Davari, Sadegh; Sha, Lui
1992-01-01
In the design of real-time systems, tasks are often assigned priorities. Preemptive priority driven schedulers are used to schedule tasks to meet the timing requirements. Priority inversion is the term used to describe the situation when a higher priority task's execution is delayed by lower priority tasks. Priority inversion can occur when there is contention for resources among tasks of different priorities. The duration of priority inversion could be long enough to cause tasks to miss their dead lines. Priority inversion cannot be completely eliminated. However, it is important to identify sources of priority inversion and minimize the duration of priority inversion. In this paper, a comprehensive review of the problem of and solutions to unbounded priority inversion is presented.
Formal solutions of inverse scattering problems. III
International Nuclear Information System (INIS)
Prosser, R.T.
1980-01-01
The formal solutions of certain three-dimensional inverse scattering problems presented in papers I and II of this series [J. Math. Phys. 10, 1819 (1969); 17 1175 (1976)] are obtained here as fixed points of a certain nonlinear mapping acting on a suitable Banach space of integral kernels. When the scattering data are sufficiently restricted, this mapping is shown to be a contraction, thereby establishing the existence, uniqueness, and continuous dependence on the data of these formal solutions
Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator
Ikhsan Eka Prasetia; Trihastuti Agustinah
2015-01-01
In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desire...
Inverse Kinematics With Closed Form Solution For Denso Robot Manipulator
Directory of Open Access Journals (Sweden)
Ikhsan Eka Prasetia
2015-03-01
Full Text Available In this paper, the forward kinematics and inverse kinematics used on the Denso robot manipulator which has a 6-DOF. The forward kinematics will result in the desired position by end-effector, while inverse kinematics produce angel on each joint. Inverse kinematics problem are very difficult, therefor to obtain the solution of inverse kinematics using closed form solution with geometry approach. The simulation result obtained from forward kinematics and inverse kinematics is determining desired position by Denso robot manipulator. Forward kinematics produce the desired position by the end-effector. Inverse kinematics produce joint angle, where the inverse kinematics produce eight conditions obtained from closed form solution with geometry approach to reach the desired position by the end-effector.
Kinetic equation solution by inverse kinetic method
International Nuclear Information System (INIS)
Salas, G.
1983-01-01
We propose a computer program (CAMU) which permits to solve the inverse kinetic equation. The CAMU code is written in HPL language for a HP 982 A microcomputer with a peripheral interface HP 9876 A ''thermal graphic printer''. The CAMU code solves the inverse kinetic equation by taking as data entry the output of the ionization chambers and integrating the equation with the help of the Simpson method. With this program we calculate the evolution of the reactivity in time for a given disturbance
Liu, Peng; Zhang, Jingxue; Wang, Dunyou
2017-06-07
A double-inversion mechanism of the F - + CH 3 I reaction was discovered in aqueous solution using combined multi-level quantum mechanics theories and molecular mechanics. The stationary points along the reaction path show very different structures to the ones in the gas phase due to the interactions between the solvent and solute, especially strong hydrogen bonds. An intermediate complex, a minimum on the potential of mean force, was found to serve as a connecting-link between the abstraction-induced inversion transition state and the Walden-inversion transition state. The potentials of mean force were calculated with both the DFT/MM and CCSD(T)/MM levels of theory. Our calculated free energy barrier of the abstraction-induced inversion is 69.5 kcal mol -1 at the CCSD(T)/MM level of theory, which agrees with the one at 72.9 kcal mol -1 calculated using the Born solvation model and gas-phase data; and our calculated free energy barrier of the Walden inversion is 24.2 kcal mol -1 , which agrees very well with the experimental value at 25.2 kcal mol -1 in aqueous solution. The calculations show that the aqueous solution makes significant contributions to the potentials of mean force and exerts a big impact on the molecular-level evolution along the reaction pathway.
Spectral solution of the inverse Mie problem
Romanov, Andrey V.; Konokhova, Anastasiya I.; Yastrebova, Ekaterina S.; Gilev, Konstantin V.; Strokotov, Dmitry I.; Chernyshev, Andrei V.; Maltsev, Valeri P.; Yurkin, Maxim A.
2017-10-01
We developed a fast method to determine size and refractive index of homogeneous spheres from the power Fourier spectrum of their light-scattering patterns (LSPs), measured with the scanning flow cytometer. Specifically, we used two spectral parameters: the location of the non-zero peak and zero-frequency amplitude, and numerically inverted the map from the space of particle characteristics (size and refractive index) to the space of spectral parameters. The latter parameters can be reliably resolved only for particle size parameter greater than 11, and the inversion is unique only in the limited range of refractive index with upper limit between 1.1 and 1.25 (relative to the medium) depending on the size parameter and particular definition of uniqueness. The developed method was tested on two experimental samples, milk fat globules and spherized red blood cells, and resulted in accuracy not worse than the reference method based on the least-square fit of the LSP with the Mie theory. Moreover, for particles with significant deviation from the spherical shape the spectral method was much closer to the Mie-fit result than the estimated uncertainty of the latter. The spectral method also showed adequate results for synthetic LSPs of spheroids with aspect ratios up to 1.4. Overall, we present a general framework, which can be used to construct an inverse algorithm for any other experimental signals.
EEG-distributed inverse solutions for a spherical head model
Riera, J. J.; Fuentes, M. E.; Valdés, P. A.; Ohárriz, Y.
1998-08-01
The theoretical study of the minimum norm solution to the MEG inverse problem has been carried out in previous papers for the particular case of spherical symmetry. However, a similar study for the EEG is remarkably more difficult due to the very complicated nature of the expression relating the voltage differences on the scalp to the primary current density (PCD) even for this simple symmetry. This paper introduces the use of the electric lead field (ELF) on the dyadic formalism in the spherical coordinate system to overcome such a drawback using an expansion of the ELF in terms of longitudinal and orthogonal vector fields. This approach allows us to represent EEG Fourier coefficients on a 2-sphere in terms of a current multipole expansion. The choice of a suitable basis for the Hilbert space of the PCDs on the brain region allows the current multipole moments to be related by spatial transfer functions to the PCD spectral coefficients. Properties of the most used distributed inverse solutions are explored on the basis of these results. Also, a part of the ELF null space is completely characterized and those spherical components of the PCD which are possible silent candidates are discussed.
Solution of Milne problem by Laplace transformation with numerical inversion
International Nuclear Information System (INIS)
Campos Velho, H.F. de.
1987-12-01
The Milne problem for monoenergetic neutrons, by Laplace Transform of the neutron transport integral equation with numerical inversion of the transformed solution by gaussian quadrature, using the fatorization of the dispersion function. The resulted is solved compared its analitical solution. (author) [pt
Inverse planning and optimization: a comparison of solutions
Energy Technology Data Exchange (ETDEWEB)
Ringor, Michael [School of Health Sciences, Purdue University, West Lafayette, IN (United States); Papiez, Lech [Department of Radiation Oncology, Indiana University, Indianapolis, IN (United States)
1998-09-01
The basic problem in radiation therapy treatment planning is to determine an appropriate set of treatment parameters that would induce an effective dose distribution inside a patient. One can approach this task as an inverse problem, or as an optimization problem. In this presentation, we compare both approaches. The inverse problem is presented as a dose reconstruction problem similar to tomography reconstruction. We formulate the optimization problem as linear and quadratic programs. Explicit comparisons are made between the solutions obtained by inversion and those obtained by optimization for the case in which scatter and attenuation are ignored (the NS-NA approximation)
International Nuclear Information System (INIS)
Marchi, Daniel E.; Menghini, Jorge E.; Trimarco, Viviana G.
1999-01-01
The inverse co-precipitation method has been used at the laboratory level to produce uranium - gadolinium mixed oxides. The formation of a mixed phase in the precipitates has been determined as well as the occurrence of only one phase in the sintered pellets, corresponding to a gadolinium - uranium solution. Moreover, a modification in the calcination-reduction stage was introduced that allows the elimination of the fissures previously detected in the sintered pellets
Inverse planning for x-ray rotation therapy: a general solution of the inverse problem
International Nuclear Information System (INIS)
Oelfke, U.; Bortfeld, T.
1999-01-01
Rotation therapy with photons is currently under investigation for the delivery of intensity modulated radiotherapy (IMRT). An analytical approach for inverse treatment planning of this radiotherapy technique is described. The inverse problem for the delivery of arbitrary 2D dose profiles is first formulated and then solved analytically. In contrast to previously applied strategies for solving the inverse problem, it is shown that the most general solution for the fluence profiles consists of two independent solutions of different parity. A first analytical expression for both fluence profiles is derived. The mathematical derivation includes two different strategies, an elementary expansion of fluence and dose into polynomials and a more practical approach in terms of Fourier transforms. The obtained results are discussed in the context of previous work on this problem. (author)
Inverse opal photonic crystal of chalcogenide glass by solution processing.
Kohoutek, Tomas; Orava, Jiri; Sawada, Tsutomu; Fudouzi, Hiroshi
2011-01-15
Chalcogenide opal and inverse opal photonic crystals were successfully fabricated by low-cost and low-temperature solution-based process, which is well developed in polymer films processing. Highly ordered silica colloidal crystal films were successfully infilled with nano-colloidal solution of the high refractive index As(30)S(70) chalcogenide glass by using spin-coating method. The silica/As-S opal film was etched in HF acid to dissolve the silica opal template and fabricate the inverse opal As-S photonic crystal. Both, the infilled silica/As-S opal film (Δn ~ 0.84 near λ=770 nm) and the inverse opal As-S photonic structure (Δn ~ 1.26 near λ=660 nm) had significantly enhanced reflectivity values and wider photonic bandgaps in comparison with the silica opal film template (Δn ~ 0.434 near λ=600 nm). The key aspects of opal film preparation by spin-coating of nano-colloidal chalcogenide glass solution are discussed. The solution fabricated "inorganic polymer" opal and the inverse opal structures exceed photonic properties of silica or any organic polymer opal film. The fabricated photonic structures are proposed for designing novel flexible colloidal crystal laser devices, photonic waveguides and chemical sensors. Copyright © 2010 Elsevier Inc. All rights reserved.
Topological inversion for solution of geodesy-constrained geophysical problems
Saltogianni, Vasso; Stiros, Stathis
2015-04-01
Geodetic data, mostly GPS observations, permit to measure displacements of selected points around activated faults and volcanoes, and on the basis of geophysical models, to model the underlying physical processes. This requires inversion of redundant systems of highly non-linear equations with >3 unknowns; a situation analogous to the adjustment of geodetic networks. However, in geophysical problems inversion cannot be based on conventional least-squares techniques, and is based on numerical inversion techniques (a priori fixing of some variables, optimization in steps with values of two variables each time to be regarded fixed, random search in the vicinity of approximate solutions). Still these techniques lead to solutions trapped in local minima, to correlated estimates and to solutions with poor error control (usually sampling-based approaches). To overcome these problems, a numerical-topological, grid-search based technique in the RN space is proposed (N the number of unknown variables). This technique is in fact a generalization and refinement of techniques used in lighthouse positioning and in some cases of low-accuracy 2-D positioning using Wi-Fi etc. The basic concept is to assume discrete possible ranges of each variable, and from these ranges to define a grid G in the RN space, with some of the gridpoints to approximate the true solutions of the system. Each point of hyper-grid G is then tested whether it satisfies the observations, given their uncertainty level, and successful grid points define a sub-space of G containing the true solutions. The optimal (minimal) space containing one or more solutions is obtained using a trial-and-error approach, and a single optimization factor. From this essentially deterministic identification of the set of gridpoints satisfying the system of equations, at a following step, a stochastic optimal solution is computed corresponding to the center of gravity of this set of gridpoints. This solution corresponds to a
Inverse kinematic solution for near-simple robots and its application to robot calibration
Hayati, Samad A.; Roston, Gerald P.
1986-01-01
This paper provides an inverse kinematic solution for a class of robot manipulators called near-simple manipulators. The kinematics of these manipulators differ from those of simple-robots by small parameter variations. Although most robots are by design simple, in practice, due to manufacturing tolerances, every robot is near-simple. The method in this paper gives an approximate inverse kinematics solution for real time applications based on the nominal solution for these robots. The validity of the results are tested both by a simulation study and by applying the algorithm to a PUMA robot.
International Nuclear Information System (INIS)
Azimi, A.; Hannani, S.K.; Farhanieh, B.
2005-01-01
In this article, a comparison between two iterative inverse techniques to solve simultaneously two unknown functions of axisymmetric transient inverse heat conduction problems in semi complex geometries is presented. The multi-block structured grid together with blocked-interface nodes is implemented for geometric decomposition of physical domain. Numerical scheme for solution of transient heat conduction equation is the finite element method with frontal technique to solve algebraic system of discrete equations. The inverse heat conduction problem involves simultaneous unknown time varying heat generation and time-space varying boundary condition estimation. Two parameter-estimation techniques are considered, Levenberg-Marquardt scheme and conjugate gradient method with adjoint problem. Numerically computed exact and noisy data are used for the measured transient temperature data needed in the inverse solution. The results of the present study for a configuration including two joined disks with different heights are compared to those of exact heat source and temperature boundary condition, and show good agreement. (author)
Zhukovsky, K
2014-01-01
We present a general method of operational nature to analyze and obtain solutions for a variety of equations of mathematical physics and related mathematical problems. We construct inverse differential operators and produce operational identities, involving inverse derivatives and families of generalised orthogonal polynomials, such as Hermite and Laguerre polynomial families. We develop the methodology of inverse and exponential operators, employing them for the study of partial differential equations. Advantages of the operational technique, combined with the use of integral transforms, generating functions with exponentials and their integrals, for solving a wide class of partial derivative equations, related to heat, wave, and transport problems, are demonstrated.
Inverse scattering solution of the Chew-Low equation
International Nuclear Information System (INIS)
Nakano, K.
