating with a biodegradable polymer. For these coated probes, there is a design trade-off between the potential for successful insertion into brain tissue and the degree of trauma generated by the insertion. The objective of this study was to develop and validate a finite element model (FEM to simulate insertion of coated neural probes of varying dimensions and material properties into brain tissue. Simulations were performed to predict the buckling and insertion forces during insertion of coated probes into a tissue phantom with material properties of brain. The simulations were validated with parallel experimental studies where probes were inserted into agarose tissue phantom, ex vivo chick embryonic brain tissue, and ex vivo rat brain tissue. Experiments were performed with uncoated copper wire and both uncoated and coated SU-8 photoresist and Parylene C probes. Model predictions were found to strongly agree with experimental results (<10% error. The ratio of the predicted buckling force-to-predicted insertion force, where a value greater than one would ideally be expected to result in successful insertion, was plotted against the actual success rate from experiments. A sigmoidal relationship was observed, with a ratio of 1.35 corresponding to equal probability of insertion and failure, and a ratio of 3.5 corresponding to a 100% success rate. This ratio was dubbed the “safety factor”, as it indicated the degree to which the coating
Singh, Sagar; Lo, Meng-Chen; Damodaran, Vinod B; Kaplan, Hilton M; Kohn, Joachim; Zahn, Jeffrey D; Shreiber, David I
2016-01-01
Single-unit recording neural probes have significant advantages towards improving signal-to-noise ratio and specificity for signal acquisition in brain-to-computer interface devices. Long-term effectiveness is unfortunately limited by the chronic injury response, which has been linked to the mechanical mismatch between rigid probes and compliant brain tissue. Small, flexible microelectrodes may overcome this limitation, but insertion of these probes without buckling requires supporting elements such as a stiff coating with a biodegradable polymer. For these coated probes, there is a design trade-off between the potential for successful insertion into brain tissue and the degree of trauma generated by the insertion. The objective of this study was to develop and validate a finite element model (FEM) to simulate insertion of coated neural probes of varying dimensions and material properties into brain tissue. Simulations were performed to predict the buckling and insertion forces during insertion of coated probes into a tissue phantom with material properties of brain. The simulations were validated with parallel experimental studies where probes were inserted into agarose tissue phantom, ex vivo chick embryonic brain tissue, and ex vivo rat brain tissue. Experiments were performed with uncoated copper wire and both uncoated and coated SU-8 photoresist and Parylene C probes. Model predictions were found to strongly agree with experimental results (<10% error). The ratio of the predicted buckling force-to-predicted insertion force, where a value greater than one would ideally be expected to result in successful insertion, was plotted against the actual success rate from experiments. A sigmoidal relationship was observed, with a ratio of 1.35 corresponding to equal probability of insertion and failure, and a ratio of 3.5 corresponding to a 100% success rate. This ratio was dubbed the "safety factor", as it indicated the degree to which the coating should be over
Analytical model for fast-shock ignition
S. A. Ghasemi; A. H. Farahbod; Sobhanian, S.
2014-01-01
A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV...
Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes1
Heise, H. M.; Küpper, L.; Butvina, L. N.
2002-10-01
Infrared-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro analysis in the clinical laboratory and for non-invasive diagnostics. In general, the analysis of biofluids such as whole blood, urine, microdialysates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of infrared silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-infrared spectroscopy could revolutionize analytical tools in the clinical chemistry laboratory, and an example is given. Infrared diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathology in particular cannot be left out using mid-infrared fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain analysis of biopsy samples from bog mummified corpses, and recent results on the chemistry of dermis and hair samples are reported. Another field of application, for which results are reported, is food analysis and bio-reactor monitoring.
Analytical models for gravitating radiating systems
Brassel, B P; Govender, G
2015-01-01
We analyse the gravitational behaviour of a relativistic heat conducting fluid in a shear-free spherically symmetric spacetime. We show that the isotropy of pressure is a consistency condition which realises a second order nonlinear ordinary differential equation with variable coefficients in the gravitational potentials. Several new classes of solutions are found to the governing equation by imposing various forms on one of the potentials. Interestingly, a complex transformation leads to an exact solution with only real metric functions. All solutions are written in terms of elementary functions. We demonstrate graphically that the fluid pressure, energy density and heat flux are well behaved for the model, and the model is consistent with a core-envelope framework.
Analytical and Numerical Modeling for Flexible Pipes
Institute of Scientific and Technical Information of China (English)
WANG Wei; CHEN Geng
2011-01-01
The unbonded flexible pipe of eight layers,in which all the layers except the carcass layer are assumed to have isotropic properties,has been analyzed.Specifically,the carcass layer shows the orthotropic characteristics.The effective elastic moduli of the carcass layer have been developed in terms of the influence of deformation to stiffness.With consideration of the effective elastic moduli,the structure can be properly analyzed.Also the relative movements of tendons and relative displacements of wires in helical armour layer have been investigated.A three-dimensional nonlinear finite element model has been presented to predict the response of flexible pipes under axial force and torque.Further,the friction and contact of interlayer have been considered.Comparison between the finite element model and experimental results obtained in literature has been given and discussed,which might provide practical and technical support for the application of unbonded flexible pipes.
Haskell financial data modeling and predictive analytics
Ryzhov, Pavel
2013-01-01
This book is a hands-on guide that teaches readers how to use Haskell's tools and libraries to analyze data from real-world sources in an easy-to-understand manner.This book is great for developers who are new to financial data modeling using Haskell. A basic knowledge of functional programming is not required but will be useful. An interest in high frequency finance is essential.
An analytically solvable time dependent Jaynes Cummings model
Das-Gupta, A
1998-01-01
Using the underlying su(2) algebra of the Jaynes-Cummings Model (JCM), we construct a time dependent interaction term that allows analytical solution for even off-resonance conditions. Exact solutions for the time evolution of any state has been found. The effect of detuning on the Rabi oscillations and the collapse and revival of inversion is indicated. It is also shown that at resonance, the time dependent JCM is analytically solvable for an arbitrary interaction term.
A parsimonious analytical model for simulating multispecies plume migration
J.-S. Chen; C.-P. Liang; C.-W. Liu; Li, L. Y.
2015-01-01
A parsimonious analytical model for rapidly predicting the long-term plume behavior of decaying contaminant such as radionuclide and dissolved chlorinated solvent is presented in this study. Generalized analytical solutions in compact format are derived for the two-dimensional advection-dispersion equations coupled with sequential first-order decay reactions involving an arbitrary number of species in groundwater system. The solution techniques involve the sequential applica...
Modeling of eddy current probe response for steam generator tubes
International Nuclear Information System (INIS)
Sample calculations were performed with a three-dimensional (3-D) finite-element model analysis that describe the response of an eddy current (EC) probe to steam generator (SG) tubing artifacts. Such calculations could be very helpful in understanding and interpreting of EC probe response to complex tube/defect geometries associated with the inservice inspection (ISI) of steam generator (SG) tubing. The governing field equations are in terms of coupled magnetic vector and electric scalar potentials in conducting media and of total or reduced scalar potentials in nonconducting regions. To establish the validity of the model, comparisons of the theoretical and experimental responses of an absolute bobbin probe are given for two types of calibration standard defects. Preliminary results are also presented from a recent theoretical study of the effect of ligament size in axial cracks on EC indications with conventional ISI bobbin probes
Evaluation of the WIND System atmospheric models: An analytic approach
International Nuclear Information System (INIS)
An analytic approach was used in this study to test the logic, coding, and the theoretical limits of the WIND System atmospheric models for the Savannah River Plant. In this method, dose or concentration estimates predicted by the models were compared to the analytic solutions to evaluate their performance. The results from AREA EVACUATION and PLTFF/PLUME were very nearly identical to the analytic solutions they are based on and the evaluation procedure demonstrated that these models were able to reproduce the theoretical characteristics of a puff or a plume. The dose or concentration predicted by PLTFF/PLUME was always within 1% of the analytic solution. Differences between the dose predicted by 2DPUF and its analytic solution were substantially greater than those associated with PUFF/PLUME, but were usually smaller than 6%. This behavior was expected because PUFF/PLUME solves a form of the analytic solution for a single puff, and 2DPUF performs an integration over a period of time for several puffs to obtain the dose. Relatively large differences between the dose predicted by 2DPUF and its analytic solution were found to occur close to the source under stable atmospheric conditions. WIND System users should be aware of these situations in which the assumptions of the System atmospheric models may be violated so that dose predictions can be interpreted correctly. The WIND System atmospheric models are similar to many other dispersion codes used by the EPA, NRC, and DOE. If the quality of the source term and meteorological data is high, relatively accurate and timely forecasts for emergency response situations can be made by the WIND System atmospheric models
Analytical model for screening potential CO2 repositories
Okwen, R.T.; Stewart, M.T.; Cunningham, J.A.
2011-01-01
Assessing potential repositories for geologic sequestration of carbon dioxide using numerical models can be complicated, costly, and time-consuming, especially when faced with the challenge of selecting a repository from a multitude of potential repositories. This paper presents a set of simple analytical equations (model), based on the work of previous researchers, that could be used to evaluate the suitability of candidate repositories for subsurface sequestration of carbon dioxide. We considered the injection of carbon dioxide at a constant rate into a confined saline aquifer via a fully perforated vertical injection well. The validity of the analytical model was assessed via comparison with the TOUGH2 numerical model. The metrics used in comparing the two models include (1) spatial variations in formation pressure and (2) vertically integrated brine saturation profile. The analytical model and TOUGH2 show excellent agreement in their results when similar input conditions and assumptions are applied in both. The analytical model neglects capillary pressure and the pressure dependence of fluid properties. However, simulations in TOUGH2 indicate that little error is introduced by these simplifications. Sensitivity studies indicate that the agreement between the analytical model and TOUGH2 depends strongly on (1) the residual brine saturation, (2) the difference in density between carbon dioxide and resident brine (buoyancy), and (3) the relationship between relative permeability and brine saturation. The results achieved suggest that the analytical model is valid when the relationship between relative permeability and brine saturation is linear or quasi-linear and when the irreducible saturation of brine is zero or very small. ?? 2011 Springer Science+Business Media B.V.
Analytical model for fast-shock ignition
Directory of Open Access Journals (Sweden)
S. A. Ghasemi
2014-07-01
Full Text Available A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI. The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012 and fast ignitor energy formula of Bellei (2013 that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ∼0.3 micron and the shock ignitor energy weight factor about 0.25.
Analytical Modeling of Uplink Cellular Networks
Novlan, Thomas D; Andrews, Jeffrey G
2012-01-01
Cellular uplink analysis has typically been undertaken by either a simple approach that lumps all interference into a single deterministic or random parameter in a Wyner-type model, or via complex system level simulations that often do not provide insight into why various trends are observed. This paper proposes a novel middle way that is both accurate and also results in easy-to-evaluate integral expressions based on the Laplace transform of the interference. We assume mobiles and base stations are randomly placed in the network with each mobile pairing up to its closest base station. The model requires two important changes compared to related recent work on the downlink. First, dependence is introduced between the user and base station point processes to make sure each base station serves a single mobile in the given resource block. Second, per-mobile power control is included, which further couples the locations of the mobiles and their receiving base stations. Nevertheless, we succeed in deriving the cov...
A non-grey analytical model for irradiated atmospheres. II: Analytical vs. numerical solutions
Parmentier, Vivien; Fortney, Jonathan J; Marley, Mark S
2013-01-01
The recent discovery and characterization of the diversity of the atmospheres of exoplanets and brown dwarfs calls for the development of fast and accurate analytical models. In this paper we first quantify the accuracy of the analytical solution derived in paper I for an irradiated, non-grey atmosphere by comparing it to a state-of-the-art radiative transfer model. Then, using a grid of numerical models, we calibrate the different coefficients of our analytical model for irradiated solar-composition atmospheres of giant exoplanets and brown dwarfs. We show that the so-called Eddington approximation used to solve the angular dependency of the radiation field leads to relative errors of up to 5% on the temperature profile. For grey or semi-grey atmospheres we show that the presence of a convective zone has a limited effect on the radiative atmosphere above it and leads to modifications of the radiative temperature profile of order 2%. However, for realistic non-grey planetary atmospheres, the presence of a con...
Analytic solution of simplified Cardan's shaft model
Directory of Open Access Journals (Sweden)
Zajíček M.
2014-12-01
Full Text Available Torsional oscillations and stability assessment of the homokinetic Cardan shaft with a small misalignment angle is described in this paper. The simplified mathematical model of this system leads to the linearized equation of the Mathieu's type. This equation with and without a stationary damping parameter is considered. The solution of the original differential equation is identical with those one of the Fredholm’s integral equation with degenerated kernel assembled by means of a periodic Green's function. The conditions of solvability of such problem enable the identification of the borders between stability and instability regions. These results are presented in the form of stability charts and they are verified using the Floquet theory. The correctness of oscillation results for the system with periodic stiffness is then validated by means of the Runge-Kutta integration method.
Z-MAC an Analytical Model for Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
Ramchand V
2011-12-01
Full Text Available This paper presents an analytical model for estimat ing throughput and energy consumption in Z-MAC protocol for Wireless Sensor Networks. The analytic al design includes transmission power control and transmission of frames through one hop, two hop and multi hop. Proposed model reduces collision under low contention level as well as high contention lev el with the use of explicit contention notification . The proposed protocol has been simulated using MATLAB. The simulations reveal better results for throughpu t and energy consumption of the proposed model as com pared to Z-MAC protoco
Modeling of current characteristics of Segmented Langmuir Probe on DEMETER
Imtiaz, Nadia; Marchand, Richard
2012-10-01
We model current characteristics of a Segmented Langmuir probe mounted on DEMETER satellite. The probe is used to measure electron density and temperature in the ionosphere on DEMETER at altitudes of 700 km.It also serves as a Mach probe and used to measure the plasma flow velocities in satellite frame of reference.The probe is partitioned into seven segments: six electrically insulated spherical caps and a Guard electrode (sphere). Comparisons are made between the model predictions and measurements for characteristics of various segments for actual ionospheric plasma conditions encountered along DEMETER orbit. Segment characteristics are computed numerically with PTetra, a 3 D PIC simulation code. The model accounts for several physical effects of importance in the interaction of spacecraft with the space environment e.g. satellite charging, photoelectron and secondary electron emission. The supersonic flow of plasma results in different characteristics for different segments of the probe. This anisotropy in turn can be used to infer the velocity of the background plasma. It is observed in that a positive bias can significantly modify plasma sheath region and wake formation around the probe.Computed characteristics and their angular anisotropy are compared with measurements.
Analytic regularization of the Yukawa model at finite temperature
Malbouisson, A P C; Svaiter, N F
1996-01-01
We analyse the one-loop fermionic contribution for the scalar effective potential in the temperature dependent Yukawa model. In order to regularize the model a mix between dimensional and analytic regularization procedures is used. We find a general expression for the fermionic contribution in arbitrary spacetime dimension. It is found that in D=3 this contribution is finite.
More on analytic bootstrap for O(N) models
Dey, Parijat; Sen, Kallol
2016-01-01
This note is an extension of a recent work on the analytical bootstrapping of $O(N)$ models. An additonal feature of the $O(N)$ model is that the OPE contains trace and antisymmetric operators apart from the symmetric-traceless objects appearing in the OPE of the singlet sector. This in addition to the stress tensor $(T_{\\mu\
An Analytical Model of Wake Deflection Due to Shear Flow
Micallef, D.; Simao Ferreira, C.J.; Sant, T.; Van Bussel, G.J.W.
2010-01-01
The main motivation behind this work is to create a purely analytical engineering model for wind turbine wake upward deflection due to shear flow, by developing a closed form solution of the velocity field due to an oblique vortex ring. The effectiveness of the model is evaluated by comparing the re
Probing NWP model deficiencies by statistical postprocessing
DEFF Research Database (Denmark)
Rosgaard, Martin Haubjerg; Nielsen, Henrik Aalborg; Nielsen, Torben S.;
2016-01-01
The objective in this article is twofold. On one hand, a Model Output Statistics (MOS) framework for improved wind speed forecast accuracy is described and evaluated. On the other hand, the approach explored identifies unintuitive explanatory value from a diagnostic variable in an operational....... Based on the statistical model candidates inferred from the data, the lifted index NWP model diagnostic is consistently found among the NWP model predictors of the best performing statistical models across sites....
An analytical model for the assessment of airline expansion strategies
Mauricio Emboaba Moreira
2014-01-01
Purpose: The purpose of this article is to develop an analytical model to assess airline expansion strategies by combining generic business strategy models with airline business models. Methodology and approach: A number of airline business models are examined, as are Porter’s (1983) industry five forces that drive competition, complemented by Nalebuff/ Brandenburger’s (1996) sixth force, and the basic elements of the general environment in which the expansion process takes place. A system ...
Experimental verification of the SP-100 TEM pump analytical models
International Nuclear Information System (INIS)
Validation of the TEM pump analytical model is conducted via experimental verification of the model prediction. Two key tests that have provided essential information toward this objective are the Magnetic Bench Test (MBT) and the ElectroMagnetic Integration Test (EMIT). The tests are briefly described and experimental results are compared with predictions of simulation models that form part of overall TEM pump performance model
Flexible Manufacturing Systems: A Review of Analytical Models
Buzacott, J.A.; David D. Yao
1986-01-01
This paper reviews recent work on the development of analytical models of Flexible Manufacturing Systems (FMSs). The contributions of each of the groups concerned with model development are summarized and an assessment is made of the strengths and weaknesses of its modelling approach. A number of directions in which models require extension are outlined, in particular the representation of such aspects of FMS operation as the tool delivery systems, the blocking phenomenon, the transient behav...
A Unified Channel Charges Expression for Analytic MOSFET Modeling
Directory of Open Access Journals (Sweden)
Hugues Murray
2012-01-01
Full Text Available Based on a 1D Poissons equation resolution, we present an analytic model of inversion charges allowing calculation of the drain current and transconductance in the Metal Oxide Semiconductor Field Effect Transistor. The drain current and transconductance are described by analytical functions including mobility corrections and short channel effects (CLM, DIBL. The comparison with the Pao-Sah integral shows excellent accuracy of the model in all inversion modes from strong to weak inversion in submicronics MOSFET. All calculations are encoded with a simple C program and give instantaneous results that provide an efficient tool for microelectronics users.
Helicopter derivative identification from analytic models and flight test data
Molusis, J. H.; Briczinski, S.
1974-01-01
Recent results of stability derivative identification from helicopter analytic models and flight test data are presented. Six and nine degree-of-freedom (DOF) linear models are identified from an analytic nonlinear helicopter simulation using a least square technique. The identified models are compared with the convectional partial differentiation method for obtaining derivatives to form the basis for interpretation of derivatives identified from flight data. Six degree-of-freedom models are identified from CH-53A and CH-54B flight data, using an extended Kalman filter modified to process several maneuvers simultaneously. The a priori derivative estimate is obtained by optimal filtering of the data and then using a least square method. The results demonstrate that a six DOF identified model is sufficient to determine the low frequency modes of motion, but a nine DOF rotor/body model is necessary for proper representation of short-term response.
Probing Leptonic Models at the LHC
Deppisch, Frank F
2015-01-01
Models of neutrino mass generation provide well motivated scenarios of Beyond-the-Standard-Model physics. The synergy between low energy and high energy LHC searches facilitates an effective approach to rule out, constrain or ideally pinpoint such models. In this proceedings report, we provide a brief overview of scenarios where searches at the LHC can help determine the mechanism of light neutrino masses and potentially falsify baryogenesis mechanisms.
Probing the Lambda-DGP Braneworld model
Ravanpak, Arvin; Farajollahi, Hossein; Fadakar, Golnaz
2016-09-01
We study cosmic dynamics in the context of the normal branch of the DGP braneworld model. Using current Planck data, we find the best fitting model and associated cosmological parameters in non-flat ΛDGP. With the transition redshift as a basic variable and statefinder parameters, our result shows that the Universe starts its accelerated expansion phase slightly earlier than expected in ΛCDM cosmology. The result also alleviates the coincidence problem of the ΛCDM model.
An analytical model for finite radius dual-beam mode-mismatched thermal lens spectroscopy
Sabaeian, Mohammad; Nadgaran, Hamid
2013-10-01
In this work, a new model for dual-beam mode-mismatch thermal lens spectroscopy is presented. The model was based on a new analytical solution of time-dependent heat equation for finite radius cylindrical samples exposed to TEM00 excitation laser beams. The Fresnel diffraction integration method was used to calculate time-dependent on-axis probe beam intensity. All aberrations in thermal lens were taken into account. The model yields accurate values for absorption coefficient and thermal diffusivity of methylene blue aqueous solution. Furthermore, the optimized mode-mismatched version of this model when applied to pure water as a very low absorbent yields its absorption coefficient and thermal diffusivity values close to literature data. In contrast to traditional model, this model does not need to omit any term in its theory to fit the experimental data.
Meta-analytic structural equation modelling with missing correlations
Jak, S.; Oort, F. J.; Roorda, D.L.; Koomen, H.M.Y.
2013-01-01
Cheung and Chan (2005) proposed a two-stage method to conduct meta-analytic structural equation modelling (MASEM). MASEM refers to the technique of fitting structural equation models to pooled correlation or covariance matrices from several studies. Unfortunately, researchers do not always report all correlations between the variables of interest. In this paper, we propose a method to deal with missing correlations in the two-stage approach. We illustrate the proposed model with a meta-analys...
Analytic models of the chemical evolution of galaxies
Clayton, Donald D.
1986-01-01
Techniques are described for constructing analytic models of the chemical evolution of galaxies subject to infall of metal-poor material onto a maturing disk. A class of linear models is discussed which takes the star-formation rate within a defined region to be proportional to the mass of interstellar gas within that region, and the instantaneous recycling approximation is adopted. The solutions are obtained by approximately matching the infall rate to parametrized familiies of functions for which the equations are exactly soluble. The masses, the primary and secondary metallicities, and the gas concentrations of radioactive chronometers can all then be analytically expressed. Surveys of galactic abundances in location and in time can be compared to the parameter spaces of the analytic representations.
A simple stationary semi-analytical wake model
DEFF Research Database (Denmark)
Larsen, Gunner Chr.
We present an idealized simple, but fast, semi-analytical algorithm for computation of stationary wind farm wind fields with a possible potential within a multi-fidelity strategy for wind farm topology optimization. Basically, the model considers wakes as linear perturbations on the ambient non......-uniform mean wind field, although the modelling of the individual stationary wake flow fields includes non-linear terms. The simulation of the individual wake contributions are based on an analytical solution of the thin shear layer approximation of the NS equations. The wake flow fields are assumed...... conditions are imposed), the present formulation of wake expansion is believed to underestimate wake expansion, because the analytical wake formulation dictates the wake expansion to behave as x1/3 with downstream distance, whereas wake expansion as primary controlled by wake meandering develops...
International Nuclear Information System (INIS)
Scanning capacitance microscopy (SCM) is based on a contact-mode variant of atomic force microscopy, which is used for imaging two-dimensional carrier (electrons and holes) distributions in semiconductor devices. We introduced a method of quantification of the carrier concentration by experimentally deduced calibration curves, which were prepared for semiconductor materials such as silicon and silicon carbide. The analytical procedure was circulated to research organizations in a round-robin test. The effectiveness of the method was confirmed for practical analysis and for what is expected for industrial pre-standardization from the viewpoint of comparability among users. It was also applied to other electric scanning probe microscopy techniques such as scanning spreading resistance microscopy and scanning nonlinear dielectric microscopy. Their depth profiles of carrier concentration were found to be in good agreement with those characterized by SCM. These results suggest that our proposed method will be compatible with future next-generation microscopy. (paper)
Web Analytics: Models of Engagement Metrics in New Media
Directory of Open Access Journals (Sweden)
Sionara Ioco Okada
2012-02-01
Full Text Available The measurement and continuous monitoring of market actions leads to knowledge of consumer behavior, not only on variables such as frequency, recentness, and value for money, but also engagement in questions and interaction with the product and / or trademark. The development of metrics for different medias increases the amount of useful information on the consumption profile enabling the optimization of digital strategies to targeted audiences. This article is an update that aims to review the latest publications on models of metrics - web analytics- WA Consistent digital strategy and emerging media platforms. The methodology used is a secondary research, particularly reviewing literature, aiming to update and conduct a comparative analysis of three models of web analytics- wa for organizations that operate in electronic retailing, using different digital channels. The study focuses on: i Model of Five Stages of competition analysis, proposed by Davenport ii Model maturity in web analytics, proposed by Hammel iii Model Web analytics Scorecard proposed by Giuntini & Morier. In order to strengthen the interaction and metrics engagement as the main protagonists of contemporary digital strategies the expansion of M-commerce and the advent of Social Commerce are assumed to be irreversible trends. It requires the participation of organizations that operate in electronic retailing, metrics and performance indicators for continuous monitoring of consumer behavior.
Analytical Model for Hook Anchor Pull-Out
DEFF Research Database (Denmark)
Brincker, Rune; Ulfkjær, Jens Peder; Adamsen, Peter; Langvad, Lotte; Toft, Rune
A simple analytical model for the pull-out of a hook anchor is presented. The model is based on a simplified version of the fictitious crack model. It is assumed that the fracture process is the pull-off of a cone shaped concrete part, simplifying the problem by assuming pure rigid body motions...... allowing elastic deformations only in a layer between the pull-out cone and the concrete base. The derived model is in good agreement with experimental results, it predicts size effects and the model parameters found by calibration of the model on experimental data are in good agreement with what should be...
Analytical Model for Fictitious Crack Propagation in Concrete Beams
DEFF Research Database (Denmark)
Ulfkjær, J. P.; Krenk, S.; Brincker, Rune
the elastic layer the deformations are modelled by the Timoshenko beam theory. The state of stress in the elastic layer is assumed to depend bi-lineary on local elongation corresponding to a linear softening relation for the fictitious crack. For different beam size results from the analytical model......An analytical model for load-displacement curves of unreinforced notched and un-notched concrete beams is presented. The load displacement-curve is obtained by combining two simple models. The fracture is modelled by a fictitious crack in an elastic layer around the mid-section of the beam. Outside...... the load-displacement curve where the fictitious crack starts to develope, and the point where the real crack starts to grow will always correspond to the same bending moment. Closed from solutions for the maximum size of the fracture zone and the minimum slope on the load-displacement curve is given...
An Analytic Radiative-Convective Model for Planetary Atmospheres
Robinson, Tyler D; 10.1088/0004-637X/757/1/104
2012-01-01
We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries, (2) worlds with some attenuation of sunli...
QSO variability: probing the Starburst model
Aretxaga, Itziar; Fernandes Jr., R. Cid; Terlevich, R. J.
1996-01-01
The consistency of the Starburst model for AGN is tested using the optical variability observed in large data bases of QSOs. Theoretical predictions for the variability--luminosity relationship and structure function are presented and compared with observations. If QSOs follow a variability--wavelength relation as that observed in nearby AGN, the model proves successful in reproducing the main characteristics of optical variability. The wavelength dependence (1) flattens the, otherwise, monoc...
Role of nuclear analytical probe techniques in biological trace element research
International Nuclear Information System (INIS)
Many biomedical experiments require the qualitative and quantitative localization of trace elements with high sensitivity and good spatial resolution. The feasibility of measuring the chemical form of the elements, the time course of trace elements metabolism, and of conducting experiments in living biological systems are also important requirements for biological trace element research. Nuclear analytical techniques that employ ion or photon beams have grown in importance in the past decade and have led to several new experimental approaches. Some of the important features of these methods are reviewed here along with their role in trace element research, and examples of their use are given to illustrate potential for new research directions. It is emphasized that the effective application of these methods necessitates a closely integrated multidisciplinary scientific team. 21 refs., 4 figs., 1 tab
An analytical model for the assessment of airline expansion strategies
Directory of Open Access Journals (Sweden)
Mauricio Emboaba Moreira
2014-01-01
Full Text Available Purpose: The purpose of this article is to develop an analytical model to assess airline expansion strategies by combining generic business strategy models with airline business models. Methodology and approach: A number of airline business models are examined, as are Porter’s (1983 industry five forces that drive competition, complemented by Nalebuff/ Brandenburger’s (1996 sixth force, and the basic elements of the general environment in which the expansion process takes place. A system of points and weights is developed to create a score among the 904,736 possible combinations considered. The model’s outputs are generic expansion strategies with quantitative assessments for each specific combination of elements inputted. Originality and value: The analytical model developed is original because it combines for the first time and explicitly elements of the general environment, industry environment, airline business models and the generic expansion strategy types. Besides it creates a system of scores that may be used to drive the decision process toward the choice of a specific strategic expansion path. Research implications: The analytical model may be adapted to other industries apart from the airline industry by substituting the element “airline business model” by other industries corresponding elements related to the different specific business models.
Learning, Learning Analytics, Activity Visualisation and Open learner Model
DEFF Research Database (Denmark)
Bull, Susan; Kickmeier-Rust, Michael; Vatrapu, Ravi;
2013-01-01
This paper draws on visualisation approaches in learning analytics, considering how classroom visualisations can come together in practice. We suggest an open learner model in situations where many tools and activity visualisations produce more visual information than can be readily interpreted....
Analytical Models of Legislative Texts for Muslim Scholars
Alwan, Ammar Abdullah Naseh; Yusoff, Mohd Yakubzulkifli Bin Mohd; Al-Hami, Mohammad Said M.
2011-01-01
The significance of the analytical models in traditional Islamic studies is that they contribute in sharpening the intellectual capacity of the students of Islamic studies. Research literature in Islamic studies has descriptive side predominantly; the information is gathered and compiled and rarely analyzed properly. This weakness is because of…
MODEL ANALYTICAL NETWORK PROCESS (ANP DALAM PENGEMBANGAN PARIWISATA DI JEMBER
Directory of Open Access Journals (Sweden)
Sukidin Sukidin
2015-04-01
Full Text Available Abstrak : Model Analytical Network Process (ANP dalam Pengembangan Pariwisata di Jember. Penelitian ini mengkaji kebijakan pengembangan pariwisata di Jember, terutama kebijakan pengembangan agrowisata perkebunan kopi dengan menggunakan Jember Fashion Carnival (JFC sebagai event marketing. Metode yang digunakan adalah soft system methodology dengan menggunakan metode analitis jaringan (Analytical Network Process. Penelitian ini menemukan bahwa pengembangan pariwisata di Jember masih dilakukan dengan menggunakan pendekatan konvensional, belum terkoordinasi dengan baik, dan lebih mengandalkan satu even (atraksi pariwisata, yakni JFC, sebagai lokomotif daya tarik pariwisata Jember. Model pengembangan konvensional ini perlu dirancang kembali untuk memperoleh pariwisata Jember yang berkesinambungan. Kata kunci: pergeseran paradigma, industry pariwisata, even pariwisata, agrowisata Abstract: Analytical Network Process (ANP Model in the Tourism Development in Jember. The purpose of this study is to conduct a review of the policy of tourism development in Jember, especially development policies for coffee plantation agro-tourism by using Jember Fashion Carnival (JFC as event marketing. The research method used is soft system methodology using Analytical Network Process. The result shows that the tourism development in Jember is done using a conventional approach, lack of coordination, and merely focus on a single event tourism, i.e. the JFC, as locomotive tourism attraction in Jember. This conventional development model needs to be redesigned to reach Jember sustainable tourism development. Keywords: paradigm shift, tourism industry, agro-tourism
Synthesis and Analytical Centrifugation of Magnetic Model Colloids
Luigjes, B.
2012-01-01
This thesis is a study of the preparation and thermodynamic properties of magnetic colloids. First, two types of magnetic model colloids are investigated: composite colloids and single-domain nanoparticles. Thermodynamics of magnetic colloids is studied using analytical centrifugation, including a s
Optimization of a coaxial electron cyclotron resonance plasma thruster with an analytical model
Energy Technology Data Exchange (ETDEWEB)
Cannat, F., E-mail: felix.cannat@onera.fr, E-mail: felix.cannat@gmail.com; Lafleur, T. [Physics and Instrumentation Department, Onera -The French Aerospace Lab, Palaiseau, Cedex 91123 (France); Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universites, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau (France); Jarrige, J.; Elias, P.-Q.; Packan, D. [Physics and Instrumentation Department, Onera -The French Aerospace Lab, Palaiseau, Cedex 91123 (France); Chabert, P. [Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universites, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau (France)
2015-05-15
A new cathodeless plasma thruster currently under development at Onera is presented and characterized experimentally and analytically. The coaxial thruster consists of a microwave antenna immersed in a magnetic field, which allows electron heating via cyclotron resonance. The magnetic field diverges at the thruster exit and forms a nozzle that accelerates the quasi-neutral plasma to generate a thrust. Different thruster configurations are tested, and in particular, the influence of the source diameter on the thruster performance is investigated. At microwave powers of about 30 W and a xenon flow rate of 0.1 mg/s (1 SCCM), a mass utilization of 60% and a thrust of 1 mN are estimated based on angular electrostatic probe measurements performed downstream of the thruster in the exhaust plume. Results are found to be in fair agreement with a recent analytical helicon thruster model that has been adapted for the coaxial geometry used here.
Palm: Easing the Burden of Analytical Performance Modeling
Energy Technology Data Exchange (ETDEWEB)
Tallent, Nathan R.; Hoisie, Adolfy
2014-06-01
Analytical (predictive) application performance models are critical for diagnosing performance-limiting resources, optimizing systems, and designing machines. Creating models, however, is difficult because they must be both accurate and concise. To ease the burden of performance modeling, we developed Palm, a modeling tool that combines top-down (human-provided) semantic insight with bottom-up static and dynamic analysis. To express insight, Palm defines a source code modeling annotation language. By coordinating models and source code, Palm's models are `first-class' and reproducible. Unlike prior work, Palm formally links models, functions, and measurements. As a result, Palm (a) uses functions to either abstract or express complexity (b) generates hierarchical models (representing an application's static and dynamic structure); and (c) automatically incorporates measurements to focus attention, represent constant behavior, and validate models. We discuss generating models for three different applications.
Accurate Load Modeling Based on Analytic Hierarchy Process
Directory of Open Access Journals (Sweden)
Zhenshu Wang
2016-01-01
Full Text Available Establishing an accurate load model is a critical problem in power system modeling. That has significant meaning in power system digital simulation and dynamic security analysis. The synthesis load model (SLM considers the impact of power distribution network and compensation capacitor, while randomness of power load is more precisely described by traction power system load model (TPSLM. On the basis of these two load models, a load modeling method that combines synthesis load with traction power load is proposed in this paper. This method uses analytic hierarchy process (AHP to interact with two load models. Weight coefficients of two models can be calculated after formulating criteria and judgment matrixes and then establishing a synthesis model by weight coefficients. The effectiveness of the proposed method was examined through simulation. The results show that accurate load modeling based on AHP can effectively improve the accuracy of load model and prove the validity of this method.
Cosmic microwave background probes models of inflation
Davis, Richard L.; Hodges, Hardy M.; Smoot, George F.; Steinhardt, Paul J.; Turner, Michael S.
1992-01-01
Inflation creates both scalar (density) and tensor (gravity wave) metric perturbations. We find that the tensor-mode contribution to the cosmic microwave background anisotropy on large-angular scales can only exceed that of the scalar mode in models where the spectrum of perturbations deviates significantly from scale invariance. If the tensor mode dominates at large-angular scales, then the value of DeltaT/T predicted on 1 deg is less than if the scalar mode dominates, and, for cold-dark-matter models, bias factors greater than 1 can be made consistent with Cosmic Background Explorer (COBE) DMR results.
Energy Technology Data Exchange (ETDEWEB)
Adur, Rohan, E-mail: adur@physics.osu.edu; Du, Chunhui; Manuilov, Sergei A.; Wang, Hailong; Yang, Fengyuan; Pelekhov, Denis V.; Hammel, P. Chris [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
2015-05-07
The dipole field from a probe magnet can be used to localize a discrete spectrum of standing spin wave modes in a continuous ferromagnetic thin film without lithographic modification to the film. Obtaining the resonance field for a localized mode is not trivial due to the effect of the confined and inhomogeneous magnetization precession. We compare the results of micromagnetic and analytic methods to find the resonance field of localized modes in a ferromagnetic thin film, and investigate the accuracy of these methods by comparing with a numerical minimization technique that assumes Bessel function modes with pinned boundary conditions. We find that the micromagnetic technique, while computationally more intensive, reveals that the true magnetization profiles of localized modes are similar to Bessel functions with gradually decaying dynamic magnetization at the mode edges. We also find that an analytic solution, which is simple to implement and computationally much faster than other methods, accurately describes the resonance field of localized modes when exchange fields are negligible, and demonstrating the accessibility of localized mode analysis.
Validation of the General Electric pressure suppression analytical model
International Nuclear Information System (INIS)
The GE Company's analytical model for pressure suppression system transient response has evolved over more than 15 years. This paper describes the validation process and results from qualification of the latest version of this model. A general description of the model, validation activities, test data used for qualification, and model/data comparisons are included. Based on drywell pressure response, the model is shown to be about 3% conservative when run in the best estimate mode, and approximately 15% conservative when run in the design basis mode. (orig.)
A Simple Analytical Model for Gaps in Protoplanetary Disks
Duffell, Paul C
2015-01-01
An analytical model is presented for calculating the surface density as a function of radius $\\Sigma(r)$ in protoplanetary disks in which a planet has opened a gap. This model is also applicable to circumbinary disks with extreme binary mass ratios. The gap profile can be solved for algebraically, without performing any numerical integrals. In contrast with previous one-dimensional gap models, this model correctly predicts that low-mass (sub-Jupiter) planets can open gaps in sufficiently low-viscosity disks, and it correctly recovers the power-law dependence of gap depth on planet-to-star mass ratio $q$, disk aspect ratio $h/r$, and dimensionless viscosity $\\alpha$ found in previous numerical studies. Analytical gap profiles are compared with numerical calculations over a range of parameter space in $q$, $h/r$, and $\\alpha$, demonstrating accurate reproduction of the "partial gap" regime, and general agreement over a wide range of parameter space.
Impact analytical models for earthquake-induced pounding simulation
Institute of Scientific and Technical Information of China (English)
Kun YE; Li LI
2009-01-01
Structural pounding under earthquake has been recently extensively investigated using various impact analytical models. In this paper, a brief review on the commonly used impact analytical models is conducted.Based on this review, the formula used to determine the damping constant related to the impact spring stiffness,coefficient of restitution, and relative approaching velocity in the Hertz model with nonlinear damping is found to be incorrect. To correct this error, a more accurate approximating formula for the damping constant is theoretically derived 5~nd numerically verified. At the same time, a modified Kelvin impact model, which can reasonably account for the physical nature of pounding and conveniently implemented in the earthquake-induced pounding simulation of structural engineering is proposed.
Stochastic modeling of consumer purchase behavior : I. Analytical Results
Bemmaor, Albert C.
1981-01-01
This paper develops alternative brand purchase models. These models are based on distinct assumptions about the product class purchasing process over a fixed time-period. In each case, the brand choice process conditioned on a product purchase being made is assumed to be heterogeneous zero order. New analytical closed-form results are derived. These results include various market statistics such as the brand penetration, the mean and variance of the brand purchase distribution and the aggrega...
An Analytical Air Pollution Model with Time Dependent Eddy Diffusivity
Tiziano Tirabassi; Marco Túllio Vilhena; Daniela Buske; Gervásio Annes Degrazia
2013-01-01
Air pollution transport and dispersion in the atmospheric boundary layer are modeled by the advection-diffusion equation, that is, essentially, a statement of conservation of the suspended material in an incompressible flow. Many models simulating air pollution dispersion are based upon the solution (numerical or analytical) of the advection-diffusion equation assuming turbulence parameterization for realistic physical scenarios. We present the general time dependent three-dimensional soluti...
A Physics-based Analytical Model for Perovskite Solar Cells
Sun, Xingshu; Asadpour, Reza; Nie, Wanyi; Mohite, Aditya D.; Alam, Muhammad A.
2015-01-01
Perovskites are promising next-generation absorber materials for low-cost and high-efficiency solar cells. Although perovskite cells are configured similar to the classical solar cells, their operation is unique and requires development of a new physical model for characterization, optimization of the cells, and prediction of the panel performance. In this paper, we develop such a physics-based analytical model to describe the operation of different types of perovskite solar cells, explicitly...
An analytic model for the Riemannian space of colors
International Nuclear Information System (INIS)
A scale-invariant generalization of Weinberg's theory of the color space is given. A minimal analytic model is constructed with Gaussian protomeric basis; the metric tensor possesses four independent Killing vectors with an U(1)xSO(1,1) symmetry group. The formalism is applied to dichromatic vision too, and a special model is shown, in which the color space is two-dimensional, however the dominant hues can be identified. 16 refs. (author)
A parsimonious analytical model for simulating multispecies plume migration
Chen, J.-S.; Liang, C.-P.; Liu, C.-W.; Li, L. Y.