1985-01-01
Techniques for solving the inverse scattering problem are applied to the Chew-Low equation to obtain the nucleon form factor directly from the experimental phase shifts. A new dispersion relation is derived for the P 11 wave because of its sign-changing phase shift. A self-consistent solution for each channel is obtained, but the universality of form factor is not confirmed. Also, an iterative procedure based on Omnes' method is developed in order to solve coupled-channel, singular integral equations. (orig.)
Inverse planning and class solutions for brachytherapy treatment planning
International Nuclear Information System (INIS)
Trnkova, P.
2010-01-01
has no additional features how to control spatial distribution of high dose regions. It is possible to create a dosimetrically acceptable treatment plans with IPSA. Nevertheless, the size of high dose regions is not acceptable. In comparison to manual treatment planning as well as to HIPO optimization, IPSA lead to the conflicting results concerning high dose regions. To be able to use IPSA for inverse treatment planning in cervical cancer brachytherapy additional tools have to be developed. The last part of the thesis is engaged with vaginal wall dosimetry. Dose volume constraints for target volume as well as for organs OARs are an input for inverse planning optimization calculation. A dose tolerance of each OAR has to be known to be able to create appropriate constraints. Until now only bladder, rectum and sigmoid were considered as OARs. The dose limits for vagina don't exist yet because of several uncertainties during assessing of dose to the vagina and vaginal morbidity. To overcome contouring uncertainties a simplified vagina contour was proposed and tested. The analysis showed that this contour is able to detect differences between different applicators as well as between different treatment plans. A prospective study comparing dosimetric results of this model and side effects in the vagina has to be done to prove whether this contour is working or not. In conclusion, this thesis proved that inverse planning can be used for cervical cancer brachytherapy. An appropriate implementation of the inverse planning algorithm has to be considered to avoid high dose regions. Prior including of a dose volume constrains of vagina as another input parameter for the inverse planning calculation vaginal dose reporting has to be solved. The feasibility of the proposed simplified vagina contour for dose reporting has to be proven with a prospective study. (author) [de
Solution of the radiative enclosure with a hybrid inverse method
Energy Technology Data Exchange (ETDEWEB)
Silva, Rogerio Brittes da; Franca, Francis Henrique Ramos [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Engenharia Mecanica], E-mail: frfranca@mecanica.ufrgs.br
2010-07-01
This work applies the inverse analysis to solve a three-dimensional radiative enclosure - which the surfaces are diffuse-grays - filled with transparent medium. The aim is determine the powers and locations of the heaters to attain both uniform heat flux and temperature on the design surface. A hybrid solution that couples two methods, the generalized extremal optimization (GEO) and the truncated singular value decomposition (TSVD) is proposed. The determination of the heat sources distribution is treated as an optimization problem, by GEO algorithm , whereas the solution of the system of equation, that embodies the Fredholm equation of first kind and therefore is expected to be ill conditioned, is build up through TSVD regularization method. The results show that the hybrid method can lead to a heat flux on the design surface that satisfies the imposed conditions with maximum error of less than 1,10%. The results illustrated the relevance of a hybrid method as a prediction tool. (author)
Classification of movement intention by spatially filtered electromagnetic inverse solutions
International Nuclear Information System (INIS)
Congedo, M; Lotte, F; Lecuyer, A
2006-01-01
We couple standardized low-resolution electromagnetic tomography, an inverse solution for electroencephalography (EEG) and the common spatial pattern, which is here conceived as a data-driven beamformer, to classify the benchmark BCI (brain-computer interface) competition 2003, data set IV. The data set is from an experiment where a subject performed a self-paced left and right finger tapping task. Available for analysis are 314 training trials whereas 100 unlabelled test trials have to be classified. The EEG data from 28 electrodes comprise the recording of the 500 ms before the actual finger movements, hence represent uniquely the left and right finger movement intention. Despite our use of an untrained classifier, and our extraction of only one attribute per class, our method yields accuracy similar to the winners of the competition for this data set. The distinct advantages of the approach presented here are the use of an untrained classifier and the processing speed, which make the method suitable for actual BCI applications. The proposed method is favourable over existing classification methods based on an EEG inverse solution, which rely either on iterative algorithms for single-trial independent component analysis or on trained classifiers
NUMERICAL SOLUTION OF SINGULAR INVERSE NODAL PROBLEM BY USING CHEBYSHEV POLYNOMIALS
NEAMATY, ABDOLALI; YILMAZ, EMRAH; AKBARPOOR, SHAHRBANOO; DABBAGHIAN, ABDOLHADI
2017-01-01
In this study, we consider Sturm-Liouville problem in two cases: the first case having no singularity and the second case having a singularity at zero. Then, we calculate the eigenvalues and the nodal points and present the uniqueness theorem for the solution of the inverse problem by using a dense subset of the nodal points in two given cases. Also, we use Chebyshev polynomials of the first kind for calculating the approximate solution of the inverse nodal problem in these cases. Finally, we...
International Nuclear Information System (INIS)
Fang Jinqing; Yao Weiguang
1993-01-01
The inverse operator method (IOM) for solutions of nonlinear dynamical systems (NDS) is briefly described and realized by the Mathematics-Mechanization (MM) in computers. For the first time IOM and MM are successfully applied to study the chaotic behaviors of Lorentz equation
International Nuclear Information System (INIS)
Kılıç, Emre; Eibert, Thomas F.
2015-01-01
An approach combining boundary integral and finite element methods is introduced for the solution of three-dimensional inverse electromagnetic medium scattering problems. Based on the equivalence principle, unknown equivalent electric and magnetic surface current densities on a closed surface are utilized to decompose the inverse medium problem into two parts: a linear radiation problem and a nonlinear cavity problem. The first problem is formulated by a boundary integral equation, the computational burden of which is reduced by employing the multilevel fast multipole method (MLFMM). Reconstructed Cauchy data on the surface allows the utilization of the Lorentz reciprocity and the Poynting's theorems. Exploiting these theorems, the noise level and an initial guess are estimated for the cavity problem. Moreover, it is possible to determine whether the material is lossy or not. In the second problem, the estimated surface currents form inhomogeneous boundary conditions of the cavity problem. The cavity problem is formulated by the finite element technique and solved iteratively by the Gauss–Newton method to reconstruct the properties of the object. Regularization for both the first and the second problems is achieved by a Krylov subspace method. The proposed method is tested against both synthetic and experimental data and promising reconstruction results are obtained
Energy Technology Data Exchange (ETDEWEB)
Kılıç, Emre, E-mail: emre.kilic@tum.de; Eibert, Thomas F.
2015-05-01
An approach combining boundary integral and finite element methods is introduced for the solution of three-dimensional inverse electromagnetic medium scattering problems. Based on the equivalence principle, unknown equivalent electric and magnetic surface current densities on a closed surface are utilized to decompose the inverse medium problem into two parts: a linear radiation problem and a nonlinear cavity problem. The first problem is formulated by a boundary integral equation, the computational burden of which is reduced by employing the multilevel fast multipole method (MLFMM). Reconstructed Cauchy data on the surface allows the utilization of the Lorentz reciprocity and the Poynting's theorems. Exploiting these theorems, the noise level and an initial guess are estimated for the cavity problem. Moreover, it is possible to determine whether the material is lossy or not. In the second problem, the estimated surface currents form inhomogeneous boundary conditions of the cavity problem. The cavity problem is formulated by the finite element technique and solved iteratively by the Gauss–Newton method to reconstruct the properties of the object. Regularization for both the first and the second problems is achieved by a Krylov subspace method. The proposed method is tested against both synthetic and experimental data and promising reconstruction results are obtained.
Use of the Location Inverse Solution to Reduce Ghost Images
Directory of Open Access Journals (Sweden)
Yong-Zhong Hu
2010-01-01
Full Text Available Through-the-wall imaging (TWI is a difficult but important task for both law enforcement and military missions. Acquiring information on both the internal features of a structure and the location of people inside plays an important role in many fields such as antiterrorism, hostage search and rescue, and barricade situations. Up to now, a number of promising experimental systems have been developed to validate and evaluate diverse imaging methods, most of which are based on a linear antenna array to obtain an image of the objects. However, these methods typically use the backward projection (BP algorithm based on ellipse curves, which usually generates additional ghost images. In this paper, the algorithm using the location inverse solution (LIS to reduce the ghost images is proposed and simulated. The results of simulation show that this approach is feasible.
Synthesis and characterization of Fe colloid catalysts in inverse micelle solutions
Energy Technology Data Exchange (ETDEWEB)
Martino, A.; Stoker, M.; Hicks, M. [Sandia National Lab., Alburquerque, NM (United States)] [and others
1995-12-31
Surfactant molecules, possessing a hydrophilic head group and a hydrophobic tail group, aggregate in various solvents to form structured solutions. In two component mixtures of surfactant and organic solvents (e.g., toluene and alkanes), surfactants aggregate to form inverse micelles. Here, the hydrophilic head groups shield themselves by forming a polar core, and the hydrophobic tails groups are free to move about in the surrounding oleic phase. The formation of Fe clusters in inverse miscelles was studied.Iron salts are solubilized within the polar interior of inverse micelles, and the addition of the reducing agent LiBH{sub 4} initiates a chemical reduction to produce monodisperse, nanometer sized Fe based particles. The reaction sequence is sustained by material exchange between inverse micelles. The surfactant interface provides a spatial constraint on the reaction volume, and reactions carried out in these micro-heterogeneous solutions produce colloidal sized particles (10-100{Angstrom}) stabilized in solution against flocculation of surfactant. The clusters were stabilized with respect to size with transmission electron microscopy (TEM) and with respect to chemical composition with Mossbauer spectroscopy, electron diffraction, and x-ray photoelectron spectroscopy (XPS). In addition, these iron based clusters were tested for catalytic activity in a model hydrogenolysis reaction. The hydrogenolysis of naphthyl bibenzyl methane was used as a model for coal pyrolysis.
Kolgotin, Alexei; Müller, Detlef; Chemyakin, Eduard; Romanov, Anton; Alehnovich, Valentin
2018-04-01
We conclude our series of publications on the development of the gradient correlation method (GCM), which can be used for an improved stabilization of the solution space of particle microphysical parameters derived from measurements with multiwavelength Raman and high-spectral-resolution lidar (3 backscatter +2 extinction coefficients). We show results of three cases studies. The data were taken with a ground-based multiwavelength Raman lidar during the Saharan Mineral Dust Experiment in the Cape Verde Islands (North Atlantic). These cases describe mixtures of dust with smoke. For our data analysis we separated the contribution of smoke to the total signal and only used these optical profiles for the test of GCM. The results show a significant stabilization of the solution space of the particle microphysical parameter retrieval on the particle radius domain from 0.03 to 10 μm, the real part of the complex refractive index domain from 1.3 to 1.8, and the imaginary part from 0 to 0.1. This new method will be included in the Tikhonov Advanced Regularization Algorithm, which is a fully automated, unsupervised algorithm that is used for the analysis of data collected with the worldwide first airborne 3 backscatter +2 extinction high-spectral-resolution lidar developed by NASA Langley Research Center.
A solution to the inverse problem in ocean acoustics
Digital Repository Service at National Institute of Oceanography (India)
Murty, T.V.R.; Somayajulu, Y.K.; Mahadevan, R.; Murty, C.S.; Sastry, J.S.
stratified ocean, considering the range independent nature of the medium, geophysical inverse techniques are employed to reconstruct the sound speed profile. The reconstructed profile for a six layer ocean, with five energetic modes, is in good agreement...
Stochastic forward and inverse groundwater flow and solute transport modeling
Janssen, G.M.C.M.
2008-01-01
Keywords: calibration, inverse modeling, stochastic modeling, nonlinear biodegradation, stochastic-convective, advective-dispersive, travel time, network design, non-Gaussian distribution, multimodal distribution, representers
This thesis offers three new approaches that contribute
Application of homotopy analysis method and inverse solution of a rectangular wet fin
International Nuclear Information System (INIS)
Panda, Srikumar; Bhowmik, Arka; Das, Ranjan; Repaka, Ramjee; Martha, Subash C.
2014-01-01
Highlights: • Solution of a wet fin with is obtained by homotopy analysis method (HAM). • Present HAM results have been well-validated with literature results. • Inverse analysis is done using genetic algorithm. • Measurement error of ±10–12% (approx.) is found to yield satisfactory reconstructions. - Abstract: This paper presents the analytical solution of a rectangular fin under the simultaneous heat and mass transfer across the fin surface and the fin tip, and estimates the unknown thermal and geometrical configurations of the fin using inverse heat transfer analysis. The local temperature field is obtained by using homotopy analysis method for insulated and convective fin tip boundary conditions. Using genetic algorithm, the thermal and geometrical parameters, viz., thermal conductivity of the material, surface heat transfer coefficient and dimensions of the fin have been simultaneously estimated for the prescribed temperature field. Earlier inverse studies on wet fin have been restricted to the analysis of nonlinear governing equation with either insulated tip condition or finite tip temperature only. The present study developed a closed-form solution with the consideration of nonlinearity effects in both governing equation and boundary condition. The study on inverse optimization leads to many feasible combination of fin materials, thermal conditions and fin dimensions. Thus allows the flexibility for designing a fin under wet conditions, based on multiple combinations of fin materials, fin dimensions and thermal configurations to achieve the required heat transfer duty. It is further determined that the allowable measurement error should be limited to ±10–12% in order to achieve satisfactory reconstruction
Toward precise solution of one-dimensional velocity inverse problems
International Nuclear Information System (INIS)
Gray, S.; Hagin, F.
1980-01-01
A family of one-dimensional inverse problems are considered with the goal of reconstructing velocity profiles to reasonably high accuracy. The travel-time variable change is used together with an iteration scheme to produce an effective algorithm for computation. Under modest assumptions the scheme is shown to be convergent
Inverse Scattering Method and Soliton Solution Family for String Effective Action
International Nuclear Information System (INIS)
Ya-Jun, Gao
2009-01-01
A modified Hauser–Ernst-type linear system is established and used to develop an inverse scattering method for solving the motion equations of the string effective action describing the coupled gravity, dilaton and Kalb–Ramond fields. The reduction procedures in this inverse scattering method are found to be fairly simple, which makes the proposed inverse scattering method applied fine and effective. As an application, a concrete family of soliton solutions for the considered theory is obtained
Inverse thermal analysis method to study solidification in cast iron
DEFF Research Database (Denmark)
Dioszegi, Atilla; Hattel, Jesper
2004-01-01
Solidification modelling of cast metals is widely used to predict final properties in cast components. Accurate models necessitate good knowledge of the solidification behaviour. The present study includes a re-examination of the Fourier thermal analysis method. This involves an inverse numerical...... solution of a 1-dimensional heat transfer problem connected to solidification of cast alloys. In the analysis, the relation between the thermal state and the fraction solid of the metal is evaluated by a numerical method. This method contains an iteration algorithm controlled by an under relaxation term...... inverse thermal analysis was tested on both experimental and simulated data....
Brown, Malcolm
2009-01-01
Inversions are fascinating phenomena. They are reversals of the normal or expected order. They occur across a wide variety of contexts. What do inversions have to do with learning spaces? The author suggests that they are a useful metaphor for the process that is unfolding in higher education with respect to education. On the basis of…
Solution of inverse localization problem associated to multistatic radar system
Directory of Open Access Journals (Sweden)
Boutkhil M.
2016-01-01
Full Text Available This work deals with the problem of inverse localization by a target with the aim to retrieve the position of the target, given the intensity and phase of the electromagnetic waves scattered by this object. Assuming the surface cross section to be known as well as the intensity and phase of the scattered waves, the target position was reconstructed through the echo signals scattered of each bistatic. We develop in the same time a multistatic ambiguity function trough bistatic ambiguity function to investigate several fundamental aspects that determine multistatic radar performance. We used a multistatic radar constructed of two bistatic radars, two transmitters and one receiver.
Solution to the inversely stated transient source-receptor problem
International Nuclear Information System (INIS)
Sajo, E.; Sheff, J.R.
1995-01-01
Transient source-receptor problems are traditionally handled via the Boltzmann equation or through one of its variants. In the atmospheric transport of pollutants, meteorological uncertainties in the planetary boundary layer render only a few approximations to the Boltzmann equation useful. Often, due to the high number of unknowns, the atmospheric source-receptor problem is ill-posed. Moreover, models to estimate downwind concentration invariably assume that the source term is known. In this paper, an inverse methodology is developed, based on downwind measurement of concentration and that of meterological parameters to estimate the source term
Solution accelerators for large scale 3D electromagnetic inverse problems
International Nuclear Information System (INIS)
Newman, Gregory A.; Boggs, Paul T.
2004-01-01
We provide a framework for preconditioning nonlinear 3D electromagnetic inverse scattering problems using nonlinear conjugate gradient (NLCG) and limited memory (LM) quasi-Newton methods. Key to our approach is the use of an approximate adjoint method that allows for an economical approximation of the Hessian that is updated at each inversion iteration. Using this approximate Hessian as a preconditoner, we show that the preconditioned NLCG iteration converges significantly faster than the non-preconditioned iteration, as well as converging to a data misfit level below that observed for the non-preconditioned method. Similar conclusions are also observed for the LM iteration; preconditioned with the approximate Hessian, the LM iteration converges faster than the non-preconditioned version. At this time, however, we see little difference between the convergence performance of the preconditioned LM scheme and the preconditioned NLCG scheme. A possible reason for this outcome is the behavior of the line search within the LM iteration. It was anticipated that, near convergence, a step size of one would be approached, but what was observed, instead, were step lengths that were nowhere near one. We provide some insights into the reasons for this behavior and suggest further research that may improve the performance of the LM methods
On the solution of the inverse scattering problem on a ray
International Nuclear Information System (INIS)
Egikyan, R.S.; Zhidkov, E.P.
1988-01-01
Quantum inverse scattering problem (ISP) is considered within the framework of two-particle scattering for local interaction case depending only on the scattering between particles. Constructing the solution of secondary integral equation solution of ISP is described in the clear image. Numerical calculations are conducted using a direct method
Inverse scattering transform method and soliton solutions for Davey-Stewartson II equation
International Nuclear Information System (INIS)
Arkadiev, V.A.; Pogrebkov, A.K.; Polivanov, M.C.
1989-01-01
The inverse scattering method for Davey-Stewartson II (DS-II) equation including both soliton and continuous spectrum solutions is developed. The explicit formulae for N-soliton solutions are given. Note that our solitons decrease as |z| -2 with z tending to infinity. (author). 8 refs
SIPPI: A Matlab toolbox for sampling the solution to inverse problems with complex prior information
DEFF Research Database (Denmark)
Hansen, Thomas Mejer; Cordua, Knud Skou; Caroline Looms, Majken
2013-01-01
on the solution. The combined states of information (i.e. the solution to the inverse problem) is a probability density function typically referred to as the a posteriori probability density function. We present a generic toolbox for Matlab and Gnu Octave called SIPPI that implements a number of methods...
Directory of Open Access Journals (Sweden)
Shoubin Wang
2017-01-01
Full Text Available The compound variable inverse problem which comprises boundary temperature distribution and surface convective heat conduction coefficient of two-dimensional steady heat transfer system with inner heat source is studied in this paper applying the conjugate gradient method. The introduction of complex variable to solve the gradient matrix of the objective function obtains more precise inversion results. This paper applies boundary element method to solve the temperature calculation of discrete points in forward problems. The factors of measuring error and the number of measuring points zero error which impact the measurement result are discussed and compared with L-MM method in inverse problems. Instance calculation and analysis prove that the method applied in this paper still has good effectiveness and accuracy even if measurement error exists and the boundary measurement points’ number is reduced. The comparison indicates that the influence of error on the inversion solution can be minimized effectively using this method.
Solution of the Cox-Thompson inverse scattering problem using finite set of phase shifts
Apagyi, B; Scheid, W
2003-01-01
A system of nonlinear equations is presented for the solution of the Cox-Thompson inverse scattering problem (1970 J. Math. Phys. 11 805) at fixed energy. From a given finite set of phase shifts for physical angular momenta, the nonlinear equations determine related sets of asymptotic normalization constants and nonphysical (shifted) angular momenta from which all quantities of interest, including the inversion potential itself, can be calculated. As a first application of the method we use input data consisting of a finite set of phase shifts calculated from Woods-Saxon and box potentials representing interactions with diffuse or sharp surfaces, respectively. The results for the inversion potentials, their first moments and asymptotic properties are compared with those provided by the Newton-Sabatier quantum inversion procedure. It is found that in order to achieve inversion potentials of similar quality, the Cox-Thompson method requires a smaller set of phase shifts than the Newton-Sabatier procedure.
Solution of the Cox-Thompson inverse scattering problem using finite set of phase shifts
International Nuclear Information System (INIS)
Apagyi, Barnabas; Harman, Zoltan; Scheid, Werner
2003-01-01
A system of nonlinear equations is presented for the solution of the Cox-Thompson inverse scattering problem (1970 J. Math. Phys. 11 805) at fixed energy. From a given finite set of phase shifts for physical angular momenta, the nonlinear equations determine related sets of asymptotic normalization constants and nonphysical (shifted) angular momenta from which all quantities of interest, including the inversion potential itself, can be calculated. As a first application of the method we use input data consisting of a finite set of phase shifts calculated from Woods-Saxon and box potentials representing interactions with diffuse or sharp surfaces, respectively. The results for the inversion potentials, their first moments and asymptotic properties are compared with those provided by the Newton-Sabatier quantum inversion procedure. It is found that in order to achieve inversion potentials of similar quality, the Cox-Thompson method requires a smaller set of phase shifts than the Newton-Sabatier procedure
An investigation on the solutions for the linear inverse problem in gamma ray tomography
International Nuclear Information System (INIS)
Araujo, Bruna G.M.; Dantas, Carlos C.; Santos, Valdemir A. dos; Finkler, Christine L.L.; Oliveira, Eric F. de; Melo, Silvio B.; Santos, M. Graca dos
2009-01-01
This paper the results obtained in single beam gamma ray tomography are investigated according to direct problem formulation and the applied solution for the linear system of equations. By image reconstruction based algebraic computational algorithms are used. The sparse under and over-determined linear system of equations was analyzed. Build in functions of Matlab software were applied and optimal solutions were investigate. Experimentally a section of the tube is scanned from various positions and at different angles. The solution, to find the vector of coefficients μ, from the vector of measured p values through the W matrix inversion, constitutes an inverse problem. A industrial tomography process requires a numerical solution of the system of equations. The definition of inverse problem according to Hadmard's is considered and as well the requirement of a well posed problem to find stable solutions. The formulation of the basis function and the computational algorithm to structure the weight matrix W were analyzed. For W full rank matrix the obtained solution is unique as expected. Total Least Squares was implemented which theory and computation algorithm gives adequate treatment for the problems due to non-unique solutions of the system of equations. Stability of the solution was investigating by means of a regularization technique and the comparison shows that it improves the results. An optimal solution as a function of the image quality, computation time and minimum residuals were quantified. The corresponding reconstructed images are shown in 3D graphics in order to compare with the solution. (author)
Energy Technology Data Exchange (ETDEWEB)
Krukovsky, P G [Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kiev (Ukraine)
1998-12-31
The description of method and software FRIEND which provide a possibility of solution of inverse and inverse design problems on the basis of existing (base) CFD-software for solution of direct problems (in particular, heat-transfer and fluid-flow problems using software PHOENICS) are presented. FRIEND is an independent additional module that widens the operational capacities of the base software unified with this module. This unifying does not require any change or addition to the base software. Interfacing of FRIEND and the base software takes place through input and output files of the base software. A brief description of the computational technique applied for the inverse problem solution, same detailed information on the interfacing of FRIEND and CFD-software and solution results for testing inverse and inverse design problems, obtained using the tandem CFD-software PHOENICS and FRIEND, are presented. (author) 9 refs.
Energy Technology Data Exchange (ETDEWEB)
Krukovsky, P.G. [Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kiev (Ukraine)
1997-12-31
The description of method and software FRIEND which provide a possibility of solution of inverse and inverse design problems on the basis of existing (base) CFD-software for solution of direct problems (in particular, heat-transfer and fluid-flow problems using software PHOENICS) are presented. FRIEND is an independent additional module that widens the operational capacities of the base software unified with this module. This unifying does not require any change or addition to the base software. Interfacing of FRIEND and the base software takes place through input and output files of the base software. A brief description of the computational technique applied for the inverse problem solution, same detailed information on the interfacing of FRIEND and CFD-software and solution results for testing inverse and inverse design problems, obtained using the tandem CFD-software PHOENICS and FRIEND, are presented. (author) 9 refs.
Class solution for inversely planned permanent prostate implants to mimic an experienced dosimetrist
International Nuclear Information System (INIS)
Lessard, Etienne; Kwa, Stefan L. S.; Pickett, Barby; Roach, Mach III; Pouliot, Jean
2006-01-01
The purpose of this paper is to present a method for the selection of inverse planning parameters and to establish a set of inverse planning parameters (class solution) for the inverse planning included in a commercial permanent prostate implant treatment planning system. The manual planning of more than 750 patients since 1996 led to the establishment of general treatment planning rules. A class solution is tuned to fulfill the treatment planning rules and generate equivalent implants. For ten patients, the inverse planning is compared with manual planning performed by our experienced physicist. The prostate volumes ranged from 17 to 51 cc and are implanted with low activity I-125 seeds. Dosimetric indices are calculated for comparison. The inverse planning needed about 15 s for each optimization (400 000 iterations on a 2.5 GHz PC). In comparison, the physicist needed about 20 min to perform each manual plan. A class solution is found that consistently produces dosimetric indices equivalent or better than the manual planning. Moreover, even with strict seed placement rules, the inverse planning can produce adequate prostate dose coverage and organ at risk protection. The inverse planning avoids implant with seeds outside of the prostate and too close to the urethra. It also avoids needles with only one seed and needles with three consecutive seeds. This reduces the risk of complication due to seed misplacement and edema. The inverse planning also uses a smaller number of needles, reducing the cause of trauma. The quality of the treatment plans is independent of the gland size and shape. A class solution is established that consistently and rapidly produces equivalent dosimetric indices as manual planning while respecting severe seed placement rules. The class solution can be used as a starting point for every patient, dramatically reducing the time needed to plan individual patient treatments. The class solution works with inverse preplanning, intraoperative
A Structure-dependent matrix representation of manipulator kinematics and its inverse solution
International Nuclear Information System (INIS)
Sasaki, Shinobu
1987-03-01
In this paper, derivation of kinematic equations for a six-link manipulator is presented using the homogeneous transformation (A i -matrix) based on Denavit-Hartenberg method, and additionally a solution procedure of its inverse problem is outlined. In order to examine the validity of a system of equations, solutions were compared with the exact ones of the inverse kinematics (for the same type of a manipulator) expressed in arbitrarily given co-ordinate systems. Through complete agreement of joint solutions between the two, the present purpose was accomplished. As shown in this paper, an explicit description between adjacent links will give a possible clue to a systematic treatment of the inverse problem for a class of manipulators. (author)
Irving, J.; Koepke, C.; Elsheikh, A. H.
2017-12-01
Bayesian solutions to geophysical and hydrological inverse problems are dependent upon a forward process model linking subsurface parameters to measured data, which is typically assumed to be known perfectly in the inversion procedure. However, in order to make the stochastic solution of the inverse problem computationally tractable using, for example, Markov-chain-Monte-Carlo (MCMC) methods, fast approximations of the forward model are commonly employed. This introduces model error into the problem, which has the potential to significantly bias posterior statistics and hamper data integration efforts if not properly accounted for. Here, we present a new methodology for addressing the issue of model error in Bayesian solutions to hydrogeophysical inverse problems that is geared towards the common case where these errors cannot be effectively characterized globally through some parametric statistical distribution or locally based on interpolation between a small number of computed realizations. Rather than focusing on the construction of a global or local error model, we instead work towards identification of the model-error component of the residual through a projection-based approach. In this regard, pairs of approximate and detailed model runs are stored in a dictionary that grows at a specified rate during the MCMC inversion procedure. At each iteration, a local model-error basis is constructed for the current test set of model parameters using the K-nearest neighbour entries in the dictionary, which is then used to separate the model error from the other error sources before computing the likelihood of the proposed set of model parameters. We demonstrate the performance of our technique on the inversion of synthetic crosshole ground-penetrating radar traveltime data for three different subsurface parameterizations of varying complexity. The synthetic data are generated using the eikonal equation, whereas a straight-ray forward model is assumed in the inversion
Fymat, A. L.