2015-09-01
A parsimonious analytical model for rapidly predicting the long-term plume behavior of decaying contaminant such as radionuclide and dissolved chlorinated solvent is presented in this study. Generalized analytical solutions in compact format are derived for the two-dimensional advection-dispersion equations coupled with sequential first-order decay reactions involving an arbitrary number of species in groundwater system. The solution techniques involve the sequential applications of the Laplace, finite Fourier cosine, and generalized integral transforms to reduce the coupled partial differential equation system to a set of linear algebraic equations. The system of algebraic equations is next solved for each species in the transformed domain, and the solutions in the original domain are then obtained through consecutive integral transform inversions. Explicit form solutions for a special case are derived using the generalized analytical solutions and are verified against the numerical solutions. The analytical results indicate that the parsimonious analytical solutions are robust and accurate. The solutions are useful for serving as simulation or screening tools for assessing plume behaviors of decaying contaminants including the radionuclides and dissolved chlorinated solvents in groundwater systems.
Modeling the hysteresis of a scanning probe microscope
DEFF Research Database (Denmark)
Dirscherl, Kai; Garnæs, Jørgen; Nielsen, L.;
2000-01-01
Most scanning probe microscopes use piezoelectric actuators in open loop configurations. Therefore a major problem related to these instruments is the image distortion due to the hysteresis effect of the piezo. In order to eliminate the distortions, cost effective software control based on a model...
High Redshift Intergalactic Medium: Probes and Physical Models
Sethi, S K
2004-01-01
Recent years have seen major advances in understanding the state of the intergalactic medium (IGM) at high redshift. Some aspects of this understanding are reviewed here. In particular, we discuss: (1) Different probes of IGM like Gunn-Peterson test, CMBR anisotropies, and neutral hydrogen emission from reionization, and (2) some models of reionization of the universe.
A model of plasma current through a hole of Rogowski probe including sheath effects
Furui, H.; Ejiri, A.; Nagashima, Y.; Takase, Y.; Sonehara, M.; Tsujii, N.; Yamaguchi, T.; Shinya, T.; Togashi, H.; Homma, H.; Nakamura, K.; Takeuchi, T.; Yajima, S.; Yoshida, Y.; Toida, K.; Takahashi, W.; Yamazaki, H.
2016-04-01
In TST-2 Ohmic discharges, local current is measured using a Rogowski probe by changing the angle between the local magnetic field and the direction of the hole of the Rogowski probe. The angular dependence shows a peak when the direction of the hole is almost parallel to the local magnetic field. The obtained width of the peak was broader than that of the theoretical curve expected from the probe geometry. In order to explain this disagreement, we consider the effect of sheath in the vicinity of the Rogowski probe. A sheath model was constructed and electron orbits were numerically calculated. From the calculation, it was found that the electron orbit is affected by E × B drift due to the sheath electric field. Such orbit causes the broadening of the peak in the angular dependence and the dependence agrees with the experimental results. The dependence of the broadening on various plasma parameters was studied numerically and explained qualitatively by a simplified analytical model.
ANALYTICAL CHIP FORMATION MODEL OF MICRO-END-MILLING
Institute of Scientific and Technical Information of China (English)
LI Chengfeng; LAI Xinmin; LI Hongtao; PENG Linfa; NI Jun
2008-01-01
A new analytical chip formation model is proposed for micro-end-milling operations. The model calculates an instantaneous uncut chip thickness by considering the combination of exact trochoidal trajectory of the tool tip and tool run-out, while the simplified circular trajectory and the neglected run-out create negligible change in conventional-scale chip formation models. Newton-Raphson iterative method is employed during the calculation to obtain quadratic convergence. The proposed approach allows the calculation of instantaneous uncut chip thickness to be done accurately and rapidly, and the prediction accuracy of this model is also verified by comparing the simulation results to experimental cutting forces.
An Analytical Model for Top-Hat Long Transient Mode-Mismatched Thermal Lens Spectroscopy
Sabaeian, M.; Rezaei, H.
2016-02-01
It has been shown that a top-hat excitation beam gives rise to a more sensitive signal for the thermal lens spectroscopy (TLS). Recently, a numerical model has been presented for a top- hat excitation beam in a dual-beam mod-mismatched TLS [Opt. Lett. 33(13), 1464-1466 (2008)]. In this work, we present a full analytical version of this model. Our model was based on a new solution of time-dependent heat equation for a finite radius cylindrical sample exposed to a top-hat excitation laser beam. The Fresnel diffraction integration method was then used to calculate on-axis probe-beam intensity variations due to thermal lensing by taking the aberrant nature of the thermal lens into account. The model was confirmed with experimental data of LSCAS-2 with an excellent agreement.
Analytical Modeling for the Grating Eddy Current Displacement Sensors
Directory of Open Access Journals (Sweden)
Lv Chunfeng
2015-02-01
Full Text Available As a new type of displacement sensor, grating eddy current displacement sensor (GECDS combines traditional eddy current sensors and grating structure in one. The GECDS performs a wide range displacement measurement without precision reduction. This paper proposes an analytical modeling approach for the GECDS. The solution model is established in the Cartesian coordinate system, and the solving domain is limited to finite extents by using the truncated region eigenfunction expansion method. Based on the second order vector potential, expressions for the electromagnetic field as well as coil impedance related to the displacement can be expressed in closed-form. Theoretical results are then confirmed by experiments, which prove the suitability and effectiveness of the analytical modeling approach.
A semi-analytic model of magnetized liner inertial fusion
McBride, Ryan D
2015-01-01
Presented is a semi-analytic model of magnetized liner inertial fusion (MagLIF). This model accounts for several key aspects of MagLIF, including: (1) preheat of the fuel (optionally via laser absorption); (2) pulsed-power-driven liner implosion; (3) liner compressibility with an analytic equation of state, artificial viscosity, internal magnetic pressure, and ohmic heating; (4) adiabatic compression and heating of the fuel; (5) radiative losses and fuel opacity; (6) magnetic flux compression with Nernst thermoelectric losses; (7) magnetized electron and ion thermal conduction losses; (8) end losses; (9) enhanced losses due to prescribed dopant concentrations and contaminant mix; (10) deuterium-deuterium and deuterium-tritium primary fusion reactions for arbitrary deuterium to tritium fuel ratios; and (11) magnetized alpha-particle fuel heating. We show that this simplified model, with its transparent and accessible physics, can be used to reproduce the general 1D behavior presented throughout the original Ma...
Selection Of Analytical Computational Model Of Contact Pressure
Directory of Open Access Journals (Sweden)
Maršálek Ondřej
2015-11-01
Full Text Available This paper presents a comparison of two contact pressure calculation methods between two real rough surfaces: a calculation based on FEM (Finite Element Method using commercial software tool ANSYS and a calculation based on FDM (Finite Difference Method using analytical functions implemented in programing tool MATLAB. This comparison, lately, leads to the selection of the most appropriate analytical contact model useful for time-effective and precise contact pressure determination. Surface data for numerical simulations are obtained by optical profilometry. For the case of the modelling process of 3D FEM models of rough surfaces the description of their building is included in this article. Furthermore, this paper discusses all challenges connected with the convergence of such simulations and essential post-processing of FEM simulation results, together with their comparison, along the results obtained by user-written MATLAB functions.
Galactic chemical evolution and nucleocosmochronology - Analytic quadratic models
Clayton, D. D.
1985-01-01
Quadratic models of the chemical evolution of the Galaxy for a star formation rate proportional to the square of the gas mass are studied. The search for analytic solutions to the gas mass and star mass for time-dependent rates of gaseous infall onto the disk is examined. The quadratic models are compared to models having linear star formation rates. The mass, metallicity, number of stars, and U-235/U-238 isotopic ratio for the models which are subjected to the same infall rate, the same initial disk mass, and the same final gas fraction are compared. The results of the comparison indicate that: (1) the average dwarf age is greater in the quadratic model, (2) the metallicity grows initially faster in the quadratic model, (3) the quadratic model has a smaller percentage of low-Z dwarfs, and (4) the U-235/U-238 isotopic ratio indicates a younger quadratic model.
Modeling the effect of probe force on length measurements on polymer parts
DEFF Research Database (Denmark)
Mohammadi, Ali; Sonne, Mads Rostgaard; Dalla Costa, Giuseppe;
2016-01-01
Measurement uncertainty at micrometer level is in the future going to be very common in dimensional measurements on polymer parts. Accurate dimensional measurement of polymer parts is becoming a key and common practice in the industry, especially when micrometer tolerances are required. When...... conducting measurements with a contact probe there is always a force applied to the part. This force (0.3N – 3.3N) leads to deformations that an influence the final result. The unknown deformation of the part under the measurement conditions can produce significant errors in the measurement. In the present...... work, Hertzian contact theory was applied to find the deformation analytically, where the measuring force was imposed to the part. Material properties of the polymer and radius of the probe tip were known parameters. The finite element software ABAQUS was then used to model the contact problem...
Aeroecology: probing and modeling the aerosphere.
Kunz, Thomas H; Gauthreaux, Sidney A; Hristov, Nickolay I; Horn, Jason W; Jones, Gareth; Kalko, Elisabeth K V; Larkin, Ronald P; McCracken, Gary F; Swartz, Sharon M; Srygley, Robert B; Dudley, Robert; Westbrook, John K; Wikelski, Martin
2008-07-01
Aeroecology is a discipline that embraces and integrates the domains of atmospheric science, ecology, earth science, geography, computer science, computational biology, and engineering. The unifying concept that underlies this emerging discipline is its focus on the planetary boundary layer, or aerosphere, and the myriad of organisms that, in large part, depend upon this environment for their existence. The aerosphere influences both daily and seasonal movements of organisms, and its effects have both short- and long-term consequences for species that use this environment. The biotic interactions and physical conditions in the aerosphere represent important selection pressures that influence traits such as size and shape of organisms, which in turn facilitate both passive and active displacements. The aerosphere also influences the evolution of behavioral, sensory, metabolic, and respiratory functions of organisms in a myriad of ways. In contrast to organisms that depend strictly on terrestrial or aquatic existence, those that routinely use the aerosphere are almost immediately influenced by changing atmospheric conditions (e.g., winds, air density, precipitation, air temperature), sunlight, polarized light, moon light, and geomagnetic and gravitational forces. The aerosphere has direct and indirect effects on organisms, which often are more strongly influenced than those that spend significant amounts of time on land or in water. Future advances in aeroecology will be made when research conducted by biologists is more fully integrated across temporal and spatial scales in concert with advances made by atmospheric scientists and mathematical modelers. Ultimately, understanding how organisms such as arthropods, birds, and bats aloft are influenced by a dynamic aerosphere will be of importance for assessing, and maintaining ecosystem health, human health, and biodiversity. PMID:21669768
Modeling of current characteristics of segmented Langmuir probe on DEMETER
Energy Technology Data Exchange (ETDEWEB)
Imtiaz, Nadia; Marchand, Richard [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada); Lebreton, Jean-Pierre [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace (LPC2E), CNRS-Université d' Orléans, Orléans Cedex (France)
2013-05-15
We model the current characteristics of the DEMETER Segmented Langmuir probe (SLP). The probe is used to measure electron density and temperature in the ionosphere at an altitude of approximately 700 km. It is also used to measure the plasma flow velocity in the satellite frame of reference. The probe is partitioned into seven collectors: six electrically insulated spherical segments and a guard electrode (the rest of the sphere and the small post). Comparisons are made between the predictions of the model and DEMETER measurements for actual ionospheric plasma conditions encountered along the satellite orbit. Segment characteristics are computed numerically with PTetra, a three-dimensional particle in cell simulation code. In PTetra, space is discretized with an unstructured tetrahedral mesh, thus, enabling a good representation of the probe geometry. The model also accounts for several physical effects of importance in the interaction of spacecraft with the space environment. These include satellite charging, photoelectron, and secondary electron emissions. The model is electrostatic, but it accounts for the presence of a uniform background magnetic field. PTetra simulation results show different characteristics for the different probe segments. The current collected by each segment depends on its orientation with respect to the ram direction, the plasma composition, the magnitude, and the orientation of the magnetic field. It is observed that the presence of light H{sup +} ions leads to a significant increase in the ion current branch of the I-V curves of the negatively polarized SLP. The effect of the magnetic field is demonstrated by varying its magnitude and direction with respect to the reference magnetic field. It is found that the magnetic field appreciably affects the electron current branch of the I-V curves of certain segments on the SLP, whereas the ion current branch remains almost unaffected. PTetra simulations are validated by comparing the computed
Secondary metallicity in analytic models of chemical evolution of galaxies
Clayton, D. D.; Pantelaki, I.
1986-01-01
Analytic models of the chemical evolution of galactic regions that grow in mass owing to the continuous infall of matter are characterized, emphasizing the solutions for secondary nuclei (defined as those nuclei whose stellar yields are proportional to the abundance of a primary seed nucleus) in the families of models described by Clayton (1984 and 1985). Wide variations in time dependence of both primary and secondary nuclei as well as in the ratio of secondary to primary are displayed by these model families, confirming again the usefulness of these families as interpretive guides if galaxies do in fact evolve with substantial infall. Additionally, analytic solutions are presented for two other possible interesting systems: the evolution of abundances if the primary metallicity in the infall is increasing in time, and the evolution of abundances if the primary yield changes linearly with time owing to continuous changes in the stellar mass function, the opacity, or other astrophysical agents. Finally, test evaluations of the instantaneous recycling approximation on which these analytic models rely are presented.
A Flexible Python Design for Analytic Modeling of Groundwater Flow
Bakker, M.
2008-12-01
We present a simple and flexible, object-oriented design for the modeling of groundwater flow using analytic elements in Python. The primary feature is that new analytic elements may be added to the code without the need to make any changes in the existing part of the code. The code consists of a Model class and an Element base class. Each new element is derived from the Element base class (or a derived class) and added to the model. Boundary conditions are implemented by each element itself, because they generate their own equations. Significant speed-up may be obtained through the use of FORTRAN extensions of the computationally intensive functions. Another way to increase performance is by grouping elements with same-type boundary conditions, although that requires changes to the existing code when elements with new boundary conditions are implemented. The described design has been applied successfully to three types of flow: steady multi-aquifer flow, transient periodic flow, and steady unsaturated flow. All systems include wells (point-sinks), line-sinks and circular inhomogeneities. Heads and velocities can be computed analytically at any point; path lines may be computed through numerical integration of the velocity field. The multi-aquifer code is the most extensive and includes many other features such as polygonal inhomogeneities and impermeable walls. Additional Python features make it very easy to create models; input scripts can be generated from GIS coverages of elements; high-quality and interactive graphical output is generated with the matplotlib package.
Barrierless Electronic Relaxation in Solution: An Analytically Solvable Model
Chakraborty, Aniruddha
2013-01-01
We propose an analytical method for understanding the problem of electronic relaxation in solution, modeled by a particle undergoing diffusive motion under the influence of two potentials. The coupling between the two potentials is assumed to be represented by a Dirac Delta function. The diffusive motion in this paper is described by the Smoluchowskii equation. Our solution requires the knowledge of the Laplace transform of the Green's function for the motion in both the uncoupled potentials. Our model is more general than all the earlier models, because we are the first one to consider the effect of ground state potential energy surface explicitly.
An Analytic Model of Galactic Winds and Mass Outflows
Institute of Scientific and Technical Information of China (English)
Cheng-Gang Shu; Hou-Jun Mo; Shu-De Mao
2005-01-01
Galactic winds and mass outflows are observed both in nearby starburst galaxies and in high-redshift star-forming galaxies. We develop a simple analytic model to understand the observed superwind phenomenon with a discussion of the model uncertainties. Our model is built upon the model of McKee & Ostriker for the interstellar medium. It allows one to predict how properties of a superwind,such as wind velocity and mass outflow rate, are related to properties of its star forming host galaxy, such as size, gas density and star formation rate. The model predicts a threshold of star formation rate density for the generation of observable galactic winds. Galaxies with more concentrated star formation activities produce superwinds with higher velocities. The predicted mass outflow rates are compara ble to (or slightly larger than) the corresponding star formation rates. We apply our model to both local starburst galaxies and high-redshift Lyman break galaxies, and find its predictions to be in good agreement with current observations. Our model is simple and so can be easily incorporated into numerical simulations and semi-analytical models of galaxy formation.
Human performance modeling for system of systems analytics.
Energy Technology Data Exchange (ETDEWEB)
Dixon, Kevin R.; Lawton, Craig R.; Basilico, Justin Derrick; Longsine, Dennis E. (INTERA, Inc., Austin, TX); Forsythe, James Chris; Gauthier, John Henry; Le, Hai D.
2008-10-01
A Laboratory-Directed Research and Development project was initiated in 2005 to investigate Human Performance Modeling in a System of Systems analytic environment. SAND2006-6569 and SAND2006-7911 document interim results from this effort; this report documents the final results. The problem is difficult because of the number of humans involved in a System of Systems environment and the generally poorly defined nature of the tasks that each human must perform. A two-pronged strategy was followed: one prong was to develop human models using a probability-based method similar to that first developed for relatively well-understood probability based performance modeling; another prong was to investigate more state-of-art human cognition models. The probability-based modeling resulted in a comprehensive addition of human-modeling capability to the existing SoSAT computer program. The cognitive modeling resulted in an increased understanding of what is necessary to incorporate cognition-based models to a System of Systems analytic environment.
Analytical Modelling of a Plucked Piezoelectric Bimorph for Energy Harvesting
Pozzi, Michele
2012-01-01
Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of sufficient power to operate targeted low-power applications. Piezoelectric transducers are often used for vibrational, inertial and direct movement EH. One problem is that, due to the stiffness of the most common material (PZT) and typically useful sizes, intrinsic resonant frequencies are normally high, whereas the available power is often concentrated at low frequencies. The aim of the plucking technique of frequency up-conversion, also known as "pizzicato" excitation, is to bridge this frequency gap. In this paper, the technique is modelled analytically. The analytical model is developed starting from the Euler-Bernoulli beam equations modified for piezoelectric coupling. A system of differential equations and associated initial conditions are derived which describe the free vibration of a piezoelectric bimorph in the last part of the plucki...
An analytical model for the effect in magnetic materials
Daniel, L.; Hubert, O.
2009-01-01
Abstract The effect is often presented as the dependency of the Young's modulus of a material on its state of magnetization. Nevertheless, the elastic properties of a magnetic material do not depend on the magnetization state. Actually, the sensitivity of the magnetostriction strain to the application of a stress explains the effect. According to this statement, a semi-analytical model for the effect is proposed, in which magnetization rotation is not considered. An experimental...
The linear Ising model and its analytic continuation, random walk
B. H. Lavenda
2004-01-01
A generalization of Gauss's principle is used to derive the error laws corresponding to Types II and VII distributions in Pearson's classification scheme. Student's $r$-pdf (Type II) governs the distribution of the internal energy of a uniform, linear chain, Ising model, while analytic continuation of the uniform exchange energy converts it into a Student $t$-density (Type VII) for the position of a random walk in a single spatial dimension. Higher dimensional spaces, corresponding to larger ...
New analytically solvable models of relativistic point interactions
International Nuclear Information System (INIS)
Two new analytically solvable models of relativistic point interactions in one dimension (being natural extensions of the nonrelativistic δ-resp, δ'-interaction) are considered. Their spectral properties in the case of finitely many point interactions as well as in the periodic case are fully analyzed. Moreover the spectrum is explicitely determined in the case of independent, identically distributed random coupling constants and the analog of the Saxon and Huther conjecture concerning gaps in the energy spectrum of such systems is derived
Approximate analytical solutions of the baby Skyrme model
Ioannidou, T. A.; Kopeliovich, V. B.; Zakrzewski, W. J.
2002-01-01
In present paper we show that many properties of the baby skyrmions, which have been determined numerically, can be understood in terms of an analytic approximation. In particular, we show that this approximation captures properties of the multiskyrmion solutions (derived numerically) such as their stability towards decay into various channels, and that it is more accurate for the "new baby Skyrme model" which describes anisotropic physical systems in terms of multiskyrmion fields with axial ...
Fractal approach to computer-analytical modelling of tree crown
International Nuclear Information System (INIS)
In this paper we discuss three approaches to the modeling of a tree crown development. These approaches are experimental (i.e. regressive), theoretical (i.e. analytical) and simulation (i.e. computer) modeling. The common assumption of these is that a tree can be regarded as one of the fractal objects which is the collection of semi-similar objects and combines the properties of two- and three-dimensional bodies. We show that a fractal measure of crown can be used as the link between the mathematical models of crown growth and light propagation through canopy. The computer approach gives the possibility to visualize a crown development and to calibrate the model on experimental data. In the paper different stages of the above-mentioned approaches are described. The experimental data for spruce, the description of computer system for modeling and the variant of computer model are presented. (author). 9 refs, 4 figs
Challenges in the development of analytical soil compaction models
DEFF Research Database (Denmark)
Keller, Thomas; Lamandé, Mathieu
2010-01-01
Soil compaction can cause a number of environmental and agronomic problems (e.g. flooding, erosion, leaching of agrochemicals to recipient waters, emission of greenhouse gases to the atmosphere, crop yield losses), resulting in significant economic damage to society and agriculture. Strategies and...... recommendations for the prevention of soil compaction often rely on simulation models. This paper highlights some issues that need further consideration in order to improve soil compaction modelling, with the focus on analytical models. We discuss the different issues based on comparisons between experimental...... data and model simulations. The upper model boundary condition (i.e. contact area and stresses at the tyre-soil interface) is highly influential in stress propagation, but knowledge on the effects of loading and soil conditions on the upper model boundary condition is inadequate. The accuracy of stress...
A new analytical model for wind farm power prediction
Niayifar, Amin; Porté-Agel, Fernando
2015-06-01
In this study, a new analytical approach is presented and validated to predict wind farm power production. The new model is an extension of the recently proposed by Bastankhah and Porté-Agel for a single wake. It assumes a self-similar Gaussian shape of the velocity deficit and satisfies conservation of mass and momentum. To estimate the velocity deficit in the wake, this model needs the local wake growth rate parameter which is calculated based on the local turbulence intensity in the wind farm. The interaction of the wakes is modeled by use of the velocity deficit superposition principle. Finally, the power curve is used to estimate the power production from the wind turbines. The wind farm model is compared to large-eddy simulation (LES) data and measurments of Horns Rev wind farm for a wide range of wind directions. Reasonable agreement between the proposed analytical model, LES data and measurments is obtained. This prediction is also found to be substantially better than the one obtained with a commonly used wind farm wake model.
Model and Analytic Processes for Export License Assessments
Energy Technology Data Exchange (ETDEWEB)
Thompson, Sandra E.; Whitney, Paul D.; Weimar, Mark R.; Wood, Thomas W.; Daly, Don S.; Brothers, Alan J.; Sanfilippo, Antonio P.; Cook, Diane; Holder, Larry
2011-09-29
This paper represents the Department of Energy Office of Nonproliferation Research and Development (NA-22) Simulations, Algorithms and Modeling (SAM) Program's first effort to identify and frame analytical methods and tools to aid export control professionals in effectively predicting proliferation intent; a complex, multi-step and multi-agency process. The report focuses on analytical modeling methodologies that alone, or combined, may improve the proliferation export control license approval process. It is a follow-up to an earlier paper describing information sources and environments related to international nuclear technology transfer. This report describes the decision criteria used to evaluate modeling techniques and tools to determine which approaches will be investigated during the final 2 years of the project. The report also details the motivation for why new modeling techniques and tools are needed. The analytical modeling methodologies will enable analysts to evaluate the information environment for relevance to detecting proliferation intent, with specific focus on assessing risks associated with transferring dual-use technologies. Dual-use technologies can be used in both weapons and commercial enterprises. A decision-framework was developed to evaluate which of the different analytical modeling methodologies would be most appropriate conditional on the uniqueness of the approach, data availability, laboratory capabilities, relevance to NA-22 and Office of Arms Control and Nonproliferation (NA-24) research needs and the impact if successful. Modeling methodologies were divided into whether they could help micro-level assessments (e.g., help improve individual license assessments) or macro-level assessment. Macro-level assessment focuses on suppliers, technology, consumers, economies, and proliferation context. Macro-level assessment technologies scored higher in the area of uniqueness because less work has been done at the macro level. An
Analytical model for a fast-response calorimeter: with applications
International Nuclear Information System (INIS)
This paper describes the development of an electrical analogue thermal-control model for the ANL-type fast-response calorimeter and its application to a new small sample, analytical-type fast-response calorimeter. This was done to obtain a better understanding of the sources of variations in experimentally measured sample power. Thermal quantities of temperature, heat flow and heat storage were reduced to electrical analogues so that the whole calorimeter could be modeled and analyzed as an electrical circuit with the thermal parts of the calorimeter treated as a series of lumped-circuit constants. Latest results of this work are discussed
A completely analytical family of anisotropic Plummer models
International Nuclear Information System (INIS)
In spherical stellar systems a given mass density allows an infinity of distribution functions. This indeterminacy is illustrated with a one-parameter family of anisotropic models. They all satisfy the Plummer law in the mass density, but have different velocity dispersions. Moreover, the stars are not confined to a particular subset of the total accessible phase space. This family is explored analytically in detail. Even when both the mass density and the velocity dispersion profiles are required to be the same, a degeneracy in the model space persists, which can be shown with a three-parameter generalization of the above family. (author)
Analytical properties of a three-compartmental dynamical demographic model
Postnikov, E. B.
2015-07-01
The three-compartmental demographic model by Korotaeyv-Malkov-Khaltourina, connecting population size, economic surplus, and education level, is considered from the point of view of dynamical systems theory. It is shown that there exist two integrals of motion, which enables the system to be reduced to one nonlinear ordinary differential equation. The study of its structure provides analytical criteria for the dominance ranges of the dynamics of Malthus and Kremer. Additionally, the particular ranges of parameters enable the derived general ordinary differential equations to be reduced to the models of Gompertz and Thoularis-Wallace.
Analytical Heat Transfer Modeling of a New Radiation Calorimeter
Ndong, Elysée Obame; Aitken, Frédéric
2016-01-01
This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from -50 {\\deg}C to 150 {\\deg}C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ~1 mW. From these results the calorimeter has been successfully implemented and patented.
Analytical model for fusion first-wall temperature calculations
International Nuclear Information System (INIS)
A primarily analytical thermal analysis model is presented which allows for calculation of temperatures in fusion reactor first walls. The model utilizes input quantities based on plasma physics calculations and couples a two-and-one-half-dimensional geometric analysis with a one-dimensional heat conduction analysis in determining temperature profiles over the surface of and within materials used to confine the plasma and vacuum. Given materials-related temperature limitations, methods are also provided for calculating maximum allowable wall power loadings. The results are primarily applicable to the steady-state operation of magnetic confinement devices such as tokamaks. 31 refs, 50 figs., 8 tabs
An Analytic Model for Buoyancy Resonances in Protoplanetary Disks
Lubow, Stephen H
2014-01-01
Zhu, Stone, and Rafikov (2012) found in 3D shearing box simulations a new form of planet-disk interaction that they attributed to a vertical buoyancy resonance in the disk. We describe an analytic linear model for this interaction. We adopt a simplified model involving azimuthal forcing that produces the resonance and permits an analytic description of its structure. We derive an analytic expression for the buoyancy torque and show that the vertical torque distribution agrees well with results of Athena simulations and a Fourier method for linear numerical calculations carried out with the same forcing. The buoyancy resonance differs from the classic Lindblad and corotation resonances in that the resonance lies along tilted planes. Its width depends on damping effects and is independent of the gas sound speed. The resonance does not excite propagating waves. At a given large azimuthal wavenumber k_y > 1/h (for disk thickness h), the buoyancy resonance exerts a torque over a region that lies radially closer to...
Modeling and Technical Analysis of Electronics Commerce and Predictive Analytics
Directory of Open Access Journals (Sweden)
KAMAL NAIN CHOPRA
2014-08-01
Full Text Available Recently, the Electronics Commerce and Predictive Analytics has become the subject of much interest and research activity. The present communication brings out the technical analysis of the various intelligence techniques, and also the characterization of various parameters like - Web analytics, and the related technologies, terminologies, and tools.The concepts of business intelligence like - benefits of Business Intelligence (BI, factors influencing BI, technology requirements, designing and implementing business intelligence, and the related parameters like - the data warehouse, online analytical processing (OLAP, Data Mining, representation technologies, and their role in improving the enterprise operation effectiveness have been discussed from the point of view of Information Technology. Various business research experts are pursuing the work on the modeling of some of these techniques rigorously. The predictive accuracy of the Predictive Modeling Methods has been briefly discussed. It is expected that the techniques described in the paper, and the technical discussions on the subject will be very useful to the new entrants in the field.
An analytic model for buoyancy resonances in protoplanetary disks
Energy Technology Data Exchange (ETDEWEB)
Lubow, Stephen H. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Zhu, Zhaohuan, E-mail: lubow@stsci.edu, E-mail: zhzhu@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
2014-04-10
Zhu et al. found in three-dimensional shearing box simulations a new form of planet-disk interaction that they attributed to a vertical buoyancy resonance in the disk. We describe an analytic linear model for this interaction. We adopt a simplified model involving azimuthal forcing that produces the resonance and permits an analytic description of its structure. We derive an analytic expression for the buoyancy torque and show that the vertical torque distribution agrees well with the results of the Athena simulations and a Fourier method for linear numerical calculations carried out with the same forcing. The buoyancy resonance differs from the classic Lindblad and corotation resonances in that the resonance lies along tilted planes. Its width depends on damping effects and is independent of the gas sound speed. The resonance does not excite propagating waves. At a given large azimuthal wavenumber k{sub y} > h {sup –1} (for disk thickness h), the buoyancy resonance exerts a torque over a region that lies radially closer to the corotation radius than the Lindblad resonance. Because the torque is localized to the region of excitation, it is potentially subject to the effects of nonlinear saturation. In addition, the torque can be reduced by the effects of radiative heat transfer between the resonant region and its surroundings. For each azimuthal wavenumber, the resonance establishes a large scale density wave pattern in a plane within the disk.
An Analytic Model for Buoyancy Resonances in Protoplanetary Disks
Lubow, Stephen H.; Zhu, Zhaohuan
2014-04-01
Zhu et al. found in three-dimensional shearing box simulations a new form of planet-disk interaction that they attributed to a vertical buoyancy resonance in the disk. We describe an analytic linear model for this interaction. We adopt a simplified model involving azimuthal forcing that produces the resonance and permits an analytic description of its structure. We derive an analytic expression for the buoyancy torque and show that the vertical torque distribution agrees well with the results of the Athena simulations and a Fourier method for linear numerical calculations carried out with the same forcing. The buoyancy resonance differs from the classic Lindblad and corotation resonances in that the resonance lies along tilted planes. Its width depends on damping effects and is independent of the gas sound speed. The resonance does not excite propagating waves. At a given large azimuthal wavenumber ky > h -1 (for disk thickness h), the buoyancy resonance exerts a torque over a region that lies radially closer to the corotation radius than the Lindblad resonance. Because the torque is localized to the region of excitation, it is potentially subject to the effects of nonlinear saturation. In addition, the torque can be reduced by the effects of radiative heat transfer between the resonant region and its surroundings. For each azimuthal wavenumber, the resonance establishes a large scale density wave pattern in a plane within the disk.
HTS axial flux induction motor with analytic and FEA modeling
International Nuclear Information System (INIS)
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested
HTS axial flux induction motor with analytic and FEA modeling
Energy Technology Data Exchange (ETDEWEB)
Li, S., E-mail: alexlee.zn@gmail.com; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J.H.
2013-11-15
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested.
Universal analytic model for tunnel FET circuit simulation
Lu, Hao; Esseni, David; Seabaugh, Alan
2015-06-01
A simple analytic model based on the Kane-Sze formula is used to describe the current-voltage characteristics of tunnel field-effect transistors (TFETs). This model captures the unique features of the TFET including the decrease in subthreshold swing with drain current and the superlinear onset of the output characteristic. The model also captures the ambipolar current characteristic at negative gate-source bias and the negative differential resistance for negative drain-source biases. A simple empirical capacitance model is also included to enable circuit simulation. The model has fairly general validity and is not specific to a particular TFET geometry. Good agreement is shown with published atomistic simulations of an InAs double-gate TFET with gate perpendicular to the tunnel junction and with numerical simulations of a broken-gap AlGaSb/InAs TFET with gate in parallel with the tunnel junction.
Analytical modelling of hydrogen transport in reactor containments
International Nuclear Information System (INIS)
A versatile computational model of hydrogen transport in nuclear plant containment buildings is developed. The background and significance of hydrogen-related nuclear safety issues are discussed. A computer program is constructed that embodies the analytical models. The thermofluid dynamic formulation spans a wide applicability range from rapid two-phase blowdown transients to slow incompressible hydrogen injection. Detailed ancillary models of molecular and turbulent diffusion, mixture transport properties, multi-phase multicomponent thermodynamics and heat sink modelling are addressed. The numerical solution of the continuum equations emphasizes both accuracy and efficiency in the employment of relatively coarse discretization and long time steps. Reducing undesirable numerical diffusion is addressed. Problem geometry options include lumped parameter zones, one dimensional meshs, two dimensional Cartesian or axisymmetric coordinate systems and three dimensional Cartesian or cylindrical regions. An efficient lumped nodal model is included for simulation of events in which spatial resolution is not significant. Several validation calculations are reported
Analytical expressions for transition edge sensor excess noise models
International Nuclear Information System (INIS)
Transition edge sensors (TESs) are high-sensitivity thermometers used in cryogenic microcalorimeters which exploit the steep gradient in resistivity with temperature during the superconducting phase transition. Practical TES devices tend to exhibit a white noise of uncertain origin, arising inside the device. We discuss two candidate models for this excess noise, phase slip shot noise (PSSN) and percolation noise. We extend the existing PSSN model to include a magnetic field dependence and derive a basic analytical model for percolation noise. We compare the predicted functional forms of the noise current vs. resistivity curves of both models with experimental data and provide a set of equations for both models to facilitate future experimental efforts to clearly identify the source of excess noise.
Analytical models of optical response in one-dimensional semiconductors
Energy Technology Data Exchange (ETDEWEB)
Pedersen, Thomas Garm, E-mail: tgp@nano.aau.dk
2015-09-04
The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron–hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed. - Highlights: • Optical response of one-dimensional semiconductors including excitons. • Analytical model of excitonic Franz–Keldysh effect. • Computation of optical response of impurity-localized excitons.
Probing the Universal Randall-Sundrum Model at the ILC
Davoudiasl, H; Rizzo, T G
2005-01-01
The Randall-Sundrum model with all Standard Model (SM) fields in the bulk, including the Higgs, can be probed by precision measurements at the ILC. In particular, the couplings of the Higgs to the gauge bosons of the SM can be determined with high accuracy at the ILC. Here we examine the deviations in these couplings from their SM values within the framework of the Universal Randall-Sundrum Model (URSM) as well as the corresponding couplings of the first Higgs Kaluza-Klein excitation.
An analytical model of a longitudinal-torsional ultrasonic transducer
International Nuclear Information System (INIS)
The combination of longitudinal and torsional (LT) vibrations at high frequencies finds many applications such as ultrasonic drilling, ultrasonic welding, and ultrasonic motors. The LT mode can be obtained by modifications to the design of a standard bolted Langevin ultrasonic transducer driven by an axially poled piezoceramic stack, by a technique that degenerates the longitudinal mode to an LT motion by a geometrical alteration of the wave path. The transducer design is developed and optimised through numerical modelling which can represent the geometry and mechanical properties of the transducer and its vibration response to an electrical input applied across the piezoceramic stack. However, although these models can allow accurate descriptions of the mechanical behaviour, they do not generally provide adequate insights into the electrical characteristics of the transducer. In this work, an analytical model is developed to present the LT transducer based on the equivalent circuit method. This model can represent both the mechanical and electrical aspects and is used to extract many of the design parameters, such as resonance and anti-resonance frequencies, the impedance spectra and the coupling coefficient of the transducer. The validity of the analytical model is demonstrated by close agreement with experimental results.
Architecture, modeling, and analysis of a plasma impedance probe
Jayaram, Magathi
Variations in ionospheric plasma density can cause large amplitude and phase changes in the radio waves passing through this region. Ionospheric weather can have detrimental effects on several communication systems, including radars, navigation systems such as the Global Positioning Sytem (GPS), and high-frequency communications. As a result, creating models of the ionospheric density is of paramount interest to scientists working in the field of satellite communication. Numerous empirical and theoretical models have been developed to study the upper atmosphere climatology and weather. Multiple measurements of plasma density over a region are of marked importance while creating these models. The lack of spatially distributed observations in the upper atmosphere is currently a major limitation in space weather research. A constellation of CubeSat platforms would be ideal to take such distributed measurements. The use of miniaturized instruments that can be accommodated on small satellites, such as CubeSats, would be key to achieving these science goals for space weather. The accepted instrumentation techniques for measuring the electron density are the Langmuir probes and the Plasma Impedance Probe (PIP). While Langmuir probes are able to provide higher resolution measurements of relative electron density, the Plasma Impedance Probes provide absolute electron density measurements irrespective of spacecraft charging. The central goal of this dissertation is to develop an integrated architecture for the PIP that will enable space weather research from CubeSat platforms. The proposed PIP chip integrates all of the major analog and mixed-signal components needed to perform swept-frequency impedance measurements. The design's primary innovation is the integration of matched Analog-to-Digital Converters (ADC) on a single chip for sampling the probes current and voltage signals. A Fast Fourier Transform (FFT) is performed by an off-chip Field-Programmable Gate Array (FPGA
Modeling and experimental vibration analysis of nanomechanical cantilever active probes
International Nuclear Information System (INIS)
Nanomechanical cantilever (NMC) active probes have recently received increased attention in a variety of nanoscale sensing and measurement applications. Current modeling practices call for a uniform cantilever beam without considering the intentional jump discontinuities associated with the piezoelectric layer attachment and the NMC cross-sectional step. This paper presents a comprehensive modeling framework for modal characterization and dynamic response analysis of NMC active probes with geometrical discontinuities. The entire length of the NMC is divided into three segments of uniform beams followed by applying appropriate continuity conditions. The characteristics matrix equation is then used to solve for system natural frequencies and mode shapes. Using an equivalent electromechanical moment of a piezoelectric layer, forced motion analysis of the system is carried out. An experimental setup consisting of a commercial NMC active probe from Veeco and a state-of-the-art microsystem analyzer, the MSA-400 from Polytec, is developed to verify the theoretical developments proposed here. Using a parameter estimation technique based on minimizing the modeling error, optimal values of system parameters are identified. Mode shapes and the modal frequency response of the system for the first three modes determined from the proposed model are compared with those obtained from the experiment and commonly used theory for uniform beams. Results indicate that the uniform beam model fails to accurately predict the actual system response, especially in multiple-mode operation, while the proposed discontinuous beam model demonstrates good agreement with the experimental data. Such detailed and accurate modeling framework can lead to significant enhancement in the sensitivity of piezoelectric-based NMC sensors for use in variety of sensing and imaging applications
John (Jack) P. Riegel III; David Davison
2016-01-01
Historically, there has been little correlation between the material properties used in (1) empirical formulae, (2) analytical formulations, and (3) numerical models. The various regressions and models may each provide excellent agreement for the depth of penetration into semi-infinite targets. But the input parameters for the empirically based procedures may have little in common with either the analytical model or the numerical model. This paper builds on previous work by Riegel and Anderso...
Comparison between analytical and numerical solution of mathematical drying model
Shahari, N.; Rasmani, K.; Jamil, N.
2016-02-01
Drying is often related to the food industry as a process of shifting heat and mass inside food, which helps in preserving food. Previous research using a mass transfer equation showed that the results were mostly concerned with the comparison between the simulation model and the experimental data. In this paper, the finite difference method was used to solve a mass equation during drying using different kinds of boundary condition, which are equilibrium and convective boundary conditions. The results of these two models provide a comparison between the analytical and the numerical solution. The result shows a close match between the two solution curves. It is concluded that the two proposed models produce an accurate solution to describe the moisture distribution content during the drying process. This analysis indicates that we have confidence in the behaviour of moisture in the numerical simulation. This result demonstrated that a combined analytical and numerical approach prove that the system is behaving physically. Based on this assumption, the model of mass transfer was extended to include the temperature transfer, and the result shows a similar trend to those presented in the simpler case.
HTS axial flux induction motor with analytic and FEA modeling
Li, S.; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J. H.
2013-11-01
This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested.
Analytical performance models for geologic repositories. Volume 2
Energy Technology Data Exchange (ETDEWEB)
Chambre, P.L.; Pigford, T.H.; Fujita, A.; Kanki, T.; Kobayashi, A.; Lung, H.; Ting, D.; Sato, Y.; Zavoshy, S.J.
1982-10-01
This report presents analytical solutions of the dissolution and hydrogeologic transport of radionuclides in geologic repositories. Numerical examples are presented to demonstrate the equations resulting from these analyses. The subjects treated in this report are: solubility-limited transport with transverse dispersion (chapter 2); transport of a radionuclide chain with nonequilibrium chemical reactions (chapter 3); advective transport in a two-dimensional flow field (chapter 4); radionuclide transport in fractured media (chapter 5); a mathematical model for EPA's analysis of generic repositories (chapter 6); and dissolution of radionuclides from solid waste (chapter 7). Volume 2 contains chapters 5, 6, and 7.
"Violent Intent Modeling: Incorporating Cultural Knowledge into the Analytical Process
Energy Technology Data Exchange (ETDEWEB)
Sanfilippo, Antonio P.; Nibbs, Faith G.
2007-08-24
While culture has a significant effect on the appropriate interpretation of textual data, the incorporation of cultural considerations into data transformations has not been systematic. Recognizing that the successful prevention of terrorist activities could hinge on the knowledge of the subcultures, Anthropologist and DHS intern Faith Nibbs has been addressing the need to incorporate cultural knowledge into the analytical process. In this Brown Bag she will present how cultural ideology is being used to understand how the rhetoric of group leaders influences the likelihood of their constituents to engage in violent or radicalized behavior, and how violent intent modeling can benefit from understanding that process.
Mathematical Model of Suspension Filtration and Its Analytical Solution
Directory of Open Access Journals (Sweden)
Normahmad Ravshanov
2013-01-01
Full Text Available The work develops advanced mathematical model and computing algorithm to analyze, predict and identify the basic parameters of filter units and their variation ranges. Numerical analytic solution of liquid ionized mixtures filtration was got on their basis. Computing experiments results are presented in graphics form. Calculation results analysis enables to determine the optimum performance of filter units, used for liquid ionized mixtures filtration, food preparation, drug production and water purification. Selection of the most suitable parameters contributes to the improvement of economic and technological efficiency of production and filter units working efficiency.
Mathematical Model of Suspension Filtering and Its Analytical Solution
Directory of Open Access Journals (Sweden)
Normahmad Ravshanov
2013-01-01
Full Text Available The work develops mathematical model and computing algorithm to analyze, project and identify the basic parameters of filter units operation and their variation range. On their basis, numerical analytic solution of the problem of ionized liquid solutions filtering was obtained. Computing experiments, resulting in graphic format were presented. Analysis of calculation results enables to determine the optimum modes of filter units operation, used in liquid ionized solutions filtration technology, in food preparation, in drug production and for drinking water purification. Selection of the most suitable parameters contributes to the improvement of economic and technologic efficiency of production and filter units operability.
X: A Comprehensive Analytic Model for Parallel Machines
Energy Technology Data Exchange (ETDEWEB)
Li, Ang; Song, Shuaiwen; Brugel, Eric; Kumar, Akash; Chavarría-Miranda, Daniel; Corporaal, Henk
2016-05-23
To continuously comply with Moore’s Law, modern parallel machines become increasingly complex. Effectively tuning application performance for these machines therefore becomes a daunting task. Moreover, identifying performance bottlenecks at application and architecture level, as well as evaluating various optimization strategies, are becoming extremely difficult when the entanglement of numerous correlated factors is being presented. To tackle these challenges, we present a visual analytical model named “X”. It is intuitive and sufficiently flexible to track all the typical features of a parallel machine.
An analytic model for flow reversal in divertor plasmas
International Nuclear Information System (INIS)
An analytic model is developed and used to study the phenomenon of flow reversal which is observed in two-dimensional simulations of divertor plasmas. The effect is shown to be caused by the radial spread of neutral particles emitted from the divertor target which can lead to a strong peaking of the ionization source at certain radial locations. The results indicate that flow reversal over a portion of the width of the scrape-off layer is inevitable in high recycling conditions. Implications for impurity transport and particle removal in reactors are discussed
Analytical Solution of The Two-Qubit Quantum Rabi Model
Abo-Kahla, Doaa A M; Abdel-Aty, Mahmoud
2015-01-01
In this paper, an analytical solution of the two-qubit Rabi model for the general case is presented. Furthermore, a comparison between the information entropies and the Von Neumann entropy $(\\rho_{A})$ is given for some special values of the qubit-photon coupling constants in case of the detuning parameters. It is demonstrated that oscillations of the occupation probabilities $\\rho_{11}, \\rho_{22}, \\rho_{33}$ and $\\rho_{44}$ are equivalent to the case of the spontaneous emission. The occupation probability $\\rho_{11}$ reaches the case of sudden death, when the detuning parameters $\\Delta_{2}$ equals zero.
Analytical performance models for geologic repositories. Volume 1
International Nuclear Information System (INIS)
This report presents analytical solutions of the dissolution and hydrogeologic transport of radionuclides in geologic repositories. Numerical examples are presented to demonstrate the equations resulting from these analyses. The subjects treated in this present report are: Solubility-limited transport with transverse dispersion (Chapter 2); Transport of a radionuclide chain with nonequilibrium chemical reactions (Chapter 3); Advective transport in a two-dimensional flow field (Chapter 4); Radionuclide transport in fractured media (Chapter 5); A mathematical model for EPA's analysis of generic repositories (Chapter 6); and Dissolution of radionuclides from solid waste (Chapter 7)
An analytical model of accretion onto white dwarfs
Ospina, N.; Hernanz, M.
2013-05-01
The analytical model of Frank et al. (2002) has been used to investigate the structure of the accretion stream onto white dwarfs (WD). In particular, the post-shock region (temperature, density and gas velocity distributions) and X-ray spectrum emitted by this region. We have obtained the temperature, density and gas velocity distributions of the emission region for different masses of white dwarfs and at different positions in the shock coordinate. Also, we calculated the emitted spectrum for different WD masses and at different positions of the shock with the principal objective of study the accretion at different points of the emission region.
Approximate analytical solutions of the baby Skyrme model
Ioannidou, T A; Zakrzewski, W J
2002-01-01
In present paper we show that many properties of the baby skyrmions, which have been determined numerically, can be understood in terms of an analytic approximation. In particular, we show that this approximation captures properties of the multiskyrmion solutions (derived numerically) such as their stability towards decay into various channels, and that it is more accurate for the "new baby Skyrme model" which describes anisotropic physical systems in terms of multiskyrmion fields with axial symmetry. Some universal characteristics of configurations of this kind are demonstrated, which do not depend on their topological number.
Numerical and Analytical Modelling of Galaxy Formation and Evolution
Frenk, C S; Cole, S; Lacey, C
1996-01-01
We review recent developments in theoretical studies of galaxy formation and evolution. In combination with new data from HST, Keck and other large telescopes, numerical and semi-analytic modelling is beginning to build up a coherent picture of galaxy formation. We summarize the current status of modelling of various galactic properties such as the structure of dark matter halos, the galaxy luminosity function, the Tully-Fisher relation, the colour-magnitude relation for ellipticals, the gross morphological properties of galaxies and the counts of faint galaxies as a function of magnitude, redshift and morphology. Many of these properties can be explained, at least at some level, within a broad class of CDM cosmologies, but a number of fundamental issues remain unresolved. We use our semi-analytic model of galaxy formation to interpret the evolutionary status of the Lyman-break galaxies at $z\\simeq 3-3.5$ recently discovered by Steidel et al. The abundance and global properties of these objects are compatible...
Analytic solution of Hubbell's model of local community dynamics
McKane, A; Sole, R; Kane, Alan Mc; Alonso, David; Sole, Ricard
2003-01-01
Recent theoretical approaches to community structure and dynamics reveal that many large-scale features of community structure (such as species-rank distributions and species-area relations) can be explained by a so-called neutral model. Using this approach, species are taken to be equivalent and trophic relations are not taken into account explicitly. Here we provide a general analytic solution to the local community model of Hubbell's neutral theory of biodiversity by recasting it as an urn model i.e.a Markovian description of states and their transitions. Both stationary and time-dependent distributions are analysed. The stationary distribution -- also called the zero-sum multinomial -- is given in closed form. An approximate form for the time-dependence is obtained by using an expansion of the master equation. The temporal evolution of the approximate distribution is shown to be a good representation for the true temporal evolution for a large range of parameter values.
Analytical modeling of sandwich beam for piezoelectric bender elements
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Piezoelectric bender elements are widely used as electromechanical sensors and actuators. An analytical sandwich beam model for piezoelectric bender elements was developed based on the first-order shear deformation theory (FSDT), which assumes a single rotation angle for the whole cross-section and a quadratic distribution function for coupled electric potential in piezoelectric layers, and corrects the effect of transverse shear strain on the electric displacement integration. Free vibration analysis of simplysupported bender elements was carried out and the numerical results showed that, solutions of the present model for various thickness-to-length ratios are compared well with the exact two-dimensional solutions, which presents an efficient and accurate model for analyzing dynamic electromechanical responses of bender elements.
Analytical Model of Symmetric Halo Doped DG-Tunnel FET
Directory of Open Access Journals (Sweden)
S. Nagarajan
2015-11-01
Full Text Available Two-dimensional analytical model of symmetric halo doped double gate tunnel field effect transistor has been presented in this work. This model is developed based on the 2-D Poisson’s equation. Some important parameters such that surface potential, vertical and lateral electric field, electric field intensity and band energy have been modelled. The doping concentration and length of halo regions are varied and dependency of various parameters is studied. The halo doping is imparted to improve the ON current and to reduce the intrinsic ambipolarity of the device. Hence we can achieve improved ION/IOFF ratio. The scaling property of halo doped structure is analyzed with various dielectric constants.
Modelling of packet traffic with matrix analytic methods
DEFF Research Database (Denmark)
Andersen, Allan T.
1995-01-01
The dissertation is concerned with modelling various performance aspects pertaining to packet switched telecommunication networks. The emphsis has been put on versatile modelling of the packet arrival process which is a very relevant issue in cotext with the future Broadband Integrated Service Data...... network services i.e. 800 and 900 calls and advanced mobile communication services. The Markovian Arrival Process (MAP) has been used as a versatile tool to model the packet arrival process. Applying the MAP facilitates the use of Matrix Analytic methods to obtain performance measures associated with for...... example the single server queue with a MAP arrival process and a general service time distribution. Measured SS7 traffic data has been analyzed as a part of this study. Recently there has been expressed concern regarding adverse behaviour of measured SS7 traffic i.e. long range dependence. Our studies did...
Model Mismatch Paradigm for Probe based Nanoscale Imaging
Agarwal, Pranav
Scanning Probe Microscopes (SPMs) are widely used for investigation of material properties and manipulation of matter at the nanoscale. These instruments are considered critical enablers of nanotechnology by providing the only technique for direct observation of dynamics at the nanoscale and affecting it with sub Angstrom resolution. Current SPMs are limited by low throughput and lack of quantitative measurements of material properties. Various applications like the high density data storage, sub-20 nm lithography, fault detection and functional probing of semiconductor circuits, direct observation of dynamical processes involved in biological samples viz. motor proteins and transport phenomena in various materials demand high throughput operation. Researchers involved in material characterization at nanoscale are interested in getting quantitative measurements of stiffness and dissipative properties of various materials in a least invasive manner. In this thesis, system theoretic concepts are used to address these limitations. The central tenet of the thesis is to model, the known information about the system and then focus on perturbations of these known dynamics or model, to sense the effects due to changes in the environment such as changes in material properties or surface topography. Thus a model mismatch paradigm for probe based nanoscale imaging is developed. The topic is developed by presenting physics based modeling of a particular mode of operation of SPMs called the dynamic mode operation. This mode is modeled as a forced Lure system where a linear time invariant system is in feedback with an unknown static memoryless nonlinearity. Tools from averaging theory are used to tame this complex nonlinear system by approximating it as a linear system with time varying parameters. Material properties are thus transformed from being parameters of unknown nonlinear functions to being unknown coefficients of a linear plant. The first contribution of this thesis
An analytical model for soil-atmosphere feedback
Directory of Open Access Journals (Sweden)
B. Schaefli
2012-07-01
Full Text Available Soil-atmosphere feedback is a key for understanding the hydrological cycle and the direction of potential system changes. This paper presents an analytical framework to study the interplay between soil and atmospheric moisture, using as input only the boundary conditions at the upstream end of trajectory, assuming advective moisture transport with average wind speed along this trajectory and vertical moisture exchange with the soil compartment of uniform vertical properties. Precipitation, evaporation from interception and runoff are assumed to depend through simple functional relationships on the soil moisture or the atmospheric moisture. Evaporation from soil moisture (including transpiration depends on both state variables, which introduces a nonlinear relationship between the two compartments. This nonlinear relationship can explain some apparently paradoxical phenomena such as a local decrease of precipitation accompanied by a runoff increase.
The solutions of the resulting water balance equations correspond to two different spatial moisture regimes showing either an increasing or a decreasing atmospheric moisture content along a trajectory starting at the coast, depending on boundary conditions and parameters. The paper discusses how different model parameters (e.g. time scales of precipitation, evaporation or runoff influence these regimes and how they can create regime switches. Such an analysis has potential to anticipate the range of possible land use and climate changes or to interpret the results of complex land-atmosphere interaction models. Based on derived analytical expressions for the Horton index, the Budyko curve and a precipitation recycling ratio, the analytical framework opens new perspectives for the classification of hydrological systems.
An analytical model for soil-atmosphere feedback
Directory of Open Access Journals (Sweden)
B. Schaefli
2011-09-01
Full Text Available Soil-atmosphere feedback is a key for understanding the hydrological cycle and the direction of potential system changes. This paper presents an analytical framework to study the interplay between soil and atmospheric moisture, using as input only the boundary conditions at the upstream end of an atmospheric moisture stream line. The underlying Eulerian-Langrangean approach assumes advective moisture transport with average wind speed along the stream line and vertical moisture exchange with the soil compartment of uniform vertical properties. Precipitation, evaporation from interception and runoff are assumed to depend through simple functional relationships on the soil moisture or the atmospheric moisture. Evaporation from soil moisture (including transpiration depends on both state variables, which introduces a nonlinear relationship between the two compartments. This nonlinear relationship can explain some apparently paradoxical phenomena such as a local decrease of precipitation accompanied by a runoff increase.
The solutions of the resulting water balance equations correspond to two different moisture regimes along a stream line, either monotonically increasing or decreasing when traveling inland, depending on boundary conditions and parameters. The paper discusses how different model parameters (e.g. time scales of precipitation, evaporation or runoff influence these regimes and how they can create regime switches. Such an analysis has potential to anticipate the range of possible land use and climate changes or to interpret the results of complex land-atmosphere interaction models. Based on derived analytical expressions for the Horton index, the Budyko curve and a precipitation recycling ratio, the analytical framework opens new perspectives for the classification of hydrological systems.
Analytical models for a small LFR core dynamics studies
International Nuclear Information System (INIS)
Highlights: ► An analytical model for the study of a small LFR core dynamics is developed. ► A benchmark with the SAS4A/SASSYS-1 Code System is performed for validation. ► Transient responses to UTOP, ULOHS, ULOF accidents and to a SCRAM are investigated. ► The effect of the model linearization and the 1-group approximation is evaluated. ► The system stability is confirmed by analyses performed with the linear analysis tools. - Abstract: Analytical models for the study of a small Lead-cooled Fast Reactor (LFR) demonstrator (DEMO) core dynamics, in a control-oriented perspective, have been developed aimed at providing a useful, very flexible and straightforward tool allowing relatively quick transient design-basis and stability analyses. A simplified approach has been developed consisting in a lumped-parameter modeling of the coupled neutronics and thermal-hydraulics. The reactor transient responses following both postulated accident initiators such as Unprotected Transient of OverPower (UTOP), Loss of Heat Sink (ULOHS) and Loss of Flow (ULOF), and an emergency SCRAM event have been studied in MATLAB/SIMULINK® environment. A benchmark analysis has been then performed by means of the SAS4A/SASSYS-1 Liquid Metal Reactor Code System with the purpose of providing verification for the analytical outcomes of the nonlinear model and indicating how the latter relate to more realistic one-dimensional calculations. As a general result, responses concerning the main core characteristics (namely, power, reactivity, etc.) have turned out to be mutually consistent in terms of both steady-state absolute figures and transient developments, showing discrepancies of the order of only few per cents. DEMO dynamic behavior has been studied through a linear approach as well, so as to enable the use of linear analysis tools allowing to verify the system stability, thanks to the possibility of expressing a physical model in terms of transfer functions or state
A Simplified Analytical Modeling of the Hole Erosion Test
Directory of Open Access Journals (Sweden)
Mohammed Bezzazi
2010-01-01
Full Text Available Problem statement: Internal erosion occurs in soils containing fine particles under the action of high pressure gradients that could result from water discharge. This phenomenon can yield in its final stage to the formation of piping which constitutes a real threat for hydraulics infrastructures as it can precipitate their entire rupture in very short time. In order to mitigate this insidious hazard, it is important to characterize piping dynamics. In this context, the Hole Erosion Test was introduced to assess the erosive features of soils by means of two parameters, the erosion rate and the critical shear stress indicating the beginning of erosion. Modeling this test can enable to understand more comprehensibly the piping phenomenology. Approach: A simplified analytical modeling of the Hole Erosion Test was considered in this study. A closed form solution of erosion taking place during piping was derived without resorting to the habitual cumbersome developments that are needed to achieve complete solution of the rational equations describing this highly coupled problem. This was achieved by assuming formal analogy between the erosive shear stress and the friction shear that develops at a cylindrical piping wall under an axial viscous flow. The flow was assumed to be uniform along the tube. Results: A closed form analytical formula describing erosion dynamics associated to piping was derived. Theoretical predictions were compared with experimental results and the simplified model was found to predict accurately the increase of flow rate that results from piping erosion. Conclusion/Recommendations: The one-dimensional modeling that was proposed for the Hole Erosion Test under strong simplifying assumptions was found to yield the same features as those obtained in the literature by using other approaches. It gives furthermore the dynamics as function of the fluid regime existing inside the tube. In order to get further insight
An analytically tractable model for community ecology with many species
Dickens, Benjamin; Fisher, Charles; Mehta, Pankaj; Pankaj Mehta Biophysics Theory Group Team
A fundamental problem in community ecology is to understand how ecological processes such as selection, drift, and immigration yield observed patterns in species composition and diversity. Here, we present an analytically tractable, presence-absence (PA) model for community assembly and use it to ask how ecological traits such as the strength of competition, diversity in competition, and stochasticity affect species composition in a community. In our PA model, we treat species as stochastic binary variables that can either be present or absent in a community: species can immigrate into the community from a regional species pool and can go extinct due to competition and stochasticity. Despite its simplicity, the PA model reproduces the qualitative features of more complicated models of community assembly. In agreement with recent work on large, competitive Lotka-Volterra systems, the PA model exhibits distinct ecological behaviors organized around a special (``critical'') point corresponding to Hubbell's neutral theory of biodiversity. Our results suggest that the concepts of ``phases'' and phase diagrams can provide a powerful framework for thinking about community ecology and that the PA model captures the essential ecological dynamics of community assembly. Pm was supported by a Simons Investigator in the Mathematical Modeling of Living Systems and a Sloan Research Fellowship.
A physically based analytical spatial air temperature and humidity model
Yang, Yang; Endreny, Theodore A.; Nowak, David J.
2013-09-01
Spatial variation of urban surface air temperature and humidity influences human thermal comfort, the settling rate of atmospheric pollutants, and plant physiology and growth. Given the lack of observations, we developed a Physically based Analytical Spatial Air Temperature and Humidity (PASATH) model. The PASATH model calculates spatial solar radiation and heat storage based on semiempirical functions and generates spatially distributed estimates based on inputs of topography, land cover, and the weather data measured at a reference site. The model assumes that for all grids under the same mesoscale climate, grid air temperature and humidity are modified by local variation in absorbed solar radiation and the partitioning of sensible and latent heat. The model uses a reference grid site for time series meteorological data and the air temperature and humidity of any other grid can be obtained by solving the heat flux network equations. PASATH was coupled with the USDA iTree-Hydro water balance model to obtain evapotranspiration terms and run from 20 to 29 August 2010 at a 360 m by 360 m grid scale and hourly time step across a 285 km2 watershed including the urban area of Syracuse, NY. PASATH predictions were tested at nine urban weather stations representing variability in urban topography and land cover. The PASATH model predictive efficiency R2 ranged from 0.81 to 0.99 for air temperature and 0.77 to 0.97 for dew point temperature. PASATH is expected to have broad applications on environmental and ecological models.
Analytic Models of Brown Dwarfs and The Substellar Mass Limit
Auddy, Sayantan; Valluri, S R
2016-01-01
We present the current status of the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main sequence stars. In the spirit of a simplified analytic theory we also introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal non-relativistic Fermi gas at a finite temperature, therefore allowing for non-zero values of the degeneracy parameter ($\\psi = \\frac{kT}{\\mu_{F}}$, where $\\mu_{F}$ is the Fermi energy). We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially-ionized hydrogen in the inner region. We also discuss the results of modern simulations of the plasma phase transition, which illustrate the uncertainties in determining its critical temperature. Based on the existing models and with some simple modification we find the maximum mass for a brown dwarf to be in the range $0.064M_\\odot...
Predictability in Semi-Analytic Models of Galaxy Formation
Forero-Romero, Jaime E
2008-01-01
We propose a general framework to scrutinize the performance of semi-analytic codes of galaxy formation. The approach is based on the analysis of the outputs from the model after a series of perturbations in the input parameters controlling the baryonic physics. The perturbations are chosen in a way that they do not change the results in the luminosity function or mass function of the galaxy population. We apply this approach on a particular semi-analytic model called GalICS. We chose to perturb the parameters controlling the efficiency of star formation and the efficiency of supernova feedback. We keep track of the baryonic and observable properties of the central galaxies in a sample of dark matter halos with masses ranging from 10^{10} M_sol to 10^{13} M_sol. We find very different responses depending on the halo mass. For small dark matter halos its central galaxy responds in a highly predictable way to small perturbation in the star formation and feedback efficiency. For massive dark matter halos, minor ...
Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter
Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos
2015-11-01
This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.
Applying generalized Pad\\'e approximants in analytic QCD models
Cvetič, Gorazd
2011-01-01
A method of resummation of truncated perturbation series, related to diagonal Pad\\'e approximants but giving results exactly independent of the renormalization scale, was developed more than ten years ago by us with a view of applying it in perturbative QCD. We now apply this method in analytic QCD models, i.e., models where the running coupling has no unphysical singularities, and we show that the method has attractive features such as a rapid convergence. The method can be regarded as a generalization of the scale-setting methods of Stevenson, Grunberg, and Brodsky-Lepage-Mackenzie. The method involves the fixing of various scales and weight coefficients via an auxiliary construction of diagonal Pad\\'e approximant. In low-energy QCD observables, some of these scales become sometimes low at high order, which prevents the method from being effective in perturbative QCD where the coupling has unphysical singularities at low spacelike momenta. There are no such problems in analytic QCD.
Streaming instability of slime mold amoebae: An analytical model
Höfer, Thomas; Maini, Philip K.
1997-08-01
During the aggregation of amoebae of the cellular slime mould Dictyostelium, the interaction of chemical waves of the signaling molecule cAMP with cAMP-directed cell movement causes the breakup of a uniform cell layer into branching patterns of cell streams. Recent numerical and experimental investigations emphasize the pivotal role of the cell-density dependence of the chemical wave speed for the occurrence of the streaming instability. A simple, analytically tractable, model of Dictyostelium aggregation is developed to test this idea. The interaction of cAMP waves with cAMP-directed cell movement is studied in the form of coupled dynamics of wave front geometries and cell density. Comparing the resulting explicit instability criterion and dispersion relation for cell streaming with the previous findings of model simulations and numerical stability analyses, a unifying interpretation of the streaming instability as a cAMP wave-driven chemotactic instability is proposed.
Strong field coherent control of molecular torsions--Analytical models.
Ashwell, Benjamin A; Ramakrishna, S; Seideman, Tamar
2015-08-14
We introduce analytical models of torsional alignment by moderately intense laser pulses that are applicable to the limiting cases of the torsional barrier heights. Using these models, we explore in detail the role that the laser intensity and pulse duration play in coherent torsional dynamics, addressing both experimental and theoretical concerns. Our results suggest strategies for minimizing the risk of off-resonant ionization, noting the qualitative differences between the case of torsional alignment subject to a field-free torsional barrier and that of torsional alignment of a barrier-less system (equivalent to a 2D rigid rotor). We also investigate several interesting torsional phenomena, including the onset of impulsive alignment of torsions, field-driven oscillations in quantum number space, and the disappearance of an alignment upper bound observed for a rigid rotor in the impulsive torsional alignment limit. PMID:26277138
Strong field coherent control of molecular torsions—Analytical models
Energy Technology Data Exchange (ETDEWEB)
Ashwell, Benjamin A.; Ramakrishna, S.; Seideman, Tamar, E-mail: t-seideman@northwestern.edu [Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)
2015-08-14
We introduce analytical models of torsional alignment by moderately intense laser pulses that are applicable to the limiting cases of the torsional barrier heights. Using these models, we explore in detail the role that the laser intensity and pulse duration play in coherent torsional dynamics, addressing both experimental and theoretical concerns. Our results suggest strategies for minimizing the risk of off-resonant ionization, noting the qualitative differences between the case of torsional alignment subject to a field-free torsional barrier and that of torsional alignment of a barrier-less system (equivalent to a 2D rigid rotor). We also investigate several interesting torsional phenomena, including the onset of impulsive alignment of torsions, field-driven oscillations in quantum number space, and the disappearance of an alignment upper bound observed for a rigid rotor in the impulsive torsional alignment limit.
Strong field coherent control of molecular torsions—Analytical models
International Nuclear Information System (INIS)
We introduce analytical models of torsional alignment by moderately intense laser pulses that are applicable to the limiting cases of the torsional barrier heights. Using these models, we explore in detail the role that the laser intensity and pulse duration play in coherent torsional dynamics, addressing both experimental and theoretical concerns. Our results suggest strategies for minimizing the risk of off-resonant ionization, noting the qualitative differences between the case of torsional alignment subject to a field-free torsional barrier and that of torsional alignment of a barrier-less system (equivalent to a 2D rigid rotor). We also investigate several interesting torsional phenomena, including the onset of impulsive alignment of torsions, field-driven oscillations in quantum number space, and the disappearance of an alignment upper bound observed for a rigid rotor in the impulsive torsional alignment limit
An analytical model for pyrolysis of a single biomass particle
Institute of Scientific and Technical Information of China (English)
Mehdi Bidabadi; Mohammad Rastegar Moghaddam; Seyed Alireza Mostafavi; Farzad Faraji Dizaji; Hossein Beidaghy Dizaji
2015-01-01
Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers’ works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.
Leśniewska, Barbara; Kisielewska, Katarzyna; Wiater, Józefa; Godlewska-Żyłkiewicz, Beata
2015-01-01
A new fast method for determination of mobile zinc fractions in soil is proposed in this work. The three-stage modified BCR procedure used for fractionation of zinc in soil was accelerated by using ultrasounds. The working parameters of an ultrasound probe, a power and a time of sonication, were optimized in order to acquire the content of analyte in soil extracts obtained by ultrasound-assisted sequential extraction (USE) consistent with that obtained by conventional modified Community Burea...
An analytic model for the galactic winds and mass outflows
Shu, C; Mao, S; Shu, Chenggang; Mao, Shude
2003-01-01
Galactic winds and mass outflows are observed both in nearby starburst galaxies and in high-redshift star-forming galaxies. In this paper we develop a simple analytic model to understand the observed superwind phenomenon. Our model is built upon the model of McKee & Ostriker (1977) for the interstellar medium. It allows one to predict how properties of a superwind, such as wind velocity and mass outflow rate, are related to properties of its star-forming host galaxy, such as size, gas density and star formation rate. The model predicts a threshold of star formation rate density for the generation of observable galactic winds. Galaxies with more concentrated star formation produce superwinds with higher velocities. The predicted mass outflow rates are comparable to (or slightly larger than) the corresponding star formation rates. We apply our model to both local starburst galaxies and high-redshift Lyman break galaxies, and find its predictions to be in good agreement with current observations. Our model i...
An analytical model for a pulsed neutron gauge
International Nuclear Information System (INIS)
An analytical model for pulsed-neutron borehole gauges is developed. It takes into account the decrease of the γ-flux due both to thermal neutron absorption and to the movement of the neutrons away from the source. The model is one-dimensional, i.e. the effect of the borehole is not included. The fast neutrons are treated by use of Fermi-age theory, the thermal neutrons by use of diffusion theory. In the present version of the model the γ-detector is assumed to be very close to the pulsed source. The contribution of the scattered capture-γ-quanta to the γ-flux at the γ-detector is calculated by use of build-up factors. Numerical examples of the use of the model are presented. The model is compared with the usual, simplified model which assumes an exponential decay of the γ-detector count-rate. Formulas for the neutron slowing-down time and the thermal neutron lifetime are also presented together with numerical values of these lifetimes for various media of geological relevance. (author)
Low Energy Probes of Physics Beyond the Standard Model
Cirigliano, Vincenzo; Ramsey-Musolf, Michael J.
2013-01-01
Low-energy tests of fundamental symmetries and studies of neutrino properties provide a powerful window on physics beyond the Standard Model (BSM). In this article, we provide a basic theoretical framework for a subsequent set of articles that review the progress and opportunities in various aspects of the low-energy program. We illustrate the physics reach of different low-energy probes in terms of an effective BSM mass scale and illustrate how this reach matches and, in some cases, even exc...
Probing Beyond Standard Model via Hawking Radiated Gravitational Waves
Fujita, Tomohiro
2014-01-01
We propose a novel technique to probe the beyond standard model (BSM) of particle physics. The mass spectrum of unknown BSM particles can be scanned by observing gravitational waves (GWs) emitted by Hawking radiation of black holes. This is because information on the radiation of the BSM particles is imprinted in the spectrum of the GWs. We fully calculate the GW spectrum from evaporating black holes taking into account the greybody factor. As an observationally interesting application, we consider primordial black holes which evaporate in the very early universe. In that case, since the frequencies of GWs are substantially redshifted, the GWs emitted with the BSM energy scales become accessible by observations.
A hidden analytic structure of the Rabi model
International Nuclear Information System (INIS)
The Rabi model describes the simplest interaction between a cavity mode with a frequency ωc and a two-level system with a resonance frequency ω0. It is shown here that the spectrum of the Rabi model coincides with the support of the discrete Stieltjes integral measure in the orthogonality relations of recently introduced orthogonal polynomials. The exactly solvable limit of the Rabi model corresponding to Δ=ω0/(2ωc)=0, which describes a displaced harmonic oscillator, is characterized by the discrete Charlier polynomials in normalized energy ϵ, which are orthogonal on an equidistant lattice. A non-zero value of Δ leads to non-classical discrete orthogonal polynomials ϕk(ϵ) and induces a deformation of the underlying equidistant lattice. The results provide a basis for a novel analytic method of solving the Rabi model. The number of ca. 1350 calculable energy levels per parity subspace obtained in double precision (cca 16 digits) by an elementary stepping algorithm is up to two orders of magnitude higher than is possible to obtain by Braak’s solution. Any first n eigenvalues of the Rabi model arranged in increasing order can be determined as zeros of ϕN(ϵ) of at least the degree N=n+nt. The value of nt>0, which is slowly increasing with n, depends on the required precision. For instance, nt≃26 for n=1000 and dimensionless interaction constant κ=0.2, if double precision is required. Given that the sequence of the lth zeros xnl’s of ϕn(ϵ)’s defines a monotonically decreasing discrete flow with increasing n, the Rabi model is indistinguishable from an algebraically solvable model in any finite precision. Although we can rigorously prove our results only for dimensionless interaction constant κ<1, numerics and exactly solvable example suggest that the main conclusions remain to be valid also for κ≥1. -- Highlights: •A significantly simplified analytic solution of the Rabi model. •The spectrum is the lattice of discrete orthogonal polynomials
Analytical model of peptide mass cluster centres with applications
Directory of Open Access Journals (Sweden)
Lehrach Hans
2006-09-01
Full Text Available Abstract Background The elemental composition of peptides results in formation of distinct, equidistantly spaced clusters across the mass range. The property of peptide mass clustering is used to calibrate peptide mass lists, to identify and remove non-peptide peaks and for data reduction. Results We developed an analytical model of the peptide mass cluster centres. Inputs to the model included, the amino acid frequencies in the sequence database, the average length of the proteins in the database, the cleavage specificity of the proteolytic enzyme used and the cleavage probability. We examined the accuracy of our model by comparing it with the model based on an in silico sequence database digest. To identify the crucial parameters we analysed how the cluster centre location depends on the inputs. The distance to the nearest cluster was used to calibrate mass spectrometric peptide peak-lists and to identify non-peptide peaks. Conclusion The model introduced here enables us to predict the location of the peptide mass cluster centres. It explains how the location of the cluster centres depends on the input parameters. Fast and efficient calibration and filtering of non-peptide peaks is achieved by a distance measure suggested by Wool and Smilansky.
Hydrogeologic role of geologic structures. Part 2: analytical models
Levens, Russell L.; Williams, Roy E.; Ralston, Dale R.
1994-04-01
This paper is the second of two papers that address the influence of geologic structures on ground water flow at various scales in fractured rocks. The ultimate purpose of this research is to investigate the feasibility of grouting preferentially permeable zones as a strategy to minimize the production of acid mine drainage in underground hard rock mines in which the major permeability is structure and fracture controlled. The aim of grouting is to reduce permeability around mined-out openings, to minimize the rate of inflow of ground water into such openings via the structurally controlled preferentially permeable pathways. A series of hydraulic stress tests were conducted to help characterize the role of geologic structures in controlling the ground water flow system in the vicinity of the Bunker Hill Mine in north Idaho. The results of these tests indicate that most of the ground water that flows from the underground drillholes used for hydraulic stress testing is derived from a few discrete, structurally produced fracture zones that are more or less connected through smaller-scale fractures. Four types of analytical models are considered as a means of analyzing the results of multiple drillhole hydraulic stress tests, as follows: cross-hole equivalent porous media; double-porosity equivalent porous media; a solution to flow in and around a single vertical fracture; leaky equivalent porous media, partial penetration. The estimation of hydraulic coefficients in complex fractured rock environments involves the combined application of a number of deterministic analytical models. The models to be used are selected dependent on the location of the drawdown observations relative to the water-producing zone and the length of the test. The result of the tests can be related to the permeability hierarchy discussed in our first paper.
Analytic model and frequency characteristics of plasma synthetic jet actuator
Zong, Hao-hua; Wu, Yun; Li, Ying-hong; Song, Hui-min; Zhang, Zhi-bo; Jia, Min
2015-02-01
This paper reports a novel analytic model of a plasma synthetic jet actuator (PSJA), considering both the heat transfer effect and the inertia of the throat gas. Both the whole cycle characteristics and the repetitive working process of PSJA can be predicted with this model. The frequency characteristics of a PSJA with 87 mm3 volume and different orifice diameters are investigated based on the analytic model combined with experiments. In the repetitive working mode, the actuator works initially in the transitional stage with 20 cycles and then in the dynamic balanced stage. During the transitional stage, major performance parameters of PSJA experience stepped growth, while during the dynamic balanced stage, these parameters are characterized by periodic variation. With a constant discharge energy of 6.9 mJ, there exists a saturated frequency of 4 kHz/6 kHz for an orifice diameter of 1 mm/1.5 mm, at which the time-averaged total pressure of the pulsed jet reaches a maximum. Between 0.5 mm and 1.5 mm, a larger orifice diameter leads to a higher saturated frequency due to the reduced jet duration time. As the actuation frequency increases, both the time-averaged cavity temperature and the peak jet velocity initially increase and then remain almost unchanged at 1600 K and 280 m/s, respectively. Besides, with increasing frequency, the mechanical energy incorporated in single pulsed jet, the expelled mass per pulse, and the time-averaged density in the cavity, decline in a stair stepping way, which is caused by the intermittent decrease of refresh stage duration in one period.
Probing models of quantum decoherence in particle physics and cosmology
International Nuclear Information System (INIS)
In this review we discuss the string theoretical motivations for induced decoherence and deviations from ordinary quantum-mechanical behaviour; this leads to intrinsic CPT violation in the context of an extended class of quantum-gravity models. We proceed to a description of precision tests of CPT symmetry and quantum mechanics using mainly neutral kaons and neutrinos. We emphasize the possibly unique role of neutral meson factories in providing tests of models where the quantum-mechanical CPT operator is not well-defined, leading to modifications of Einstein-Podolsky-Rosen particle correlators. Finally, we discuss experimental probes of decoherence in cosmology, including studies of dissipative relaxation models of dark energy in non-critical (non-equilibrium) string theory and the associated modifications of the Boltzmann equation for the evolution of species abundances
MATHEMATICAL MODELING OF A DISTANCE DEPENDENCE OF A SCANNING KELVIN PROBE LATERAL RESOLUTION
Tyavlovsky, A. K.
2015-01-01
A mathematical model of cylindrical shaped plane-ended scanning Kelvin probe output signal is proposed considering the case of an infinite plane sample's surface with local defects represented by dot charges. Modeling results were obtained for the case of two closely situated dot charges anddifferent combinations of scanning Kelvin probe tip's diameter and sample-to-probe gap. It was found that the most effective way to improve the lateral resolution of a scanning Kelvin probe is to reduce th...
Analytic model for the bispectrum of galaxies in redshift space
International Nuclear Information System (INIS)
We develop an analytic theory for the redshift space bispectrum of dark matter, haloes, and galaxies. This is done within the context of the halo model of structure formation, as this allows for the self-consistent inclusion of linear and nonlinear redshift-space distortions and also for the nonlinearity of the halo bias. The model is applicable over a wide range of scales: on the largest scales the predictions reduce to those of the standard perturbation theory (PT); on smaller scales they are determined primarily by the nonlinear virial velocities of galaxies within haloes, and this gives rise to the U-shaped anisotropy in the reduced bispectrum--a finger print of the Finger-Of-God distortions. We then confront the predictions with measurements of the redshift-space bispectrum of dark matter from an ensemble of numerical simulations. On very large scales, k=0.05h Mpc-1, we find reasonably good agreement between our halo model, PT and the data, to within the errors. On smaller scales, k=0.1h Mpc-1, the measured bispectra differ from the PT at the level of ∼10%-20%, especially for colinear triangle configurations. The halo model predictions improve over PT, but are accurate to no better than 10%. On smaller scales k=0.5-1.0h Mpc-1, our model provides a significant improvement over PT, which breaks down. This implies that studies which use the lowest order PT to extract galaxy bias information are not robust on scales k > or approx. 0.1h Mpc-1. The analytic and simulation results also indicate that there is no observable scale for which the configuration dependence of the reduced bispectrum is constant--hierarchical models for the higher-order correlation functions in redshift space are unlikely to be useful. It is hoped that our model will facilitate extraction of information from large-scale structure surveys of the Universe, because different galaxy populations are naturally included into our description.
Analytical model for CO(2) laser ablation of fused quartz.
Nowak, Krzysztof M; Baker, Howard J; Hall, Denis R
2015-10-10
This paper reports the development of an analytical model, with supporting experimental data, which quite accurately describes the key features of CO2 laser ablation of fused silica glass. The quantitative model of nonexplosive, evaporative material removal is shown to match the experimental data very well, to the extent that it can be used as a tool for ablative measurements of absorption coefficient and vaporization energy. The experimental results indicated that a minimum of 12 MJ kg-1 is required to fully vaporize fused quartz initially held at room temperature, which is in good agreement with the prediction of the model supplied with input data available in the literature. An optimal window for the machining of fused quartz was revealed in terms of pulse duration 20-80 μs and CO2 laser wavelength optimized for maximum absorption coefficient. Material removal rates of 0.33 μm per J cm-2 allow for a high-precision depth control with modest laser stability. The model may also be used as a parameter selection guide for CO2 laser ablation of fused silica or other materials of similar thermophysical properties. PMID:26479800
A semi-analytic dynamical friction model for cored galaxies
Petts, James A; Gualandris, Alessia
2016-01-01
We present a dynamical friction model based on Chandrasekhar's formula that reproduces the fast inspiral and stalling experienced by satellites orbiting galaxies with a large constant density core. We show that the fast inspiral phase does not owe to resonance. Rather, it owes to the background velocity distribution function for the constant density cores being dissimilar from the usually-assumed Maxwellian distribution. Using the correct background velocity distribution function and the semi-analytic model from Petts et al. (2015), we are able to correctly reproduce the infall rate in both cored and cusped potentials. However, in the case of large cores, our model is no longer able to correctly capture core-stalling. We show that this stalling owes to the tidal radius of the satellite approaching the size of the core. By switching off dynamical friction when rt(r) = r (where rt is the tidal radius at the satellite's position) we arrive at a model which reproduces the N-body results remarkably well. Since the...