1976-01-01
The paper studies the inversion of the radiative transfer equation describing the interaction of electromagnetic radiation with atmospheric aerosols. The interaction can be considered as the propagation in the aerosol medium of two light beams: the direct beam in the line-of-sight attenuated by absorption and scattering, and the diffuse beam arising from scattering into the viewing direction, which propagates more or less in random fashion. The latter beam has single scattering and multiple scattering contributions. In the former case and for single scattering, the problem is reducible to first-kind Fredholm equations, while for multiple scattering it is necessary to invert partial integrodifferential equations. A nonlinear minimization search method, applicable to the solution of both types of problems has been developed, and is applied here to the problem of monitoring aerosol pollution, namely the complex refractive index and size distribution of aerosol particles.
Inverse operator method for solutions of nonlinear dynamical equations and some typical applications
International Nuclear Information System (INIS)
Fang Jinqing; Yao Weiguang
1993-01-01
The inverse operator method (IOM) is described briefly. We have realized the IOM for the solutions of nonlinear dynamical equations by the mathematics-mechanization (MM) with computers. They can then offer a new and powerful method applicable to many areas of physics. We have applied them successfully to study the chaotic behaviors of some nonlinear dynamical equations. As typical examples, the well-known Lorentz equation, generalized Duffing equation and two coupled generalized Duffing equations are investigated by using the IOM and the MM. The results are in good agreement with those given by Runge-Kutta method. So the IOM realized by the MM is of potential application valuable in nonlinear physics and many other fields
3-D inverse solution for continuous casting taking an air cap into consideration
Directory of Open Access Journals (Sweden)
I. Nowak
2008-12-01
Full Text Available The paper discusses a 3-D numerical solution of the inverse boundary problem for a continuous casting process of an aluminium alloy. Since the verified information on the heat flux distribution is crucial for a good design of a mould, effective cooling system and generally the whole caster, the main goal of the analysis presented within the paper was an identification of the heat fluxes along the external walls of the ingot. In the study an enthalpy-porosity technique implemented in a commercial Fluent package was used for modelling the solidification process. In this method, the phase change interface was determined on the basis of the liquid fraction approach. Moreover, the mathematical model included the pull velocity, the temperature-dependent properties for a liquid phase, mushy zone and solid phase, and a spatially local distribution of the thermal contact resistance between the ingot and crystallizer walls. In the inverse procedure, a sensitivity analysis was employed for the estimation of the boundary conditions retrieval. Although, the measured temperatures required to solve the problem are always burdened by measurement errors, a comparison of the measured and retrieved values showed a high accuracy of the computations.
Fundamental solutions for Schrödinger operators with general inverse square potentials
Chen, Huyuan
2017-03-17
In this paper, we clarify the fundamental solutions for Schrödinger operators given as (Formula presented.), where the potential V is a general inverse square potential in (Formula presented.) with (Formula presented.). In particular, letting (Formula presented.),(Formula presented.) where (Formula presented.), we discuss the existence and nonexistence of positive fundamental solutions for Hardy operator (Formula presented.), which depend on the parameter t.
Fundamental solutions for Schrödinger operators with general inverse square potentials
Chen, Huyuan; Alhomedan, Suad; Hajaiej, Hichem; Markowich, Peter A.
2017-01-01
In this paper, we clarify the fundamental solutions for Schrödinger operators given as (Formula presented.), where the potential V is a general inverse square potential in (Formula presented.) with (Formula presented.). In particular, letting (Formula presented.),(Formula presented.) where (Formula presented.), we discuss the existence and nonexistence of positive fundamental solutions for Hardy operator (Formula presented.), which depend on the parameter t.
Simplified solutions of the Cox-Thompson inverse scattering method at fixed energy
International Nuclear Information System (INIS)
Palmai, Tamas; Apagyi, Barnabas; Horvath, Miklos
2008-01-01
Simplified solutions of the Cox-Thompson inverse quantum scattering method at fixed energy are derived if a finite number of partial waves with only even or odd angular momenta contribute to the scattering process. Based on new formulae various approximate methods are introduced which also prove applicable to the generic scattering events
Petit, Jean-Pierre; D'Agostini, G.
2015-03-01
We reconsider the classical Schwarzschild solution in the context of a Janus cosmological model. We show that the central singularity can be eliminated through a simple coordinate change and that the subsequent transit from one fold to the other is accompanied by mass inversion. In such scenario matter swallowed by black holes could be ejected as invisible negative mass and dispersed in space.
International Nuclear Information System (INIS)
Lee, Jay Min; Yang, Dong-Seok; Bunker, Grant B
2013-01-01
Using the FEFF kernel A(k,r), we describe the inverse computation from χ(k)-data to g(r)-solution in terms of a singularity regularization method based on complete Bayesian statistics process. In this work, we topologically decompose the system-matched invariant projection operators into two distinct types, (A + AA + A) and (AA + AA + ), and achieved Synthesized Topological Inversion Computation (STIC), by employing a 12-operator-closed-loop emulator of the symplectic transformation. This leads to a numerically self-consistent solution as the optimal near-singular regularization parameters are sought, dramatically suppressing instability problems connected with finite precision arithmetic in ill-posed systems. By statistically correlating a pair of measured data, it was feasible to compute an optimal EXAFS phase retrieval solution expressed in terms of the complex-valued χ(k), and this approach was successfully used to determine the optimal g(r) for a complex multi-component system.
The algebraic method of the scattering inverse problem solution under untraditional statements
Popushnoj, M N
2001-01-01
The algebraic method of the scattering inverse problem solution under untraditional statements is proposed consistently in this review, in the framework of which some quantum theory od scattering charged particles problem were researched afterwards. The inverse problem of scattering theory of charged particles on the complex plane of the Coulomb coupling constant (CCC) is considered. A procedure of interaction potential restoration is established for the case when the energy, orbital moment quadrate and CCC are linearly dependent. The relation between one-parametric problems of the potential scattering of charged particles is investigated
Solution of the Inverse Problem for Thin Film Patterning by Electrohydrodynamic Forces
Zhou, Chengzhe; Troian, Sandra
2017-11-01
Micro- and nanopatterning techniques for applications ranging from optoelectronics to biofluidics have multiplied in number over the past decade to include adaptations of mature technologies as well as novel lithographic techniques based on periodic spatial modulation of surface stresses. We focus here on one such technique which relies on shape changes in nanofilms responding to a patterned counter-electrode. The interaction of a patterned electric field with the polarization charges at the liquid interface causes a patterned electrostatic pressure counterbalanced by capillary pressure which leads to 3D protrusions whose shape and evolution can be terminated as needed. All studies to date, however, have investigated the evolution of the liquid film in response to a preset counter-electrode pattern. In this talk, we present solution of the inverse problem for the thin film equation governing the electrohydrodynamic response by treating the system as a transient control problem. Optimality conditions are derived and an efficient corresponding solution algorithm is presented. We demonstrate such implementation of film control to achieve periodic, free surface shapes ranging from simple circular cap arrays to more complex square and sawtooth patterns.
Decontamination solution development studies
International Nuclear Information System (INIS)
Allen, R.P.; Fetrow, L.K.; Kjarmo, H.E.; Pool, K.H.
1993-09-01
This study was conducted for the Westinghouse Hanford Company (WHC) by Pacific Northwest Laboratory (PNL) as part of the Hanford Grout Technology Program (HGTP). The objective of this study was to identify decontamination solutions capable of removing radioactive contaminants and grout from the Grout Treatment Facility (GTF) process equipment and to determine the impact of these solutions on equipment components and disposal options. The reference grout used in this study was prepared with simulated double-shell slurry feed (DSSF) and a dry blend consisting of 40 wt % limestone flour, 28 wt % blast furnace slag, 28 wt % fly ash, and 4 wt % type I/II Portland cement
International Nuclear Information System (INIS)
Choi, C. Y.; Park, C. T.; Kim, T. H.; Han, K. N.; Choe, S. H.
1995-01-01
A geometrical inverse heat conduction problem is solved for the development of Infrared Computerized-Axial-Tomography (IR CAT) Scan by using a boundary element method in conjunction with regularization procedure. In this problem, an overspecified temperature condition by infrared scanning is provided on the surface, and is used together with other conditions to solve the position of an unknown boundary (cavity). An auxiliary problem is introduced in the solution of this problem. By defining a hypothetical inner boundary for the auxiliary problem domain, the cavity is located interior to the domain and its position is determined by solving a potential problem. Boundary element method with regularization procedure is used to solve this problem, and the effects of regularization on the inverse solution method are investigated by means of numerical analysis
Forward and inverse solutions for Risley prism based on the Denavit-Hartenberg methodology
Beltran-Gonzalez, A.; Garcia-Torales, G.; Strojnik, M.; Flores, J. L.; Garcia-Luna, J. L.
2017-08-01
In this work forward and inverse solutions for two-element Risley prism for pointing and scanning beam systems are developed. A more efficient and faster algorithm is proposed to make an analogy of the Risley prism system compared with a robotic system with two degrees of freedom. This system of equations controls each Risley prism individually as a planar manipulator arm of two links. In order to evaluate the algorithm we implement it in a pointing system. We perform popular routines such as the linear, spiral and loops traces. Using forward and inverse solutions for two-element Risley prism it is also possible to point at coordinates specified by the user, provided they are within the pointer area of work area. Experimental results are showed as a validation of our proposal.
Inverse problems with non-trivial priors: efficient solution through sequential Gibbs sampling
DEFF Research Database (Denmark)
Hansen, Thomas Mejer; Cordua, Knud Skou; Mosegaard, Klaus
2012-01-01
Markov chain Monte Carlo methods such as the Gibbs sampler and the Metropolis algorithm can be used to sample solutions to non-linear inverse problems. In principle, these methods allow incorporation of prior information of arbitrary complexity. If an analytical closed form description of the prior...... is available, which is the case when the prior can be described by a multidimensional Gaussian distribution, such prior information can easily be considered. In reality, prior information is often more complex than can be described by the Gaussian model, and no closed form expression of the prior can be given....... We propose an algorithm, called sequential Gibbs sampling, allowing the Metropolis algorithm to efficiently incorporate complex priors into the solution of an inverse problem, also for the case where no closed form description of the prior exists. First, we lay out the theoretical background...
International Nuclear Information System (INIS)
Alvarez-Estrada, R.F.
1979-01-01
A comprehensive review of the inverse scattering solution of certain non-linear evolution equations of physical interest in one space dimension is presented. We explain in some detail the interrelated techniques which allow to linearize exactly the following equations: (1) the Korteweg and de Vries equation; (2) the non-linear Schrodinger equation; (3) the modified Korteweg and de Vries equation; (4) the Sine-Gordon equation. We concentrate in discussing the pairs of linear operators which accomplish such an exact linearization and the solution of the associated initial value problem. The application of the method to other non-linear evolution equations is reviewed very briefly
Vasil'ev, V. I.; Kardashevsky, A. M.; Popov, V. V.; Prokopev, G. A.
2017-10-01
This article presents results of computational experiment carried out using a finite-difference method for solving the inverse Cauchy problem for a two-dimensional elliptic equation. The computational algorithm involves an iterative determination of the missing boundary condition from the override condition using the conjugate gradient method. The results of calculations are carried out on the examples with exact solutions as well as at specifying an additional condition with random errors are presented. Results showed a high efficiency of the iterative method of conjugate gradients for numerical solution
Mai, P. M.; Schorlemmer, D.; Page, M.
2012-04-01
Earthquake source inversions image the spatio-temporal rupture evolution on one or more fault planes using seismic and/or geodetic data. Such studies are critically important for earthquake seismology in general, and for advancing seismic hazard analysis in particular, as they reveal earthquake source complexity and help (i) to investigate earthquake mechanics; (ii) to develop spontaneous dynamic rupture models; (iii) to build models for generating rupture realizations for ground-motion simulations. In applications (i - iii), the underlying finite-fault source models are regarded as "data" (input information), but their uncertainties are essentially unknown. After all, source models are obtained from solving an inherently ill-posed inverse problem to which many a priori assumptions and uncertain observations are applied. The Source Inversion Validation (SIV) project is a collaborative effort to better understand the variability between rupture models for a single earthquake (as manifested in the finite-source rupture model database) and to develop robust uncertainty quantification for earthquake source inversions. The SIV project highlights the need to develop a long-standing and rigorous testing platform to examine the current state-of-the-art in earthquake source inversion, and to develop and test novel source inversion approaches. We will review the current status of the SIV project, and report the findings and conclusions of the recent workshops. We will briefly discuss several source-inversion methods, how they treat uncertainties in data, and assess the posterior model uncertainty. Case studies include initial forward-modeling tests on Green's function calculations, and inversion results for synthetic data from spontaneous dynamic crack-like strike-slip earthquake on steeply dipping fault, embedded in a layered crustal velocity-density structure.