Analytic Solutions of Three-Level Dressed-Atom Model
Institute of Scientific and Technical Information of China (English)
WANG Zheng-Ling; YIN Jian-Ping
2004-01-01
On the basis of the dressed-atom model, the general analytic expressions for the eigenenergies, eigenstates and their optical potentials of the A-configuration three-level atom system are derived and analysed. From the calculation of dipole matrix element of different dressed states, we obtain the spontaneous-emission rates in the dressed-atom picture. We find that our general expressions of optical potentials for the three-level dressed atom can be reduced to the same as ones in previous references under the approximation of a small saturation parameter. We also analyse the dependences of the optical potentials of a three-level 85Rb atom on the laser detuning and the dependences of spontaneous-emission rates on the radial position in the dark hollow beam, and discuss the probability (population) evolutions of dressed-atomic eigenstates in three levels in the hollow beam.
Analytical model of carbon dioxide emission with energy payback effect
International Nuclear Information System (INIS)
An analytical model is proposed to account for carbon emission behaviour during replacement of power source from fossil fuel to renewable energy in which sustainability of energy supply is stressed. Logistic function of time is assumed for producing renewable power sources. Analyses show that energy payback time (EPT) should be much shorter than the doubling time of manufacturing cycle to secure adequate available energy during, as well as after, the replacement. A nuclear plant, small hydropower plant, wind power plant and photovoltaic cell are taken as representative candidates and investigated as options to replace fossil power until toward the end of this century. Nuclear or small hydropower plants are promising candidates but the photovoltaic cell needs further development efforts to reduce EPT and avoid energy expense after the replacement. (author)
Analytical Deriving of the Field Capacity through Soil Bundle Model
Arnone, E.; Viola, F.; Antinoro, C.; Noto, L. V.
2015-12-01
The concept of field capacity as soil hydraulic parameter is widely used in many hydrological applications. Althought its recurring usage, its definition is not univocal. Traditionally, field capacity has been related to the amount of water that remains in the soil after the excess water has drained away and the water downward movement experiences a significant decresase. Quantifying the drainage of excess of water may be vague and several definitions, often subjective, have been proposed. These definitions are based on fixed thresholds either of time, pressure, or flux to which the field capacity condition is associated. The flux-based definition identifies the field capacity as the soil moisture value corresponding to an arbitrary fixed threshold of free drainage flux. Recently, many works have investigated the flux-based definition by varying either the drainage threshold, the geometry setting and mainly the description of the drainage flux. Most of these methods are based on the simulation of the flux through a porous medium by using the Darcy's law or Richard's equation. Using the above-mentioned flux-based definition, in this work we propose an alternative analytical approach for deriving the field capacity based on a bundle-of-tubes model. The pore space of a porous medium is conceptualized as a bundle of capillary tubes of given length of different radii, derived from a known distribution. The drainage from a single capillary tube is given by the analytical solution of the differential equation describing the water height evolution within the capillary tube. This equation is based on the Poiseuille's law and describes the drainage flux with time as a function of tube radius. The drainage process is then integrated for any portion of soil taking into account the tube radius distribution which in turns depends on the soil type. This methodology allows to analytically derive the dynamics of drainage water flux for any soil type and consequently to define the
Distributed-Channel Bipolar Device: Experimentation, Analytical Modeling and Applications.
Jiang, Fenglai
Experimental results and theoretical modeling for four terminal distributed channel bipolar devices (DCBD) are presented. The DCBD device is comprised of an interwoven BJT and MOSFET. The device may be characterized as a MOSFET with a bipolar transistor source distributed under the MOSFET channel. Alternatively, the device may be represented as a BJT where a MOSFET channel provides the current collection function. The physical layout of the device is that of a n-channel MOSFET placed above a p-Si epitaxial base region which was grown on an n^+-Si substrate emitter. Distributed electronic behavior exhibits itself through self-biasing influences of the channel-collected current on the channel-base junction bias. For appropriate biasing, the MOSFET channel divides itself into two regions exhibiting forward active and saturation BJT behavior. Both experimental results and theoretical modeling are provided. Experimental results for "large area" rectangular gate, circular gate and trapezoidal gate DCBD are reported. The experimental results exhibit the transconductance threshold voltage, beta fall off and transconductance fall-off features reported previously by others. A "large area" trapezoidal gate structure is incorporated to illustrate the gate area influences on the electrical characteristics and to provide a model sensitive structure for evaluating the validity of the theory developed in the dissertation. An analytical model based on conventional MOSFET and bipolar theories is developed. The analytical model is applied to the large gate area devices (example: 0.127 mm rectangular gate length) and smaller dimensional gate devices down to 0.9 micron rectangular gate length. The theoretical results show good agreement with the large gate area experimental results. Application examples are provided. The use of the base current invariant transconductance threshold voltage as a reference voltage is discussed. Comparison of the transconductance threshold voltage
Probing Minimal 5D Extensions of the Standard Model
Mück, A; Rückl, R; Mück, Alexander; Pilaftsis, Apostolos; R\\"uckl, Reinhold
2004-01-01
We analyze non-universal 5D standard model extension, where some or all of the gauge and Higgs fields propagate in a flat extra dimension, while all other degrees of freedom are localized on a S^1/Z_2 orbifold brane. From LEP data, model-dependent bounds on the compactification scale M between 4 and 6 TeV are derived. We analyze the correlations between M and the SM Higgs mass m_H. Investigating the prospects at an e^+e^- linear collider such as TESLA, we show that the so-called GigaZ option has the potential to improve the LEP bounds by about a factor 2. At the center of mass energy of 800 GeV and with an integrated luminosity of 10^3 fb^{-1}, linear collider experiments can probe compactification scales up to 20-30 TeV and beyond, depending on the systematic errors.
Bodzenta, J.; Chirtoc, M.; Juszczyk, J.
2014-08-01
The thermal model of a nanofabricated thermal probe (NTP) used in scanning thermal microscopy is proposed. It is based on consideration of the heat exchange channels between electrically heated probe, a sample, and their surroundings, in transient and harmonic regimes. Three zones in the probe-sample system were distinguished and modeled by using electrical analogies of heat flow through a chain of quadrupoles built from thermal resistances and thermal capacitances. The analytical transfer functions for two- and three-cell quadrupoles are derived. A reduced thermal quadrupole with merged RC elements allows for thermo-electrical modeling of the complex architecture of a NTP, with a minimum of independent parameters (two resistance ratios and two time constants). The validity of the model is examined by comparing computed values of discrete RC elements with results of finite element simulations and with experimental data. It is proved that the model consisting of two or three-cell quadrupole is sufficient for accurate interpretation of experimental results. The bandwidth of the NTP is limited to 10 kHz. The performance in dc regime can be simply obtained in the limit of zero frequency. One concludes that the low NTP sensitivity to sample thermal conductivity is due, much like in dc regime, to significant heat by-pass by conduction through the cantilever, and to the presence of probe-sample contact resistance in series with the sample.
GENERALIZED SEMI-ANALYTICAL MODELS OF SUPERNOVA LIGHT CURVES
International Nuclear Information System (INIS)
We present generalized supernova (SN) light curve (LC) models for a variety of power inputs including the previously proposed ideas of radioactive decay of 56Ni and 56Co and magnetar spin-down. We extend those solutions to include finite progenitor radius and stationary photospheres as might be the case for SN that are powered by interaction of the ejecta with circumstellar matter (CSM). We provide an expression for the power input that is produced by self-similar forward and reverse shocks that efficiently convert their kinetic energy into radiation. We find that this ejecta-CSM interaction luminosity that we derive is in agreement with results from multi-dimensional radiation hydrodynamics simulations in the case of an optically thin CSM. We develop a semi-analytical model for the case of an optically thick CSM by invoking an approximation for the effects of radiative diffusion similar to that adopted by Arnett for SN II and compare this model to the results of numerical radiation hydrodynamics models. This model can give complex LCs, but for monotonically declining shock input, the LCs have a smooth rise, peak, and decline. In the context of this model, we provide predictions of the shock breakout of the forward shock from the optically thick part of the CSM envelope. We also introduce a hybrid LC model that incorporates ejecta-CSM interaction plus 56Ni and 56Co radioactive decay input. We fit this hybrid model to the LC of the super-luminous supernova (SLSN) 2006gy. We find that shock heating produced by ejecta-CSM interaction plus some contribution from radioactive decay provides a better fit to the LC of this event than previously presented models. We also address the relation between SN IIL and SN IIn with ejecta-CSM interaction models. The faster decline of SN IIL can be reproduced by the diffusion of previously deposited shock power if the shock power input to the diffusive component vanishes when the reverse shock sweeps up the whole ejecta and/or the
Analysing an Analytical Solution Model for Simultaneous Mobility
Directory of Open Access Journals (Sweden)
Md. Ibrahim Chowdhury
2013-12-01
Full Text Available Current mobility models for simultaneous mobility h ave their convolution in designing simultaneous movement where mobile nodes (MNs travel randomly f rom the two adjacent cells at the same time and also have their complexity in the measurement of th e occurrences of simultaneous handover. Simultaneou s mobility problem incurs when two of the MNs start h andover approximately at the same time. As Simultaneous mobility is different for the other mo bility pattern, generally occurs less number of tim es in real time; we analyze that a simplified simultaneou s mobility model can be considered by taking only symmetric positions of MNs with random steps. In ad dition to that, we simulated the model using mSCTP and compare the simulation results in different sce narios with customized cell ranges. The analytical results shows that with the bigger the cell sizes, simultaneous handover with random steps occurrences become lees and for the sequential mobility (where initial positions of MNs is predetermined with ran dom steps, simultaneous handover is more frequent.
Machine learning and cosmological simulations - I. Semi-analytical models
Kamdar, Harshil M.; Turk, Matthew J.; Brunner, Robert J.
2016-01-01
We present a new exploratory framework to model galaxy formation and evolution in a hierarchical Universe by using machine learning (ML). Our motivations are two-fold: (1) presenting a new, promising technique to study galaxy formation, and (2) quantitatively analysing the extent of the influence of dark matter halo properties on galaxies in the backdrop of semi-analytical models (SAMs). We use the influential Millennium Simulation and the corresponding Munich SAM to train and test various sophisticated ML algorithms (k-Nearest Neighbors, decision trees, random forests, and extremely randomized trees). By using only essential dark matter halo physical properties for haloes of M > 1012 M⊙ and a partial merger tree, our model predicts the hot gas mass, cold gas mass, bulge mass, total stellar mass, black hole mass and cooling radius at z = 0 for each central galaxy in a dark matter halo for the Millennium run. Our results provide a unique and powerful phenomenological framework to explore the galaxy-halo connection that is built upon SAMs and demonstrably place ML as a promising and a computationally efficient tool to study small-scale structure formation.
Machine Learning and Cosmological Simulations I: Semi-Analytical Models
Kamdar, Harshil M; Brunner, Robert J
2016-01-01
We present a new exploratory framework to model galaxy formation and evolution in a hierarchical universe by using machine learning (ML). Our motivations are two-fold: (1) presenting a new, promising technique to study galaxy formation, and (2) quantitatively analyzing the extent of the influence of dark matter halo properties on galaxies in the backdrop of semi-analytical models (SAMs). We use the influential Millennium Simulation and the corresponding Munich SAM to train and test various sophisticated machine learning algorithms (k-Nearest Neighbors, decision trees, random forests and extremely randomized trees). By using only essential dark matter halo physical properties for haloes of $M>10^{12} M_{\\odot}$ and a partial merger tree, our model predicts the hot gas mass, cold gas mass, bulge mass, total stellar mass, black hole mass and cooling radius at z = 0 for each central galaxy in a dark matter halo for the Millennium run. Our results provide a unique and powerful phenomenological framework to explore...
Applying fuzzy analytic network process in quality function deployment model
Directory of Open Access Journals (Sweden)
Mohammad Ali Afsharkazemi
2012-08-01
Full Text Available In this paper, we propose an empirical study of QFD implementation when fuzzy numbers are used to handle the uncertainty associated with different components of the proposed model. We implement fuzzy analytical network to find the relative importance of various criteria and using fuzzy numbers we calculate the relative importance of these factors. The proposed model of this paper uses fuzzy matrix and house of quality to study the products development in QFD and also the second phase i.e. part deployment. In most researches, the primary objective is only on CRs to implement the quality function deployment and some other criteria such as production costs, manufacturing costs etc were disregarded. The results of using fuzzy analysis network process based on the QFD model in Daroupat packaging company to develop PVDC show that the most important indexes are being waterproof, resistant pill packages, and production cost. In addition, the PVDC coating is the most important index in terms of company experts’ point of view.
Green Transport Balanced Scorecard Model with Analytic Network Process Support
Directory of Open Access Journals (Sweden)
David Staš
2015-11-01
Full Text Available In recent decades, the performance of economic and non-economic activities has required them to be friendly with the environment. Transport is one of the areas having considerable potential within the scope. The main assumption to achieve ambitious green goals is an effective green transport evaluation system. However, these systems are researched from the industrial company and supply chain perspective only sporadically. The aim of the paper is to design a conceptual framework for creating the Green Transport (GT Balanced Scorecard (BSC models from the viewpoint of industrial companies and supply chains using an appropriate multi-criteria decision making method. The models should allow green transport performance evaluation and support of an effective implementation of green transport strategies. Since performance measures used in Balanced Scorecard models are interdependent, the Analytic Network Process (ANP was used as the appropriate multi-criteria decision making method. The verification of the designed conceptual framework was performed on a real supply chain of the European automotive industry.
More on analytic bootstrap for O( N) models
Dey, Parijat; Kaviraj, Apratim; Sen, Kallol
2016-06-01
This note is an extension of a recent work on the analytical bootstrapping of O( N) models. An additonal feature of the O( N) model is that the OPE contains trace and antisymmetric operators apart from the symmetric-traceless objects appearing in the OPE of the singlet sector. This in addition to the stress tensor ( T μν ) and the ϕ i ϕ i scalar, we also have other minimal twist operators as the spin-1 current J μ and the symmetric-traceless scalar in the case of O( N). We determine the effect of these additional objects on the anomalous dimensions of the corresponding trace, symmetric-traceless and antisymmetric operators in the large spin sector of the O( N) model, in the limit when the spin is much larger than the twist. As an observation, we also verified that the leading order results for the large spin sector from the ɛ-expansion are an exact match with our n = 0 case. A plausible holographic setup for the special case when N = 2 is also mentioned which mimics the calculation in the CFT.
Analytical modeling of bwr safety relief valve blowdown phenomenon
International Nuclear Information System (INIS)
An analytical, qualitative understanding of the pool pressures measured during safety relief valve discharge in boiling water reactors equipped with X-quenchers has been developed and compared to experimental data. A pressure trace typically consists of a brief 25-35 Hz. oscillation followed by longer 5-15 Hz. oscillation. In order to explain the pressure response, a discharge line vent clearing model has been coupled with a Rayleigh bubble dynamic model. The local conditions inside the safety relief valve discharge lines and inside of the X-quencher were simulated successfully with RELAP5. The simulation allows one to associate the peak pressure inside the quencher arm with the onset of air discharge into the suppression pool. Using the pressure and thermodynamic quality at quencher exit of RELAP5 calculation as input, a Rayleigh model of pool bubble dynamics has successfully explained both the higher and lower frequency pressure oscillations. The higher frequency oscillations are characteristic of an air bubble emanating from a single row of quencher holes. The lower frequency pressure oscillations are characteristic of a larger air bubble containing all the air expelled from one side of an X-quencher arm
Computational and analytical modeling of eye refractive surgery
Cabrera, Delia
As the number of corneal refractive procedures increases annually, concerns about their long-term stability and predictability have become the center of attention in the ophthalmic community. This thesis focuses on developing quantitative biomechanical models of the cornea that will overcome shortcomings of previous models and incorporate new observations of corneal elastic properties. Our intent is to provide a more accurate model of the corneal structure to guide current and future developments. The second chapter shows that neural networks could rapidly prototype practical solutions to obtain a better estimate of the average corneal power using the contrast and image size parameters provided by the topographic systems. After establishing improved measurements of the corneal shape the thesis focuses on the development of various corneal models. The analytical model proposed shows that geometric optics, corneal structural properties and surgical nomograms could be used to gain a better understanding of corneal response to surgical interventions. The predictions of this model are closer to the values provided by the published nomograms and clinical data than that obtained by the traditional geometric model. Three surgical procedures (Ultrafast Laser-Automated Lamellar Keratomileusis, Corneal Transplant and Intrastromal Refractive Keratectomy) were simulated using the finite element method. A new formulation was developed that simulates the changes on corneal curvature after refractive surgery when the stiffness inhomogeneities across the corneal thickness are considered. It has been shown that the predictability of the surgical outcome is improved when the stiffness inhomogeneities and nonlinearities of the deformations are included in the finite element simulations. Moreover, a finite element formulation has been developed first time to characterize the intrastromal refractive keratectomy procedure. An inhomogeneous (small displacements) model was identified as an
D-Brane Probes in the Matrix Model
Ferrari, Frank
2013-01-01
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general xi-gauge to compute the brane action. The action depends on xi in a very non-trivial way, yet we show explicitly that its critical value does not and coincide with twice the free energy, as required by general consistency...
D-brane probes in the matrix model
International Nuclear Information System (INIS)
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general ξ-gauge to compute the brane action. The action depends on ξ in a very non-trivial way, yet we show explicitly that its critical value does not and coincides with twice the free energy, as required by general consistency. This is made possible by a phenomenon of ghost condensation and the spontaneous breaking of the equivariant BRST symmetry
D-brane probes in the matrix model
Ferrari, Frank
2014-03-01
Recently, a new approach to large N gauge theories, based on a generalization of the concept of D-brane probes to any gauge field theory, was proposed. In the present note, we compute the probe action in the one matrix model with a quartic potential. This allows to illustrate several non-trivial aspects of the construction in an exactly solvable set-up. One of our main goal is to test the bare bubble approximation. The approximate free energy found in this approximation, which can be derived from a back-of-an-envelope calculation, matches the exact result for all values of the 't Hooft coupling with a surprising accuracy. Another goal is to illustrate the remarkable properties of the equivariant partial gauge-fixing procedure, which is at the heart of the formalism. For this we use a general ξ-gauge to compute the brane action. The action depends on ξ in a very non-trivial way, yet we show explicitly that its critical value does not and coincides with twice the free energy, as required by general consistency. This is made possible by a phenomenon of ghost condensation and the spontaneous breaking of the equivariant BRST symmetry.
Enabling analytical and Modeling Tools for Enhanced Disease Surveillance
Energy Technology Data Exchange (ETDEWEB)
Dawn K. Manley
2003-04-01
Early detection, identification, and warning are essential to minimize casualties from a biological attack. For covert attacks, sick people are likely to provide the first indication of an attack. An enhanced medical surveillance system that synthesizes distributed health indicator information and rapidly analyzes the information can dramatically increase the number of lives saved. Current surveillance methods to detect both biological attacks and natural outbreaks are hindered by factors such as distributed ownership of information, incompatible data storage and analysis programs, and patient privacy concerns. Moreover, because data are not widely shared, few data mining algorithms have been tested on and applied to diverse health indicator data. This project addressed both integration of multiple data sources and development and integration of analytical tools for rapid detection of disease outbreaks. As a first prototype, we developed an application to query and display distributed patient records. This application incorporated need-to-know access control and incorporated data from standard commercial databases. We developed and tested two different algorithms for outbreak recognition. The first is a pattern recognition technique that searches for space-time data clusters that may signal a disease outbreak. The second is a genetic algorithm to design and train neural networks (GANN) that we applied toward disease forecasting. We tested these algorithms against influenza, respiratory illness, and Dengue Fever data. Through this LDRD in combination with other internal funding, we delivered a distributed simulation capability to synthesize disparate information and models for earlier recognition and improved decision-making in the event of a biological attack. The architecture incorporates user feedback and control so that a user's decision inputs can impact the scenario outcome as well as integrated security and role-based access-control for communicating
Probing cosmology with weak lensing selected clusters II: Dark energy and f(R) gravity models
Shirasaki, Masato; Yoshida, Naoki
2015-01-01
Ongoing and future wide-field galaxy surveys can be used to locate a number of clusters of galaxies with cosmic shear measurement alone. We study constraints on cosmological models using statistics of weak lensing selected galaxy clusters. We extend our previous theoretical framework to model the statistical properties of clusters in variants of cosmological models as well as in the standard LCDM model. Weak lensing selection of clusters does not rely on the conventional assumption such as the relation between luminosity and mass and/or hydrostatic equilibrium, but a number of observational effects compromise robust identification. We use a large set of realistic mock weak-lensing catalogs as well as analytic models to perform a Fisher analysis and make forecast for constraining two competing cosmological models, wCDM model and f(R) model proposed by Hu & Sawicki, with our lensing statistics. We show that weak lensing selected clusters are excellent probe of cosmology when combined with cosmic shear power...
3D CMM Strain-Gauge Triggering Probe Error Characteristics Modeling
DEFF Research Database (Denmark)
Achiche, Sofiane; Wozniak, Adam; Fan, Zhun;
2008-01-01
The error values of CMMs depends on the probing direction; hence its spatial variation is a key part of the probe inaccuracy. This paper presents genetically-generated fuzzy knowledge bases (FKBs) to model the spatial error characteristics of a CMM module-changing probe. Two automatically generat...
3D CMM strain-gauge triggering probe error characteristics modeling using fuzzy logic
DEFF Research Database (Denmark)
Achiche, Sofiane; Wozniak, A; Fan, Zhun;
2008-01-01
The error values of CMMs depends on the probing direction; hence its spatial variation is a key part of the probe inaccuracy. This paper presents genetically-generated fuzzy knowledge bases (FKBs) to model the spatial error characteristics of a CMM module-changing probe. Two automatically generat...
Linjiang, QIN; Changfu, YANG
2016-03-01
The rocks in the crust and the upper mantle of the Earth are believed to exhibit electrical anisotropy to some extent. It is beneficial to further understand and recognize the propagation of the electromagnetic waves in the Earth by investigating the magnetotelluric (which is one of the main geophysical techniques to probe the deep structures in the Earth) responses of the media with anisotropic conductivity structures. In the present study, we examine the magnetotelluric fields over an idealized 2-D model consisting of two segments with axially anisotropic conductivity structures overlying a perfect conductor basement by a quasi-static analytic approach. The resulting analytic solution could not only contribute to the electromagnetic induction theory in the anisotropic Earth but also serve as at least an initial standard solution which could be used to validate the reliability and accuracy of the numerical algorithms developed for modeling the magnetotelluric responses of the 2-D media with much more general anisotropic conductivity.
Qin, Linjiang; Yang, Changfu
2016-06-01
The rocks in the crust and the upper mantle of the Earth are believed to exhibit electrical anisotropy to some extent. It is beneficial to further understand and recognize the propagation of the electromagnetic waves in the Earth by investigating the magnetotelluric (which is one of the main geophysical techniques to probe the deep structures in the Earth) responses of the media with anisotropic conductivity structures. In this study, we examine the magnetotelluric fields over an idealized 2-D model consisting of two segments with axially anisotropic conductivity structures overlying a perfect conductor basement by a quasi-static analytic approach. The resulting analytic solution could not only contribute to the electromagnetic induction theory in the anisotropic Earth but also serve as at least an initial standard solution which could be used to validate the reliability and accuracy of the numerical algorithms developed for modelling the magnetotelluric responses of the 2-D media with much more general anisotropic conductivity.
Stability and sensitivity of Learning Analytics based prediction models
Tempelaar, D.T.; Rienties, B.; Giesbers, B
2015-01-01
Learning analytics seek to enhance the learning processes through systematic measurements of learning related data and to provide informative feedback to learners and educators. Track data from Learning Management Systems (LMS) constitute a main data source for learning analytics. This empirical contribution provides an application of Buckingham Shum and Deakin Crick’s theoretical framework of dispositional learning analytics: an infrastructure that combines learning dispositions data with da...
Analytical model for an electrostatically actuated miniature diaphragm compressor
International Nuclear Information System (INIS)
This paper presents a new analytical approach for quasi-static modeling of an electrostatically actuated diaphragm compressor that could be employed in a miniature scale refrigeration system. The compressor consists of a flexible circular diaphragm clamped at its circumference. A conformal chamber encloses the diaphragm completely. The membrane and the chamber surfaces are coated with metallic electrodes. A potential difference applied between the diaphragm and the chamber pulls the diaphragm toward the chamber surface progressively from the outer circumference toward the center. This zipping actuation reduces the volume available to the refrigerant gas, thereby increasing its pressure. A segmentation technique is proposed for analysis of the compressor by which the domain is divided into multiple segments for each of which the forces acting on the diaphragm are estimated. The pull-down voltage to completely zip each individual segment is thus obtained. The required voltage for obtaining a specific pressure rise in the chamber can thus be determined. Predictions from the model compare well with other simulation results from the literature, as well as to experimental measurements of the diaphragm displacement and chamber pressure rise in a custom-built setup
Analytical model of neutral gas shielding for hydrogen pellet ablation
Energy Technology Data Exchange (ETDEWEB)
Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)
2001-11-01
A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)
New analytic solutions for modeling vertical gravity gradient anomalies
Kim, Seung-Sep; Wessel, Paul
2016-05-01
Modern processing of satellite altimetry for use in marine gravimetry involves computing the along-track slopes of observed sea-surface heights, projecting them into east-west and north-south deflection of the vertical grids, and using Laplace's equation to algebraically obtain a grid of the vertical gravity gradient (VGG). The VGG grid is then integrated via overlapping, flat Earth Fourier transforms to yield a free-air anomaly grid. Because of this integration and associated edge effects, the VGG grid retains more short-wavelength information (e.g., fracture zone and seamount signatures) that is of particular importance for plate tectonic investigations. While modeling of gravity anomalies over arbitrary bodies has long been a standard undertaking, similar modeling of VGG anomalies over oceanic features is not commonplace yet. Here we derive analytic solutions for VGG anomalies over simple bodies and arbitrary 2-D and 3-D sources. We demonstrate their usability in determining mass excess and deficiency across the Mendocino fracture zone (a 2-D feature) and find the best bulk density estimate for Jasper seamount (a 3-D feature). The methodologies used herein are implemented in the Generic Mapping Tools, available from gmt.soest.hawaii.edu.
Analytical model of neutral gas shielding for hydrogen pellet ablation
International Nuclear Information System (INIS)
A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dRpe/dt∼Sn2/3Rp-2/3qeo1/3mi-1/3 is confirmed. Here Rp is the pellet radius, Sn is the optical thickness of a cloud, qeo is the electron energy flux density and mi is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)
Design and analytical modeling of folded waveguide traveling wave tube
International Nuclear Information System (INIS)
We are developing a simple analytical model for the design of the folded waveguide traveling wave tube (FWTWT). Numerical software does exist for the design of FWTWT but requires large computer run time, is costly and does not provide the physical view for rapid design optimization of the FWTWT. In this paper, the design and analysis of the FWTWT using the spatial harmonics method of the TE10 mode of the EM wave are presented. An X-band FWTWT is used to verify this method. The normalized dispersion and beam line equations are used to simplify the design process so that the FWTWT can be designed to operate at any desired frequency. Both the S parameter-ABCD-S parameter conversion method and the equivalent circuit model method using Marcuvitz theorem are used for deriving the S parameters and for the analysis of dispersion curve of the 90 deg. sharp-cornered bend of the FWTWT. The analysis is developed by considering the straight and curved portions of the structure supporting the TE10 mode of the EM wave.
Analytical thermal hydraulic model for steam chugging phenomenon
International Nuclear Information System (INIS)
The Indian Pressurized Heavy Water Reactors (PHWRs) of the current design and Boiling Water Reactors incorporate a vapour suppression pool in the containment to mitigate the consequences of a loss of coolant accident. The thermal hydraulic phenomena occurring within the suppression pool following a loss of coolant accident are the vent clearing phase, pool swell and condensation of steam in the pool, which could be steady or intermittent depending on the steam mass flux. At low flow rates when steady condensation cannot be maintained at the steam-water interface, intermittent vapor condensation and bubble collapse process can be observed. This phenomenon is called steam chugging, during which rapid fluid and pressure oscillations occur. These oscillations may induce significant pressure loads on the submerged structures and are significant from safety perspective. This report addresses the problem of steam chugging. A thermal hydraulic model has been developed from fundamental conservation laws, for the process of steam chugging. The objective of developing the model is to present an approximation of the real phenomena and to obtain an analytical solution. The emphasis is however laid on studying the effect of presence of small amount of air in steam on chugging. Chugging is dominated by a number of important parameters hence, at the outset, a parametric study was undertaken using the above model to study the effect of important variables and to capture some essential features of the phenomena. This was done for a case when drywell contains only steam. Subsequently, the effect of presence of air in steam was studied using the non-condensable gas model. An attempt has been made to show numerically that the presence of a small amount of air in steam would effectively stabilize condensation and prevent inception chugging. Typical results are presented in this report. (author)
MATHEMATICAL MODELING OF A DISTANCE DEPENDENCE OF A SCANNING KELVIN PROBE LATERAL RESOLUTION
Directory of Open Access Journals (Sweden)
A. K. Tyavlovsky
2015-04-01
Full Text Available A mathematical model of cylindrical shaped plane-ended scanning Kelvin probe output signal is proposed considering the case of an infinite plane sample's surface with local defects represented by dot charges. Modeling results were obtained for the case of two closely situated dot charges anddifferent combinations of scanning Kelvin probe tip's diameter and sample-to-probe gap. It was found that the most effective way to improve the lateral resolution of a scanning Kelvin probe is to reduce the sample-to-probe gap in line with the reduction of sensor's vibration amplitude.
Distributed force probe bending model of critical dimension atomic force microscopy bias
Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.
2013-04-01
Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.
A semi-analytical model for semiconductor solar cells
Ding, D.; Johnson, S. R.; Yu, S.-Q.; Wu, S.-N.; Zhang, Y.-H.
2011-12-01
A semi-analytical model is constructed for single- and multi-junction solar cells. This model incorporates the key performance aspects of practical devices, including nonradiative recombination, photon recycling within a given junction, spontaneous emission coupling between junctions, and non-step-like absorptance and emittance with below-bandgap tail absorption. Four typical planar structures with the combinations of a smooth/textured top surface and an absorbing/reflecting substrate (or backside surface) are investigated, through which the extracted power and four types of fundamental loss mechanisms, transmission, thermalization, spatial-relaxation, and recombination loss are analyzed for both single- and multi-junction solar cells. The below-bandgap tail absorption increases the short-circuit current but decreases the output and open-circuit voltage. Using a straightforward formulism this model provides the initial design parameters and the achievable efficiencies for both single- and multiple-junction solar cells over a wide range of material quality. The achievable efficiency limits calculated using the best reported materials and AM1.5 G one sun for GaAs and Si single-junction solar cells are, respectively, 27.4 and 21.1% for semiconductor slabs with a flat surface and a non-reflecting index-matched absorbing substrate, and 30.8 and 26.4% for semiconductor slabs with a textured surface and an ideal 100% reflecting backside surface. Two important design rules for both single- and multi-junction solar cells are established: i) the optimal junction thickness decreases and the optimal bandgap energy increases when nonradiative recombination increases; and ii) the optimal junction thickness increases and the optimal bandgap energy decreases for higher solar concentrations.
INFORMATIONAL-ANALYTIC MODEL OF REGIONAL PROJECT PORTFOLIO FORMING
Directory of Open Access Journals (Sweden)
I. A. Osaulenko
2016-03-01
Full Text Available The article is devoted to the problem of regional project portfolio management in context of interaction of the regional development’s motive forces interaction. The features of innovation development on the regional level and their influence on the portfolio forming process considered. An existing approaches for portfolio modelling and formal criterion of the projects selection analyzed. At the same time the organization of key subjects of regional development interaction described. The aim of the article is investigation of informational aspects of project selection in process of the main development’s motive forces interaction and analytic model of portfolio filling validation. At that an inclination of stakeholders to reach a consensus taking into account. The Triple Helix conception using for concrete definition of the functions of the regional development’s motive forces. Asserted, that any component of innovation triad «science–business–government» can be an initiator of regional project, but it need to support two another components. Non-power interaction theory using for investigation of subjects interrelations in process of joint activity proposed. One of the key concept of the theory is information distance. It characterizes inclination of the parties to reach a consensus based on statistics. Projections of information distance onto directions of development axes using for more accurate definition of mutual positions in the all lines of development proposed. Another important parameter of the model which has an influence on the project support is awareness of stakeholders about it. Formalized description of project in the form of fast set of parameters proposes to use for determination of the awareness. The weighting coefficients for each parameter by expert way. Simultaneously the precision of the each parameter setting for all presented projects determines. On the base of appointed values of information distances and
33 CFR 385.33 - Revisions to models and analytical tools.
2010-07-01
... analytical tools. 385.33 Section 385.33 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE... Incorporating New Information Into the Plan § 385.33 Revisions to models and analytical tools. (a) In carrying... and other analytical tools for conducting analyses for the planning, design, construction,...
Analytical model for minority games with evolutionary learning
Campos, Daniel; Méndez, Vicenç; Llebot, Josep E.; Hernández, Germán A.
2010-06-01
In a recent work [D. Campos, J.E. Llebot, V. Méndez, Theor. Popul. Biol. 74 (2009) 16] we have introduced a biological version of the Evolutionary Minority Game that tries to reproduce the intraspecific competition for limited resources in an ecosystem. In comparison with the complex decision-making mechanisms used in standard Minority Games, only two extremely simple strategies ( juveniles and adults) are accessible to the agents. Complexity is introduced instead through an evolutionary learning rule that allows younger agents to learn taking better decisions. We find that this game shows many of the typical properties found for Evolutionary Minority Games, like self-segregation behavior or the existence of an oscillation phase for a certain range of the parameter values. However, an analytical treatment becomes much easier in our case, taking advantage of the simple strategies considered. Using a model consisting of a simple dynamical system, the phase diagram of the game (which differentiates three phases: adults crowd, juveniles crowd and oscillations) is reproduced.
An analytical study of various telecomminication networks using markov models
Ramakrishnan, M.; Jayamani, E.; Ezhumalai, P.
2015-04-01
The main aim of this paper is to examine issues relating to the performance of various Telecommunication networks, and applied queuing theory for better design and improved efficiency. Firstly, giving an analytical study of queues deals with quantifying the phenomenon of waiting lines using representative measures of performances, such as average queue length (on average number of customers in the queue), average waiting time in queue (on average time to wait) and average facility utilization (proportion of time the service facility is in use). In the second, using Matlab simulator, summarizes the finding of the investigations, from which and where we obtain results and describing methodology for a) compare the waiting time and average number of messages in the queue in M/M/1 and M/M/2 queues b) Compare the performance of M/M/1 and M/D/1 queues and study the effect of increasing the number of servers on the blocking probability M/M/k/k queue model.
Analytical model of coincidence resolving time in TOF-PET.
Wieczorek, H; Thon, A; Dey, T; Khanin, V; Rodnyi, P
2016-06-21
The coincidence resolving time (CRT) of scintillation detectors is the parameter determining noise reduction in time-of-flight PET. We derive an analytical CRT model based on the statistical distribution of photons for two different prototype scintillators. For the first one, characterized by single exponential decay, CRT is proportional to the decay time and inversely proportional to the number of photons, with a square root dependence on the trigger level. For the second scintillator prototype, characterized by exponential rise and decay, CRT is proportional to the square root of the product of rise time and decay time divided by the doubled number of photons, and it is nearly independent of the trigger level. This theory is verified by measurements of scintillation time constants, light yield and CRT on scintillator sticks. Trapping effects are taken into account by defining an effective decay time. We show that in terms of signal-to-noise ratio, CRT is as important as patient dose, imaging time or PET system sensitivity. The noise reduction effect of better timing resolution is verified and visualized by Monte Carlo simulation of a NEMA image quality phantom. PMID:27245232
Numerical and Analytical Modelling of Transit Time Variations
Hadden, Sam
2015-01-01
We develop and apply methods to extract planet masses and eccentricities from observed transit time variations (TTVs). First, we derive simple analytic expressions for the TTV that include the effects of both first- and second-order resonances. Second, we use N-body Markov chain Monte Carlo (MCMC) simulations, as well as the analytic formulae, to measure the masses and eccentricities of ten planets discovered by Kepler that have not previously been analyzed. Most of the ten planets have low densities. Using the analytic expressions to partially circumvent degeneracies, we measure small eccentricities of a few percent or less.
Analytical model of impact disruption of satellites and asteroids
Leliwa-Kopystyński, J.; Włodarczyk, I.; Burchell, M. J.
2016-04-01
A model of impact disruption of the bodies with sizes from the laboratory scale to that of an order of 100 km is developed. On the lowermost end of the target size the model is based on the numerous laboratory data related to the mass-velocity distribution of the impact produced fragments. On the minor-planets scale the model is supported by the data related to the largest observed craters on small icy satellites and on some asteroids (Leliwa-Kopystynski, J., Burchell, M.J., Lowen, D. [2008]. Icarus 195, 817-826). The model takes into account the target disruption and the dispersion of the impact produced fragments against the intermolecular forces acting on the surfaces of the contacts of the fragments and against self-gravitation of the target. The head-on collisions of non-rotating and non-porous targets and impactors are considered. The impactor delivers kinetic energy but its mass is neglected in comparison to mass of the target. For this simple case the analytical formulae for specific disruption energy as well as for specific energy of formation of the largest craters are found. They depend on a set of parameters. Of these the most important (i.e. with the greatest influence on the final result) are three rather weakly known parameters. They are: (i) The exponent γ in the distribution function of the fragments. (ii) The characteristic velocity v0 that appears in the velocity distribution of the ejected fragments. (iii) The exponent β in the mass-velocity distribution. The influence of the choice of the numerical values of these parameters on the final results has been studied. Another group of parameters contains the relevant material data. They are: (a) The energy σ of breaking of the intermolecular bonds of the target material per unit of the fragment surface and (b) the density ρ of the target. According to our calculations the transition between the strength regime and the gravitational regime is in the range of the target radius from ∼0.4 km to
Hansen C; Emin V.; Wasson B.; Mor Y.; Rodriguez-Triana M.J.; Dascalu M.; Ferguson R.; Pernin J.-P.
2013-01-01
This poster introduces the first version of an integrated model of three traditions of re- search in TEL: Teacher Inquiry into Student Learning (TISL) [1], Learning Design (LD) [2] and Learning Analytics (LA) [3]. The integrated model, is based on four existing models: TISL Heart Model [4], Design Inquiry Model [2], Scenario Design Process Model [5], and the Model for Integrating Design and Analytics in Scripting for CSCL (MIDAS4CSCL) [6]. The result is leading towards a new strand of inquiry...
Probes of Yukawa unification in supersymmetric SO(10) models
Energy Technology Data Exchange (ETDEWEB)
Westhoff, Susanne
2009-10-23
This work is composed as follows: In Chapter 1, the disposed reader is made familiar with the foundations of flavourphysics and Grand Unification, including group-theoretical aspects of SO(10). In Chapter 2, we introduce a specific supersymmetric GUT model based on SO(10) and designed to probe down-quark-lepton Yukawa unification. Within this framework we explore the effects of large atmospheric neutrino mixing in bottom-strange transitions on the mass difference and CP phase in B{sub s}- anti B{sub s} meson mixing. Chapter 3 is devoted to corrections to Yukawa unification. We derive constraints on Yukawa corrections for light fermions from K- anti K and B{sub d}- anti B {sub d} mixing. As an application we study implications of neutrino mixing effects in CP-violating K and B{sub d} observables on the unitrity triangle. Finally, in Chapter 4, we discuss effects of large tan {beta} in B{yields}(D){tau}{nu} decays with respect to their potential to discover charged Higgs bosons and to discriminate between different GUT models of flavour.
Ghorai, Debabrata
2015-01-01
In this paper, we analytically investigate the properties of holographic superconductors in higher dimensions in the framework of Born-Infeld electrodynamics taking into account the backreaction of the spacetime using the Sturm-Liouville eigenvalue method. In the background of pure Einstein and Gauss-Bonnet gravity, based on a perturbative approach, we obtain the relation between the critical temperature and the charge density. Higher value of the backreaction and Born-Infeld parameters result in a harder condensation to form in both cases. The analytical results are found to agree with the existing numerical results.
An analytical model for the influence of contact resistance on thermoelectric efficiency
Bjørk, R
2016-01-01
An analytical model is presented that can account for both electrical and hot and cold thermal contact resistances when calculating the efficiency of a thermoelectric generator. The model is compared to a numerical model of a thermoelectric leg, for 16 different thermoelectric materials, as well as the analytical models of Ebling et. al. (2010) and Min \\& Rowe (1992). The model presented here is shown to accurately calculate the efficiency for all systems and all contact resistances considered, with an average difference in efficiency between the numerical model and the analytical model of $-0.07\\pm0.35$ pp. This makes the model more accurate than previously published models. The maximum absolute difference in efficiency between the analytical model and the numerical model is 1.14 pp for all materials and all contact resistances considered.
Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D
2015-08-19
Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems. PMID:26061541
Nawaz AHMAD
2009-01-01
The thesis work aims at devising analytical thermodynamic model and numerical modeling of the compressor of a small gas turbine to be operated on producer gas with lower heating contents. The turbine will serve as a component of “EXPLORE-Biomass Based Polygeneration” project to meet the internal electrical power requirements of 2-5 KW. The gas turbine engine is of radial type (one stage radial compressor, one stage radial turbine). Small gas turbines give less electrical efficiencies especial...
Analytical Model of Nano-Electromechanical (NEM) Nonvolatile Memory Cells
Han, Boram; Choi, Woo Young
The fringe field effects of nano-electromechanical (NEM) nonvolatile memory cells have been investigated analytically for the accurate evaluation of NEM memory cells. As the beam width is scaled down, fringe field effect becomes more severe. It has been observed that pull-in, release and hysteresis voltage decrease more than our prediction. Also, the fringe field on cell characteristics has been discussed.
Large-eddy simulation and analytical modelling of katabatic winds
Axelsen, S.L.
2010-01-01
This thesis is concerned with numerical and analytical modellig of over sloping terrain, also called katabatic winds. These winds are induced when a stably stratified atmospheric boundary layer is cooled from below. A horizontal potential temperature difference is produced between an air parcel clos
Analytical Model of Fixed-Frequency Variable Duty-Cycle Controlled LLC Resonant Converter
DEFF Research Database (Denmark)
Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede;
2016-01-01
-state equations are complex, and the analytical model cannot be directly derived. Thus, cumbersome numerical calculation has to be conducted. In this digest, all possible operation modes with variable duty-cycle control are identified and discussed, and an accurate analytical model for the most commonly used mode...
Analytical Model-based Fault Detection and Isolation in Control Systems
DEFF Research Database (Denmark)
Vukic, Z.; Ozbolt, H.; Blanke, M.
1998-01-01
The paper gives an introduction and an overview of the field of fault detection and isolation for control systems. The summary of analytical (quantitative model-based) methodds and their implementation are presented. The focus is given to mthe analytical model-based fault-detection and fault...
An Analytical Model for Vertical Profiles in Submarine Channels
Bolla Pittaluga, M.; Imran, J.
2011-12-01
Turbidity currents are the primary agents carrying sediments from the continental shelf to the deep-sea. They are the counterpart of fluvial currents in the deep-sea environment and are responsible for the shaping of submarine channels. Due to the unpredictability of events and to their ability to destroy installed monitoring instruments, only a few attempts to directly measure the properties of turbidity currents in submarine channels has proved to be successful (Xu et al., 2004; Xu, 2010). Consequently the vast majority of the studies concerning the vertical structure of turbidity currents were either laboratory experiments or numerical models. In spite of the relevance of the problem, related to the consequences of flow field on sedimentary deposits, at present an ongoing debate still exist on similarities and differences between submarine and fluvial channels related in particular to the orientation of the helical flow in channel bends. Here we expand on the above ideas and develop an analytical theory for flow and suspended sediment transport in submarine channels able to describe vertical profiles of both flow field and suspendend sediment concentration. The turbulence closure needed to account for density stratification is adapted from the model of Mellor and Yamada (1982). Solutions are found for both straight and constant curvature channels. In the latter case, in order to evaluate the secondary flow induced by curvature, we take advantage of the fact that the ratio of flow depth to radius of curvature is typically small in the field, which leads to a solution of the governing equations through an appropriate asymptotic expansion. Steady fully developed flow conditions in a bend of constant width are considered. Results for longitudinal velocity and concentration profiles in straight channels are then compared with experimental observations of Sequeiros et al. (2010) providing good agreement. We also expect to find under which values of the controlling
Energy Technology Data Exchange (ETDEWEB)
Xu, Zhijie; Fang, Yilin; Scheibe, Timothy D.; Bonneville, Alain
2012-05-15
We present a hydro-mechanical model for geological sequestration of carbon dioxide. The model considers the poroelastic effects by taking into account the coupling between the geomechanical response and the fluid flow in greater detail. The simplified hydro-mechanical model includes the geomechanical part that relies on the linear elasticity, while the fluid flow is based on the Darcy’s law. Two parts were coupled using the standard linear poroelasticity. Analytical solutions for pressure field were obtained for a typical geological sequestration scenario. The model predicts the temporal and spatial variation of pressure field and effects of permeability and elastic modulus of formation on the fluid pressure distribution.
Modelling a flows in supply chain with analytical models: Case of a chemical industry
Benhida, Khalid; Azougagh, Yassine; Elfezazi, Said
2016-02-01
This study is interested on the modelling of the logistics flows in a supply chain composed on a production sites and a logistics platform. The contribution of this research is to develop an analytical model (integrated linear programming model), based on a case study of a real company operating in the phosphate field, considering a various constraints in this supply chain to resolve the planning problems for a better decision-making. The objectives of this model is to determine and define the optimal quantities of different products to route, to and from the various entities in the supply chain studied.
Analytical Model of Water Flow in Coal with Active Matrix
Siemek, Jakub; Stopa, Jerzy
2014-12-01
This paper presents new analytical model of gas-water flow in coal seams in one dimension with emphasis on interactions between water flowing in cleats and coal matrix. Coal as a flowing system, can be viewed as a solid organic material consisting of two flow subsystems: a microporous matrix and a system of interconnected macropores and fractures. Most of gas is accumulated in the microporous matrix, where the primary flow mechanism is diffusion. Fractures and cleats existing in coal play an important role as a transportation system for macro scale flow of water and gas governed by Darcy's law. The coal matrix can imbibe water under capillary forces leading to exchange of mass between fractures and coal matrix. In this paper new partial differential equation for water saturation in fractures has been formulated, respecting mass exchange between coal matrix and fractures. Exact analytical solution has been obtained using the method of characteristics. The final solution has very simple form that may be useful for practical engineering calculations. It was observed that the rate of exchange of mass between the fractures and the coal matrix is governed by an expression which is analogous to the Newton cooling law known from theory of heat exchange, but in present case the mass transfer coefficient depends not only on coal and fluid properties but also on time and position. The constant term of mass transfer coefficient depends on relation between micro porosity and macro porosity of coal, capillary forces, and microporous structure of coal matrix. This term can be expressed theoretically or obtained experimentally. W artykule zaprezentowano nowy model matematyczny przepływu wody i gazu w jednowymiarowej warstwie węglowej z uwzględnieniem wymiany masy między systemem szczelin i matrycą węglową. Węgiel jako system przepływowy traktowany jest jako układ o podwójnej porowatości i przepuszczalności, składający się z mikroporowatej matrycy węglowej oraz z
Semi-Analytic Model Predictions of Mass Segregation from Groups to Clusters
Contini, Emanuele
2015-01-01
Taking advantage of a set of high-resolution simulations coupled with a state-of-art semi-analytic model of galaxy formation we probe the mass segregation of galaxies in groups and clusters, focusing on which physical mechanisms are driving it. We find evidence of mass segregation in groups and clusters up to the virial radius, with a trend that weakens with increasing halo mass. The physical mechanism responsible for that is found to be dynamical friction, a drag-force that brings more massive galaxies faster towards the innermost regions of the halo. We argue that the intrinsic dependence of dynamical friction timescale on halo mass explains the weakening of mass segregation from groups to clusters. At odds with observational results, we do not find the inclusion of low-mass galaxies in the samples, down to stellar mass $M_* = 10^9 \\, M_{\\odot}$, to change the overall trend shown by intermediate and massive galaxies. Moreover, stellar stripping as well as the growth of galaxies after their accretion, do not...
An analytical model for soil-atmosphere feedback
Schaefli, B.; R. J. van der Ent; Woods, R; Savenije, H. H. G.
2012-01-01
Soil-atmosphere feedback is a key for understanding the hydrological cycle and the direction of potential system changes. This paper presents an analytical framework to study the interplay between soil and atmospheric moisture, using as input only the boundary conditions at the upstream end of an atmospheric moisture stream line. The underlying Eulerian-Langrangean approach assumes advective moisture transport with average wind speed along the stream line and vertical moisture exchange with t...
A simple analytical aerodynamic model of Langley Winged-Cone Aerospace Plane concept
Pamadi, Bandu N.
1994-01-01
A simple three DOF analytical aerodynamic model of the Langley Winged-Coned Aerospace Plane concept is presented in a form suitable for simulation, trajectory optimization, and guidance and control studies. The analytical model is especially suitable for methods based on variational calculus. Analytical expressions are presented for lift, drag, and pitching moment coefficients from subsonic to hypersonic Mach numbers and angles of attack up to +/- 20 deg. This analytical model has break points at Mach numbers of 1.0, 1.4, 4.0, and 6.0. Across these Mach number break points, the lift, drag, and pitching moment coefficients are made continuous but their derivatives are not. There are no break points in angle of attack. The effect of control surface deflection is not considered. The present analytical model compares well with the APAS calculations and wind tunnel test data for most angles of attack and Mach numbers.
Analytical model for chip formation in case of orthogonal machining process
International Nuclear Information System (INIS)
The present work deals with the presentation of analytical methodology allowing the modelling of chip formation. For that a 'decomposition approach', based on assuming that the material removal is the summation of two contributions: ploughing and pure cut was adopted. Moreover, this analytical model was calibrated by a finite element model and experimental data in terms of temperature and forces evolutions. The global aim is to propose to the industrial community, an efficient rapid-execution analytical model concerning the material removal in the case of an orthogonal cutting process.
Analytical coupled vibroacoustic modeling of membrane-type acoustic metamaterials: membrane model
CHEN, Yangyang; Zhou, Xiaoming; Hu, Gengkai; Sun, Chin-teh; Huang, Guoliang
2013-01-01
Membrane-type Acoustic Metamaterials (MAMs) have demonstrated unusual capacity in controlling low-frequency sound transmission/reflection. In this paper, an analytical vibroacoustic membrane model is developed to study sound transmission behavior of the MAM under a normal incidence. The MAM is composed of a prestretched elastic membrane with attached rigid masses. To accurately capture finite-dimension rigid mass effects on the membrane deformation, the point matching approach is adopted by a...
Analytical solution of a stochastic content-based network model
International Nuclear Information System (INIS)
We define and completely solve a content-based directed network whose nodes consist of random words and an adjacency rule involving perfect or approximate matches for an alphabet with an arbitrary number of letters. The analytic expression for the out-degree distribution shows a crossover from a leading power law behaviour to a log-periodic regime bounded by a different power law decay. The leading exponents in the two regions have a weak dependence on the mean word length, and an even weaker dependence on the alphabet size. The in-degree distribution, on the other hand, is much narrower and does not show any scaling behaviour
Interaction model between a liquid film and a spherical probe
Ledesma Alonso, Rene; Legendre, Dominique; Tordjeman, Philippe
2012-11-01
To find a liquid surface profile, when performing AFM measurements, probe interaction effects should be identified. Herein, the behavior of a liquid film free surface (thickness E, surface tension γ and density difference Δρ), disposed over a flat surface and in the presence of a spherical probe (radius R) is forecast. A bump-like surface shape is observed, due to the probe/film interaction (characterized by the Hamaker constant Hpl). In addition, the attraction between the film and the substrate (depicted by Hsl) opposes the axial and radial deformation ranges. Several parameters portray the equilibrium shape: Bond Bo = (ΔρgR2) / γ and modified Hamaker Ha = 4Hpl / (3 πγR2) numbers, Hamaker ratio A =Hls /Hpl , separation distance D / R and film thickness E / R . We focus on the effect of geometry, nevertheless special attention is given to the role of physical parameters. Employing an augmented Young-Laplace equation, the equilibrium profile is described by a strongly non-linear ODE. A critical distance, below which the irreversible wetting process of the spherical probe occurs, is predicted. Our results provide simple relationships between parameters, which determine the optimal scanning conditions over liquid films.
Budsankom, Prayoonsri; Sawangboon, Tatsirin; Damrongpanit, Suntorapot; Chuensirimongkol, Jariya
2015-01-01
The purpose of the research is to develop and identify the validity of factors affecting higher order thinking skills (HOTS) of students. The thinking skills can be divided into three types: analytical, critical, and creative thinking. This analysis is done by applying the meta-analytic structural equation modeling (MASEM) based on a database of…
Promoting Active Learning by Practicing the "Self-Assembly" of Model Analytical Instruments
Algar, W. Russ; Krull, Ulrich J.
2010-01-01
In our upper-year instrumental analytical chemistry course, we have developed "cut-and-paste" exercises where students "build" models of analytical instruments from individual schematic images of components. These exercises encourage active learning by students. Instead of trying to memorize diagrams, students are required to think deeply about…
An Analytic Hierarchy Process for School Quality and Inspection: Model Development and Application
Al Qubaisi, Amal; Badri, Masood; Mohaidat, Jihad; Al Dhaheri, Hamad; Yang, Guang; Al Rashedi, Asma; Greer, Kenneth
2016-01-01
Purpose: The purpose of this paper is to develop an analytic hierarchy planning-based framework to establish criteria weights and to develop a school performance system commonly called school inspections. Design/methodology/approach: The analytic hierarchy process (AHP) model uses pairwise comparisons and a measurement scale to generate the…
Analytic model approach to the inversion of scattering data. [to obtain ozone profile
Green, A. E. S.; Klenk, K. F.
1977-01-01
An analytic model approach is applied to several simple atmospheric inversion problems. This method gives a sharp determination of aerosol size distribution parameters. It is shown that this analytic approach, together with ground level point sampling data measurements, can be used to infer information on the tropospheric ozone profile.
Improved Analytical Model of a Permanent-Magnet Brushless DC Motor
P. Kumar; Bauer, P
2008-01-01
In this paper, we develop a comprehensive model of a permanent-magnet brushless DC (BLDC) motor. An analytical model for determining instantaneous air-gap field density is developed. This instantaneous field distribution can be further used to determine the cogging torque, induced back electromotive force, and iron losses in the motor. The advantage of analytical models is that they can be readily used for optimization of BLDC motor because they are fast.
Taillade, Frédéric; Belin, Etienne; Dumont, Eric
2008-01-01
We propose an analytical model for backscattered luminance in fog and derive an expression for the visibility signal-to-noise ratio as a function of meteorological visibility distance. The model uses single scattering processes. It is based on the Mie theory and the geometry of the optical device (emitter and receiver). In particular, we present an overlap function and take the phase function of fog into account. The results of the backscattered luminance obtained with our analytical model...
Dot-Product Join: An Array-Relation Join Operator for Big Model Analytics
Qin, Chengjie; Rusu, Florin
2016-01-01
Big Data analytics has been approached exclusively from a data-parallel perspective, where data are partitioned to multiple workers -- threads or separate servers -- and model training is executed concurrently over different partitions, under various synchronization schemes that guarantee speedup and/or convergence. The dual -- Big Model -- problem that, surprisingly, has received no attention in database analytics, is how to manage models with millions if not billions of parameters that do n...
An analytical model of pipelined circuit switching in hypercubes in the presence of hot spot traffic
Safaei, F.; Khonsari, A.; Fathy, M.; Ould-Khaoua, M.
2005-01-01
Several recent studies have revealed that PCS can provide superior performance characteristics over wormhole switching under uniform traffic. Analytical model of PCS for common networks (e.g., hypercube) under uniform traffic pattern have recently been reported in the literature. In this paper we propose an analytical model of PCS in the hypercube network augmented with virtual channel in the presence of hot spot traffic. The model has a good agreement with simulation experiments.
Directory of Open Access Journals (Sweden)
John (Jack P. Riegel III
2016-04-01
Full Text Available Historically, there has been little correlation between the material properties used in (1 empirical formulae, (2 analytical formulations, and (3 numerical models. The various regressions and models may each provide excellent agreement for the depth of penetration into semi-infinite targets. But the input parameters for the empirically based procedures may have little in common with either the analytical model or the numerical model. This paper builds on previous work by Riegel and Anderson (2014 to show how the Effective Flow Stress (EFS strength model, based on empirical data, can be used as the average flow stress in the analytical Walker–Anderson Penetration model (WAPEN (Anderson and Walker, 1991 and how the same value may be utilized as an effective von Mises yield strength in numerical hydrocode simulations to predict the depth of penetration for eroding projectiles at impact velocities in the mechanical response regime of the materials. The method has the benefit of allowing the three techniques (empirical, analytical, and numerical to work in tandem. The empirical method can be used for many shot line calculations, but more advanced analytical or numerical models can be employed when necessary to address specific geometries such as edge effects or layering that are not treated by the simpler methods. Developing complete constitutive relationships for a material can be costly. If the only concern is depth of penetration, such a level of detail may not be required. The effective flow stress can be determined from a small set of depth of penetration experiments in many cases, especially for long penetrators such as the L/D = 10 ones considered here, making it a very practical approach. In the process of performing this effort, the authors considered numerical simulations by other researchers based on the same set of experimental data that the authors used for their empirical and analytical assessment. The goals were to establish a
Institute of Scientific and Technical Information of China (English)
John Jack P. RIEGEL III; David DAVISON
2016-01-01
Historically, there has been little correlation between the material properties used in (1) empirical formulae, (2) analytical formulations, and (3) numerical models. The various regressions and models may each provide excellent agreement for the depth of penetration into semi-infinite targets. But the input parameters for the empirically based procedures may have little in common with either the analytical model or the numerical model. This paper builds on previous work by Riegel and Anderson (2014) to show how the Effective Flow Stress (EFS) strength model, based on empirical data, can be used as the average flow stress in the analytical Walker–Anderson Penetration model (WAPEN) (Anderson and Walker, 1991) and how the same value may be utilized as an effective von Mises yield strength in numerical hydrocode simulations to predict the depth of penetration for eroding projectiles at impact velocities in the mechanical response regime of the materials. The method has the benefit of allowing the three techniques (empirical, analytical, and numerical) to work in tandem. The empirical method can be used for many shot line calculations, but more advanced analytical or numerical models can be employed when necessary to address specific geometries such as edge effects or layering that are not treated by the simpler methods. Developing complete constitutive relationships for a material can be costly. If the only concern is depth of penetration, such a level of detail may not be required. The effective flow stress can be determined from a small set of depth of penetration experiments in many cases, especially for long penetrators such as the L/D=10 ones considered here, making it a very practical approach. In the process of performing this effort, the authors considered numerical simulations by other researchers based on the same set of experimental data that the authors used for their empirical and analytical assessment. The goals were to establish a baseline with a full
Evaluation of Analytical Modeling Functions for the Phonation Onset Process
Petermann, Simon; Kniesburges, Stefan; Ziethe, Anke; Schützenberger, Anne; Döllinger, Michael
2016-01-01
The human voice originates from oscillations of the vocal folds in the larynx. The duration of the voice onset (VO), called the voice onset time (VOT), is currently under investigation as a clinical indicator for correct laryngeal functionality. Different analytical approaches for computing the VOT based on endoscopic imaging were compared to determine the most reliable method to quantify automatically the transient vocal fold oscillations during VO. Transnasal endoscopic imaging in combination with a high-speed camera (8000 fps) was applied to visualize the phonation onset process. Two different definitions of VO interval were investigated. Six analytical functions were tested that approximate the envelope of the filtered or unfiltered glottal area waveform (GAW) during phonation onset. A total of 126 recordings from nine healthy males and 210 recordings from 15 healthy females were evaluated. Three criteria were analyzed to determine the most appropriate computation approach: (1) reliability of the fit function for a correct approximation of VO; (2) consistency represented by the standard deviation of VOT; and (3) accuracy of the approximation of VO. The results suggest the computation of VOT by a fourth-order polynomial approximation in the interval between 32.2 and 67.8% of the saturation amplitude of the filtered GAW. PMID:27066108
International Nuclear Information System (INIS)
Minkowski functionals are a powerful tool to constrain the Gaussianity of the Cosmic Microwave Background (CMB). In the limit of a weakly non Gaussian field, a perturbative approach can be derived [Hikage C., Komatsu E., and Matsubara T., 2006, ApJ, 653, 11] that is completely based on analytical formulae without requiring computationally intensive, dedicated Monte Carlo non Gaussian simulations of the CMB anisotropy. We apply this machinery to an intensity map derived from the 1998 and 2003 flights of BOOMERanG, analyzed here together for the first time. We set limits on the non-linear coupling parameter fNL as -1020NL<390 at 95% CL, markedly improving the previous constraints set by [De Troia G. et al., 2007, ApJ, 670, L73] whose analysis was limited to the BOOMERanG 2003 dataset. These limits are the most stringent ever set among suborbital experiments.
Energy Technology Data Exchange (ETDEWEB)
Migliaccio, M.; Natoli, P.; De Troia, G. [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 1 I-00133 Roma (Italy); Hikage, C. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Komatsu, E. [Texas Cosmology Center, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States); Ade, P.A.R. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Bock, J.J. [Jet Propulsion Laboratory, Pasadena, CA (United States); Bond, J.R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario (Canada); Borrill, J. [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boscaleri, A. [IFAC-CNR, Firenze (Italy); Contaldi, C.R. [Theoretical Physics Group, Imperial College, London (United Kingdom); Crill, B.P. [Jet Propulsion Laboratory, Pasadena, CA (United States); Bernardis, P. de [Dipartimento di Fisica, Universita La Sapienza, Roma (Italy); Gasperis, G. de [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , Via della Ricerca Scientifica, 1 I-00133 Roma (Italy); Oliveira-Costa, A. de [Department of Physics, MIT, Cambridge, MA 02139 (United States); Di Stefano, G. [Istituto Nazionale di Geofisica e Vulcanologia, 00143 Rome (Italy); Hivon, E. [Institut d' Astrophysique, Paris (France); Kisner, T.S. [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Jones, W.C. [Department of Physics, Princeton University, Princeton, NJ 0854 (United States); Lange, A.E. [Observational Cosmology, California Institute of Technology, Pasadena, CA (United States)
2009-10-15
Minkowski functionals are a powerful tool to constrain the Gaussianity of the Cosmic Microwave Background (CMB). In the limit of a weakly non Gaussian field, a perturbative approach can be derived [Hikage C., Komatsu E., and Matsubara T., 2006, ApJ, 653, 11] that is completely based on analytical formulae without requiring computationally intensive, dedicated Monte Carlo non Gaussian simulations of the CMB anisotropy. We apply this machinery to an intensity map derived from the 1998 and 2003 flights of BOOMERanG, analyzed here together for the first time. We set limits on the non-linear coupling parameter f{sub NL} as -1020
Migliaccio, M.; Natoli, P.; De Troia, G.; Hikage, C.; Komatsu, E.; Ade, P. A. R.; Bock, J. J.; Bond, J. R.; Borrill, J.; Boscaleri, A.; Contaldi, C. R.; Crill, B. P.; de Bernardis, P.; de Gasperis, G.; de Oliveira-Costa, A.; Di Stefano, G.; Hivon, E.; Kisner, T. S.; Jones, W. C.; Lange, A. E.; Masi, S.; Mauskopf, P. D.; MacTavish, C. J.; Melchiorri, A.; Montroy, T. E.; Netterfield, C. B.; Pascale, E.; Piacentini, F.; Polenta, G.; Ricciardi, S.; Romeo, G.; Ruhl, J. E.; Tegmark, M.; Veneziani, M.; Vittorio, N.
2009-10-01
Minkowski functionals are a powerful tool to constrain the Gaussianity of the Cosmic Microwave Background (CMB). In the limit of a weakly non Gaussian field, a perturbative approach can be derived [Hikage C., Komatsu E., & Matsubara T., 2006, ApJ, 653, 11] that is completely based on analytical formulae without requiring computationally intensive, dedicated Monte Carlo non Gaussian simulations of the CMB anisotropy. We apply this machinery to an intensity map derived from the 1998 and 2003 flights of BOOMERanG, analyzed here together for the first time. We set limits on the non-linear coupling parameter f as -1020Troia G. et al., 2007, ApJ, 670, L73] whose analysis was limited to the BOOMERanG 2003 dataset. These limits are the most stringent ever set among suborbital experiments.
Design Evaluation of Wind Turbine Spline Couplings Using an Analytical Model: Preprint
Energy Technology Data Exchange (ETDEWEB)
Guo, Y.; Keller, J.; Wallen, R.; Errichello, R.; Halse, C.; Lambert, S.
2015-02-01
Articulated splines are commonly used in the planetary stage of wind turbine gearboxes for transmitting the driving torque and improving load sharing. Direct measurement of spline loads and performance is extremely challenging because of limited accessibility. This paper presents an analytical model for the analysis of articulated spline coupling designs. For a given torque and shaft misalignment, this analytical model quickly yields insights into relationships between the spline design parameters and resulting loads; bending, contact, and shear stresses; and safety factors considering various heat treatment methods. Comparisons of this analytical model against previously published computational approaches are also presented.
3D Modelling of CMMs Probing Accuracy and Settings using Fuzzy Knowledge Bases
DEFF Research Database (Denmark)
Achiche, Sofiane; Wozniack, Adam
2011-01-01
probes are proposed. The fuzzy models are automatically generated using a dedicated genetic algorithm developed by the authors. The algorithm uses hybrid coding, binary for the rule base and real for the data base. This hybrid coding, used with a set of specialized operators of reproduction, proved......One of the fundamental elements that determines the precision of Coordinate Measuring Machines (CMMs) is the probe, which locates measuring points within measurement volume. In this paper genetically generated fuzzy knowledge based models of 3D probing accuracy for one and two stage touch trigger...... to be an effective learning environment in this case. Data collection of the measured objects’ coordinates was carried out using a special set-up for probe testing. The authors used a novel method that applies a low-force high-resolution displacement transducer for probe error examination in 3D space outside the CMM...
Hunt, R.J.; Anderson, M.P.; Kelson, V.A.
1998-01-01
This paper demonstrates that analytic element models have potential as powerful screening tools that can facilitate or improve calibration of more complicated finite-difference and finite-element models. We demonstrate how a two-dimensional analytic element model was used to identify errors in a complex three-dimensional finite-difference model caused by incorrect specification of boundary conditions. An improved finite-difference model was developed using boundary conditions developed from a far-field analytic element model. Calibration of a revised finite-difference model was achieved using fewer zones of hydraulic conductivity and lake bed conductance than the original finite-difference model. Calibration statistics were also improved in that simulated base-flows were much closer to measured values. The improved calibration is due mainly to improved specification of the boundary conditions made possible by first solving the far-field problem with an analytic element model.This paper demonstrates that analytic element models have potential as powerful screening tools that can facilitate or improve calibration of more complicated finite-difference and finite-element models. We demonstrate how a two-dimensional analytic element model was used to identify errors in a complex three-dimensional finite-difference model caused by incorrect specification of boundary conditions. An improved finite-difference model was developed using boundary conditions developed from a far-field analytic element model. Calibration of a revised finite-difference model was achieved using fewer zones of hydraulic conductivity and lake bed conductance than the original finite-difference model. Calibration statistics were also improved in that simulated base-flows were much closer to measured values. The improved calibration is due mainly to improved specification of the boundary conditions made possible by first solving the far-field problem with an analytic element model.
Polymer as a function of monomer: Analytical quantum modeling
Nakhaee, Mohammad
2016-01-01
To identify an analytical relation between the properties of polymers and their's monomer a Metal-Molecule-Metal (MMM) junction has been presented as an interesting and widely used object of research in which the molecule is a polymer which is able to conduct charge. The method used in this study is based on the Green's function approach in the tight-binding approximation using basic properties of matrices. For a polymer base MMM system, transmission, density of states (DOS) and local density of states (LDOS) have been calculated as a function of the hamiltonian of the monomer. After that, we have obtained a frequency for LDOS variations in pass from a subunit to the next one which is a function of energy.
Operational risk modeled analytically II: the consequences of classification invariance
Vivien Brunel
2015-01-01
Most of the banks' operational risk internal models are based on loss pooling in risk and business line categories. The parameters and outputs of operational risk models are sensitive to the pooling of the data and the choice of the risk classification. In a simple model, we establish the link between the number of risk cells and the model parameters by requiring invariance of the bank's loss distribution upon a change in classification. We provide details on the impact of this requirement on...
Analytical Model of Planar Double Split Ring Resonator
DEFF Research Database (Denmark)
Zhurbenko, Vitaliy; Jensen, Thomas; Krozer, Viktor;
2007-01-01
This paper focuses on accurate modelling of microstrip double split ring resonators. The impedance matrix representation for coupled lines is applied for the first time to model the SRR, resulting in excellent model accuracy over a wide frequency range. Phase compensation is implemented to take...
Kokona, Bashkim; Winesett, Emily S; von Krusenstiern, A Nikolai; Cryle, Max J; Fairman, Robert; Charkoudian, Louise K
2016-02-15
Bacteria and fungi use non-ribosomal peptide synthetases (NRPSs) to produce peptides of broad structural diversity and biological activity, many of which have proven to be of great importance for human health. The impressive diversity of non-ribosomal peptides originates in part from the action of tailoring enzymes that modify the structures of single amino acids and/or the mature peptide. Studying the interplay between tailoring enzymes and the peptidyl carrier proteins (PCPs) that anchor the substrates is challenging owing to the transient and complex nature of the protein-protein interactions. Using sedimentation velocity (SV) methods, we studied the collaboration between the PCPs and cytochrome P450 enzyme that results in the installation of β-hydroxylated amino acid precursors in the biosynthesis of the depsipeptide skyllamycin. We show that SV methods developed for the analytical ultracentrifuge are ideally suited for a quantitative exploration of PCP-enzyme equilibrium interactions. Our results suggest that the PCP itself and the presence of substrate covalently tethered to the PCP together facilitate productive PCP-P450 interactions, thereby revealing one of nature's intricate strategies for installing interesting functionalities using natural product synthetases. PMID:26655390
International Nuclear Information System (INIS)
Analytic calculations of the magnetic fields available to magnetic diagnostics are performed for tokamaks with circular and elliptical cross sections. The explicit dependence of the magnetic fields on the poloidal beta and internal inductances is sought. For tokamaks with circular cross sections, Shafranov's results are reproduced and extended. To first order in the inverse aspect ratio expansion of the magnetic fields, only a specific combination of beta poloidal and internal inductance is found to be measurable. To second order in the expansion, the measurements of beta poloidal and the internal inductance are demonstrated to be separable but excessively sensitive to experimental error. For tokamaks with elliptical cross sections, magnetic measurements are found to determine beta poloidal and the internal inductance separately. A second harmonic component of the zeroth order field in combination with the dc harmonic of the zeroth order field specifies the internal inductance. The internal inductance in hand, measurement of the first order, first harmonic component of the magnetic field then determined beta poloidal. The degeneracy implicit in Shafranov's result (i.e. that only a combination of beta poloidal and internal inductance is measurable for a circular plasma cross section) reasserts itself as the elliptic results are collapsed to their circular limits
Analytical model of a burst assembly algorithm for the VBR in the OBS networks
International Nuclear Information System (INIS)
This paper presents a proposed analytical model for the number of bursts aggregated in a period of time in OBS networks. The model considers the case of VBR traffic with two different sending rates, which are SCR and PCR. The model is validated using extensive simulations. Where results from simulations are in total agreement with the results obtained by the proposed model. (author)
Yuya, Philip A.; Patel, Nimitt G.
2014-08-01
In the last few decades, nanoindentation has gained widespread acceptance as a technique for materials properties characterization at micron and submicron length scales. Accurate and precise characterization of material properties with a nanoindenter is critically dependent on the ability to correctly model the response of the test equipment in contact with the material. In dynamic nanoindention analysis, a simple Kelvin-Voigt model is commonly used to capture the viscoelastic response. However, this model oversimplifies the response of real viscoelastic materials such as polymers. A model is developed that captures the dynamic nanoindentation response of a viscoelastic material. Indenter tip-sample contact forces are modelled using a generalized Maxwell model. The results on a silicon elastomer were analysed using conventional two element Kelvin-Voigt model and contrasted to analysis done using the Maxwell model. The results show that conventional Kelvin-Voigt model overestimates the storage modulus of the silicone elastomer by ~30%. Maxwell model represents a significant improvement in capturing the viscoelastic material behaviour over the Voigt model.
Directory of Open Access Journals (Sweden)
Suresh V.
2016-02-01
Full Text Available In this paper, an analytical model is proposed to predict magnetic flux leakage (MFL signals from the surface defects in ferromagnetic tubes. The analytical expression consists of elliptic integrals of first kind based on the magnetic dipole model. The radial (Bz component of leakage fields is computed from the cylindrical holes in ferromagnetic tubes. The effectiveness of the model has been studied by analyzing MFL signals as a function of the defect parameters and lift-off. The model predicted results are verified with experimental results and a good agreement is observed between the analytical and the experimental results. This analytical expression could be used for quick prediction of MFL signals and also input data for defect reconstructions in inverse MFL problem.
International Nuclear Information System (INIS)
Geological storage of carbon dioxide (CO2) is becoming one of the most promising options for carbon mitigation. Because of the large number of existing wells, special consideration is required of geological storage of CO2 in mature sedimentary basins in North America. These wells represent potential leakage pathways for the stored CO2, and therefore, must be analyzed in the context of an overall environmental risk assessment. This paper examined the development of large-scale modeling tools to quantify potential CO2 leakage along existing wells. It presented an overview of the problem, including specific analyses that quantified spatial statistics of well locations in a mature basin. Modeling options and their relationship to uncertainty analysis were also presented. The study focused particularly on new analytical solutions for injection and leakage. It was concluded that new semi-analytical models for injection and leakage provide simple computational tools for quantitative estimation of leakage. Although they are more restrictive than general numerical models, they provide extreme efficiency while capturing the essential features of the flow processes. 20 refs., 1 tab., 6 figs
Automated refinement and inference of analytical models for metabolic networks
Schmidt, Michael D.; Vallabhajosyula, Ravishankar R.; Jenkins, Jerry W.; Hood, Jonathan E.; Soni, Abhishek S.; Wikswo, John P.; Lipson, Hod
2011-10-01
The reverse engineering of metabolic networks from experimental data is traditionally a labor-intensive task requiring a priori systems knowledge. Using a proven model as a test system, we demonstrate an automated method to simplify this process by modifying an existing or related model--suggesting nonlinear terms and structural modifications--or even constructing a new model that agrees with the system's time series observations. In certain cases, this method can identify the full dynamical model from scratch without prior knowledge or structural assumptions. The algorithm selects between multiple candidate models by designing experiments to make their predictions disagree. We performed computational experiments to analyze a nonlinear seven-dimensional model of yeast glycolytic oscillations. This approach corrected mistakes reliably in both approximated and overspecified models. The method performed well to high levels of noise for most states, could identify the correct model de novo, and make better predictions than ordinary parametric regression and neural network models. We identified an invariant quantity in the model, which accurately derived kinetics and the numerical sensitivity coefficients of the system. Finally, we compared the system to dynamic flux estimation and discussed the scaling and application of this methodology to automated experiment design and control in biological systems in real time.
Automated refinement and inference of analytical models for metabolic networks
International Nuclear Information System (INIS)
The reverse engineering of metabolic networks from experimental data is traditionally a labor-intensive task requiring a priori systems knowledge. Using a proven model as a test system, we demonstrate an automated method to simplify this process by modifying an existing or related model-–suggesting nonlinear terms and structural modifications–-or even constructing a new model that agrees with the system's time series observations. In certain cases, this method can identify the full dynamical model from scratch without prior knowledge or structural assumptions. The algorithm selects between multiple candidate models by designing experiments to make their predictions disagree. We performed computational experiments to analyze a nonlinear seven-dimensional model of yeast glycolytic oscillations. This approach corrected mistakes reliably in both approximated and overspecified models. The method performed well to high levels of noise for most states, could identify the correct model de novo, and make better predictions than ordinary parametric regression and neural network models. We identified an invariant quantity in the model, which accurately derived kinetics and the numerical sensitivity coefficients of the system. Finally, we compared the system to dynamic flux estimation and discussed the scaling and application of this methodology to automated experiment design and control in biological systems in real time
International Nuclear Information System (INIS)
The analytical drift-diffusion formalism is able to accurately simulate a wide range of solar cell architectures and was recently extended to include those with back surface reflectors. However, as solar cells approach the limits of material quality, photon recycling effects become increasingly important in predicting the behavior of these cells. In particular, the minority carrier diffusion length is significantly affected by the photon recycling, with consequences for the solar cell performance. In this paper, we outline an approach to account for photon recycling in the analytical Hovel model and compare analytical model predictions to GaAs-based experimental devices operating close to the fundamental efficiency limit
Further inspection of the stochastic growth model by an analytical approach
Lau, SHP
2002-01-01
It has been argued that a clear understanding of the stochastic growth model can best be achieved by working out an approximate analytical solution. This paper follows that idea but streamlines the presentation of the loglinear approximate solution for the neoclassical model of capital accumulation. By focusing on the partial elasticity of capital stock with respect to its lag term, this paper is able to confirm analytically some conclusions based on numerical calculations in previous papers,...
Analytical Model of Planar Double Split Ring Resonator
Zhurbenko, Vitaliy; Jensen, Thomas; Krozer, Viktor; Meincke, Peter
2007-01-01
This paper focuses on accurate modelling of microstrip double split ring resonators. The impedance matrix representation for coupled lines is applied for the first time to model the SRR, resulting in excellent model accuracy over a wide frequency range. Phase compensation is implemented to take into account the curved shape of the resonators. The presented results show that the accuracy better than 0.5% for the first four resonances. Analysis of a periodical structure with frequency selective...
Predicting population dynamics with analytical, simulation and supercomputer models
Energy Technology Data Exchange (ETDEWEB)
Onstad, D.W.
1987-07-01
A set of epizootiological models describing the influence of a microsporidian disease on the population dynamics of an herbivorous insect demonstrate the similarities and differences between the three major approaches now available for ecological modeling. Simulation modeling allows the incorporation of randomness or the timing of discrete events in the temporal dynamics. More complex models incorporating both temporal and spatial dynamics in variable and heterogeneous environments require the use of supercomputers. Under a number of realistic circumstances, the qualitative predictions of the approaches may differ.
Analytic solutions for degenerate Raman-coupled model
Institute of Scientific and Technical Information of China (English)
Zhang Zhi-Ming; Yu Ya-Fei
2008-01-01
The Raman-coupled interaction between an atom and a single mode of a cavity field is studied. For the cases in which a light field is initially in a coherent state and in a thermal state separately, we have derived the analytic expressions for the time evolutions of atomic population difference W, modulus B of the Bloch vector, and entropy E. We find that the time evolutions of these quantities are periodic with a period of e. The maxima of W and B appear at the scaled interaction time points (τ) = κπ(κ =0, 1, 2,...). At these time points, E = 0, which shows that the atom and the field are not entangled. Between these time points, E ≠ 0, which means that the atom and the field are entangled. When the field is initially in a coherent state, near the maxima, the envelope of W is a Gaussian function with a variance of 1/(4(-n)) ((-n) is the mean number of photons). Under the envelope, W oscillates at a frequency of (-n)/e.When the field is initially in a thermal state, near the maxima, W is a Lorentz function with a width of 1/(-n).
Energy demand analytics using coupled technological and economic models
Impacts of a range of policy scenarios on end-use energy demand are examined using a coupling of MARKAL, an energy system model with extensive supply and end-use technological detail, with Inforum LIFT, a large-scale model of the us. economy with inter-industry, government, and c...
Analytic model for ring pattern formation by bacterial swarmers
Arouh, Scott
2001-03-01
We analyze a model proposed by Medvedev, Kaper, and Kopell (the MKK model) for ring formation in two-dimensional bacterial colonies of Proteus mirabilis. We correct the model to formally include a feature crucial of the ring generation mechanism: a bacterial density threshold to the nonlinear diffusivity of the MKK model. We numerically integrate the model equations, and observe the logarithmic profiles of the bacterial densities near the front. These lead us to define a consolidation front distinct from the colony radius. We find that this consolidation front propagates outward toward the colony radius with a nearly constant velocity. We then implement the corrected MKK equations in two dimensions and compare our results with biological experiment. Our numerical results indicate that the two-dimensional corrected MKK model yields smooth (rather than branched) rings, and that colliding colonies merge if grown in phase but not if grown out of phase. We also introduce a model, based on coupling the MKK model to a nutrient field, for simulating experimentally observed branched rings.
On the Development of Parameterized Linear Analytical Longitudinal Airship Models
Kulczycki, Eric A.; Johnson, Joseph R.; Bayard, David S.; Elfes, Alberto; Quadrelli, Marco B.
2008-01-01
In order to explore Titan, a moon of Saturn, airships must be able to traverse the atmosphere autonomously. To achieve this, an accurate model and accurate control of the vehicle must be developed so that it is understood how the airship will react to specific sets of control inputs. This paper explains how longitudinal aircraft stability derivatives can be used with airship parameters to create a linear model of the airship solely by combining geometric and aerodynamic airship data. This method does not require system identification of the vehicle. All of the required data can be derived from computational fluid dynamics and wind tunnel testing. This alternate method of developing dynamic airship models will reduce time and cost. Results are compared to other stable airship dynamic models to validate the methods. Future work will address a lateral airship model using the same methods.