International Nuclear Information System (INIS)
Najafi Mohammad; Arbabi Somayeh
2014-01-01
In this paper, we establish exact solutions for five complex nonlinear Schrödinger equations. The semi-inverse variational principle (SVP) is used to construct exact soliton solutions of five complex nonlinear Schrödinger equations. Many new families of exact soliton solutions of five complex nonlinear Schrödinger equations are successfully obtained. (general)
Fu, Zhongtao; Yang, Wenyu; Yang, Zhen
2013-08-01
In this paper, we present an efficient method based on geometric algebra for computing the solutions to the inverse kinematics problem (IKP) of the 6R robot manipulators with offset wrist. Due to the fact that there exist some difficulties to solve the inverse kinematics problem when the kinematics equations are complex, highly nonlinear, coupled and multiple solutions in terms of these robot manipulators stated mathematically, we apply the theory of Geometric Algebra to the kinematic modeling of 6R robot manipulators simply and generate closed-form kinematics equations, reformulate the problem as a generalized eigenvalue problem with symbolic elimination technique, and then yield 16 solutions. Finally, a spray painting robot, which conforms to the type of robot manipulators, is used as an example of implementation for the effectiveness and real-time of this method. The experimental results show that this method has a large advantage over the classical methods on geometric intuition, computation and real-time, and can be directly extended to all serial robot manipulators and completely automatized, which provides a new tool on the analysis and application of general robot manipulators.
The uniqueness of the solution of cone-like inversion models for halo CMEs
Zhao, X. P.
2006-12-01
Most of elliptic halo CMEs are believed to be formed by the Thompson scattering of the photospheric light by the 3-D cone-like shell of the CME plasma. To obtain the real propagation direction and angular width of the halo CMEs, such cone-like inversion models as the circular cone, the elliptic cone and the ice-cream cone models have been suggested recently. Because the number of given parameters that are used to characterize 2-D elliptic halo CMEs observed by one spacecraft are less than the number of unknown parameters that are used to characterize the 3-D elliptic cone model, the solution of the elliptic cone model is not unique. Since it is difficult to determine whether or not an observed halo CME is formed by an circular cone or elliptic cone shell, the solution of circular cone model may often be not unique too. To fix the problem of the uniqueness of the solution of various 3-D cone-like inversion models, this work tries to develop the algorithm for using the data from multi-spacecraft, such as the STEREO A and B, and the Solar Sentinels.
International Nuclear Information System (INIS)
Garratt, T.J.
1989-05-01
Compartment models for the transport of radionuclides in the biosphere are conventionally solved using a numerical time-stepping procedure. This report examines an alternative method based on the numerical inversion of Laplace transforms, which is potentially more efficient and accurate for some classes of problem. The central problem considered is the most efficient and robust technique for solving the Laplace-transformed rate equations. The conclusion is that Gaussian elimination is the most efficient and robust solution method. A general compartment model has been implemented on a personal computer and used to solve a realistic case including radionuclide decay chains. (author)
International Nuclear Information System (INIS)
Sakhnovich, Alexander
2008-01-01
A Borg–Marchenko-type uniqueness theorem (in terms of the Weyl function) is obtained here for the system auxiliary to the N-wave equation. A procedure to solve the inverse problem is used for this purpose. The asymptotic condition on the Weyl function, under which the inverse problem is uniquely solvable, is completed by a new and simple sufficient condition on the potential, which implies this asymptotic condition. The evolution of the Weyl function is discussed and the solution of an initial-boundary-value problem for the N-wave equation follows. Explicit solutions of an inverse problem are obtained. The system with a shifted argument is treated
Energy Technology Data Exchange (ETDEWEB)
Hampden-Smith, M.; Kawola, J.S.; Martino, A.; Sault, A.G.; Yamanaka, S.A.
1999-01-05
The mission of this project was to use inverse micelle solutions to synthesize nanometer sized metal particles and test the particles as catalysts in the liquefaction of coal and other related reactions. The initial focus of the project was the synthesis of iron based materials in pseudo-homogeneous form. The frost three chapters discuss the synthesis, characterization, and catalyst testing in coal liquefaction and model coal liquefaction reactions of iron based pseudo-homogeneous materials. Later, we became interested in highly dispersed catalysts for coprocessing of coal and plastic waste. Bifunctional catalysts . to hydrogenate the coal and depolymerize the plastic waste are ideal. We began studying, based on our previously devised synthesis strategies, the synthesis of heterogeneous catalysts with a bifunctional nature. In chapter 4, we discuss the fundamental principles in heterogeneous catalysis synthesis with inverse micelle solutions. In chapter 5, we extend the synthesis of chapter 4 to practical systems and use the materials in catalyst testing. Finally in chapter 6, we return to iron and coal liquefaction now studied with the heterogeneous catalysts.
International Nuclear Information System (INIS)
Moura, C.A. de.
1976-09-01
We propose an algorithm for computing the potential V(x) associated to the one-dimensional Schroedinger operator E identical to - d 2 /dx 2 + V(x) -infinite < x< infinite from knowledge of the S.matrix, more exactly, of one of the reelection coefficients. The convergence of the algorithm is guaranteed by the stability results obtained for both the direct and inverse problems
Greedy solution of ill-posed problems: error bounds and exact inversion
International Nuclear Information System (INIS)
Denis, L; Lorenz, D A; Trede, D
2009-01-01
The orthogonal matching pursuit (OMP) is a greedy algorithm to solve sparse approximation problems. Sufficient conditions for exact recovery are known with and without noise. In this paper we investigate the applicability of the OMP for the solution of ill-posed inverse problems in general, and in particular for two deconvolution examples from mass spectrometry and digital holography, respectively. In sparse approximation problems one often has to deal with the problem of redundancy of a dictionary, i.e. the atoms are not linearly independent. However, one expects them to be approximatively orthogonal and this is quantified by the so-called incoherence. This idea cannot be transferred to ill-posed inverse problems since here the atoms are typically far from orthogonal. The ill-posedness of the operator probably causes the correlation of two distinct atoms to become huge, i.e. that two atoms look much alike. Therefore, one needs conditions which take the structure of the problem into account and work without the concept of coherence. In this paper we develop results for the exact recovery of the support of noisy signals. In the two examples, mass spectrometry and digital holography, we show that our results lead to practically relevant estimates such that one may check a priori if the experimental setup guarantees exact deconvolution with OMP. Especially in the example from digital holography, our analysis may be regarded as a first step to calculate the resolution power of droplet holography
Cerebellum-inspired neural network solution of the inverse kinematics problem.
Asadi-Eydivand, Mitra; Ebadzadeh, Mohammad Mehdi; Solati-Hashjin, Mehran; Darlot, Christian; Abu Osman, Noor Azuan
2015-12-01
The demand today for more complex robots that have manipulators with higher degrees of freedom is increasing because of technological advances. Obtaining the precise movement for a desired trajectory or a sequence of arm and positions requires the computation of the inverse kinematic (IK) function, which is a major problem in robotics. The solution of the IK problem leads robots to the precise position and orientation of their end-effector. We developed a bioinspired solution comparable with the cerebellar anatomy and function to solve the said problem. The proposed model is stable under all conditions merely by parameter determination, in contrast to recursive model-based solutions, which remain stable only under certain conditions. We modified the proposed model for the simple two-segmented arm to prove the feasibility of the model under a basic condition. A fuzzy neural network through its learning method was used to compute the parameters of the system. Simulation results show the practical feasibility and efficiency of the proposed model in robotics. The main advantage of the proposed model is its generalizability and potential use in any robot.
Rectangular Full Packed Format for Cholesky's Algorithm: Factorization, Solution, and Inversion
DEFF Research Database (Denmark)
Gustavson, Fred G.; Wasniewski, Jerzy; Dongarra, Jack J
2010-01-01
of the storage space but provide high performance via the use of Level 3 BLAS. Standard packed format arrays fully utilize storage (array space) but provide low performance as there is no Level 3 packed BLAS. We combine the good features of packed and full storage using RFPF to obtain high performance via using...... Level 3 BLAS as RFPF is a standard full-format representation. Also, RFPF requires exactly the same minimal storage as packed the format. Each LAPACK full and/or packed triangular, symmetric, and Hermitian routine becomes a single new RFPF routine based on eight possible data layouts of RFPF. This new...... RFPF routine usually consists of two calls to the corresponding LAPACK full-format routine and two calls to Level 3 BLAS routines. This means no new software is required. As examples, we present LAPACK routines for Cholesky factorization, Cholesky solution, and Cholesky inverse computation in RFPF...
International Nuclear Information System (INIS)
Fang Jinqing; Yao Weiguang
1992-12-01
Inverse operator theory method (IOTM) has developed rapidly in the last few years. It is an effective and useful procedure for quantitative solution of nonlinear or stochastic continuous dynamical systems. Solutions are obtained in series form for deterministic equations, and in the case of stochastic equation it gives statistic measures of the solution process. A very important advantage of the IOTM is to eliminate a number of restrictive and assumption on the nature of stochastic processes. Therefore, it provides more realistic solutions. The IOTM and its mathematics-mechanization (MM) are briefly introduced. They are used successfully to study the chaotic behaviors of the nonlinear dynamical systems for the first time in the world. As typical examples, the Lorentz equation, generalized Duffing equation, two coupled generalized Duffing equations are investigated by the use of the IOTM and the MM. The results are in good agreement with ones by the Runge-Kutta method (RKM). It has higher accuracy and faster convergence. So the IOTM realized by the MM is of potential application valuable in nonlinear science
The boundary element method for the solution of the multidimensional inverse heat conduction problem
International Nuclear Information System (INIS)
Lagier, Guy-Laurent
1999-01-01
This work focuses on the solution of the inverse heat conduction problem (IHCP), which consists in the determination of boundary conditions from a given set of internal temperature measurements. This problem is difficult to solve due to its ill-posedness and high sensitivity to measurement error. As a consequence, numerical regularization procedures are required to solve this problem. However, most of these methods depend on the dimension and the nature, stationary or transient, of the problem. Furthermore, these methods introduce parameters, called hyper-parameters, which have to be chosen optimally, but can not be determined a priori. So, a new general method is proposed for solving the IHCP. This method is based on a Boundary Element Method formulation, and the use of the Singular Values Decomposition as a regularization procedure. Thanks to this method, it's possible to identify and eliminate the directions of the solution where the measurement error plays the major role. This algorithm is first validated on two-dimensional stationary and one-dimensional transient problems. Some criteria are presented in order to choose the hyper-parameters. Then, the methodology is applied to two-dimensional and three-dimensional, theoretical or experimental, problems. The results are compared with those obtained by a standard method and show the accuracy of the method, its generality, and the validity of the proposed criteria. (author) [fr
Nuclear reaction studies using inverse kinematics
International Nuclear Information System (INIS)
Shapira, D.
1985-01-01
Reaction studies with reversed kinematics refer to studies of nuclear reactions induced by a heavy projectile colliding with lighter target nuclei. The technique of using reversed kinematics is costly in terms of the available center-of-mass energy. Most of the projectile's energy goes into forward motion of the reaction products in the laboratory system. Examples are presented where the use of reversed kinematics techniques has provided new information on certain reaction processes. A list of kinematic properties and advantages they may afford is shown. Clearly the possible studies listed can be done without using reversed kinematics but because of the difficulty associated with some of these studies they were never performed until more energetic heavier beams have become available and the reversed kinematics technique was utilized
International Nuclear Information System (INIS)
El-Morshedy, Salah El-Din
2010-01-01
Research reactors of power greater than 20 MW are usually designed to be cooled with upward coolant flow direction inside the reactor core. This is mainly to prevent flow inversion problems following a pump coast down. However, in some designs and under certain operating conditions, flow inversion phenomenon is predicted. In the present work, the best-estimate Material Testing Reactors Thermal-Hydraulic Analysis program (MTRTHA) is used to simulate a typical MTR reactor behavior with upward cooling under a hypothetical case of loss of off-site power. The flow inversion phenomenon is predicted under certain decay heat and/or pool temperature values below the design values. The reactor simulation under loss of off-site power is performed for two cases namely; two-flap valves open and one flap-valve fails to open. The model results for the flow inversion phenomenon prediction is analyzed and a solution of the problem is suggested. (orig.)
Savenkov, S M
2002-01-01
Using the Mueller matrix representation in the basis of the matrices of amplitude and phase anisotropies, a generalized solution of the inverse problem of polarimetry for deterministic objects on the base of incomplete Mueller matrices, which have been measured by method of three input polarization, is obtained.
International Nuclear Information System (INIS)
Savenkov, S.M.; Oberemok, Je.A.
2002-01-01
Using the Mueller matrix representation in the basis of the matrices of amplitude and phase anisotropies, a generalized solution of the inverse problem of polarimetry for deterministic objects on the base of incomplete Mueller matrices, which have been measured by method of three input polarization, is obtained
Energy Technology Data Exchange (ETDEWEB)
Etim, E; Basili, C [Rome Univ. (Italy). Ist. di Matematica
1978-08-21
The lagrangian in the path integral solution of the master equation of a stationary Markov process is derived by application of the Ehrenfest-type theorem of quantum mechanics and the Cauchy method of finding inverse functions. Applied to the non-linear Fokker-Planck equation the authors reproduce the result obtained by integrating over Fourier series coefficients and by other methods.
Energy Technology Data Exchange (ETDEWEB)
Hawley, B.W.; Zandt, G.; Smith, R.B.
1981-08-10
An iterative inversion technique has been developed that uses the direct P and S wave arrival times from local earthquakes to compute simultaneously a three-dimensional velocity structure and relocated hypocenters. Crustal structure is modeled by subdiving flat layers into rectangular blocks. An interpolation function is used to smoothly vary velocities between blocks, allowing ray trace calculations of travel times in a three-dimensional medium. Tests using synthetic data from known models show that solutions are reasonably independent of block size and spatial distribution but are sensitive to the choice of layer thicknesses. Application of the technique to observed earthquake data from north-central Utah shown the following: (1) lateral velcoity variations in the crust as large as 7% occur over 30-km distance, (2) earthquake epicenters computed with the three-dimensional velocity structure were shifted an average of 3.0 km from location determined assuming homogeneous flat layered models, and (3) the laterally varying velocity structure correlates with anomalous variations in the local gravity and aeromagnetic fields, suggesting that the new velocity information can be valuable in acquiring a better understanding of crustal structure.