Probing protein orientation near charged surfaces with an implicit-solvent model and the PyGBe code
Cooper, Christopher D
2015-01-01
Protein-surface interactions are ubiquitous in biological processes and bioengineering, yet are not fully understood. In the field of biosensors, a key factor in biosensor performance is the orientation of biomolecules near charged surfaces. The aim of this work is developing and assessing a computational model to study proteins interacting with charged surfaces and obtain orientation data. After extending the implicit-solvent model used in the open-source code PyGBe and deriving an analytical solution for simple geometry, our careful grid-convergence analysis builds confidence on the correctness and value of our approach for probing protein orientation. Further computational experiments support it: they study preferred orientations for protein GB1 D4' and immunoglobulin G. Sampling the free energy for protein GB1 at a range of tilt and rotation angles with respect to the charged surface, we calculated the probability of the protein orientation and observed a dipolar behavior. This result is consistent with p...
Compact objects from gravitational collapse: an analytical toy model
Energy Technology Data Exchange (ETDEWEB)
Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Joshi, Pankaj S. [Tata Institute of Fundamental Research, Mumbai (India)
2015-12-15
We develop here a procedure to obtain regular static configurations resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature. (orig.)
Compact objects from gravitational collapse: an analytical toy model
Joshi, Pankaj S
2015-01-01
We develop here a procedure to obtain regular static configurations as resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.
Compact objects from gravitational collapse: an analytical toy model
Malafarina, Daniele; Joshi, Pankaj S.
2015-12-01
We develop here a procedure to obtain regular static configurations resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.
Recent Analytical and Numerical Results for The Navier-Stokes-Voigt Model and Related Models
Larios, Adam; Titi, Edriss; Petersen, Mark; Wingate, Beth
2010-11-01
The equations which govern the motions of fluids are notoriously difficult to handle both mathematically and computationally. Recently, a new approach to these equations, known as the Voigt-regularization, has been investigated as both a numerical and analytical regularization for the 3D Navier-Stokes equations, the Euler equations, and related fluid models. This inviscid regularization is related to the alpha-models of turbulent flow; however, it overcomes many of the problems present in those models. I will discuss recent work on the Voigt-regularization, as well as a new criterion for the finite-time blow-up of the Euler equations based on their Voigt-regularization. Time permitting, I will discuss some numerical results, as well as applications of this technique to the Magnetohydrodynamic (MHD) equations and various equations of ocean dynamics.
Analytical improvements to the Breit-Wigner isobar models
Szczepaniak, Adam P.
2015-01-01
We discuss the derivation and properties of the general representation of partial wave amplitudes in the context of improving the models currently used in analysis of three particle Dalitz distributions.
Human performance modeling for system of systems analytics :soldier fatigue.
Energy Technology Data Exchange (ETDEWEB)
Lawton, Craig R.; Campbell, James E.; Miller, Dwight Peter
2005-10-01
The military has identified Human Performance Modeling (HPM) as a significant requirement and challenge of future systems modeling and analysis initiatives as can be seen in the Department of Defense's (DoD) Defense Modeling and Simulation Office's (DMSO) Master Plan (DoD 5000.59-P 1995). To this goal, the military is currently spending millions of dollars on programs devoted to HPM in various military contexts. Examples include the Human Performance Modeling Integration (HPMI) program within the Air Force Research Laboratory, which focuses on integrating HPMs with constructive models of systems (e.g. cockpit simulations) and the Navy's Human Performance Center (HPC) established in September 2003. Nearly all of these initiatives focus on the interface between humans and a single system. This is insufficient in the era of highly complex network centric SoS. This report presents research and development in the area of HPM in a system-of-systems (SoS). Specifically, this report addresses modeling soldier fatigue and the potential impacts soldier fatigue can have on SoS performance.
The role of analytical models: Issues and frontiers
International Nuclear Information System (INIS)
A number of modeling attempts to analyze the implications of increasing competition in the electric power industry appeared in the early 1970s and occasionally throughout the early 1980s. Most of these of these analyses, however, considered only modest mechanisms to facilitate increased bulk power transactions between utility systems. More fundamental changes in market structure, such as the existence of independent power producers or wheeling transactions between customers and utility producers, were not considered. More recently in the course of the policy debate over increasing competition, a number of models have been used to analyze altemative scenarios of industry structure and regulation. In this Energy Modeling Forum (EMF) exercise, we attempted to challenge existing modeling frameworks beyond their original design capabilities. We tried to interpret altemative scenarios or other means of increasing competition in the electric power industry in the terms of existing modeling frameworks, to gain perspective using such models on how the different market players would interact, and to predict how electricity prices and other indicators of industry behavior might evolve under the altemative scenarios
Analytic model for the dynamic Z-pinch
Energy Technology Data Exchange (ETDEWEB)
Piriz, A. R., E-mail: roberto.piriz@uclm.es; Sun, Y. B. [E. T. S. I. Industriales, CYTEMA, and Instituto de Investigaciones Energéticas (INEI), Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Tahir, N. A. [GSI Helmholtzzentrum für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany)
2015-06-15
A model is presented for describing the cylindrical implosion of a shock wave driven by an accelerated piston. It is based in the identification of the acceleration of the shocked mass with the acceleration of the piston. The model yields the separate paths of the piston and the shock. In addition, by considering that the shocked region evolves isentropically, the approximate profiles of all the magnitudes in the shocked region are obtained. The application to the dynamic Z-pinch is presented and the results are compared with the well known snowplow and slug models which are also derived as limiting cases of the present model. The snowplow model is seen to yield a trajectory in between those of the shock and the piston. Instead, the neglect of the inertial effects in the slug model is seen to produce a too fast implosion, and the pressure uniformity is shown to lead to an unphysical instantaneous piston stopping when the shock arrives to the axis.
A simplified analytical model of radiative heat transfer in open cell foams
International Nuclear Information System (INIS)
A simplified one-dimensional analytical model of radiative heat transfer in foams is presented, based on the idea of dividing the porous material into layers at the pore level and then modeling each layer of the porous material as an equivalent semi-transparent, absorbing and reflecting plane. Compared to existing models, the model proposed in this paper has the advantage of explicitly accounting for the geometry of the foam and the radiative energy fluxes, at the same time ensuring self-consistency and offering the computational lightness of analytical models, without sacrificing the mathematical simplicity of the formulation. Using a regular cubic lattice representation and assuming diffuse radiation, straightforward analytical correlations are derived to evaluate the characteristics both of single layers of foam and of finite thickness samples, accounting for various boundary conditions. The predictions of the model are in good agreement with experimental data taken from the literature
Short-Term Forecasting Models for Photovoltaic Plants: Analytical versus Soft-Computing Techniques
Monteiro, Claudio; Fernandez-Jimenez, L. Alfredo; Ignacio J. Ramirez-Rosado; Muñoz-Jimenez, Andres; Lara-Santillan, Pedro M.
2013-01-01
We present and compare two short-term statistical forecasting models for hourly average electric power production forecasts of photovoltaic (PV) plants: the analytical PV power forecasting model (APVF) and the multiplayer perceptron PV forecasting model (MPVF). Both models use forecasts from numerical weather prediction (NWP) tools at the location of the PV plant as well as the past recorded values of PV hourly electric power production. The APVF model consists of an original modeling for adj...
ANALYTICAL STUDY OF MAINTAINABILITY MODELS FOR QUALITY EVALUATION
Directory of Open Access Journals (Sweden)
Rimmi Saini
2011-06-01
Full Text Available The interest in software system is increasing day by day. Dealing with the software systems is a complex task. Software must have some qualities on the basis of which it can be applied to any software system. Every software quality model has some characteristics and sub-characteristics, which affect software quality. In this Paper the main emphasis is given on maintainability characteristics. Every system requires that maintainability measure should be done in early stages of development life-cycle which will help the designers to correct the software, if there is any fault, in early phases of designing. By doing this, cost of the development of software will be reduced. The paper gives the overview of various quality models in which maintainability is described. Paper provides the analysis of maintainability in various quality models.
SIRS Dynamics on Random Networks: Simulations and Analytical Models
Rozhnova, Ganna; Nunes, Ana
The standard pair approximation equations (PA) for the Susceptible-Infective-Recovered-Susceptible (SIRS) model of infection spread on a network of homogeneous degree k predict a thin phase of sustained oscillations for parameter values that correspond to diseases that confer long lasting immunity. Here we present a study of the dependence of this oscillatory phase on the parameter k and of its relevance to understand the behaviour of simulations on networks. For k = 4, we compare the phase diagram of the PA model with the results of simulations on regular random graphs (RRG) of the same degree. We show that for parameter values in the oscillatory phase, and even for large system sizes, the simulations either die out or exhibit damped oscillations, depending on the initial conditions. This failure of the standard PA model to capture the qualitative behaviour of the simulations on large RRGs is currently being investigated.
Improving intellectual capital model using analytic network process
Directory of Open Access Journals (Sweden)
Ratapol Wudhikarn
2013-06-01
Full Text Available This study proposes a new approach to prioritize the key company’s indicators and relative elements following process model of intellectual capital (IC. The IC is improved by the application ofanalytic network process (ANP. The ANP provides the weights and priorities to all focused key performance indicators (KPIs serving to the business concept. These obtained weights can also be passedto other relative elements, those of key success factors (KSFs and IC categories, in the process model of IC. These prioritized KPIs, KSFs and IC categories assist the managers and decision-makers to focus on the crucial elements that mostly affect the business concept.
International Nuclear Information System (INIS)
Transport threshold models of neoclassical tearing modes in tokamaks are investigated analytically. An analysis is made of the competition between strong transverse heat transport, on the one hand, and longitudinal heat transport, longitudinal heat convection, longitudinal inertial transport, and rotational transport, on the other hand, which leads to the establishment of the perturbed temperature profile in magnetic islands. It is shown that, in all these cases, the temperature profile can be found analytically by using rigorous solutions to the heat conduction equation in the near and far regions of a chain of magnetic islands and then by matching these solutions. Analytic expressions for the temperature profile are used to calculate the contribution of the bootstrap current to the generalized Rutherford equation for the island width evolution with the aim of constructing particular transport threshold models of neoclassical tearing modes. Four transport threshold models, differing in the underlying competing mechanisms, are analyzed: collisional, convective, inertial, and rotational models. The collisional model constructed analytically is shown to coincide exactly with that calculated numerically; the reason is that the analytical temperature profile turns out to be the same as the numerical profile. The results obtained can be useful in developing the next generation of general threshold models. The first steps toward such models have already been made
Analytic model for assessing thermal performance of SCUBA divers
Montgomery, L. D.
1975-01-01
To assist design of adequate protective clothing, mathematical model of man's thermoregulatory system has been developed so that body thermal responses under immersed conditions can be predicted accurately. Experimental data encompassed wide range of water temperatures, protective clothing, breathing-gas mixtures, and durations of immersion.
A Meta-Analytic Review of Behavior Modeling Training
Taylor, Paul J.; Russ-Eft, Darlene F.; Chan, Daniel W. L.
2005-01-01
A meta-analysis of 117 studies evaluated the effects of behavior modeling training (BMT) on 6 training outcomes, across characteristics of training design. BMT effects were largest for learning outcomes, smaller for job behavior, and smaller still for results outcomes. Although BMT effects on declarative knowledge decayed over time, training…
Analytical model of LDMOS with a single step buried oxide layer
Yuan, Song; Duan, Baoxing; Cao, Zhen; Guo, Haijun; Yang, Yintang
2016-09-01
In this paper, a two-dimensional analytical model is established for the Single-Step Buried Oxide SOI structure proposed by the authors. Based on the two-dimensional Poisson equation, the analytic expression of the surface electric field and potential distributions for the device is achieved. In the SBOSOI (Single-Step Buried Oxide Silicon On Insulator) structure, the buried oxide layer thickness changes stepwise along the drift region, and the electric field in the oxide layer also varies with the different buried oxide layer thickness. These variations will modulate the surface electric field distribution through the electric field modulation effects, which makes the surface electric field distribution more uniform. As a result, the breakdown voltage of the device is improved by 60% compared with the conventional SOI structure. To verify the accuracy of the analytical model, the device simulation software ISE TCAD is utilized, the analytical values are in good agreement with the simulation results by the simulation software. The results verified the established two-dimensional analytical model for SBOSOI structure is valid, and it also illustrates the breakdown voltage enhancement by the electric field modulation effect sufficiently. The established analytical models will provide the physical and mathematical basis for further analysis of the new power devices with the patterned buried oxide layer.
Analytical model of LDMOS with a double step buried oxide layer
Yuan, Song; Duan, Baoxing; Cao, Zhen; Guo, Haijun; Yang, Yintang
2016-09-01
In this paper, a two-dimensional analytical model is established for the Buried Oxide Double Step Silicon On Insulator structure proposed by the authors. Based on the two-dimensional Poisson equation, the analytic expressions of the surface electric field and potential distributions for the device are achieved. In the BODS (Buried Oxide Double Step Silicon On Insulator) structure, the buried oxide layer thickness changes stepwise along the drift region, and the positive charge in the drift region can be accumulated at the corner of the step. These accumulated charge function as the space charge in the depleted drift region. At the same time, the electric field in the oxide layer also varies with the different drift region thickness. These variations especially the accumulated charge will modulate the surface electric field distribution through the electric field modulation effects, which makes the surface electric field distribution more uniform. As a result, the breakdown voltage of the device is improved by 30% compared with the conventional SOI structure. To verify the accuracy of the analytical model, the device simulation software ISE TCAD is utilized, the analytical values are in good agreement with the simulation results by the simulation software. That means the established two-dimensional analytical model for BODS structure is valid, and it also illustrates the breakdown voltage enhancement by the electric field modulation effect sufficiently. The established analytical models will provide the physical and mathematical basis for further analysis of the new power devices with the patterned buried oxide layer.
Analytical and Numerical Modelling of FRP Debonding from Concrete Substrate under Pure Shearing
Institute of Scientific and Technical Information of China (English)
PAN Jinlong; XU Zhun; C K Y Leung; LI Zongjin
2012-01-01
External bonding of fiber reinforced polymer (FRP) composites on the concrete structures has been proved to be an effective and efficient way to strengthen concrete structures.For a FRP strengthened concrete beam,it is usually observed that the failure occurs in the concrete and a thin layer of concrete is attached on the surface of the debonded FRP plate.To study the debond behavior between concrete and FRP composites,an analytical model based on the three-parameter model is developed to study the debonding behavior for the FRP-to-concrete joint under pure shearing.Then,nonlinear FEM analysis is conducted to verify the proposed analytical model.The FEM results shows good agreement with the results from the model.Finally,with the analytical model,sensitivity analyses are performed to study the effect of the interfacial parameters or the geometric parameters on the debonding behavior.
Some analytic solutions for stochastic reactor models based on the joint composition PDF
Kraft, Markus; Fey, Harald
1999-06-01
The stochastic reactor models, partially stirred reactor (PaSR) and partially stirred plug flow reactor (PaSPFR) have been investigated. These models are based on a simplified joint composition PDF transport equation. Analytic solutions for five different Cauchy problems for the PDF transport equation as given by the stochastic reactor models are presented. In all cases, molecular mixing in the stochastic reactor models is described by the linear mean-square estimation (LMSE) mixing model for turbulent diffusion. The analytic solutions have been found by combining the method of characteristics with a set of ordinary differential equations for the statistical moments to account for the functional dependence of the coefficients in the corresponding PDF transport equation. For each case an example problem is discussed to illustrate the behaviour of the analytic solution.
Analytical models for well-mixed populations of cooperators and defectors under limiting resources
Requejo, Rubén J; 10.1103/PhysRevE.85.066112
2012-01-01
In the study of the evolution of cooperation, resource limitations are usually assumed just to provide a finite population size. Recently, however, agent-based models have pointed out that resource limitation may modify the original structure of the interactions and allow for the survival of unconditional cooperators in well-mixed populations. Here, we present analytical simplified versions of two types of agent-based models recently published: one in which the limiting resource constrains the ability of reproduction of individuals but not their survival, and a second one where the limiting resource is necessary for both reproduction and survival. One finds that the analytical models display, with a few differences, the same qualitative behavior of the more complex agent-based models. In addition, the analytical models allow us to expand the study and identify the dimensionless parameters governing the final fate of the system, such as coexistence of cooperators and defectors, or dominance of defectors or of ...
Analytical and Numerical Models to Predict the Behaviorof Unbonded Flexible Risers Under Torsion
Institute of Scientific and Technical Information of China (English)
任少飞; 薛鸿祥; 唐文勇
2016-01-01
This paper presents analytical and numerical models to predict the behavior of unbonded flexible risers under torsion. The analytical model takes local bending and torsion of tensile armor wires into consideration, and equilibrium equations of forces and displacements of layers are deduced. The numerical model includes lay angle, cross-sectional profiles of carcass, pressure armor layer and contact between layers. Abaqus/Explicit quasi-static simulation and mass scaling are adopted to avoid convergence problem and excessive computation time caused by geometric and contact nonlinearities. Results show that local bending and torsion of helical strips may have great influence on torsional stiffness, but stress related to bending and torsion is negligible; the presentation of anti-friction tapes may have great influence both on torsional stiffness and stress; hysteresis of torsion-twist relationship under cyclic loading is obtained by numerical model, which cannot be predicted by analytical model because of the ignorance of friction between layers.
Probe modeling for millimeter-wave integrated-circuit horn antennas
Guo, Yong; Chiao, Jung-Chih; Potter, Kent A.; Rutledge, David B.
1992-01-01
Integrated-circuit probe-excited horn-antenna arrays etched in silicon are well developed. They are a very promising class of antenna arrays for milli-meter and submillimeter applications. Further development of this technology involves integrating mixers and amplifiers into the antenna arrays. In an effort to develop an antenna-mixer array based on the existing technology, various antenna probes inside the pyramidal horns have been examined on scaled model-horns at the micr...
An analytical model for in situ extraction of organic vapors
Roy, W.R.; Griffin, R.A.
1991-01-01
This paper introduces a simple convective-flow model that can be used as a screening tool and for conducting sensitivity analyses for in situ vapor extraction of organic compounds from porous media. An assumption basic to this model was that the total mass of volatile organic chemicals (VOC) exists in three forms: as vapors, in the soil solution, and adsorbed to soil particles. The equilibrium partitioning between the vapor-liquid phase was described by Henry's law constants (K(H)) and between the liquid-soil phase by soil adsorption constants (K(d)) derived from soil organic carbon-water partition coefficients (K(oc)). The model was used to assess the extractability of 36 VOCs from a hypothetical site. Most of the VOCs appeared to be removable from soil by this technology, although modeling results suggested that rates for the alcohols and ketones may be very slow. In general, rates for weakly adsorbed compounds (K(oc) < 100 mL/g) were significantly higher when K(H) was greater than 10-4 atm??m3??mol-1. When K(oc) was greater than about 100 mL/g, the rates of extraction were sensitive to the amount of organic carbon present in the soil. The air permeability of the soil material (k) was a critical factor. In situ extraction needs careful evaluation when k is less than 10 millidarcies to determine its applicability. An increase in the vacuum applied to an extraction well accelerated removal rates but the diameter of the well had little effect. However, an increase in the length of the well screen open to the contaminated zone significantly affected removal rates, especially in low-permeability materials.This paper introduces a simple convective-flow model that can be used as a screening tool and for conducting sensitivity analyses for in situ vapor extraction of organic compounds from porous media. An assumption basic to this model was that the total mass of volatile organic chemicals (VOC) exists in three forms: as vapors, in the soil solution, and adsorbed to soil
An Analytical hierarchy process model for the evaluation of college
Yin, Qingli
2013-01-01
Taking into account the characteristcs of college experimental teaching, through investgaton and analysis, evaluaton indices and an Analytcal Hierarchy Process (AHP) model of experimental teaching quality have been established following the analytcal hierarchy process method, and the evaluaton indices have been given reasonable weights. An example is given, and the evaluaton results show that the evaluaton indices proposed in this paper are capable of refectng objectvely, exactly ...
ANALYTICAL STUDY OF MAINTAINABILITY MODELS FOR QUALITY EVALUATION
Rimmi Saini; Sanjay Kumar Dubey; (Dr.) Ajay Rana
2011-01-01
The interest in software system is increasing day by day. Dealing with the software systems is a complex task. Software must have some qualities on the basis of which it can be applied to any software system. Every software quality model has some characteristics and sub-characteristics, which affect software quality. In this Paper the main emphasis is given on maintainability characteristics. Every system requires that maintainability measure should be done in early stages of development life...
INFORMATIONAL-ANALYTIC MODEL OF REGIONAL PROJECT PORTFOLIO FORMING
I. A. Osaulenko
2016-01-01
The article is devoted to the problem of regional project portfolio management in context of interaction of the regional development’s motive forces interaction. The features of innovation development on the regional level and their influence on the portfolio forming process considered. An existing approaches for portfolio modelling and formal criterion of the projects selection analyzed. At the same time the organization of key subjects of regional development interaction described. The aim ...
Analytical approach to the modeling of radiation effects in tissue
International Nuclear Information System (INIS)
This paper reports the application of reactor physics calculational methods to the analysis of the interaction of radiation with tissue with the objective of developing a radiation effects model that is equivalent to the reactor point kinetics equations in mathematical rigor and utility. A primary motivation for this effort is that concerns about exposure to low levels of radiation have caused enormous expense to the nuclear industry in terms of both lack of public acceptance and regulation of activities involving minor amounts of radioactivity. These concerns might be alleviated if there were a rigorous yet mathematically tractable model of the effects of radiation on tissue. Our understanding of such effects is derived by extrapolation from high-level exposures. These extrapolations involve statistical considerations that are not readily understood by the public. Regulators also have difficulty in that existing mathematical models of the biological effects of radiation do little to promote understanding by the nonspecialist. There are two approaches. At one extreme are simple calculational methods that combine the definition of dose with information on the range of the radiation. For example, for charged particles, all of the energy is deposited locally
Gedge, M. R.
1979-01-01
Analytical models were developed to study the effect of flow contraction and screening on inflow distortions to identify qualitative design criteria. Results of the study are that: (1) static testing distortions are due to atmospheric turbulence, nacelle boundary layer, exhaust flow reingestion, flow over stand, ground plane, and engine casing; (2) flow contraction suppresses, initially, turbulent axial velocity distortions and magnifies turbulent transverse velocity distortions; (3) perforated plate and gauze screens suppress axial components of velocity distortions to a degree determined by the screen pressure loss coefficient; (4) honeycomb screen suppress transverse components of velocity distortions to a degree determined by the length to diameter ratio of the honeycomb; (5) acoustic transmission loss of perforated plate is controlled by the reactance of its acoustic impedance; (6) acoustic transmission loss of honeycomb screens is negligible; and (7) a model for the direction change due to a corner between honeycomb panels compares favorably with measured data.
Numerical and analytical modelling of battery thermal management using passive cooling systems
Greco, Angelo
2016-01-01
This thesis presents the battery thermal management systems (BTMS) modelling of Li-ions batteries and investigates the design and modelling of different passive cooling management solutions from single battery to module level. A simplified one-dimensional transient computational model of a prismatic lithium-ion battery cell is developed using thermal circuit approach in conjunction with the thermal model of the heat pipe. The proposed model is compared to an analytical solution based on varia...
Wang Xinzhi; He Yurong; Zheng Yan; Ma Junjun; H. Inaki Schlaberg
2014-01-01
Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis (FEA) is applied to the numerical simulation. Temperature and stres...
Modeling strategies using predictive analytics : Forecasting future sales and churn management
Aronsson, Henrik
2015-01-01
This project was carried out for a company named Attollo, a consulting firm specialized in Business Intelligence and Corporate Performance Management. The project aims to explore a new area for Attollo, predictive analytics, which is then applied to Klarna, a client of Attollo. Attollo has a partnership with IBM, which sells services for predictive analytics. The tool that this project is carried out with, is a software from IBM: SPSS Modeler. Five different examples are given of what and how...
Tyrychtr, J.; A. Vasilenko
2015-01-01
Econometric model application in farms is a very complex process requiring knowledge not only the economy but also statistical and mathematical methods in agriculture workers themselves. The solution may be an application of econometric problems in analytical decision support systems for farms managers. For such a solution is necessary to design a multidimensional database for support online analytical data processing (OLAP). This paper proposes a new method (called TEM-CM) fo...
Analytical modeling of squeeze air film damping of biomimetic MEMS directional microphone
Ishfaque, Asif; Kim, Byungki
2016-08-01
Squeeze air film damping is introduced in microelectromechanical systems due to the motion of the fluid between two closely spaced oscillating micro-structures. The literature is abundant with different analytical models to address the squeeze air film damping effects, however, there is a lack of work in modeling the practical sensors like directional microphones. Here, we derive an analytical model of squeeze air film damping of first two fundamental vibration modes, namely, rocking and bending modes, of a directional microphone inspired from the fly Ormia ochracea's ear anatomy. A modified Reynolds equation that includes compressibility and rarefaction effects is used in the analysis. Pressure distribution under the vibrating diaphragm is derived by using Green's function. From mathematical modeling of the fly's inspired mechanical model, we infer that bringing the damping ratios of both modes in the critical damping range enhance the directional sensitivity cues. The microphone parameters are varied in derived damping formulas to bring the damping ratios in the vicinity of critical damping, and to show the usefulness of the analytical model in tuning the damping ratios of both modes. The accuracy of analytical damping results are also verified by finite element method (FEM) using ANSYS. The FEM results are in full compliance with the analytical results.
Tian, Zhen; Folkerts, Michael; Shi, Feng; Jiang, Steve B; Jia, Xun
2015-01-01
Monte Carlo (MC) simulation is considered as the most accurate method for radiation dose calculations. Accuracy of a source model for a linear accelerator is critical for the overall dose calculation accuracy. In this paper, we presented an analytical source model that we recently developed for GPU-based MC dose calculations. A key concept called phase-space-ring (PSR) was proposed. It contained a group of particles that are of the same type and close in energy and radial distance to the center of the phase-space plane. The model parameterized probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. For a primary photon PSRs, the particle direction is assumed to be from the beam spot. A finite spot size is modeled with a 2D Gaussian distribution. For a scattered photon PSR, multiple Gaussian components were used to model the particle direction. The direction distribution of an electron PSRs was also modeled as a 2D Gaussian distributi...
Analytical models of calcium binding in a calcium channel
International Nuclear Information System (INIS)
The anomalous mole fraction effect of L-type calcium channels is analyzed using a Fermi like distribution with the experimental data of Almers and McCleskey [J. Physiol. 353, 585 (1984)] and the atomic resolution model of Lipkind and Fozzard [Biochemistry 40, 6786 (2001)] of the selectivity filter of the channel. Much of the analysis is algebraic, independent of differential equations. The Fermi distribution is derived from the configuration entropy of ions and water molecules with different sizes, different valences, and interstitial voids between particles. It allows us to calculate potentials and distances (between the binding ion and the oxygen ions of the glutamate side chains) directly from the experimental data using algebraic formulas. The spatial resolution of these results is comparable with those of molecular models, but of course the accuracy is no better than that implied by the experimental data. The glutamate side chains in our model are flexible enough to accommodate different types of binding ions in different bath conditions. The binding curves of Na+ and Ca2+ for [CaCl2] ranging from 10−8 to 10−2 M with a fixed 32 mM background [NaCl] are shown to agree with published Monte Carlo simulations. The Poisson-Fermi differential equation—that includes both steric and correlation effects—is then used to obtain the spatial profiles of energy, concentration, and dielectric coefficient from the solvent region to the filter. The energy profiles of ions are shown to depend sensitively on the steric energy that is not taken into account in the classical rate theory. We improve the rate theory by introducing a steric energy that lumps the effects of excluded volumes of all ions and water molecules and empty spaces between particles created by Lennard-Jones type and electrostatic forces. We show that the energy landscape varies significantly with bath concentrations. The energy landscape is not constant
Analytics For Distracted Driver Behavior Modeling in Dilemma Zone
Energy Technology Data Exchange (ETDEWEB)
Li, Jan-Mou [ORNL; Malikopoulos, Andreas [ORNL; Thakur, Gautam [ORNL; Vatsavai, Raju [ORNL
2014-01-01
In this paper, we present the results obtained and insights gained through the analysis of TRB contest data. We used exploratory analysis, regression, and clustering models for gaining insights into the driver behavior in a dilemma zone while driving under distraction. While simple exploratory analysis showed the distinguishing driver behavior patterns among different popu- lation groups in the dilemma zone, regression analysis showed statically signification relationships between groups of variables. In addition to analyzing the contest data, we have also looked into the possible impact of distracted driving on the fuel economy.
An analytical solution to a simplified EDXRF model for Monte Carlo code verification
International Nuclear Information System (INIS)
The objective of this study is to obtain an analytical solution to the scalar photon transport equation that can be used to obtain benchmark results for the verification of energy dispersive X-Ray fluorescence (EDXRF) Monte Carlo simulation codes. The multi-collided flux method (multiple scattering method) is implemented to obtain analytical expressions for the space-, energy-, and angle-dependent scalar photon flux for a one dimensional EDXRF model problem. In order to obtain benchmark results, higher-order multiple scattering terms are included in the multi-collided flux method. The details of the analytical solution and of the proposed EDXRF model problem are presented. Analytical expressions obtained are then used to calculate the energy-dependent current. The analytically-calculated energy-dependent current is compared with Monte Carlo code results. The findings of this study show that analytical solutions to the scalar photon transport equation with the proposed model problem can be used as a verification tool in EDXRF Monte Carlo code development.
Semi-analytical modelling of positive corona discharge in air
Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong
2013-09-01
Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.
Directory of Open Access Journals (Sweden)
Marc R Birtwistle
Full Text Available Numerous unimolecular, genetically-encoded Förster Resonance Energy Transfer (FRET probes for monitoring biochemical activities in live cells have been developed over the past decade. As these probes allow for collection of high frequency, spatially resolved data on signaling events in live cells and tissues, they are an attractive technology for obtaining data to develop quantitative, mathematical models of spatiotemporal signaling dynamics. However, to be useful for such purposes the observed FRET from such probes should be related to a biological quantity of interest through a defined mathematical relationship, which is straightforward when this relationship is linear, and can be difficult otherwise. First, we show that only in rare circumstances is the observed FRET linearly proportional to a biochemical activity. Therefore in most cases FRET measurements should only be compared either to explicitly modeled probes or to concentrations of products of the biochemical activity, but not to activities themselves. Importantly, we find that FRET measured by standard intensity-based, ratiometric methods is inherently non-linear with respect to the fraction of probes undergoing FRET. Alternatively, we find that quantifying FRET either via (1 fluorescence lifetime imaging (FLIM or (2 ratiometric methods where the donor emission intensity is divided by the directly-excited acceptor emission intensity (denoted R(alt is linear with respect to the fraction of probes undergoing FRET. This linearity property allows one to calculate the fraction of active probes based on the FRET measurement. Thus, our results suggest that either FLIM or ratiometric methods based on R(alt are the preferred techniques for obtaining quantitative data from FRET probe experiments for mathematical modeling purposes.
Analytical modeling and experimental validation of a V-shape piezoelectric ultrasonic transducer
Li, Xiaoniu; Yao, Zhiyuan
2016-07-01
In this paper, an analytical model of a V-shape piezoelectric ultrasonic transducer is presented. The V-shape piezoelectric ultrasonic transducer has been widely applied to the piezoelectric actuator (ultrasonic motor), ultrasonic aided fabrication, sensor, and energy harvesting device. The V-shape piezoelectric ultrasonic transducer consists of two Langevin-type transducers connected together through a coupling point with a certain coupling angle. Considering the longitudinal and lateral movements of a single beam, the symmetrical and asymmetrical modals of the V-shape piezoelectric ultrasonic transducer are calculated. By using Hamilton–Lagrange equations, the electromechanical coupling model of the V-shape piezoelectric ultrasonic transducer is proposed. The influence of the coupling angle and cross-section on modal characteristics and electromechanical coupling coefficient are analyzed by the analytical model. A prototype of the V-shape piezoelectric ultrasonic transducer is fabricated, and the results of the experiments are in good agreement with the analytical model.
Directory of Open Access Journals (Sweden)
J. Tyrychtr
2015-09-01
Full Text Available Econometric model application in farms is a very complex process requiring knowledge not only the economy but also statistical and mathematical methods in agriculture workers themselves. The solution may be an application of econometric problems in analytical decision support systems for farms managers. For such a solution is necessary to design a multidimensional database for support online analytical data processing (OLAP. This paper proposes a new method (called TEM-CM for formal transformation of econometric model to the conceptual data model for creating multidimensional schemes. This new method allows to formalize the process of transferring production function in agriculture to multidimensional data model and thus contribute to a more efficient design of data warehouses and OLAP databases for decision support in the agricultural analytics systems.
Leśniewska, Barbara; Kisielewska, Katarzyna; Wiater, Józefa; Godlewska-Żyłkiewicz, Beata
2016-01-01
A new fast method for determination of mobile zinc fractions in soil is proposed in this work. The three-stage modified BCR procedure used for fractionation of zinc in soil was accelerated by using ultrasounds. The working parameters of an ultrasound probe, a power and a time of sonication, were optimized in order to acquire the content of analyte in soil extracts obtained by ultrasound-assisted sequential extraction (USE) consistent with that obtained by conventional modified Community Bureau of Reference (BCR) procedure. The content of zinc in extracts was determined by flame atomic absorption spectrometry. The developed USE procedure allowed for shortening the total extraction time from 48 h to 27 min in comparison to conventional modified BCR procedure. The method was fully validated, and the uncertainty budget was evaluated. The trueness and reproducibility of the developed method was confirmed by analysis of certified reference material of lake sediment BCR-701. The applicability of the procedure for fast, low costs and reliable determination of mobile zinc fraction in soil, which may be useful for assessing of anthropogenic impacts on natural resources and environmental monitoring purposes, was proved by analysis of different types of soil collected from Podlaskie Province (Poland). PMID:26666658
Analytical modelling and experimental studies of SIS tunnel solar cells
Energy Technology Data Exchange (ETDEWEB)
Cheknane, Ali [Laboratoire de Valorisation des Energies Renouvelables et Environnements Agressifs, Universite Amar Telidji de Laghouat, BP 37G route de Ghardaia, Laghouat (03000) Algerie (Algeria)], E-mail: cheknanali@yahoo.com
2009-06-07
This paper presents an experimental and computational study of semiconductor-insulator-semiconductor (SIS) tunnel solar cells. A transparent and conductive film of thallium trioxide Tl{sub 2}O{sub 3} has been deposited by anodic oxidation onto an n-Si(1 0 0) face to realize the SIS tunnel solar cells based on Si/SiO{sub x}/Tl{sub 2}O{sub 3}. An efficiency of 8.77% has been obtained under an incident power density of 33 mW cm{sup -2} illumination condition. A PSPICE model is implemented. The calculated results show that the theoretical values are in good agreement with experimental data. Moreover, the simulation clearly demonstrates that the performance of the tested device can be significantly improved.
Analytical model for intergrain expansion and cleavage: random grain boundaries
International Nuclear Information System (INIS)
A description of rigid-body grain boundary relaxation and cleavage in tungsten is performed using a pair-wise Morse interatomic potential in real and reciprocal spaces. Cleavage energies and grain boundary dilatation of random grain boundaries were formulated and computed using atomic layer interaction energies. These values were determined using a model for a relaxed random grain boundary that consists of rigid grains on either side of the boundary plane that are allowed to float to reach the equilibrium position. Expressions are given that describe in real space the energy of interatomic interaction on random grain boundaries with twist orientation. It was shown that grain-boundary expansion and cleavage energies of the most widespread random grain boundaries are mainly determined by grain boundary atomic density
An analytical model for wind-driven Arctic summer sea ice drift
Park, H. -S.; Stewart, A L
2016-01-01
The authors present an analytical model for wind-driven free drift of sea ice that allows for an arbitrary mixture of ice and open water. The model includes an ice–ocean boundary layer with an Ekman spiral, forced by transfers of wind-input momentum both through the sea ice and directly into the open water between the ice floes. The analytical tractability of this model allows efficient calculation of the ice velocity provided that the surface wind field is known and t...
Analytical modeling of circuit aerodynamics in the new NASA Lewis Altitude Wind Tunnel
Towne, C. E.; Povinelli, L. A.; Kunik, W. G.; Muramoti, K. K.; Hughes, C. E.; Levy, R.
1985-01-01
Rehabilitation and extention of the capability of the altitude wind tunnel (AWT) was analyzed. The analytical modelling program involves the use of advanced axisymmetric and three dimensional viscous analyses to compute the flow through the various AWT components. Results for the analytical modelling of the high speed leg aerodynamics are presented; these include: an evaluation of the flow quality at the entrance to the test section, an investigation of the effects of test section bleed for different model blockages, and an examination of three dimensional effects in the diffuser due to reentry flow and due to the change in cross sectional shape of the exhaust scoop.
Analytical modeling of circuit aerodynamics in the new NASA Lewis wind tunnel
Towne, C. E.; Povinelli, L. A.; Kunik, W. G.; Muramoto, K. K.; Hughes, C. E.; Levy, R.
1985-01-01
Rehabilitation and extention of the capability of the altitude wind tunnel (AWT) was analyzed. The analytical modeling program involves the use of advanced axisymmetric and three dimensional viscous analyses to compute the flow through the various AWT components. Results for the analytical modeling of the high speed leg aerodynamics are presented; these include: an evaluation of the flow quality at the entrance to the test section, an investigation of the effects of test section bleed for different model blockages, and an examination of three dimensional effects in the diffuser due to reentry flow and due to the change in cross sectional shape of the exhaust scoop.
A New Analytical Model for TCP Reno with Bursts Error Considered
Institute of Scientific and Technical Information of China (English)
DENG Jian-min; JI Hong; YUE Guang-xin; YIN Chang-chuan
2003-01-01
In this paper, we present a new analytical model for TCP Reno, and this method can also be used in other versions of TCP. The first order two-state Markovian model is used to describe the wireless link, so as to deal with the burst error in wireless links very well. The tineout mechanism of TCP is also considered and a geometric method describes the erponential growth of TCP timeout . Also this method is effective for the study of the growth of TCP transmission window. Analytical results indicate that this model is effective.
Design of Analytical Model for Ultra Wideband System
Directory of Open Access Journals (Sweden)
Alpana P. Adsul
2010-05-01
Full Text Available The UWB (Ultra Wideband technology has drawn phenomenal interest in industry as well as academia.Ultra Wide Band impulse radios are microwave systems that communicate using baseband pulses of veryshort duration. UWB systems transmit information data over a wide frequency spectrum with low powerconsumption and high speed for local area wireless network applications. Unlike the traditional digitalcommunication method based on a carrier wave, UWB is pulse based. Pulse Generation, modulation, andmultiple access are time domain dependent functions. This paper presents the development of analyticalmodel for UWB system. A theoretical reference for UWB system performances is designed in non-idealchannels. In this mathematical models for biphase, pulse–position and hybrid modulation are developed.The detection rules are formulated for detecting signals in AWGN channels. The performance of UWBsystem is described with the help of BER. The BER of a UWB system depends on the modulation schemeand detection method it uses. It is observed that for optimum performance modulation parameterselection is important.
Global sensitivity analysis of analytical vibroacoustic transmission models
Christen, Jean-Loup; Ichchou, Mohamed; Troclet, Bernard; Bareille, Olivier; Ouisse, Morvan
2016-04-01
Noise reduction issues arise in many engineering problems. One typical vibroacoustic problem is the transmission loss (TL) optimisation and control. The TL depends mainly on the mechanical parameters of the considered media. At early stages of the design, such parameters are not well known. Decision making tools are therefore needed to tackle this issue. In this paper, we consider the use of the Fourier Amplitude Sensitivity Test (FAST) for the analysis of the impact of mechanical parameters on features of interest. FAST is implemented with several structural configurations. FAST method is used to estimate the relative influence of the model parameters while assuming some uncertainty or variability on their values. The method offers a way to synthesize the results of a multiparametric analysis with large variability. Results are presented for transmission loss of isotropic, orthotropic and sandwich plates excited by a diffuse field on one side. Qualitative trends found to agree with the physical expectation. Design rules can then be set up for vibroacoustic indicators. The case of a sandwich plate is taken as an example of the use of this method inside an optimisation process and for uncertainty quantification.
Mechanistic analytical models for long-distance seed dispersal by wind.