International Nuclear Information System (INIS)
Hu Xianquan; Luo Guang; Cui Lipeng; Niu Lianbin; Li Fangyu
2009-01-01
The analytic solution of the radial Schroedinger equation is studied by using the tight coupling condition of several positive-power and inverse-power potential functions in this article. Furthermore, the precisely analytic solutions and the conditions that decide the existence of analytic solution have been searched when the potential of the radial Schroedinger equation is V(r) = α 1 r 8 + α 2 r 3 + α 3 r 2 + β 3 r -1 + β 2 r -3 + β 1 r -4 . Generally speaking, there is only an approximate solution, but not analytic solution for Schroedinger equation with several potentials' superposition. However, the conditions that decide the existence of analytic solution have been found and the analytic solution and its energy level structure are obtained for the Schroedinger equation with the potential which is motioned above in this paper. According to the single-value, finite and continuous standard of wave function in a quantum system, the authors firstly solve the asymptotic solution through the radial coordinate r → and r → 0; secondly, they make the asymptotic solutions combining with the series solutions nearby the neighborhood of irregular singularities; and then they compare the power series coefficients, deduce a series of analytic solutions of the stationary state wave function and corresponding energy level structure by tight coupling among the coefficients of potential functions for the radial Schroedinger equation; and lastly, they discuss the solutions and make conclusions. (general)
Directory of Open Access Journals (Sweden)
Shirley Carro
2017-01-01
Full Text Available Inverse emulsion polymerization technique was employed to synthesize hydrophobically modified polyacrylamide polymers with hydrophobe contents near to feed composition. Three different structures were obtained: multisticker, telechelic, and combined. N-Dimethyl-acrylamide (DMAM, n-dodecylacrylamide (DAM, and n-hexadecylacrylamide (HDAM were used as hydrophobic comonomers. The effect of the hydrophobe length of comonomer, the initial monomer, and surfactant concentrations on shear viscosity was studied. Results show that the molecular weight of copolymer increases with initial monomer concentration and by increasing emulsifier concentration it remained almost constant. Shear viscosity measurements results show that the length of the hydrophobic comonomer augments the hydrophobic interactions causing an increase in viscosity and that the polymer thickening ability is higher for combined polymers.
Solution of the nonlinear inverse scattering problem by T-matrix completion. I. Theory.
Levinson, Howard W; Markel, Vadim A
2016-10-01
We propose a conceptually different method for solving nonlinear inverse scattering problems (ISPs) such as are commonly encountered in tomographic ultrasound imaging, seismology, and other applications. The method is inspired by the theory of nonlocality of physical interactions and utilizes the relevant formalism. We formulate the ISP as a problem whose goal is to determine an unknown interaction potential V from external scattering data. Although we seek a local (diagonally dominated) V as the solution to the posed problem, we allow V to be nonlocal at the intermediate stages of iterations. This allows us to utilize the one-to-one correspondence between V and the T matrix of the problem. Here it is important to realize that not every T corresponds to a diagonal V and we, therefore, relax the usual condition of strict diagonality (locality) of V. An iterative algorithm is proposed in which we seek T that is (i) compatible with the measured scattering data and (ii) corresponds to an interaction potential V that is as diagonally dominated as possible. We refer to this algorithm as to the data-compatible T-matrix completion. This paper is Part I in a two-part series and contains theory only. Numerical examples of image reconstruction in a strongly nonlinear regime are given in Part II [H. W. Levinson and V. A. Markel, Phys. Rev. E 94, 043318 (2016)10.1103/PhysRevE.94.043318]. The method described in this paper is particularly well suited for very large data sets that become increasingly available with the use of modern measurement techniques and instrumentation.
Sensitivity study on hydraulic well testing inversion using simulated annealing
International Nuclear Information System (INIS)
Nakao, Shinsuke; Najita, J.; Karasaki, Kenzi
1997-11-01
For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion
Sensitivity study on hydraulic well testing inversion using simulated annealing
Energy Technology Data Exchange (ETDEWEB)
Nakao, Shinsuke; Najita, J.; Karasaki, Kenzi
1997-11-01
For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion.
Theoretical study on the inverse modeling of deep body temperature measurement
International Nuclear Information System (INIS)
Huang, Ming; Chen, Wenxi
2012-01-01
We evaluated the theoretical aspects of monitoring the deep body temperature distribution with the inverse modeling method. A two-dimensional model was built based on anatomical structure to simulate the human abdomen. By integrating biophysical and physiological information, the deep body temperature distribution was estimated from cutaneous surface temperature measurements using an inverse quasilinear method. Simulations were conducted with and without the heat effect of blood perfusion in the muscle and skin layers. The results of the simulations showed consistently that the noise characteristics and arrangement of the temperature sensors were the major factors affecting the accuracy of the inverse solution. With temperature sensors of 0.05 °C systematic error and an optimized 16-sensor arrangement, the inverse method could estimate the deep body temperature distribution with an average absolute error of less than 0.20 °C. The results of this theoretical study suggest that it is possible to reconstruct the deep body temperature distribution with the inverse method and that this approach merits further investigation. (paper)
International Nuclear Information System (INIS)
Maksudov, F.G.; Gusejnov, G.Sh.
1986-01-01
Inverse scattering problem for the quadratic bundle of the Schroedinger one-dimensional operators in the whole axis is solved. The problem solution is given on the assumption of the discrete spectrum absence. In the discrete spectrum presence the inverse scattering problem solution is known for the Shroedinger differential equation considered
Selective data extension for full-waveform inversion: An efficient solution for cycle skipping
Wu, Zedong; Alkhalifah, Tariq Ali
2017-01-01
Standard full-waveform inversion (FWI) attempts to minimize the difference between observed and modeled data. However, this difference is obviously sensitive to the amplitude of observed data, which leads to difficulties because we often do
Butler, T.; Graham, L.; Estep, D.; Dawson, C.; Westerink, J. J.
2015-04-01
The uncertainty in spatially heterogeneous Manning's n fields is quantified using a novel formulation and numerical solution of stochastic inverse problems for physics-based models. The uncertainty is quantified in terms of a probability measure and the physics-based model considered here is the state-of-the-art ADCIRC model although the presented methodology applies to other hydrodynamic models. An accessible overview of the formulation and solution of the stochastic inverse problem in a mathematically rigorous framework based on measure theory is presented. Technical details that arise in practice by applying the framework to determine the Manning's n parameter field in a shallow water equation model used for coastal hydrodynamics are presented and an efficient computational algorithm and open source software package are developed. A new notion of "condition" for the stochastic inverse problem is defined and analyzed as it relates to the computation of probabilities. This notion of condition is investigated to determine effective output quantities of interest of maximum water elevations to use for the inverse problem for the Manning's n parameter and the effect on model predictions is analyzed.
International Nuclear Information System (INIS)
Dinh Nho Hao; Nguyen Trung Thanh; Sahli, Hichem
2008-01-01
In this paper we consider a multi-dimensional inverse heat conduction problem with time-dependent coefficients in a box, which is well-known to be severely ill-posed, by a variational method. The gradient of the functional to be minimized is obtained by aids of an adjoint problem and the conjugate gradient method with a stopping rule is then applied to this ill-posed optimization problem. To enhance the stability and the accuracy of the numerical solution to the problem we apply this scheme to the discretized inverse problem rather than to the continuous one. The difficulties with large dimensions of discretized problems are overcome by a splitting method which only requires the solution of easy-to-solve one-dimensional problems. The numerical results provided by our method are very good and the techniques seem to be very promising.
International Nuclear Information System (INIS)
Li Qi; Duan Qiuyuan; Zhang Jianbing
2012-01-01
The mixed discrete modified Korteweg-de Vries (mKdV) hierarchy and the Lax pair are derived. The hierarchy related to the Ablowitz-Ladik spectral problem is reduced to the isospectral discrete mKdV hierarchy and to the non-isospectral discrete mKdV hierarchy. N-soliton solutions of the hierarchies are obtained through inverse scattering transform.
Directory of Open Access Journals (Sweden)
Maciejewska Beata
2017-01-01
Full Text Available This paper shows the results concerning flow boiling heat transfer in an asymmetrically heated vertical minichannel. The heated element for FC-72 Fluorinert flowing in that minichannel was a thin foil. The foil surface temperature was monitored continuously at 18 points by K-type thermocouples from the outer foil surface. Fluid temperature and pressure in the minichannel inlet and outlet, current supplied to the foil and voltage drop were also monitored. Measurements were carried out at 1 s intervals. The objective was to determine the heat transfer coefficient on the heated foil–fluid contact surface in the minichannel. It was obtained from the Robin boundary condition. The foil temperature was the result of solving the nonstationary two-dimensional inverse boundary problem in the heated foil. Using the FEM combined with Trefftz functions as basis functions solved the problem. The unknown temperature values at nodes were calculated by minimising the adequate functional. The values of local heat transfer coefficients were consistent with the results obtained by the authors in their previous studies when steady-state conditions were analysed. This time, however, these values were analysed as time dependent, which facilitated observation of coefficient changes that were impossible to observe under the steady-state conditions.
Full Waveform Inversion for Reservoir Characterization - A Synthetic Study
Zabihi Naeini, E.; Kamath, N.; Tsvankin, I.; Alkhalifah, Tariq Ali
2017-01-01
Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI
SIPPI: A Matlab toolbox for sampling the solution to inverse problems with complex prior information
DEFF Research Database (Denmark)
Hansen, Thomas Mejer; Cordua, Knud Skou; Looms, Majken Caroline
2013-01-01
We present an application of the SIPPI Matlab toolbox, to obtain a sample from the a posteriori probability density function for the classical tomographic inversion problem. We consider a number of different forward models, linear and non-linear, such as ray based forward models that rely...
Study of liquids and solutions
International Nuclear Information System (INIS)
Bellissent-Funel, M.C.
1994-01-01
A critical review of what has been achieved on the structure of liquids and solutions and the capabilities and developments of neutron scattering in this domain, are presented. A great variety of simple to complex systems has been investigated with the aim of obtaining a full microscopic description of the structure. Selected examples demonstrate the neutron scattering determination of interaction potentials, intermolecular structures and partial structure factors of complex systems. The isotopic substitution method is illustrated by the application to the study of the solvation of ions in aqueous and non aqueous solutions. (author). 9 figs., 32 refs
Study of inverse methods in remote sensing with laser
International Nuclear Information System (INIS)
Jesus, Wellington Carlos de
2009-01-01
The Laboratory of Environmental Applications of Lasers at IPEN realizes a study about atmospherics properties, such as extinction and backscattering coefficient. These coefficient are estimated by an inverse method, whose estimate quality is difficult to measure. This work presents a method with good statistic approach to retrieval the same coefficients. The new method, however, offers a number of advantages compared to the first method in use, including (1) the ability to incorporate different kinds of information under a common retrieval philosophy and (2) the method provides number of ways for evaluating the quality of the retrieval. Thus we hope improve the accuracy of estimates. (author)
Energy Technology Data Exchange (ETDEWEB)
Watanabe, T; Sassa, K [Kyoto University, Kyoto (Japan); Uesaka, S [Kyoto University, Kyoto (Japan). Faculty of Engineering
1996-10-01
The effect of initial models on full-wave inversion (FWI) analysis based on acoustic wave-equation was studied for elastic wave tomography of underground structures. At present, travel time inversion using initial motion travel time is generally used, and inverse analysis is conducted using the concept `ray,` assuming very high wave frequency. Although this method can derive stable solutions relatively unaffected by initial model, it uses only the data of initial motion travel time. FWI calculates theoretical waveform at each receiver using all of observed waveforms as data by wave equation modeling where 2-D underground structure is calculated by difference calculus under the assumption that wave propagation is described by wave equation of P wave. Although it is a weak point that FWI is easily affected by noises in an initial model and data, it is featured by high resolution of solutions. This method offers very excellent convergence as a proper initial model is used, resulting in sufficient performance, however, it is strongly affected by initial model. 2 refs., 7 figs., 1 tab.
Solution of the inverse scattering problem at fixed energy with non-physical S matrix elements
International Nuclear Information System (INIS)
Eberspaecher, M.; Amos, K.; Apagyi, B.
1999-12-01
The quantum mechanical inverse elastic scattering problem is solved with the modified Newton-Sabatier method. A set of S matrix elements calculated from a realistic analytic optical model potential serves as input data. It is demonstrated that the quality of the inversion potential can be improved by including non-physical S matrix elements to half, quarter and eighth valued partial waves if the original set does not contain enough information to determine the interaction potential. We demonstrate that results can be very sensitive to the choice of those non-physical S matrix values both with the analytic potential model and in a real application in which the experimental cross section for the symmetrical scattering system of 12 C+ 12 C at E=7.998 MeV is analyzed
Inverse probability weighting for covariate adjustment in randomized studies.
Shen, Changyu; Li, Xiaochun; Li, Lingling
2014-02-20
Covariate adjustment in randomized clinical trials has the potential benefit of precision gain. It also has the potential pitfall of reduced objectivity as it opens the possibility of selecting a 'favorable' model that yields strong treatment benefit estimate. Although there is a large volume of statistical literature targeting on the first aspect, realistic solutions to enforce objective inference and improve precision are rare. As a typical randomized trial needs to accommodate many implementation issues beyond statistical considerations, maintaining the objectivity is at least as important as precision gain if not more, particularly from the perspective of the regulatory agencies. In this article, we propose a two-stage estimation procedure based on inverse probability weighting to achieve better precision without compromising objectivity. The procedure is designed in a way such that the covariate adjustment is performed before seeing the outcome, effectively reducing the possibility of selecting a 'favorable' model that yields a strong intervention effect. Both theoretical and numerical properties of the estimation procedure are presented. Application of the proposed method to a real data example is presented. Copyright © 2013 John Wiley & Sons, Ltd.
DEFF Research Database (Denmark)
Sakellariou, Jason; Roudi, Yasser; Mezard, Marc
2012-01-01
We study how the degree of symmetry in the couplings influences the performance of three mean field methods used for solving the direct and inverse problems for generalized Sherrington-Kirkpatrick models. In this context, the direct problem is predicting the potentially time-varying magnetizations...... than the other two approximations, TAP outperforms MF when the coupling matrix is nearly symmetric, while MF works better when it is strongly asymmetric. For the inverse problem, MF performs better than both TAP and nMF, although an ad hoc adjustment of TAP can make it comparable to MF. For high...