Katul, G G; Porporato, A; Nathan, R; Siqueira, M; Soons, M B; Poggi, D; Horn, H S; Levin, S A
2005-09-01
We introduce an analytical model, the Wald analytical long-distance dispersal (WALD) model, for estimating dispersal kernels of wind-dispersed seeds and their escape probability from the canopy. The model is based on simplifications to well-established three-dimensional Lagrangian stochastic approaches for turbulent scalar transport resulting in a two-parameter Wald (or inverse Gaussian) distribution. Unlike commonly used phenomenological models, WALD's parameters can be estimated from the key factors affecting wind dispersal--wind statistics, seed release height, and seed terminal velocity--determined independently of dispersal data. WALD's asymptotic power-law tail has an exponent of -3/2, a limiting value verified by a meta-analysis for a wide variety of measured dispersal kernels and larger than the exponent of the bivariate Student t-test (2Dt). We tested WALD using three dispersal data sets on forest trees, heathland shrubs, and grassland forbs and compared WALD's performance with that of other analytical mechanistic models (revised versions of the tilted Gaussian Plume model and the advection-diffusion equation), revealing fairest agreement between WALD predictions and measurements. Analytical mechanistic models, such as WALD, combine the advantages of simplicity and mechanistic understanding and are valuable tools for modeling large-scale, long-term plant population dynamics. PMID:16224691
International Nuclear Information System (INIS)
Analytical solutions of the stationary conduction equation are obtained. The solutions are used for developing the transport threshold models (TTM) of the neoclassical tearing modes (NTM) in tokamaks. The following TTM are considered: collisional, convective, inertial and rotational. These TTM may be the fragments of the more general models of NTM
Cheung, Mike W. L.; Chan, Wai
2009-01-01
Structural equation modeling (SEM) is widely used as a statistical framework to test complex models in behavioral and social sciences. When the number of publications increases, there is a need to systematically synthesize them. Methodology of synthesizing findings in the context of SEM is known as meta-analytic SEM (MASEM). Although correlation…
Validation of analytical models for the design of basal reinforced piled embankments
Van Eekelen, S.J.M.; Bezuijen, A.; Van Tol, A.F.
2014-01-01
Van Eekelen et al., 2012a, Van Eekelen et al., 2012b and Van Eekelen et al., 2013) have introduced an analytical model for the design of the geosynthetic reinforcement (GR) in a piled embankment. This paper further validates this model with measurements from seven full-scale tests and four series of
Analytical model for double split ring resonators with arbitrary ring width
DEFF Research Database (Denmark)
Zhurbenko, Vitaliy; Jensen, Thomas; Krozer, Viktor;
2008-01-01
For the first time, the analytical model for a double split ring resonator with unequal width rings is developed. The proposed models for the resonators with equal and unequal widths are based on an impedance matrix representation and provide the prediction of performance in a wide frequency range...
Several advances in the analytic element method have been made to enhance its performance and facilitate three-dimensional ground-water flow modeling in a regional aquifer setting. First, a new public domain modular code (ModAEM) has been developed for modeling ground-water flow ...
Analytical models of operational risk and new results on the correlation problem
Vivien Brunel
2013-01-01
We propose a portfolio approach for operational risk quantification based on a class of analytical models from which we derive new results on the correlation problem. In particular, we show that uniform correlation is a robust assumption for measuring capital charges in these models.
Improved Analytical Model of a Permanent-Magnet Brushless DC Motor
Kumar, P.; Bauer, P.
2008-01-01
In this paper, we develop a comprehensive model of a permanent-magnet brushless DC (BLDC) motor. An analytical model for determining instantaneous air-gap field density is developed. This instantaneous field distribution can be further used to determine the cogging torque, induced back electromotive
A Bayesian Multi-Level Factor Analytic Model of Consumer Price Sensitivities across Categories
Duvvuri, Sri Devi; Gruca, Thomas S.
2010-01-01
Identifying price sensitive consumers is an important problem in marketing. We develop a Bayesian multi-level factor analytic model of the covariation among household-level price sensitivities across product categories that are substitutes. Based on a multivariate probit model of category incidence, this framework also allows the researcher to…
Analytical models and system topologies for remote multispectral data acquisition and classification
Huck, F. O.; Park, S. K.; Burcher, E. E.; Kelly, W. L., IV
1978-01-01
Simple analytical models are presented of the radiometric and statistical processes that are involved in multispectral data acquisition and classification. Also presented are basic system topologies which combine remote sensing with data classification. These models and topologies offer a preliminary but systematic step towards the use of computer simulations to analyze remote multispectral data acquisition and classification systems.
DEFF Research Database (Denmark)
Kushch, V.I.; Shmegera, S.V.; Mishnaevsky, Leon
2011-01-01
Two micromechanical, representative unit cell type models of fiber reinforced composite (FRC) are applied to simulate explicitly onset and accumulation of scattered local damage in the form of interface debonding. The first model is based on the analytical, multipole expansion type solution of th...... both models are discussed. It has been shown that the developed models provide detailed analysis of the progressive debonding phenomena including the interface crack cluster formation, overall stiffness reduction and induced anisotropy of the effective elastic moduli of composite....
Two-phase bounded acceleration traffic flow model: Analytical solutions and applications
LEBACQUE, JP
2003-01-01
The present paper describes a two phase traffic flow model. One phase is traffic equilibrium: flow and speed are functions of density, and traffic acceleration is low. The second phase is characterized by constant acceleration. This model extends first order traffic flow models and recaptures the fact that traffic acceleration is bounded. The paper show how to calculate analytical solutions of the two-phase model for dynamic traffic situations, provides a set of calculation rules, and analyze...
An Analytical Gate-All-Around MOSFET Model for Circuit Simulation
Directory of Open Access Journals (Sweden)
Kuan-Chou Lin
2015-01-01
Full Text Available A generic charge-based compact model for undoped (lightly doped quadruple-gate (QG and cylindrical-gate MOSFETs using Verilog-A is developed. This model is based on the exact solution of Poisson’s equation with scale length. The fundamental DC and charging currents of QG MOSFETs are physically and analytically calculated. In addition, as the Verilog-A modeling is portable for different circuit simulators, the modeling scheme provides a useful tool for circuit designers.
anQCD: Fortran programs for couplings at complex momenta in various analytic QCD models
Ayala, César; Cvetič, Gorazd
2016-02-01
We provide three Fortran programs which evaluate the QCD analytic (holomorphic) couplings Aν(Q2) for complex or real squared momenta Q2. These couplings are holomorphic analogs of the powers a(Q2)ν of the underlying perturbative QCD (pQCD) coupling a(Q2) ≡αs(Q2) / π, in three analytic QCD models (anQCD): Fractional Analytic Perturbation Theory (FAPT), Two-delta analytic QCD (2 δanQCD), and Massive Perturbation Theory (MPT). The index ν can be noninteger. The provided programs do basically the same job as the Mathematica package anQCD.m published by us previously (Ayala and Cvetič, 2015), but are now written in Fortran.
Analytical Model for Pair Dispersion in Gaussian Models of Eulerian Turbulence
Eyink, Gregory; Benveniste, Damien
2012-11-01
Synthetic models of Eulerian turbulence are often used as computational shortcuts for studying Lagrangian properties of turbulence (e.g. Elliott & Majda, 1996). These models have been criticized by Thomson & Devenish (2005), who argued on physical grounds that their sweeping effects are very different from true turbulence. We give analytical results for Eulerian turbulence modeled by Gaussian fields. Our starting point is an exact integrodifferential equation for the particle pair separation distribution obtained from Gaussian integration-by-parts. When velocity correlation times are short, a Markovian approximation leads to a Richardson-type diffusion model. We obtain a time-dependent pair diffusivity tensor of the form Kij (r , t) =Sij (r) τ (r , t) where Sij (r) is the structure-function tensor and τ (r , t) is an effective correlation time of velocity increments. Crucially, this is found to be the minimum value of three times: the intrinsic turnover time τeddy (r) at separation r, the overall evolution time t , and the sweeping time r /v0 with v0 the rms velocity. We thus verify the main argument of Thomson & Devenish (2005), but we predict scaling laws for pair dispersion different from theirs for zero-mean velocity ensembles.
Comprehensive analytical model for CW laser induced heat in turbid media.
Erkol, Hakan; Nouizi, Farouk; Luk, Alex; Unlu, Mehmet Burcin; Gulsen, Gultekin
2015-11-30
In this work, we present a new analytical approach to model continuous wave laser induced temperature in highly homogeneous turbid media. First, the diffusion equation is used to model light transport and a comprehensive solution is derived analytically by obtaining a special Greens' function. Next, the time-dependent bio-heat equation is used to describe the induced heat increase and propagation within the medium. The bio-heat equation is solved analytically utilizing the separation of variables technique. Our theoretical model is successfully validated using numerical simulations and experimental studies with agarose phantoms and ex-vivo chicken breast samples. The encouraging results show that our method can be implemented as a simulation tool to determine important laser parameters that govern the magnitude of temperature rise within homogenous biological tissue or organs. PMID:26698736
Approximate analytic solutions to 3D unconfined groundwater flow within regional 2D models
Luther, K.; Haitjema, H. M.
2000-04-01
We present methods for finding approximate analytic solutions to three-dimensional (3D) unconfined steady state groundwater flow near partially penetrating and horizontal wells, and for combining those solutions with regional two-dimensional (2D) models. The 3D solutions use distributed singularities (analytic elements) to enforce boundary conditions on the phreatic surface and seepage faces at vertical wells, and to maintain fixed-head boundary conditions, obtained from the 2D model, at the perimeter of the 3D model. The approximate 3D solutions are analytic (continuous and differentiable) everywhere, including on the phreatic surface itself. While continuity of flow is satisfied exactly in the infinite 3D flow domain, water balance errors can occur across the phreatic surface.
Analytical modeling and simulation of germanium single gate silicon on insulator TFET
International Nuclear Information System (INIS)
This paper proposes a new two dimensional (2D) analytical model for a germanium (Ge) single gate silicon-on-insulator tunnel field effect transistor (SG SOI TFET). The parabolic approximation technique is used to solve the 2D Poisson equation with suitable boundary conditions and analytical expressions are derived for the surface potential, the electric field along the channel and the vertical electric field. The device output tunnelling current is derived further by using the electric fields. The results show that Ge based TFETs have significant improvements in on-current characteristics. The effectiveness of the proposed model has been verified by comparing the analytical model results with the technology computer aided design (TCAD) simulation results and also comparing them with results from a silicon based TFET. (semiconductor devices)
Energy Technology Data Exchange (ETDEWEB)
Khater, Antoine; Szczesniak, Dominik [Laboratoire de Physique de l' Etat Condense UMR 6087, Universite du Maine, 72085 Le Mans (France)
2011-04-01
An analytical model is presented for the electronic conductance in a one dimensional atomic chain across an isolated defect. The model system consists of two semi infinite lead atomic chains with the defect atom making the junction between the two leads. The calculation is based on a linear combination of atomic orbitals in the tight-binding approximation, with a single atomic one s-like orbital chosen in the present case. The matching method is used to derive analytical expressions for the scattering cross sections for the reflection and transmission processes across the defect, in the Landauer-Buttiker representation. These analytical results verify the known limits for an infinite atomic chain with no defects. The model can be applied numerically for one dimensional atomic systems supported by appropriate templates. It is also of interest since it would help establish efficient procedures for ensemble averages over a field of impurity configurations in real physical systems.
Anisotropic Multishell Analytical Modeling of an Intervertebral Disk Subjected to Axial Compression.
Demers, Sébastien; Nadeau, Sylvie; Bouzid, Abdel-Hakim
2016-04-01
Studies on intervertebral disk (IVD) response to various loads and postures are essential to understand disk's mechanical functions and to suggest preventive and corrective actions in the workplace. The experimental and finite-element (FE) approaches are well-suited for these studies, but validating their findings is difficult, partly due to the lack of alternative methods. Analytical modeling could allow methodological triangulation and help validation of FE models. This paper presents an analytical method based on thin-shell, beam-on-elastic-foundation and composite materials theories to evaluate the stresses in the anulus fibrosus (AF) of an axisymmetric disk composed of multiple thin lamellae. Large deformations of the soft tissues are accounted for using an iterative method and the anisotropic material properties are derived from a published biaxial experiment. The results are compared to those obtained by FE modeling. The results demonstrate the capability of the analytical model to evaluate the stresses at any location of the simplified AF. It also demonstrates that anisotropy reduces stresses in the lamellae. This novel model is a preliminary step in developing valuable analytical models of IVDs, and represents a distinctive groundwork that is able to sustain future refinements. This paper suggests important features that may be included to improve model realism. PMID:26833355
A Semi-Analytical Model for Short Range Dispersion From Ground Sources
Gavze, E.; Fattal, E.; Reichman, R.
2014-12-01
A semi-analytical model for dispersion of passive scalars from ground sources up to distances of a few hundred meters is presented. Most widely used analytical models are Gaussian models which assume both a uniform wind field and homogeneous turbulence. These assumptions are not valid when ground sources are involved since both the wind and the turbulence depend on height. The model presented here is free of these two assumptions. The formulation of the vertical dispersion is based on approximating the vertical profiles of the wind and the the vertical diffusion coefficient, based on Monin Obukhov Similarity Theory, as power laws. One advantage of this approach is that it allows for non Gaussian vertical profiles of the concentration which better fit the experimental data. For the lateral dispersion the model still assumes a Gaussian form. A system of equations was developed to compute the cloud width. This system of equations is based on an analytical solution of a Langevin equation which takes into account the non-homogeneity of the wind and the turbulence in the vertical direction. The model was tested against two field experiments. Comparison with a Gaussian model showed that it performed much better in predicting both the integrated cross wind ground concentration and the cloud width. Analytical, or semi-analytical models are useful as they are simple to use and require only a short computation time, compared, for example, to Lagrangian Stochastic Models. The presented model is very efficient from the computational point of view. As such it is suitable for cases in which repeated computations of the concentration field are required, as for example in risk assessments and in the inverse problem of source determination.
Coupled thermodynamic-dynamic semi-analytical model of Free Piston Stirling engines
Formosa, Fabien
2013-01-01
The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standard...
Analytical and numerical modeling of non-collinear shear wave mixing at an imperfect interface
Zhang, Ziyin; Nagy, Peter B.; Hassan, Waled
2016-02-01
Non-collinear shear wave mixing at an imperfect interface between two solids can be exploited for nonlinear ultrasonic assessment of bond quality. In this study we developed two analytical models for nonlinear imperfect interfaces. The first model uses a finite nonlinear interfacial stiffness representation of an imperfect interface of vanishing thickness, while the second model relies on a thin nonlinear interphase layer to represent an imperfect interface region. The second model is actually a derivative of the first model obtained by calculating the equivalent interfacial stiffness of a thin isotropic nonlinear interphase layer in the quasi-static approximation. The predictions of both analytical models were numerically verified by comparison to COMSOL finite element simulations. These models can accurately predict the excess nonlinearity caused by interface imperfections based on the strength of the reflected and transmitted mixed longitudinal waves produced by them under non-collinear shear wave interrogation.
International Nuclear Information System (INIS)
Huffaker and Cohen (ref.1) claim that the perturbed-Morse-oscillator (PMO) model, for the potential energy function for hydrogen, gives very high accuracy results; surpassing that of the RKR potential. A more efficient approach to formulating analytical functions based on the PMO model is given, and some defects of the PMO model are discussed
DEFF Research Database (Denmark)
Musaeus, Peter; Bennedsen, Andreas Brændstrup; Hansen, Janne Saltoft;
2015-01-01
I denne artikel vil vi præsentere en strategi til inddragelse af læringsanalytik (learning analytics) ved evaluering af universitetsunderviseres brug af et nyt LMS på Aarhus Universitet: Blackboard. Vi diskuterer en model (BLAME: Blended Learning Analytics Model of Evaluation) for, hvordan...... kategorisering af kurser og data om læringsanalytik indsamlet på Blackboard kan integreres. Endvidere belyser vi, hvilke implikationer en sådan læringsanalytik kan have for blended learning ved at analysere to forskellige uddannelses-cases/illustrationer. Dernæst diskuterer vi pædagogisk udvikling i forbindelse...
International Nuclear Information System (INIS)
The objective of this work is provide analytical formula of the dispersion parameters to describe the polluted point source in space release to the atmosphere. The Gaussian Plume Model (GPM) choice as appropriates framework to illustrate this work. The analytical formula of the Gaussian Plume Model dispersion parameters in spherical coordinate was written. These parameters were calculated at different azimuth and polar angle and with different stability index and plotted in family of curves. This curves show a symmetrical distribution of the vertical and horizontal dispersion parameters around the polar angleπ /2
SPICE compatible analytical electron mobility model for biaxial strained-Si-MOSFETs
International Nuclear Information System (INIS)
This paper describes an analytical model for bulk electron mobility in strained-Si layers as a function of strain. Phonon scattering, columbic scattering and surface roughness scattering are included to analyze the full mobility model. Analytical explicit calculations of all of the parameters to accurately estimate the electron mobility have been made. The results predict an increase in the electron mobility with the application of biaxial strain as also predicted from the basic theory of strain physics of metal oxide semiconductor (MOS) devices. The results have also been compared with numerically reported results and show good agreement. (semiconductor devices)
Evaluation of subject contrast and normalized average glandular dose by semi-analytical models
International Nuclear Information System (INIS)
In this work, two semi-analytical models are described to evaluate the subject contrast of nodules and the normalized average glandular dose in mammography. Both models were used to study the influence of some parameters, such as breast characteristics (thickness and composition) and incident spectra (kVp and target-filter combination) on the subject contrast of a nodule and on the normalized average glandular dose. From the subject contrast results, detection limits of nodules were also determined. Our results are in good agreement with those reported by other authors, who had used Monte Carlo simulation, showing the robustness of our semi-analytical method.
Useful measures and models for analytical quality management in medical laboratories.
Westgard, James O
2016-02-01
The 2014 Milan Conference "Defining analytical performance goals 15 years after the Stockholm Conference" initiated a new discussion of issues concerning goals for precision, trueness or bias, total analytical error (TAE), and measurement uncertainty (MU). Goal-setting models are critical for analytical quality management, along with error models, quality-assessment models, quality-planning models, as well as comprehensive models for quality management systems. There are also critical underlying issues, such as an emphasis on MU to the possible exclusion of TAE and a corresponding preference for separate precision and bias goals instead of a combined total error goal. This opinion recommends careful consideration of the differences in the concepts of accuracy and traceability and the appropriateness of different measures, particularly TAE as a measure of accuracy and MU as a measure of traceability. TAE is essential to manage quality within a medical laboratory and MU and trueness are essential to achieve comparability of results across laboratories. With this perspective, laboratory scientists can better understand the many measures and models needed for analytical quality management and assess their usefulness for practical applications in medical laboratories. PMID:26426893
On Improving Analytical Models of Cosmic Reionization for Matching Numerical Simulations
Energy Technology Data Exchange (ETDEWEB)
Kaurov, Alexander A. [Univ. of Chicago, IL (United States)
2016-01-01
The methods for studying the epoch of cosmic reionization vary from full radiative transfer simulations to purely analytical models. While numerical approaches are computationally expensive and are not suitable for generating many mock catalogs, analytical methods are based on assumptions and approximations. We explore the interconnection between both methods. First, we ask how the analytical framework of excursion set formalism can be used for statistical analysis of numerical simulations and visual representation of the morphology of ionization fronts. Second, we explore the methods of training the analytical model on a given numerical simulation. We present a new code which emerged from this study. Its main application is to match the analytical model with a numerical simulation. Then, it allows one to generate mock reionization catalogs with volumes exceeding the original simulation quickly and computationally inexpensively, meanwhile reproducing large scale statistical properties. These mock catalogs are particularly useful for CMB polarization and 21cm experiments, where large volumes are required to simulate the observed signal.
Analytical coupled vibroacoustic modeling of membrane-type acoustic metamaterials: membrane model.
Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming; Hu, Gengkai; Sun, Chin-Teh
2014-09-01
Membrane-type acoustic metamaterials (MAMs) have demonstrated unusual capacity in controlling low-frequency sound transmission/reflection. In this paper, an analytical vibroacoustic membrane model is developed to study sound transmission behavior of the MAM under a normal incidence. The MAM is composed of a prestretched elastic membrane with attached rigid masses. To accurately capture finite-dimension rigid mass effects on the membrane deformation, the point matching approach is adopted by applying a set of distributed point forces along the interfacial boundary between masses and the membrane. The accuracy and capability of the theoretical model is verified through the comparison with the finite element method. In particular, microstructure effects such as weight, size, and eccentricity of the attached mass, pretension, and thickness of the membrane on the resulting transmission peak and dip frequencies of the MAM are quantitatively investigated. New peak and dip frequencies are found for the MAM with one and multiple eccentric attached masses. The developed model can be served as an efficient tool for design of such membrane-type metamaterials. PMID:25190372
Towards an Analytical Age-Dependent Model of Contrast Sensitivity Functions for an Ageing Society
Joulan, Karine; Brémond, Roland
2015-01-01
The Contrast Sensitivity Function (CSF) describes how the visibility of a grating depends on the stimulus spatial frequency. Many published CSF data have demonstrated that contrast sensitivity declines with age. However, an age-dependent analytical model of the CSF is not available to date. In this paper, we propose such an analytical CSF model based on visual mechanisms, taking into account the age factor. To this end, we have extended an existing model from Barten (1999), taking into account the dependencies of this model's optical and physiological parameters on age. Age-dependent models of the cones and ganglion cells densities, the optical and neural MTF, and optical and neural noise are proposed, based on published data. The proposed age-dependent CSF is finally tested against available experimental data, with fair results. Such an age-dependent model may be beneficial when designing real-time age-dependent image coding and display applications. PMID:26078994
An analytical incremental model for the analysis of the cup drawing
Directory of Open Access Journals (Sweden)
H. Gharib
2006-04-01
Full Text Available Purpose: of this paper Develop an analytical model for the cup drawing process to solve for the induced stresses and strains over the deforming sheet at any stage of deformation until a full cup is formed.Design/methodology/approach: An analytical model is developed for the cup drawing process by determining the variation of stresses and strains over the deforming sheet. The model uses finite difference approach and numerical procedures to solve for equilibrium, continuity, and plasticity equations in an incremental fashion.Findings: The developed analytical model results showed good correlation with experimental ones from the literature. Also, the analytical model was found to be useful in conducting parametric studies in order to determine how the different process parameters can affect the deforming cup.Research limitations/implications: This paper includes the development of an analytical model to analyze the deep drawing of axisymmetric cups. This model is then used as the solution engine for the optimization of the blank holder force for such cups avoiding failure by wrinkling or tearing. This model also gives an insight of the modes of deformation in the deep drawing process.Practical implications: This paper is part of a procedure that leads to the optimization of the blank holder loading scheme. The full procedure as presented in the two parts of the work may be applied in industry to minimize the maximum punch load or the work done during deep drawing process by modifying the blank holder force and at the same time avoid failures by wrinkling or tearing.Originality/value: Developing a predictive/corrective technique for solving the unknown boundaries of the deforming sheet.
Probing models of information spreading in social networks
Zoller, J; Montangero, S.
2014-01-01
We apply signal processing analysis to the information spreading in scale-free network. To reproduce typical behaviors obtained from the analysis of information spreading in the world wide web we use a modified SIS model where synergy effects and influential nodes are taken into account. This model depends on a single free parameter that characterize the memory-time of the spreading process. We show that by means of fractal analysis it is possible -from aggregated easily accessible data- to g...
Biomolecular pleiomorphism probed by spatial interpolation of coarse models
Rusu, Mirabela; Birmanns, Stefan; Wriggers, Willy
2008-01-01
In low resolution structures of biological assemblies one can often observe conformational deviations that require a flexible rearrangement of structural domains fitted at the atomic level. We are evaluating interpolation methods for the flexible alignment of atomic models based on coarse models. Spatial interpolation is well established in image-processing and visualization to describe the overall deformation or warping of an object or an image. Combined with a coarse representation of the b...
Analytical Charge Voltage Model in MOS Inversion Layer Based on Space Charge Capacitance
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC,continuous expressions of surface potential and inversion layer carrier density are derived.Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.
A quasi-analytical breakdown voltage model in four-layer punch-through TVS devices
Urresti, Jesus; Hidalgo, Salvador; Flores, David; Roig, Jaume; Rebollo, José; Mazarredo, Imanol
2005-08-01
A quasi-analytical model addressed to predict the breakdown voltage in four-layer transient voltage suppressor (TVS) diodes based on the punch-through effect is reported in this paper. For breakdown voltage in excess of 1 V, a closed form expression is derived. In addition, the three-layer TVS diode can also be described with the developed model. Finally, results obtained from the model are in good agreement with simulation and experimental data.
Analytic models for the density of a ground-state spinor condensate
Gautam, Sandeep; Adhikari, S. K.
2015-08-01
We demonstrate that the ground state of a trapped spin-1 and spin-2 spinor ferromagnetic Bose-Einstein condensate (BEC) can be well approximated by a single decoupled Gross-Pitaevskii (GP) equation. Useful analytic models for the ground-state densities of ferromagnetic BECs are obtained from the Thomas-Fermi approximation (TFA) to this decoupled equation. Similarly, for the ground states of spin-1 antiferromagnetic and spin-2 antiferromagnetic and cyclic BECs, some of the spin-component densities are zero, which reduces the coupled GP equation to a simple reduced form. Analytic models for ground-state densities are also obtained for antiferromagnetic and cyclic BECs from the TFA to the respective reduced GP equations. The analytic densities are illustrated and compared with the full numerical solution of the GP equation with realistic experimental parameters.
Analytical model for the density distribution in the Io plasma torus
Mei, YI; Thorne, Richard M.; Bagenal, Fran
1995-01-01
An analytical model is developed for the diffusive equilibrium plasma density distribution in the Io plasma torus. The model has been employed successfully to follow the ray path of plasma waves in the multi-ion Jovian magnetosphere; it would also be valuable for other studies of the Io torus that require a smooth and continuous description of the plasma density and its gradients. Validity of the analytical treatment requires that the temperature of thermal electrons be much lower than the ion temperature and that superthermal electrons be much less abundant than the thermal electrons; these two conditions are satisfied in the warm outer region of the Io torus from L = 6 to L = 10. The analytical solutions agree well with exact numerical calculations for the most dense portion of the Io torus within 30 deg of the equator.
Heat transfer in cellulose-based aerogels: Analytical modelling and measurements
International Nuclear Information System (INIS)
A simple analytical approach for estimating the total heat transfer inside new cellulose-based aerogels has been investigated. The model accounts for the characteristic solid matrix at the nanometric scale by using a cellular representation of the nanofoam porous structure. The radiation-conduction heat transfer is taken into account. Previous analytical correlation for the fluid phase is used to model the conduction heat transfer in gas. New analytical formulations based on mean free path theory combined with phonon tracking approach are proposed to model the conduction heat transfer in the solid phase at the nanometric scale. The contribution of radiation heat transfer is obtained from Rayleigh scattering approach combined to the Rosseland approximation. These analytical relations validated experimentally are expected to be useful for researchers aiming at developing new insulating organic aerogels since they permit to determine conduction-radiation equivalent conductivity as a function of cell dimensions, phonon and optical properties of cellulose. - Highlights: • Development of an original model for estimating the heat transfer in aerocellulose. • Radiation, fluid conduction and solid conduction contributions are treated separately. • Modelling takes into account the “nanoscopic effects”. • Results validated experimentally under different temperature and pressure
Comparing analytical and Monte Carlo optical diffusion models in phosphor-based X-ray detectors
Kalyvas, N.; Liaparinos, P.
2014-03-01
Luminescent materials are employed as radiation to light converters in detectors of medical imaging systems, often referred to as phosphor screens. Several processes affect the light transfer properties of phosphors. Amongst the most important is the interaction of light. Light attenuation (absorption and scattering) can be described either through "diffusion" theory in theoretical models or "quantum" theory in Monte Carlo methods. Although analytical methods, based on photon diffusion equations, have been preferentially employed to investigate optical diffusion in the past, Monte Carlo simulation models can overcome several of the analytical modelling assumptions. The present study aimed to compare both methodologies and investigate the dependence of the analytical model optical parameters as a function of particle size. It was found that the optical photon attenuation coefficients calculated by analytical modeling are decreased with respect to the particle size (in the region 1- 12 μm). In addition, for particles sizes smaller than 6μm there is no simultaneous agreement between the theoretical modulation transfer function and light escape values with respect to the Monte Carlo data.
Saengprom, Narumon; Erawan, Waraporn; Damrongpanit, Suntonrapot; Sakulku, Jaruwan
2015-01-01
The purposes of this study were 1) Compare analytical thinking ability by testing the same sets of students 5 times 2) Develop and verify whether analytical thinking ability of students corresponds to second-order growth curve factors model. Samples were 1,093 eighth-grade students. The results revealed that 1) Analytical thinking ability scores…
Coupled thermodynamic-dynamic semi-analytical model of free piston Stirling engines
International Nuclear Information System (INIS)
Research highlights: → The free piston Stirling behaviour relies on its thermal and dynamic features. → A global semi-analytical model for preliminary design is developed. → The model compared with NASA-RE1000 experimental data shows good correlations. -- Abstract: The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standardized description of the engine allows efficient and realistic preliminary design of FPSE.
Biomolecular pleiomorphism probed by spatial interpolation of coarse models.
Rusu, Mirabela; Birmanns, Stefan; Wriggers, Willy
2008-11-01
In low resolution structures of biological assemblies one can often observe conformational deviations that require a flexible rearrangement of structural domains fitted at the atomic level. We are evaluating interpolation methods for the flexible alignment of atomic models based on coarse models. Spatial interpolation is well established in image-processing and visualization to describe the overall deformation or warping of an object or an image. Combined with a coarse representation of the biological system by feature vectors, such methods can provide a flexible approximation of the molecular structure. We have compared three well-known interpolation techniques and evaluated the results by comparing them with constrained molecular dynamics. One method, inverse distance weighting interpolation, consistently produced models that were nearly indistinguishable on the alpha carbon level from the molecular dynamics results. The method is simple to apply and enables flexing of structures by non-expert modelers. This is useful for the basic interpretation of volumetric data in biological applications such as electron microscopy. The method can be used as a general interpretation tool for sparsely sampled motions derived from coarse models. PMID:18757874
Development of an analytical model for steamflood in stratified reservoirs of heavy oil
International Nuclear Information System (INIS)
The use of analytical models to predict reservoir behavior depends on the similarity between the mathematically modeled system and the reservoir. Currently, there are not any models available for the prediction of steamflood behavior in stratified reservoirs based on the characteristics of reservoirs found in the Colombian Middle Magdalena valley, because the existing analytical models describe homogenous or idealized reservoirs. Therefore, it is necessary to propose a new model that includes the presence of clay intercalation in zones submitted to steamflood. The new analytical model is founded on the principles describing heat flow in porous media presented in the models proposed by Marx and Langenheim (1959); Mandl and Volek (1967), and Closmann (1967). Then, a series of assumptions related to the producing and non-producing zones and steamflood were determined, thus defining the system to be modeled. Once the system is defined, the initial and boundary conditions were established to contribute to find specific solutions for the case described. A set of heat balancing procedures were proposed from which a series of integro-differential equations were found. These equations were solved by using the Laplace transform method. The mathematical expressions were defined for the calculation of parameters such as volume of the heated zone, the rate of instantaneous and cumulative heat losses, and the oil rate and recovery factor. We can find differences when comparing the model response with the simulation, because in the mathematical model, we cannot include phenomena such as drop pressure, relative permeability and the change of oil viscosity with temperature. However, the new analytical model describes approximately the steam zone behavior, when the heat flow in the clay intercalations is not in stationary state.
Probing models of information spreading in social networks
International Nuclear Information System (INIS)
We apply signal processing analysis to the information spreading in a scale-free network. To reproduce typical behaviours obtained from the analysis of information spreading in the World Wide Web, we use a modified SIS (from ‘susceptible–infectious–susceptible’) model where synergy effects and influential nodes are taken into account. This model depends on a single free parameter that characterizes the memory time of the spreading process. We show that by means of fractal analysis it is possible—from aggregated easily accessible data—to gain information on the memory time of the underlying mechanism driving the information spreading process. (paper)
Directory of Open Access Journals (Sweden)
Dina V. Lazareva
2015-06-01
Full Text Available A new mathematical model of asymmetric support structure frame type is built on the basis of numerical-analytical boundary elements method (BEM. To describe the design scheme used is the graph theory. Building the model taken into account is the effect of frame members restrained torsion, which presence is due to the fact that these elements are thin-walled. The built model represents a real object as a two-axle semi-trailer platform. To implement the BEM algorithm obtained are analytical expressions of the fundamental functions and vector load components. The effected calculations are based on the semi-trailer two different models, using finite elements and boundary elements methods. The analysis showed that the error between the results obtained on the basis of two numerical methods and experimental data is about 4%, that indicates the adequacy of the proposed mathematical model.
Analytic State Space Model for an Unsteady Finite-Span Wing
Izraelevitz, Jacob; Zhu, Qiang; Triantafyllou, Michael
2015-11-01
Real-time control of unsteady flows, such as force control in flapping wings, requires simple wake models that easily translate into robust control designs. We analytically derive a state-space model for the unsteady trailing vortex system behind a finite aspect-ratio flapping wing. Contrary to prior models, the downwash and lift distributions over the span can be arbitrary, including tip effects. The wake vorticity is assumed to be a fully unsteady distribution, with the exception of quasi-steady (no rollup) geometry. Each discretization along the span has one to four states to represent the local unsteady wake-induced downwash, lift, and circulation. The model supports independently time-varying velocity, heave, and twist along the span. We validate this state-space model through comparison with existing analytic solutions for elliptic wings and an unsteady inviscid panel method.
Probing the Inert Doublet Dark Matter Model with Cherenkov Telescopes
Garcia-Cely, Camilo; Ibarra, Alejandro
2015-01-01
We present a detailed study of the annihilation signals of the inert dark matter doublet model in its high mass regime. Concretely, we study the prospects to observe gamma-ray signals of the model in current and projected Cherenkov telescopes taking into account the Sommerfeld effect and including the contribution to the spectrum from gamma-ray lines as well as from internal bremsstrahlung. We show that present observations of the galactic center by the H.E.S.S. instrument are able exclude regions of the parameter space that give the correct dark matter relic abundance. In particular, models with the charged and the neutral components of the inert doublet nearly degenerate in mass have strong gamma-ray signals. Furthermore, for dark matter particle masses above 1 TeV, we find that the non-observation of the continuum of photons generated by the hadronization of the annihilation products typically give stronger constraints on the model parameters than the sharp spectral features associated to annihilation into...
Decision Making in Reference to Model of Marketing Predictive Analytics – Theory and Practice
Directory of Open Access Journals (Sweden)
Piotr Tarka
2014-03-01
Full Text Available Purpose: The objective of this paper is to describe concepts and assumptions of predictive marketing analytics in reference to decision making. In particular, we highlight issues pertaining to the importance of data and the modern approach to data analysis and processing with the purpose of solving real marketing problems that companies encounter in business. Methodology: In this paper authors provide two study cases showing how, and to what extent predictive marketing analytics work can be useful in practice e.g., investigation of the marketing environment. The two cases are based on organizations operating mainly on Web site domain. The fi rst part of this article, begins a discussion with the explanation of a general idea of predictive marketing analytics. The second part runs through opportunities it creates for companies in the process of building strong competitive advantage in the market. The paper article ends with a brief comparison of predictive analytics versus traditional marketing-mix analysis. Findings: Analytics play an extremely important role in the current process of business management based on planning, organizing, implementing and controlling marketing activities. Predictive analytics provides the actual and current picture of the external environment. They also explain what problems are faced with the company in business activities. Analytics tailor marketing solutions to the right time and place at minimum costs. In fact they control the effi ciency and simultaneously increases the effectiveness of the firm. Practical implications: Based on the study cases comparing two enterprises carrying business activities in different areas, one can say that predictive analytics has far more been embraces extensively than classical marketing-mix analyses. The predictive approach yields greater speed of data collection and analysis, stronger predictive accuracy, better obtained competitor data, and more transparent models where one can
Piscitelli, Francesco; Van Esch, Patrick
2013-01-01
A simple model is explored mainly analytically to calculate and understand the PHS of single and multi-layer thermal neutron detectors and to help optimize the design in different circumstances. Several theorems are deduced that can help guide the design.
Construction of Obtaining Optical Image Analytical Models of Internal Structure Controlled Objects
Tereschenko, Lidia; Semenov, Oleksander
2010-01-01
Tereschenko, Lydia. Construction of Obtaining Optical Image Analytical Models of Internal Structure Controlled Objects [Lydia Tereschenko, Alexander Semenov] // Statistical Methods of Signal and Data Processing (SMSDP-2010): Intern.Conf. Proсeed., Kiev, Ukraine, October 13-14, 2010 / Chair І. Prokopenko. – Кiev: NAU-Druk, 2010. – 36-38 pp. – англ.
A study on improvement of analytical prediction model for spacer grid pressure loss coefficients
International Nuclear Information System (INIS)
Nuclear fuel assemblies used in the nuclear power plants consist of the nuclear fuel rods, the control rod guide tubes, an instrument guide tube, spacer grids,a bottom nozzle, a top nozzle. The spacer grid is the most important component of the fuel assembly components for thermal hydraulic and mechanical design and analyses. The spacer grids fixed with the guide tubes support the fuel rods and have the very important role to activate thermal energy transfer by the coolant mixing caused to the turbulent flow and crossflow in the subchannels. In this paper, the analytical spacer grid pressure loss prediction model has been studied and improved by considering the test section wall to spacer grid gap pressure loss independently and applying the appropriate friction drag coefficient to predict pressure loss more accurately at the low Reynolds number region. The improved analytical model has been verified based on the hydraulic pressure drop test results for the spacer grids of three types with 5x5, 16x16, 17x17 arrays, respectively. The pressure loss coefficients predicted by the improved analytical model are coincident with those test results within ±12%. This result shows that the improved analytical model can be used for research and design change of the nuclear fuel assembly
The Effectiveness of CBL Model to Improve Analytical Thinking Skills the Students of Sport Science
Sudibyo, Elok; Jatmiko, Budi; Widodo, Wahono
2016-01-01
Sport science undergraduate education, one of which purposes is to produce an analyst in sport. However, generally analytical thinking skills of sport science's students is still relatively very low in the context of sport. This study aimed to describe the effectiveness of Physics Learning Model in Sport Context, Context Based Learning (CBL)…
Erratum: A Simple, Analytical Model of Collisionless Magnetic Reconnection in a Pair Plasma
Hesse, Michael; Zenitani, Seiji; Kuznetsova, Masha; Klimas, Alex
2011-01-01
The following describes a list of errata in our paper, "A simple, analytical model of collisionless magnetic reconnection in a pair plasma." It supersedes an earlier erratum. We recently discovered an error in the derivation of the outflow-to-inflow density ratio.
An Analytical Framework for Evaluating E-Commerce Business Models and Strategies.
Lee, Chung-Shing
2001-01-01
Considers electronic commerce as a paradigm shift, or a disruptive innovation, and presents an analytical framework based on the theories of transaction costs and switching costs. Topics include business transformation process; scale effect; scope effect; new sources of revenue; and e-commerce value creation model and strategy. (LRW)
Analytical Modelling of Periodical PWM Converter Fed R-L Load
Czech Academy of Sciences Publication Activity Database
Klíma, J.; Schreier, Luděk
Orlando, Florida : International Institute of Informatics and Systemics, 2003, s. 406-411. ISBN 980-6560-01-9. [World Multiconference on Systemics, Cybernetics and Informatics - SCI 2003 /7./. Orlando, Florida (US), 27.07.2003-30.07.2003] Institutional research plan: CEZ:AV0Z2057903 Keywords : analytical model * periodical PWM * Laplace transform Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Czech Academy of Sciences Publication Activity Database
Tlustý, J.; Škramlík, Jiří; Švec, J.; Valouch, Viktor
2012-01-01
Roč. 2012, č. 292178 (2012), s. 1-17. ISSN 1024-123X Institutional support: RVO:61388998 Keywords : analytical modeling * four-switch hybrid power filter * sixfold switching symmetry Subject RIV: JA - Electronic s ; Optoelectronics, Electrical Engineering Impact factor: 1.383, year: 2012 http://www.hindawi.com/journals/mpe/2012/292178/
Analytical model of asymmetrical Mixed-Mode Bending test of adhesively bonded GFRP joint
Czech Academy of Sciences Publication Activity Database
Ševčík, Martin; Hutař, Pavel; Vassilopoulos, Anastasios P.; Shahverdi, M.
2015-01-01
Roč. 9, č. 34 (2015), s. 237-246. ISSN 1971-8993 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR GA15-09347S Institutional support: RVO:68081723 Keywords : GFRP materials * Mixed-Mode bending * Fiber bridging * Analytical model Subject RIV: JL - Materials Fatigue, Friction Mechanics
Analytic model of a two wire thermal sensor for flow and sound measurements
Honschoten, van J.W.; Krijnen, G.J.M.; Svetovoy, V.B.; Bree, de H.E.; Elwenspoek, M.C.
2004-01-01
The Microflown is an acoustic sensor that measures particle velocity instead of pressure, as conventional microphones do. This paper presents an analytical model describing the physical processes that govern the behaviour of the sensor and determine its sensitivity. Forced convection by an acoustic
Robinson, Jennifer L.; Laird, Angela R.; Glahn, David C.; Blangero, John; Sanghera, Manjit K.; Pessoa, Luiz; Fox, P. Mickle; Uecker, Angela; Friehs, Gerhard; Young, Keith A.; Griffin, Jennifer L.; LOVALLO, WILLIAM R.; Fox, Peter T
2011-01-01
Meta-analysis based techniques are emerging as powerful, robust tools for developing models of connectivity in functional neuroimaging. Here, we apply meta-analytic connectivity modeling to the human caudate to 1) develop a model of functional connectivity, 2) determine if meta-analytic methods are sufficiently sensitive to detect behavioral domain specificity within region-specific functional connectivity networks, and 3) compare meta-analytic driven segmentation to structural connectivity p...