Pericentric inversion of chromosome 12; a three family study
DEFF Research Database (Denmark)
Haagerup, Annette; Hertz, Jens Michael
1992-01-01
A pericentric inversion of chromosome 12 has been followed in three large independently ascertained Danish families. Out of a total number of 52 persons examined, 25 were found to carry the inversion. The breakpoints in all three families were localized to p13 and q13, resulting in more than one...... rate is calculated to be 0.58, which is not significantly different from an expected segregation rate of 0.5. In family 3, an additional inversion of a chromosome 9 has been found in 4 individuals. Our results are discussed in relation to previous findings and with respect to the genetic counselling...... of families with pericentric inversions....
International Nuclear Information System (INIS)
Hamman, E.; Zorgati, R.
1995-01-01
Eddy current non-destructive testing is used by EDF to detect flaws affecting conductive objects such as steam generator tubes. With a view to obtaining ever more accurate information on equipment integrity, thereby facilitating diagnosis, studies aimed at using measurements to reconstruct an image of the flaw have been proceeding now for about ten years. In this context, our approach to eddy current imaging is based on inverse problem formalism. The direct problem, involving a mathematical model linking measurements provided by a probe with variables characterizing the defect, is dealt with elsewhere. Using the model results, we study the possibility of inverting it, i.e. of reconstructing an image of the flaw from the measurements. We first give an overview of the different inversion techniques, representative of the state of the art and all based on linearization of the inverse problem by means of the Born approximation. The model error resulting from an excessive Born approximation nevertheless severely limits the quantity of the images which can be obtained. In order to counteract this often critical error and extend the eddy current imaging application field, we have to del with the non-linear inverse problem. A method derived from recent research is proposed and implemented to ensure consistency with the exact model. Based on an 'optimization' type approach and provided with a convergence theorem, the method is highly efficient. (authors). 17 refs., 7 figs., 1 append
International Nuclear Information System (INIS)
Otero, F A; Frontini, G L; Elicabe, G E
2011-01-01
An analytic model for the scattering of a spherical particle with spherical inclusions has been proposed under the RG approximation. The model can be used without limitations to describe an X-ray scattering experiment. However, for light scattering several conditions must be fulfilled. Based on this model an inverse methodology is proposed to estimate the radii of host particle and inclusions, the number of inclusions and the Distance Distribution Functions (DDF's) of the distances between inclusions and the distances between inclusions and the origin of coordinates. The methodology is numerically tested in a light scattering example in which the host particle is eliminated by matching the refractive indices of host particle and medium. The results obtained for this cluster particle are very satisfactory.
Porr, Bernd; von Ferber, Christian; Wörgötter, Florentin
2003-04-01
In "Isotropic Sequence Order Learning" (pp. 831-864 in this issue), we introduced a novel algorithm for temporal sequence learning (ISO learning). Here, we embed this algorithm into a formal nonevaluating (teacher free) environment, which establishes a sensor-motor feedback. The system is initially guided by a fixed reflex reaction, which has the objective disadvantage that it can react only after a disturbance has occurred. ISO learning eliminates this disadvantage by replacing the reflex-loop reactions with earlier anticipatory actions. In this article, we analytically demonstrate that this process can be understood in terms of control theory, showing that the system learns the inverse controller of its own reflex. Thereby, this system is able to learn a simple form of feedforward motor control.
The Solution of Two-Phase Inverse Stefan Problem Based on a Hybrid Method with Optimization
Directory of Open Access Journals (Sweden)
Yang Yu
2015-01-01
Full Text Available The two-phase Stefan problem is widely used in industrial field. This paper focuses on solving the two-phase inverse Stefan problem when the interface moving is unknown, which is more realistic from the practical point of view. With the help of optimization method, the paper presents a hybrid method which combines the homotopy perturbation method with the improved Adomian decomposition method to solve this problem. Simulation experiment demonstrates the validity of this method. Optimization method plays a very important role in this paper, so we propose a modified spectral DY conjugate gradient method. And the convergence of this method is given. Simulation experiment illustrates the effectiveness of this modified spectral DY conjugate gradient method.
Directory of Open Access Journals (Sweden)
Mingzhong Gao
Full Text Available Rectangular caverns are increasingly used in underground engineering projects, the failure mechanism of rectangular cavern wall rock is significantly different as a result of the cross-sectional shape and variations in wall stress distributions. However, the conventional computational method always results in a long-winded computational process and multiple displacement solutions of internal rectangular wall rock. This paper uses a Laurent series complex method to obtain a mapping function expression based on complex variable function theory and conformal transformation. This method is combined with the Schwarz-Christoffel method to calculate the mapping function coefficient and to determine the rectangular cavern wall rock deformation. With regard to the inverse mapping concept, the mapping relation between the polar coordinate system within plane ς and a corresponding unique plane coordinate point inside the cavern wall rock is discussed. The disadvantage of multiple solutions when mapping from the plane to the polar coordinate system is addressed. This theoretical formula is used to calculate wall rock boundary deformation and displacement field nephograms inside the wall rock for a given cavern height and width. A comparison with ANSYS numerical software results suggests that the theoretical solution and numerical solution exhibit identical trends, thereby demonstrating the method's validity. This method greatly improves the computing accuracy and reduces the difficulty in solving for cavern boundary and internal wall rock displacements. The proposed method provides a theoretical guide for controlling cavern wall rock deformation failure.
On an asymptotic technique of solution of the inverse problem of helioseismology
International Nuclear Information System (INIS)
Brodskij, M.A.; Vorontsov, S.V.
1987-01-01
The technique for the solution of the universe problem for the solar 5-min. oscillations is proposed, which provides an independent determination of the second speed as a function of depth in solar interior and the frequency dependence of the effective phase shift for the reflection of the trapped acoustic waves from the outer layers. The preliminary numerical results are presented
Wyatt, Philip
2009-03-01
The electromagnetic inverse scattering problem suggests that if a homogeneous and non-absorbing object be illuminated with a monochromatic light source and if the far field scattered light intensity is known at sufficient scattering angles, then, in principle, one could derive the dielectric structure of the scattering object. In general, this is an ill-posed problem and methods must be developed to regularize the search for unique solutions. An iterative procedure often begins with a model of the scattering object, solves the forward scattering problem using this model, and then compares these calculated results with the measured values. Key to any such solution is instrumentation capable of providing adequate data. To this end, the development of the first laser based absolute light scattering photometers is described together with their continuing evolution and some of the remarkable discoveries made with them. For particles much smaller than the wavelength of the incident light (e.g. macromolecules), the inverse scattering problems are easily solved. Among the many solutions derived with this instrumentation are the in situ structure of bacterial cells, new drug delivery mechanisms, the development of new vaccines and other biologicals, characterization of wines, the possibility of custom chemotherapy, development of new polymeric materials, identification of protein crystallization conditions, and a variety discoveries concerning protein interactions. A new form of the problem is described to address bioterrorist threats. Over the many years of development and refinement, one element stands out as essential for the successes that followed: the R and D teams were always directed and executed by physics trained theorists and experimentalists. 14 Ph. D. physicists each made his/her unique contribution to the development of these evolving instruments and the interpretation of their results.
A study of block algorithms for fermion matrix inversion
International Nuclear Information System (INIS)
Henty, D.
1990-01-01
We compare the convergence properties of Lanczos and Conjugate Gradient algorithms applied to the calculation of columns of the inverse fermion matrix for Kogut-Susskind and Wilson fermions in lattice QCD. When several columns of the inverse are required simultaneously, a block version of the Lanczos algorithm is most efficient at small mass, being over 5 times faster than the single algorithms. The block algorithm is also less susceptible to critical slowing down. (orig.)
Numerical solution of an inverse 2D Cauchy problem connected with the Helmholtz equation
International Nuclear Information System (INIS)
Wei, T; Qin, H H; Shi, R
2008-01-01
In this paper, the Cauchy problem for the Helmholtz equation is investigated. By Green's formulation, the problem can be transformed into a moment problem. Then we propose a numerical algorithm for obtaining an approximate solution to the Neumann data on the unspecified boundary. Error estimate and convergence analysis have also been given. Finally, we present numerical results for several examples and show the effectiveness of the proposed method
Demirci, İsmail; Dikmen, Ünal; Candansayar, M. Emin
2018-02-01
Joint inversion of data sets collected by using several geophysical exploration methods has gained importance and associated algorithms have been developed. To explore the deep subsurface structures, Magnetotelluric and local earthquake tomography algorithms are generally used individually. Due to the usage of natural resources in both methods, it is not possible to increase data quality and resolution of model parameters. For this reason, the solution of the deep structures with the individual usage of the methods cannot be fully attained. In this paper, we firstly focused on the effects of both Magnetotelluric and local earthquake data sets on the solution of deep structures and discussed the results on the basis of the resolving power of the methods. The presence of deep-focus seismic sources increase the resolution of deep structures. Moreover, conductivity distribution of relatively shallow structures can be solved with high resolution by using MT algorithm. Therefore, we developed a new joint inversion algorithm based on the cross gradient function in order to jointly invert Magnetotelluric and local earthquake data sets. In the study, we added a new regularization parameter into the second term of the parameter correction vector of Gallardo and Meju (2003). The new regularization parameter is enhancing the stability of the algorithm and controls the contribution of the cross gradient term in the solution. The results show that even in cases where resistivity and velocity boundaries are different, both methods influence each other positively. In addition, the region of common structural boundaries of the models are clearly mapped compared with original models. Furthermore, deep structures are identified satisfactorily even with using the minimum number of seismic sources. In this paper, in order to understand the future studies, we discussed joint inversion of Magnetotelluric and local earthquake data sets only in two-dimensional space. In the light of these
International Nuclear Information System (INIS)
Ita, B. I.; Ehi-Eromosele, C. O.; Edobor-Osoh, A.; Ikeuba, A. I.
2014-01-01
By using the Nikiforov-Uvarov (NU) method, the Schrödinger equation has been solved for the interaction of inversely quadratic Hellmann (IQHP) and inversely quadratic potential (IQP) for any angular momentum quantum number, l. The energy eigenvalues and their corresponding eigenfunctions have been obtained in terms of Laguerre polynomials. Special cases of the sum of these potentials have been considered and their energy eigenvalues also obtained
Selective data extension for full-waveform inversion: An efficient solution for cycle skipping
Wu, Zedong
2017-12-29
Standard full-waveform inversion (FWI) attempts to minimize the difference between observed and modeled data. However, this difference is obviously sensitive to the amplitude of observed data, which leads to difficulties because we often do not process data in absolute units and because we usually do not consider density variations, elastic effects, or more complicated physical phenomena. Global correlation methods can remove the amplitude influence for each trace and thus can mitigate such difficulties in some sense. However, this approach still suffers from the well-known cycle-skipping problem, leading to a flat objective function when observed and modeled data are not correlated well enough. We optimize based on maximizing not only the zero-lag global correlation but also time or space lags of the modeled data to circumvent the half-cycle limit. We use a weighting function that is maximum value at zero lag and decays away from zero lag to balance the role of the lags. The resulting objective function is less sensitive to the choice of the maximum lag allowed and has a wider region of convergence compared with standard FWI. Furthermore, we develop a selective function, which passes to the gradient calculation only positive correlations, to mitigate cycle skipping. Finally, the resulting algorithm has better convergence behavior than conventional methods. Application to the Marmousi model indicates that this method converges starting with a linearly increasing velocity model, even with data free of frequencies less than 3.5 Hz. Application to the SEG2014 data set demonstrates the potential of our method.
Cost effective solution using inverse lithography OPC for DRAM random contact layer
Jun, Jinhyuck; Hwang, Jaehee; Choi, Jaeseung; Oh, Seyoung; Park, Chanha; Yang, Hyunjo; Dam, Thuc; Do, Munhoe; Lee, Dong Chan; Xiao, Guangming; Choi, Jung-Hoe; Lucas, Kevin
2017-04-01
Many different advanced devices and design layers currently employ double patterning technology (DPT) as a means to overcome lithographic and OPC limitations at low k1 values. Certainly device layers with k1 value below 0.25 require DPT or other pitch splitting methodologies. DPT has also been used to improve patterning of certain device layers with k1 values slightly above 0.25, due to the difficulty of achieving sufficient pattern fidelity with only a single exposure. Unfortunately, this broad adoption of DPT also came with a significant increase in patterning process cost. In this paper, we discuss the development of a single patterning technology process using an integrated Inverse Lithography Technology (ILT) flow for mask synthesis. A single pattering technology flow will reduce the manufacturing cost for a k1 > 0.25 full chip random contact layer in a memory device by replacing the more expensive DPT process with ILT flow, while also maintaining good lithographic production quality and manufacturable OPC/RET production metrics. This new integrated flow consists of applying ILT to the difficult core region and traditional rule-based assist features (RBAFs) with OPC to the peripheral region of a DRAM contact layer. Comparisons of wafer results between the ILT process and the non-ILT process showed the lithographic benefits of ILT and its ability to enable a robust single patterning process for this low-k1 device layer. Advanced modeling with a negative tone develop (NTD) process achieved the accuracy levels needed for ILT to control feature shapes through dose and focus. Details of these afore mentioned results will be described in the paper.
DEFF Research Database (Denmark)
Montoya-Martinez, Jair; Artes-Rodriguez, Antonio; Pontil, Massimiliano
2014-01-01
We consider the estimation of the Brain Electrical Sources (BES) matrix from noisy electroencephalographic (EEG) measurements, commonly named as the EEG inverse problem. We propose a new method to induce neurophysiological meaningful solutions, which takes into account the smoothness, structured...... sparsity, and low rank of the BES matrix. The method is based on the factorization of the BES matrix as a product of a sparse coding matrix and a dense latent source matrix. The structured sparse-low-rank structure is enforced by minimizing a regularized functional that includes the ℓ21-norm of the coding...... matrix and the squared Frobenius norm of the latent source matrix. We develop an alternating optimization algorithm to solve the resulting nonsmooth-nonconvex minimization problem. We analyze the convergence of the optimization procedure, and we compare, under different synthetic scenarios...