Numerical Verification of an Analytical Model for Phase Noise in MEMS Oscillators.
Agrawal, D K; Bizzarri, F; Brambilla, A; Seshia, A A
2016-08-01
A new analytical formulation for phase noise in MEMS oscillators was recently presented encompassing the role of essential nonlinearities in the electrical and mechanical domains. In this paper, we validate the effectiveness of the proposed analytical formulation with respect to the unified theory developed by Demir et al. describing phase noise in oscillators. In particular, it is shown that, over a range of the second-order mechanical nonlinear stiffness of the MEMS resonator, both models exhibit an excellent match in the phase diffusion coefficient calculation for a square-wave MEMS oscillator. PMID:27295660
Numerical and semi-analytical modelling of the process induced distortions in pultrusion
DEFF Research Database (Denmark)
Baran, Ismet; Carlone, P.; Hattel, Jesper Henri;
2013-01-01
the mechanical behavior generating the distortions during the process is eventually required. In the present study, two different modelling approaches are implemented and compared to calculate the development of the distortions during the pultrusion of a graphite/epoxy composite rod. In both cases...... latter, the transient distortions are inferred adopting a semi-analytical procedure, i.e. post processing numerical results by means of analytical methods. The predictions of the process induced distortion development using the aforementioned methods are found to be qualitatively close to each other.......Furthermore, the location of the detachment between the heating die and the part due to shrinkage is also investigated....
Evaluation of the Component Chemical Potentials in Analytical Models for Ordered Alloy Phases
Directory of Open Access Journals (Sweden)
W. A. Oates
2011-01-01
Full Text Available The component chemical potentials in models of solution phases with a fixed number of sites can be evaluated easily when the Helmholtz energy is known as an analytical function of composition. In the case of ordered phases, however, the situation is less straightforward, because the Helmholtz energy is a functional involving internal order parameters. Because of this, the chemical potentials are usually obtained numerically from the calculated integral Helmholtz energy. In this paper, we show how the component chemical potentials can be obtained analytically in ordered phases via the use of virtual cluster chemical potentials. Some examples are given which illustrate the simplicity of the method.
Comparison of analytical model to simulation of diffusion plume from underground CO2 storage
Energy Technology Data Exchange (ETDEWEB)
Schwarz, K.; Patzek, T.W.; Silin, D.
2008-12-01
An exact solution exists for the advection-dispersion equation when the wind profile is modeled with a power-law dependence on height. This analytical solution is compared here to a numerical simulation of the coupled air-ground system for a leaking underground CO{sub 2} storage. The two methods produced similar results far from the boundaries, but the boundary conditions had a strong effect; the simulation imposed boundary conditions at the edge of a finite domain while the analytic solution imposes them at infinity. The reverse seepage from air to ground was shown in the simulation to be very small, and the sharp contrast between time scales suggests that air and ground can be modeled separately, with gas emissions from the ground model used as inputs to the air model.
Towards Evaluating the Quality of a Spreadsheet: The Case of the Analytical Spreadsheet Model
Grossman, Thomas A; Sander, Johncharles
2011-01-01
We consider the challenge of creating guidelines to evaluate the quality of a spreadsheet model. We suggest four principles. First, state the domain-the spreadsheets to which the guidelines apply. Second, distinguish between the process by which a spreadsheet is constructed from the resulting spreadsheet artifact. Third, guidelines should be written in terms of the artifact, independent of the process. Fourth, the meaning of "quality" must be defined. We illustrate these principles with an example. We define the domain of "analytical spreadsheet models", which are used in business, finance, engineering, and science. We propose for discussion a framework and terminology for evaluating the quality of analytical spreadsheet models. This framework categorizes and generalizes the findings of previous work on the more narrow domain of financial spreadsheet models. We suggest that the ultimate goal is a set of guidelines for an evaluator, and a checklist for a developer.
Otero-Espinar, Victoria; Nieto, Juan J; Mira, Jorge
2013-01-01
An in-depth analytic study of a model of language dynamics is presented: a model which tackles the problem of the coexistence of two languages within a closed community of speakers taking into account bilingualism and incorporating a parameter to measure the distance between languages. After previous numerical simulations, the model yielded that coexistence might lead to survival of both languages within monolingual speakers along with a bilingual community or to extinction of the weakest tongue depending on different parameters. In this paper, such study is closed with thorough analytical calculations to settle the results in a robust way and previous results are refined with some modifications. From the present analysis it is possible to almost completely assay the number and nature of the equilibrium points of the model, which depend on its parameters, as well as to build a phase space based on them. Also, we obtain conclusions on the way the languages evolve with time. Our rigorous considerations also sug...
PIC modelling of plasma potential measurements by using Ball-pen probe
Czech Academy of Sciences Publication Activity Database
Adámek, Jiří; Pánek, Radomír; Komm, Michael; Stöckel, Jan
Varšava, 2007. BoA07-BoA07. [Workshop on the EFSRP, satellite meetings of 34th EPS Conference on Plasma Physics/10th./. 8.7.2007-9.7.2007, Varšava] R&D Projects: GA AV ČR KJB100430601 Institutional research plan: CEZ:AV0Z20430508 Keywords : PIC modelling * plasma potential * Langmuir probe * Ball-pen probe Subject RIV: BL - Plasma and Gas Discharge Physics http://www.ipp.cas.cz/Tokamak/conf/efsrp07/BoA07.pdf
Probing classically conformal $B-L$ model with gravitational waves
Jinno, Ryusuke
2016-01-01
We study the cosmological history of the classical conformal $B-L$ gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. Especially, we consider the thermal phase transition of the U$(1)_{B-L}$ symmetry in the early universe and resulting gravitational-wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) U$(1)_{B-L}$ is broken after the reheating, (2) the $B-L$ gauge coupling does not blow up below the Planck scale, (3) the thermal phase transition completes in almost all the patches in the universe, the gravitational wave spectrum can be as large as $\\Omega_{\\rm GW} \\sim 10^{-8}$ at the frequency $f \\sim 0.01$-$1$Hz for some model parameters, and a vast parameter region can be tested by future interferometer experiments such as eLISA, LISA, BBO and DECIGO.
2D analytical modeling of a wholly superconducting synchronous reluctance motor
Malé, G.; Lubin, T.; Mezani, S.; Lévêque, J.
2011-03-01
An analytical computation of the magnetic field distribution in a wholly superconducting synchronous reluctance motor is proposed. The stator of the studied motor consists of three-phase HTS armature windings fed by AC currents. The rotor is made with HTS bulks which have a nearly diamagnetic behavior under zero field cooling. The electromagnetic torque is obtained by the interaction between the rotating magnetic field created by the HTS windings and the HTS bulks. The proposed analytical model is based on the resolution of Laplace's and Poisson's equations (by the separation-of-variables technique) for each sub-domain, i.e. stator windings, air-gap, holes between HTS bulks and exterior iron shield. For the study, the HTS bulks are considered as perfect diamagnetic materials. The boundary and continuity conditions between the sub-domains yield to the global solution. Magnetic field distributions and electromagnetic torque obtained by the analytical method are compared with those obtained from finite element analyses.
Scholarships vs. training for happiness gained from education in creativity: an analytical model
F. Zagonari
2015-01-01
This paper presents an analytical model of the dynamic interrelationships between education, creativity, and happiness based on both theoretical insights and recent empirical neurological studies. In the model, the outcome is conditional on individual intelligence and risk aversion. Specifically, it focuses on two main determinants of creativity (divergent and convergent thinking), and compares two main educational policies (scholarships vs. training) in terms of their impacts on the happ...
The Role of decision-analytic modelling in German health technology assessments
Kuhlmann, Alexander; Treskova, Marina; Braun, Sebastian; Graf von der Schulenburg, J-Matthias
2015-01-01
Background Decision-analytic modelling (DAM) has become a widespread method in health technology assessments (HTA), but the extent to which modelling is used differs among international HTA institutions. In Germany, the use of DAM is optional within HTAs of the German Institute of Medical Documentation and Information (DIMDI). Our study examines the use of DAM in DIMDI HTA reports and its effect on the quality of information provided for health policies. Methods A review of all DIMDI HTA repo...
Analytical model development of an eddy-current-based non-contacting steel plate conveyance system
International Nuclear Information System (INIS)
A concise model for analyzing and predicting the quasi-static electromagnetic characteristics of an eddy-current-based non-contacting steel plate conveyance system has been developed. Confirmed by three-dimensional (3-D) finite element analysis (FEA), adequacy of the analytical model can be demonstrated. Such an effective approach, which can be conveniently used by the potential industries for preliminary system operational performance evaluations, will be essential for designers and on-site engineers
Analytical models for well-mixed populations of cooperators and defectors under limiting resources
Requejo Martínez, Rubén J.; Camacho Castro, Juan
2012-01-01
In the study of the evolution of cooperation, resource limitations are usually assumed just to provide a finite population size. Recently, however, agent-based models have pointed out that resource limitation may modify the original structure of the interactions and allow for the survival of unconditional cooperators in well-mixed populations. Here, we present analytical simplified versions of two types of agent-based models recently published: one in which the limiting resource constrains th...
Analytical modeling of flash-back phenomena. [premixed/prevaporized combustion system
Feng, C. C.
1979-01-01
To understand the flame flash-back phenomena more extensively, an analytical model was formed and a numerical program was written and tested to solve the set of differential equations describing the model. Results show that under a given set of conditions flame propagates in the boundary layer on a flat plate when the free stream is at or below 1.8 m/s.
Wei Sun; Ying Liu; Guangyu Du
2015-01-01
Due to the material nonlinearity of hard coating, the coated structure produces the nonlinear dynamical behaviors of variable stiffness and damping, which make the modeling of hard-coating composite structure become a challenging task. In this study, the polynomial was adopted to characterize this material nonlinearity and an analytical modeling method was developed for the hard-coating composite plate. Firstly, to relate the hard-coating material parameters obtained by test and the analytica...
New analytical model for cumulative infiltration into dual-permeability soils
Lassabatere, Laurent; Yilmaz, Deniz; PEYRARD, Xavier; PEYNEAU, Pierre Emmanuel; Lenoir, Thomas,; Simunek, Jiri; Angulo Jaramillo, R.
2014-01-01
A new analytical approach is proposed to describe water infiltration into dual-permeability soils. The proposed model, validated in our study against numerical and experimental data, can be used to design devices and procedures for detecting dual-permeability behavior using water infiltration experiments. In the vadose zone, preferential flow and transport are much more common than uniform water flow and solute transport. In recent decades, several models have been developed for preferenti...
Improved analytical model for the field of index-guiding microstructured optical fibers
Sharma, Dinesh Kumar; Sharma, Anurag
2016-05-01
We present an improved version of our earlier developed analytical field model for the fundamental mode of index-guiding microstructured optical fibers (MOFs), to obtain better accuracy in the simulated results. Using this improved field model, we have studied the splice losses between an MOF and a traditional step-index single-mode fiber (SMF). Comparisons with available experimental and numerical simulation results have also been included.
Analytical modeling and optimization of a radial permanent magnets synchronous machine
Sesanga, Bill; Wurtz, Frédéric; Foggia, Albert
2009-01-01
Nowadays, designers typically use modeling tools and numerical calculation for the electrical machine sizing, particularly the finite element method. The finite element method has been validated and has proved to be a very efficient one. However, due to problem complexity, this method is still time-consuming and large computer memory is needed. In this paper, we propose a faster analytical model (magnetic and thermal) coupled with an optimization tool CADES (Component Architecture for the Des...
Aridogan, U.; Basdogan, I.; Erturk, A.
2014-04-01
Vibration-based energy harvesting using piezoelectric cantilevers has been extensively studied over the past decade. As an alternative to cantilevered harvesters, piezoelectric patch harvesters integrated to thin plates can be more convenient for use in marine, aerospace and automotive applications since these systems are often composed of thin plate-like structures with various boundary conditions. In this paper, we present analytical electroelastic modeling of a piezoelectric energy harvester structurally integrated to a thin plate along with experimental validations. The distributed-parameter electroelastic model of the thin plate with the piezoceramic patch harvester is developed based on Kirchhoff’s plate theory for all-four-edges clamped (CCCC) boundary conditions. Closed-form steady-state response expressions for coupled electrical output and structural vibration are obtained under transverse point force excitation. Analytical electroelastic frequency response functions (FRFs) relating the voltage output and vibration response to force input are derived and generalized for different boundary conditions. Experimental validation and extensive theoretical analysis efforts are then presented with a case study employing a thin PZT-5A piezoceramic patch attached on the surface of a rectangular aluminum CCCC plate. The importance of positioning of the piezoceramic patch harvester is discussed through an analysis of dynamic strain distribution on the overall plate surface. The electroelastic model is validated by a comparison of analytical and experimental FRFs for a wide range of resistive electrical boundary conditions. Finally, power generation performance of the structurally integrated piezoceramic patch harvester from multiple vibration modes is investigated analytically and experimentally.
Directory of Open Access Journals (Sweden)
Sangeeta Singh
2016-03-01
Full Text Available In this paper, we have investigated a novel Schottky tunneling source impact ionization MOSFET (STS-IMOS to lower the breakdown voltage of conventional impact ionization MOS (IMOS and developed an analytical model for the same. In STS-IMOS there is an accumulative effect of both impact ionization and source induced barrier tunneling. The silicide source offers very low parasitic resistance, the outcome of which is an increment in voltage drop across the intrinsic region for the same applied bias. This reduces operating voltage and hence, it exhibits a significant reduction in both breakdown and threshold voltage. STS-IMOS shows high immunity against hot electron damage. As a result of this the device reliability increases magnificently. The analytical model for impact ionization current (Iii is developed based on the integration of ionization integral (M. Similarly, to get Schottky tunneling current (ITun expression, Wentzel–Kramers–Brillouin (WKB approximation is employed. Analytical models for threshold voltage and subthreshold slope is optimized against Schottky barrier height (ϕB variation. The expression for the drain current is computed as a function of gate-to-drain bias via integral expression. It is validated by comparing it with the technology computer-aided design (TCAD simulation results as well. In essence, this analytical framework provides the physical background for better understanding of STS-IMOS and its performance estimation.
Lifetime of {sup 44}Ti as probe for supernova models
Energy Technology Data Exchange (ETDEWEB)
Goerres, J.; Meissner, J.; Schatz, H.; Stech, E.; Tischhauser, P.; Wiescher, M. [Univ. of Notre Dame, Notre Dame, IN (United States); Bazin, D.; Harkewicz, R.; Hellstroem, M.; Sherrill, B.; Steiner, M. [Michigan State Univ., East Lansing, MI (United States); Boyd, R.N. [Ohio State Univ., Columbus, OH (United States); Buchmann, L. [TRIUMF, Vancouver, BC (Canada); Hartmann, D.H. [Clemson Univ., Clemson, SC (United States); Hinnefeld, J.D. [Indiana Univ. South Bend, South Bend, IN (United States)
1998-06-01
The recent observation of {sup 44}Ti radioactivity in the supernova remnant Cassiopeia A with the Compton Gamma Ray Observatory allows the determination of the absolute amount of {sup 44}Ti. This provides a test for current supernova models. The main uncertainty is the lifetime of {sup 44}Ti. We report a new measurement of the lifetime of {sup 44}Ti applying a novel technique. A mixed radioactive beam containing {sup 44}Ti as well as {sup 22}Na was implanted and the resulting {gamma}-activity was measured. This allowed the determination of the lifetime of {sup 44}Ti relative to the lifetime of {sup 22}Na, {tau} = (87.0 {+-} 1.9) y. With this lifetime, the {sup 44}Ti abundance agrees with theoretical predictions within the remaining observational uncertainties. (orig.)
Analytical Modeling of a Novel Transverse Flux Machine for Direct Drive Wind Turbine Applications
Energy Technology Data Exchange (ETDEWEB)
Hasan, IIftekhar; Husain, Tausif; Uddin, Md Wasi; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard
2015-09-02
This paper presents a nonlinear analytical model of a novel double sided flux concentrating Transverse Flux Machine (TFM) based on the Magnetic Equivalent Circuit (MEC) model. The analytical model uses a series-parallel combination of flux tubes to predict the flux paths through different parts of the machine including air gaps, permanent magnets (PM), stator, and rotor. The two-dimensional MEC model approximates the complex three-dimensional flux paths of the TFM and includes the effects of magnetic saturation. The model is capable of adapting to any geometry which makes it a good alternative for evaluating prospective designs of TFM as compared to finite element solvers which are numerically intensive and require more computation time. A single phase, 1 kW, 400 rpm machine is analytically modeled and its resulting flux distribution, no-load EMF and torque, verified with Finite Element Analysis (FEA). The results are found to be in agreement with less than 5% error, while reducing the computation time by 25 times.
Energy Technology Data Exchange (ETDEWEB)
Hasan, IIftekhar; Husain, Tausif; Uddin, Md Wasi; Sozer, Yilmaz; Husain; Iqbal; Muljadi, Eduard
2015-08-24
This paper presents a nonlinear analytical model of a novel double-sided flux concentrating Transverse Flux Machine (TFM) based on the Magnetic Equivalent Circuit (MEC) model. The analytical model uses a series-parallel combination of flux tubes to predict the flux paths through different parts of the machine including air gaps, permanent magnets, stator, and rotor. The two-dimensional MEC model approximates the complex three-dimensional flux paths of the TFM and includes the effects of magnetic saturation. The model is capable of adapting to any geometry that makes it a good alternative for evaluating prospective designs of TFM compared to finite element solvers that are numerically intensive and require more computation time. A single-phase, 1-kW, 400-rpm machine is analytically modeled, and its resulting flux distribution, no-load EMF, and torque are verified with finite element analysis. The results are found to be in agreement, with less than 5% error, while reducing the computation time by 25 times.
Probing the Heavy Neutrinos of Inverse Seesaw Model at the LHeC
Mondal, Subhadeep
2016-01-01
We consider the production of a heavy neutrino and its possible signals at the Large Hadron-electron Collider (LHeC) in the context of an inverse-seesaw model for neutrino mass generation. The inverse seesaw model extends the Standard Model (SM) particle content by adding two neutral singlet fermions for each lepton generation. It is a well motivated model in the context of generating non-zero neutrino masses and mixings. The proposed future LHeC machine presents us with a particularly interesting possibility to probe such extensions of the SM with new leptons due to the presence of an electron beam in the initial state. We show that the LHeC will be able to probe an inverse scenario with much better efficacy compared to the LHC with very nominal integrated luminosities as well as exploit the advantage of having the electron beam polarized to enhance the heavy neutrino production rates.
Experimental and Simulational Studies on the Theoretical Model of the Plasma Absorption Probe
International Nuclear Information System (INIS)
Plasma absorption probe (PAP) was developed for measuring the electron density in plasmas processing based on the surface-wave characteristics. In order to diagnose the plasma with lower density and higher pressure, a sensitive PAP was also developed. Both types of PAP were analyzed theoretically under the quasi-static approximation, which is highly problematic when a conductor exists in the resonance region of the probe. For this reason, a theoretical model for the PAP is presented in this paper. The model is derived from the electromagnetic wave equation. Its principle is then verified via experiments and numerical simulations. Both experimental and numerical results show that the electromagnetic theoretical model is valid as compared with the quasi-static model. Consequently, a new type of PAP, named as the electromagnetic PAP, is thus proposed for the measurement of electron density.
Analytical modelling of soil effects on electromagnetic induction sensor for humanitarian demining
International Nuclear Information System (INIS)
Accurate compensation of the soil effect is essential for a new generation of sensitive classification-based electromagnetic induction landmine detectors. We present an analytical model for evaluation of the soil effect suitable for straightforward numerical implementation. The modelled soil consists of arbitrary number of conductive and magnetic layers. The solution region is truncated leading to the solution in form of a series rather than infinite integrals. Frequency-dependent permeability is inherent to the model, and time domain analysis can be made using DFT. In order to illustrate the model usage, we evaluate performances of three metal detector designs.
An Analytical Model for Spectral Peak Frequency Prediction of Substrate Noise in CMOS Substrates
DEFF Research Database (Denmark)
Shen, Ming; Mikkelsen, Jan H.
2013-01-01
This paper proposes an analytical model describing the generation of switching current noise in CMOS substrates. The model eliminates the need for SPICE simulations in existing methods by conducting a transient analysis on a generic CMOS inverter and approximating the switching current waveform us......- ing a Modified Raised Cosine (MORAC) equation. The proposed model is scalable, easy to implement and capable of predicting the spectral peak frequency of the substrate noise. The validation has been done via simulations and measurements. Good agreement has been found between the modeled and the...
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A three-dimensional analytical model for heat conduction in a plate of finite size with a Gaussian distributed moving heat source, is obtained using the Heat Cumulating Principle and the Method of Image in arc welding, and an estimated method of back width of seam is introduced by making use of the model and the measured top face information of temperature field . To prove the validity of the model, a series of GTA bead-on-plate welding were performed on a medium carbon steel under various welding conditions, the experimental results show that the theoretical prediction can provide acceptable accuracy, so the next penetration control will be based on the model.
Directory of Open Access Journals (Sweden)
A. Van Hirtum
2015-01-01
Full Text Available Several engineering problems are confronted with elastic tubes. In the current work, homothetic quasi-analytical geometrical ring models, ellipse, stadium, and peanut, are formulated allowing a computationally low cost ring shape estimation as a function of a single parameter, that is, the pinching degree. The dynamics of main geometrical parameters due to the model choice is discussed. Next, the ring models are applied to each cross section of a circular elastic tube compressed between two parallel bars for pinching efforts between 40% and 95%. The characteristic error yields less than 4% of the tubes diameter when the stadium model was used.
Analytical modelling of soil effects on electromagnetic induction sensor for humanitarian demining
Vasić, D.; Ambruš, D.; Bilas, V.
2013-06-01
Accurate compensation of the soil effect is essential for a new generation of sensitive classification-based electromagnetic induction landmine detectors. We present an analytical model for evaluation of the soil effect suitable for straightforward numerical implementation. The modelled soil consists of arbitrary number of conductive and magnetic layers. The solution region is truncated leading to the solution in form of a series rather than infinite integrals. Frequency-dependent permeability is inherent to the model, and time domain analysis can be made using DFT. In order to illustrate the model usage, we evaluate performances of three metal detector designs.
Wellington Nardin Favaro; Alejandro López-Castillo
2013-01-01
The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum) shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-)quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u) was considered as a probe in order to show the quantum structure e...
Analytical model and algorithm for tracing active power flow based on extended incidence matrix
Energy Technology Data Exchange (ETDEWEB)
Xie, Kaigui; Zhou, Jiaqi [State Key Laboratory of Power Transmission Equipment and System Security and New Technology at Chongqing University, Chongqing 400044 (China); Li, Wenyuan [System Planning and Performance Assessment, BC Transmission Corporation, Vancouver (Canada)
2009-02-15
This paper proposes an analytical model and algorithm for tracing power flow (TPF). The concept, construction approach and properties of extended incidence matrix (EIM) are developed. By using results of an AC or DC power flow solution from any off-line program or state estimation, the extended incidence matrix, generation and load power vectors, and distribution factor matrix are derived so that the analytical model of power transfers between generators and loads can be built. The major advantage of the proposed method is that the matrix theory is used to directly build the TPF model and no proportional sharing assumption on the flow distribution is needed. The method was tested using a 4-bus system, and the IEEE 30-bus and IEEE 14-bus power systems. The case studies indicate that the developed technique can be applied to any power system with or without loop flows. (author)
Energy Technology Data Exchange (ETDEWEB)
Jamshidian, M., E-mail: mostafa.jamshidian@gmail.com [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Rabczuk, T., E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, Seoul (Korea, Republic of)
2014-03-15
We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale.
A Proposed Analytical Model for Integrated Pick-and-Sort Systems
Directory of Open Access Journals (Sweden)
Recep KIZILASLAN
2013-11-01
Full Text Available In this study we present an analytical approach for integration of order picking and sortation operations which are the most important, labour intensive and costly activity for warehouses. Main aim is to investigate order picking and sorting efficiencies under different design issues as a function of order wave size. Integrated analytical model is proposed to estimate the optimum order picking and order sortation efficiency. The model, which has been tested by simulations with different illustrative examples, calculates the optimum wave size that solves the trade-off between picking and sorting operations and makes the order picking and sortations efficiency maximum. Our model also allow system designer to predict the order picking and sorting capacity for different system configurations. This study presents an innovative approach for integrated warehouse operations.
Analytical boron diffusivity model in silicon for thermal diffusion from boron silicate glass film
Kurachi, Ikuo; Yoshioka, Kentaro
2015-09-01
An analytical boron diffusivity model in silicon for thermal diffusion from a boron silicate glass (BSG) film has been proposed in terms of enhanced diffusion due to boron-silicon interstitial pair formation. The silicon interstitial generation is considered to be a result of the silicon kick-out mechanism by the diffused boron at the surface. The additional silicon interstitial generation in the bulk silicon is considered to be the dissociation of the diffused pairs. The former one causes the surface boron concentration dependent diffusion. The latter one causes the local boron concentration dependent diffusion. The calculated boron profiles based on the diffusivity model are confirmed to agree with the actual diffusion profiles measured by secondary ion mass spectroscopy (SIMS) for a wide range of the BSG boron concentration. This analytical diffusivity model is a helpful tool for p+ boron diffusion process optimization of n-type solar cell manufacturing.
An analytical model of anisotropic low-field electron mobility in wurtzite indium nitride
Energy Technology Data Exchange (ETDEWEB)
Wang, Shulong; Liu, Hongxia; Song, Xin; Guo, Yulong; Yang, Zhaonian [Xidian University, School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi' an (China)
2014-03-15
This paper presents a theoretical analysis of anisotropic transport properties and develops an anisotropic low-field electron analytical mobility model for wurtzite indium nitride (InN). For the different effective masses in the Γ-A and Γ-M directions of the lowest valley, both the transient and steady state transport behaviors of wurtzite InN show different transport characteristics in the two directions. From the relationship between velocity and electric field, the difference is more obvious when the electric field is low in the two directions. To make an accurate description of the anisotropic transport properties under low field, for the first time, we present an analytical model of anisotropic low-field electron mobility in wurtzite InN. The effects of different ionized impurity scattering models on the low-field mobility calculated by Monte Carlo method (Conwell-Weisskopf and Brooks-Herring method) are also considered. (orig.)
Compact analytical model for single gate AlInSb/InSb high electron mobility transistors
International Nuclear Information System (INIS)
We have developed a 2D analytical model for the single gate AlInSb/InSb HEMT device by solving the Poisson equation using the parabolic approximation method. The developed model analyses the device performance by calculating the parameters such as surface potential, electric field distribution and drain current. The high mobility of the AlInSb/InSb quantum makes this HEMT ideal for high frequency, high power applications. The working of the single gate AlInSb/InSb HEMT device is studied by considering the variation of gate source voltage, drain source voltage, and channel length under the gate region and temperature. The carrier transport efficiency is improved by uniform electric field along the channel and the peak values near the source and drain regions. The results from the analytical model are compared with that of numerical simulations (TCAD) and a good agreement between them is achieved. (semiconductor devices)
International Nuclear Information System (INIS)
We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale
A semi-analytical stationary model of a point-to-plane corona discharge
International Nuclear Information System (INIS)
A semi-analytical model of a dc corona discharge is formulated to determine the spatial distribution of charged particles (electrons, negative ions and positive ions) and the electric field in pure oxygen using a point-to-plane electrode system. A key point in the modeling is the integration of Gauss' law and the continuity equation of charged species along the electric field lines, and the use of Warburg's law and the corona current–voltage characteristics as input data in the boundary conditions. The electric field distribution predicted by the model is compared with the numerical solution obtained using a finite-element technique. The semi-analytical solutions are obtained at a negligible computational cost, and provide useful information to characterize and control the corona discharge in different technological applications. (paper)
International Nuclear Information System (INIS)
This paper presents a modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array, which utilizes solid polydimethylsiloxane (PDMS) film as the dielectric layer. To predict the deformation of the sensing unit and capacitance changes, each sensing unit is simplified into a three-layer plate structure and divided into central, edge and corner regions. The plate structure and the three regions are studied by the general and modified models, respectively. For experimental validation, the capacitive tactile sensor array with 8 × 8 (= 64) sensing units is fabricated. Experiments are conducted by measuring the capacitance changes versus applied external forces and compared with the general and modified models’ predictions. For the developed tactile sensor array, the sensitivity predicted by the modified analytical model is 1.25%/N, only 0.8% discrepancy from the experimental measurement. Results demonstrate that the modified analytical model can accurately predict the sensing performance of the sensor array and could be utilized for model-based optimal capacitive tactile sensor array design. (paper)
Directory of Open Access Journals (Sweden)
Monier-Vinard Eric
2013-01-01
Full Text Available The recent Printed Wiring Board embedding technology is an attractive packaging alternative that allows a very high degree of miniaturization by stacking multiple layers of embedded chips. This disruptive technology will further increase the thermal management challenges by concentrating heat dissipation at the heart of the organic substrate structure. In order to allow the electronic designer to early analyze the limits of the power dissipation, depending on the embedded chip location inside the board, as well as the thermal interactions with other buried chips or surface mounted electronic components, an analytical thermal modelling approach was established. The presented work describes the comparison of the analytical model results with the numerical models of various embedded chips configurations. The thermal behaviour predictions of the analytical model, found to be within ±10% of relative error, demonstrate its relevance for modelling high density electronic board. Besides the approach promotes a practical solution to study the potential gain to conduct a part of heat flow from the components towards a set of localized cooled board pads.
Analytical positron range modelling in heterogeneous media for PET Monte Carlo simulation
Energy Technology Data Exchange (ETDEWEB)
Lehnert, Wencke; Meikle, Steven R [Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe NSW 1825 (Australia); Gregoire, Marie-Claude; Reilhac, Anthonin, E-mail: wlehnert@uni.sydney.edu.au [Australian Nuclear Science and Technology Organisation, Lucas Heights NSW 2234 (Australia)
2011-06-07
Monte Carlo simulation codes that model positron interactions along their tortuous path are expected to be accurate but are usually slow. A simpler and potentially faster approach is to model positron range from analytical annihilation density distributions. The aims of this paper were to efficiently implement and validate such a method, with the addition of medium heterogeneity representing a further challenge. The analytical positron range model was evaluated by comparing annihilation density distributions with those produced by the Monte Carlo simulator GATE and by quantitatively analysing the final reconstructed images of Monte Carlo simulated data. In addition, the influence of positronium formation on positron range and hence on the performance of Monte Carlo simulation was investigated. The results demonstrate that 1D annihilation density distributions for different isotope-media combinations can be fitted with Gaussian functions and hence be described by simple look-up-tables of fitting coefficients. Together with the method developed for simulating positron range in heterogeneous media, this allows for efficient modelling of positron range in Monte Carlo simulation. The level of agreement of the analytical model with GATE depends somewhat on the simulated scanner and the particular research task, but appears to be suitable for lower energy positron emitters, such as {sup 18}F or {sup 11}C. No reliable conclusion about the influence of positronium formation on positron range and simulation accuracy could be drawn.
Wang, Zhi-Hua; Bou-Zeid, Elie; Smith, James A.
2011-02-01
In the urban environment, surface temperatures and conductive heat fluxes through solid media (roofs, walls, roads and vegetated surfaces) are of paramount importance for the comfort of residents (indoors) and for microclimatic conditions (outdoors). Fully discrete numerical methods are currently used to model heat transfer in these solid media in parametrisations of built surfaces commonly used in weather prediction models. These discrete methods usually use finite difference schemes in both space and time. We propose a spatially-analytical scheme where the temperature field and conductive heat fluxes are solved analytically in space. Spurious numerical oscillations due to temperature discontinuities at the sublayer interfaces can be avoided since the method does not involve spatial discretisation. The proposed method is compared to the fully discrete method for a test case of one-dimensional heat conduction with sinusoidal forcing. Subsequently, the analytical scheme is incorporated into the offline version of the current urban canopy model (UCM) used in the Weather Research and Forecasting model and the new UCM is validated against field measurements using a wireless sensor network and other supporting measurements over a suburban area under real-world conditions. Results of the comparison clearly show the advantage of the proposed scheme over the fully discrete model, particularly for more complicated cases.
Analytical development and optimization of a graphene-solution interface capacitance model.
Karimi, Hediyeh; Rahmani, Rasoul; Mashayekhi, Reza; Ranjbari, Leyla; Shirdel, Amir H; Haghighian, Niloofar; Movahedi, Parisa; Hadiyan, Moein; Ismail, Razali
2014-01-01
Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs) is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs) along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE) is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO) algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy. PMID:24991496
International Nuclear Information System (INIS)
We propose an analytical model for backscattered luminance in fog and derive an expression for the visibility signal-to-noise ratio as a function of meteorological visibility distance. The model uses single scattering processes. It is based on the Mie theory and the geometry of the optical device (emitter and receiver). In particular, we present an overlap function and take the phase function of fog into account. The results of the backscattered luminance obtained with our analytical model are compared to simulations made using the Monte Carlo method based on multiple scattering processes. An excellent agreement is found in that the discrepancy between the results is smaller than the Monte Carlo standard uncertainties. If we take no account of the geometry of the optical device, the results of the model-estimated backscattered luminance differ from the simulations by a factor 20. We also conclude that the signal-to-noise ratio computed with the Monte Carlo method and our analytical model is in good agreement with experimental results since the mean difference between the calculations and experimental measurements is smaller than the experimental uncertainty
Analytical Models for Energy Consumption in Infrastructure WLAN STAs Carrying TCP Traffic
Agrawal, Pranav; Kuri, Joy; Panda, Manoj; Navda, Vishnu; Ramjee, Ramachandran
2009-01-01
We develop analytical models for estimating the energy spent by stations (STAs) in infrastructure WLANs when performing TCP controlled file downloads. We focus on the energy spent in radio communication when the STAs are in the Continuously Active Mode (CAM), or in the static Power Save Mode (PSM). Our approach is to develop accurate models for obtaining the fraction of times the STA radios spend in idling, receiving and transmitting. We discuss two traffic models for each mode of operation: (i) each STA performs one large file download, and (ii) the STAs perform short file transfers. We evaluate the rate of STA energy expenditure with long file downloads, and show that static PSM is worse than just using CAM. For short file downloads we compute the number of file downloads that can be completed with given battery capacity, and show that PSM performs better than CAM for this case. We provide a validation of our analytical models using the NS-2 simulator. In contrast to earlier work on analytical modeling of P...
Analytical Business Model for Sustainable Distributed Retail Enterprises in a Competitive Market
Directory of Open Access Journals (Sweden)
Courage Matobobo
2016-02-01
Full Text Available Retail enterprises are organizations that sell goods in small quantities to consumers for personal consumption. In distributed retail enterprises, data is administered per branch. It is important for retail enterprises to make use of data generated within the organization to determine consumer patterns and behaviors. Large organizations find it difficult to ascertain customer preferences by merely observing transactions. This has led to quantifiable losses, such as loss of market share to competitors and targeting the wrong market. Although some enterprises have implemented classical business models to address these challenging issues, they still lack analytics-based marketing programs to gain a competitive advantage to deal with likely catastrophic events. This research develops an analytical business (ARANN model for distributed retail enterprises in a competitive market environment to address the current laxity through the best arrangement of shelf products per branch. The ARANN model is built on association rules, complemented by artificial neural networks to strengthen the results of both mutually. According to experimental analytics, the ARANN model outperforms the state of the art model, implying improved confidence in business information management within the dynamically changing world economy.
Analytical development and optimization of a graphene–solution interface capacitance model
Directory of Open Access Journals (Sweden)
Hediyeh Karimi
2014-05-01
Full Text Available Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy.
Coaxial atomic force microscope probes for imaging with dielectrophoresis
Brown, Keith; Berezovsky, Jesse; Westervelt, Robert M.
2011-01-01
We demonstrate atomic force microscope (AFM) imaging using dielectrophoresis (DEP) with coaxial probes. DEP provides force contrast allowing coaxial probes to image with enhanced spatial resolution. We model a coaxial probe as an electric dipole to provide analytic formulas for DEP between a dipole, dielectric spheres, and a dielectric substrate. AFM images taken of dielectric spheres with and without an applied electric field show the disappearance of artifacts when imaging with DEP. Quantit...
L. Zhu; Jiang, S. Z.; Zhu, Z Q; Chan, C. C.
2009-01-01
We present a simple lumped magnetic circuit model for interior permanent-magnet (IPM) machines with multisegment and multilayer permanent magnets. We derived analytically the open-circuit air-gap field distribution, average air-gap flux density, and leakage fluxes. To verify the developed models and analytical method, we adopted finite-element analysis (FEA). We show that for prototype machines, the errors between the FEA and analytically predicted results are $≪$1% for multisegment IPM machi...
Boughrara, Kamel; Lubin, Thierry; Ibtiouen, Rachid; Benallal, Mohamed N.
2013-01-01
International audience This paper deals with the prediction of magnetic field distribution and electromagnetic performances of parallel double excitation and spoke-type permanent magnet (PM) motors using simplified (SM) and exact (EM) analytical models. The simplified analytical model corresponds to a simplified geometry of the studied machines where the rotor and stator tooth-tips and the shape of polar pieces are not taken into account. A 2D analytical solution of magnetic field distribu...
Particle-in-cell modeling of Dual Segmented Langmuir Probe on PROBA2
Imtiaz, Nadia; Marchand, Richard
2015-11-01
We model the current characteristics of the Dual Segmented Langmuir Probe (DSLP), which is a part of the scientific payload of the ESA satellite PROBA2. It is used for the directional measurement of plasma parameters in the ionosphere at an altitude of approximately 725 km. The DSLP consists of two independent segmented Langmuir probes. Each probe is partitioned into eight collectors: seven electrically insulated spherical segments and a Guard electrode (the rest of the sphere and a small post). The current characteristics of the DSLP are computed by using the 3D particle-in-cell code PTetra. The model is electrostatic and it accounts for a uniform background magnetic field. The computed characteristics of different probe segments exhibit significant variation which depends on their orientation with respect to the ram direction. The floating potential and ion current branch of the I-V curves of each segment illustrate the directional sensitivity of the DSLP. It is found that the magnetic field also affects the electron current branch of the I-V curves of certain segments on the DSLP. The I-V curves computed with and without the ambient magnetic field are then used to estimate the electron temperature. This study will be helpful to understand the floating potential and electron temperature anisotropies measured by the DSLP.
An analytical framework to assist decision makers in the use of forest ecosystem model predictions
Larocque, Guy R.; Bhatti, Jagtar S.; Ascough, J.C.; Liu, J.; Luckai, N.; Mailly, D.; Archambault, L.; Gordon, Andrew M.
2011-01-01
The predictions from most forest ecosystem models originate from deterministic simulations. However, few evaluation exercises for model outputs are performed by either model developers or users. This issue has important consequences for decision makers using these models to develop natural resource management policies, as they cannot evaluate the extent to which predictions stemming from the simulation of alternative management scenarios may result in significant environmental or economic differences. Various numerical methods, such as sensitivity/uncertainty analyses, or bootstrap methods, may be used to evaluate models and the errors associated with their outputs. However, the application of each of these methods carries unique challenges which decision makers do not necessarily understand; guidance is required when interpreting the output generated from each model. This paper proposes a decision flow chart in the form of an analytical framework to help decision makers apply, in an orderly fashion, different steps involved in examining the model outputs. The analytical framework is discussed with regard to the definition of problems and objectives and includes the following topics: model selection, identification of alternatives, modelling tasks and selecting alternatives for developing policy or implementing management scenarios. Its application is illustrated using an on-going exercise in developing silvicultural guidelines for a forest management enterprise in Ontario, Canada. ?? 2010.
Analytical calculation of detailed model parameters of cast resin dry-type transformers
International Nuclear Information System (INIS)
Highlights: → In this paper high frequency behavior of cast resin dry-type transformers was simulated. → Parameters of detailed model were calculated using analytical method and compared with FEM results. → A lab transformer was constructed in order to compare theoretical and experimental results. -- Abstract: Non-flammable characteristic of cast resin dry-type transformers make them suitable for different kind of usages. This paper presents an analytical method of how to obtain parameters of detailed model of these transformers. The calculated parameters are compared and verified with the corresponding FEM results and if it was necessary, correction factors are introduced for modification of the analytical solutions. Transient voltages under full and chopped test impulses are calculated using the obtained detailed model. In order to validate the model, a setup was constructed for testing on high-voltage winding of cast resin dry-type transformer. The simulation results were compared with the experimental data measured from FRA and impulse tests.