Directory of Open Access Journals (Sweden)
Vladimir I. Volchikhin
2017-12-01
Full Text Available Introduction: The aim of the study is to accelerate the solution of neural network biometrics inverse problem on an ordinary desktop computer. Materials and Methods: To speed up the calculations, the artificial neural network is introduced into the dynamic mode of “jittering” of the states of all 256 output bits. At the same time, too many output states of the neural network are logarithmically folded by transitioning to the Hamming distance space between the code of the image “Own” and the codes of the images “Alien”. From the database of images of “Alien” 2.5 % of the most similar images are selected. In the next generation, 97.5 % of the discarded images are restored with GOST R 52633.2-2010 procedures by crossing parent images and obtaining descendant images from them. Results: Over a period of about 10 minutes, 60 generations of directed search for the solution of the inverse problem can be realized that allows inversing matrices of neural network functionals of dimension 416 inputs to 256 outputs with restoration of up to 97 % information on unknown biometric parameters of the image “Own”. Discussion and Conclusions: Supporting for 10 minutes of computer time the 256 qubit quantum superposition allows on a conventional computer to bypass the actual infinity of analyzed states in 5050 (50 to 50 times more than the same computer could process realizing the usual calculations. The increase in the length of the supported quantum superposition by 40 qubits is equivalent to increasing the processor clock speed by about a billion times. It is for this reason that it is more profitable to increase the number of quantum superpositions supported by the software emulator in comparison with the creation of a more powerful processor.
On the solution of an inverse problem for confining potentials in quantum mechanics
International Nuclear Information System (INIS)
Gostev, V.B.; Mineev, V.S.; Frenkin, A.R.
1982-01-01
The problem of plotting confining (unlimitedly increasing on the infinity) potentials of the central field by the given energy spectrum is discussed. The radial Schroedinger equation has pure discrete spectrum with infinite number of levels for these potentials. The problem is solved using the Helfand-Levitan equation with a certain reference potential V(r) for which spectral characteristics differ from the given ones only in the finite number of elements. The regular solutions PHIsub(l)(E, r) of the Schroedinger equation for the reference potential V(r) are supposed to be known. The initial potential and regular solutions of the Schroedinger equation are restored by the reference potential V(r) and regular PHIsub(l)(E, r) functions by means of the known formulas. It is observed from the paper data that confining potentials with any type of spectrum can be restored. Choice of the corresponding reference potential providing Fredholm nature of the Helfand-Levitan equation is the basic problem in this case
Coarsening of Ni-Ge solid-solution precipitates in 'inverse' Ni{sub 3}Ge alloys
Energy Technology Data Exchange (ETDEWEB)
Ardell, Alan J., E-mail: alan.ardell@gmail.com [National Science Foundation, 4201 Wilson Boulevard, Arlington, VA 22230 (United States); Ma Yong [Aquatic Sensor Network Technology LLC, Storrs, CT 06268 (United States)
2012-07-30
Highlights: Black-Right-Pointing-Pointer We report microstructural evolution of disordered Ni-Ge precipitates in Ni{sub 3}Ge alloys. Black-Right-Pointing-Pointer Coarsening kinetics and particle size distributions are presented. Black-Right-Pointing-Pointer Data are analyzed quantitatively using the MSLW theory, but agreement is only fair. Black-Right-Pointing-Pointer The shapes of large precipitates are unusual, with discus or boomerang cross-sections. Black-Right-Pointing-Pointer Results are compared with morphology, kinetics of Ni-Al in inverse Ni{sub 3}Al alloys. - Abstract: The morphological evolution and coarsening kinetics of Ni-Ge solid solution precipitates from supersaturated solutions of hypostoichiometric Ni{sub 3}Ge were investigated in alloys containing from 22.48 to 23.50 at.% Ge at 600, 650 and 700 Degree-Sign C. The particles evolve from spheres to cuboids, though the flat portions of the interfaces are small. At larger sizes the precipitates coalesce into discus shapes, and are sometimes boomerang-shaped in cross section after intersection. The rate constant for coarsening increases strongly with equilibrium volume fraction, much more so than predicted by current theories; this is very different from the coarsening behavior of Ni{sub 3}Ge precipitates in normal Ni-Ge alloys and of Ni-Al precipitates in inverse Ni{sub 3}Al alloys. The activation energy for coarsening, 275.86 {+-} 24.17 kJ/mol, is somewhat larger than the result from conventional diffusion experiments, though within the limits of experimental error. Quantitative agreement between theory and experiment, estimated using available data on tracer diffusion coefficients in Ni{sub 3}Ge, is fair, the calculated rate constants exceeding measured ones by a factor of about 15. The particle size distributions are not in very good agreement with the predictions of any theory. These results are discussed in the context of recent theories and observations.
Full Waveform Inversion for Reservoir Characterization - A Synthetic Study
Zabihi Naeini, E.
2017-05-26
Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI) as an alternative tool for higher-resolution reservoir characterization. An important step in developing reservoir-oriented FWI is the implementation of facies-based rock physics constraints adapted from the classic methods. We show that such constraints can be incorporated into FWI by adding appropriately designed regularization terms to the objective function. The advantages of the proposed algorithm are demonstrated on both isotropic and VTI (transversely isotropic with a vertical symmetry axis) models with pronounced lateral and vertical heterogeneity. The inversion results are explained using the theoretical radiation patterns produced by perturbations in the medium parameters.
Directory of Open Access Journals (Sweden)
S. Fonna
2018-06-01
Full Text Available Evaluation of rebar/reinforcing-steel corrosion for the 2004 tsunami-affected reinforced concrete (RC buildings in Aceh was conducted using half-cell potential mapping technique. However, the results only show qualitative meaning as corrosion risk rather than the corrosion itself, such as the size and location of corrosion. In this study, boundary element inverse analysis was proposed to be performed to detect rebar corrosion of the 2004 tsunami-affected structure in Aceh, using several electrical potential measurement data on the concrete surface. One RC structure in Peukan Bada, an area heavily damaged by the tsunami, was selected for the study. In 2004 the structure was submerged more than 5 m by the tsunami. Boundary element inverse analysis was developed by combining the boundary element method (BEM and particle swarm optimization (PSO. The corrosion was detected by evaluating measured and calculated electrical potential data. The measured and calculated electrical potential on the concrete surface was obtained by using a half-cell potential meter and by performing BEM, respectively. The solution candidates were evaluated by employing PSO. Simulation results show that boundary element inverse analysis successfully detected the size and location of corrosion for the case study. Compared with the actual corrosion, the error of simulation result was less than 5%. Hence, it shows that boundary element inverse analysis is very promising for further development to detect rebar corrosion. Keywords: Inverse analysis, Boundary element method, PSO, Corrosion, Reinforced concrete
Nonlinear evolution-type equations and their exact solutions using inverse variational methods
International Nuclear Information System (INIS)
Kara, A H; Khalique, C M
2005-01-01
We present the role of invariants in obtaining exact solutions of differential equations. Firstly, conserved vectors of a partial differential equation (p.d.e.) allow us to obtain reduced forms of the p.d.e. for which some of the Lie point symmetries (in vector field form) are easily concluded and, therefore, provide a mechanism for further reduction. Secondly, invariants of reduced forms of a p.d.e. are obtainable from a variational principle even though the p.d.e. itself does not admit a Lagrangian. In this latter case, the reductions carry all the usual advantages regarding Noether symmetries and double reductions. The examples we consider are nonlinear evolution-type equations such as the Korteweg-deVries equation, but a detailed analysis is made on the Fisher equation (which describes reaction-diffusion waves in biology, inter alia). Other diffusion-type equations lend themselves well to the method we describe (e.g., the Fitzhugh Nagumo equation, which is briefly discussed). Some aspects of Painleve properties are also suggested
Near optimal solution to the inverse problem for gravitational-wave bursts
International Nuclear Information System (INIS)
Guersel, Y.; Tinto, M.
1989-01-01
We develop a method for determining the source direction (θ,φ) and the two waveforms h + (t), h x (t) of a gravitational-wave burst using noisy data from three wideband gravitational-wave detectors running in coincidence. The scheme does not rely on any assumptions about the waveforms and in fact it works for gravitational-wave bursts of any kind. To improve the accuracy of the solution for (θ,φ), h + (t), h x (t), we construct a near optimal filter for the noisy data which is deduced from the data themselves. We implement the method numerically using simulated data for detectors that operate, with white Gaussian noise, in the frequency band of 500--2500 Hz. We show that for broadband signals centered around 1 kHz with a conventional signal-to-noise ratio of at least 10 in each detector we are able to locate the source within a solid angle of 1x10 -5 sr. If the signals and the detectors' band were scaled downwards in frequency by a factor ι, at fixed signal-to-noise ratio, then the solid angle of the source's error box would increase by a factor ι 2 . The simulated data are assumed to be produced by three detectors: one on the east coast of the United States of America, one on the west coast of the United States of America, and the third in Germany or Western Australia. For conventional signal-to-noise ratios significantly lower than 10 the method still converges to the correct combination of the relative time delays but it is unable to distinguish between the two mirror-image directions defined by the relative time delays. The angular spread around these points increases as the signal-to-noise ratio decreases. For conventional signal-to-noise ratios near 1 the method loses its resolution completely
International Nuclear Information System (INIS)
Vrba, J; Robinson, S E; McCubbin, J; Lowery, C L; Eswaran, H; Murphy, P; Preissl, H
2007-01-01
Fetal brain signals produce weak magnetic fields at the maternal abdominal surface. In the presence of much stronger interference these weak fetal fields are often nearly indistinguishable from noise. Our initial objective was to validate these weak fetal brain fields by demonstrating that they agree with the electromagnetic model of the fetal brain. The fetal brain model is often not known and we have attempted to fit the data to not only the brain source position, orientation and magnitude, but also to the brain model position. Simulation tests of this extended model search on fetal MEG recordings using dipole fit and beamformers revealed a region of ambiguity. The region of ambiguity consists of a family of models which are not distinguishable in the presence of noise, and which exhibit large and comparable SNR when beamformers are used. Unlike the uncertainty of a dipole fit with known model plus noise, this extended ambiguity region yields nearly identical forward solutions, and is only weakly dependent on noise. The ambiguity region is located in a plane defined by the source position, orientation, and the true model centre, and will have a diameter approximately 0.67 of the modelled fetal head diameter. Existence of the ambiguity region allows us to only state that the fetal brain fields do not contradict the electromagnetic model; we can associate them with a family of models belonging to the ambiguity region, but not with any specific model. In addition to providing a level of confidence in the fetal brain signals, the ambiguity region knowledge in combination with beamformers allows detection of undistorted temporal waveforms with improved signal-to-noise ratio, even though the source position cannot be uniquely determined
Kordy, M.; Wannamaker, P.; Maris, V.; Cherkaev, E.; Hill, G.
2016-01-01
Following the creation described in Part I of a deformable edge finite-element simulator for 3-D magnetotelluric (MT) responses using direct solvers, in Part II we develop an algorithm named HexMT for 3-D regularized inversion of MT data including topography. Direct solvers parallelized on large-RAM, symmetric multiprocessor (SMP) workstations are used also for the Gauss-Newton model update. By exploiting the data-space approach, the computational cost of the model update becomes much less in both time and computer memory than the cost of the forward simulation. In order to regularize using the second norm of the gradient, we factor the matrix related to the regularization term and apply its inverse to the Jacobian, which is done using the MKL PARDISO library. For dense matrix multiplication and factorization related to the model update, we use the PLASMA library which shows very good scalability across processor cores. A synthetic test inversion using a simple hill model shows that including topography can be important; in this case depression of the electric field by the hill can cause false conductors at depth or mask the presence of resistive structure. With a simple model of two buried bricks, a uniform spatial weighting for the norm of model smoothing recovered more accurate locations for the tomographic images compared to weightings which were a function of parameter Jacobians. We implement joint inversion for static distortion matrices tested using the Dublin secret model 2, for which we are able to reduce nRMS to ˜1.1 while avoiding oscillatory convergence. Finally we test the code on field data by inverting full impedance and tipper MT responses collected around Mount St Helens in the Cascade volcanic chain. Among several prominent structures, the north-south trending, eruption-controlling shear zone is clearly imaged in the inversion.
International Nuclear Information System (INIS)
Zakhariev, B.N.; Chabanov, V.M.
2008-01-01
It was an important examination to give a review talk at the previous Conference on Inverse Quantum Scattering (1996, Lake Balaton) about computer visualization of this science in front of its fathers - creators, B.M. Levitan and V.A. Marchenko. We have achieved a new understanding that the discovered main rules of transformations of a single wave function bump, e.g., for the ground bound states of one dimensional quantum systems are applicable to any state of any potential with arbitrary number of bumps from finite to unlimited ones as scattering states and bound states embedded into continuum. It appeared that we need only to repeat the rule mentally the necessary number of times. That uttermost simplification and unification of physical notion of spectral, scattering and decay control for any potential have got an obligatory praise from B.M. Levitan at the conference and was a mighty stimulus for our further research. After that we have written both Russian (2002) and improved English editions of 'Submissive Quantum Mechanics. New Status of the Theory in Inverse Problem Approach' (appeared at the very end of 2007). This book was written for correction of the present defect in quantum education throughout the world. Recently the quantum IP intuition helped us to discover a new concept of permanent wave resonance with potential spatial oscillations. This means the constant wave swinging frequency on the whole energy intervals of spectral forbidden zones destroying physical solutions and deepening the theory of waves in periodic potentials. It also shows the other side of strengthening the fundamentally important magic structures. A 'new language' of wave bending will be presented to enrich our quantum intuition, e.g., the paradoxical effective attraction of barriers and repulsion of wells in multichannel systems, etc. (author)
Inverse problems of geophysics
International Nuclear Information System (INIS)
Yanovskaya, T.B.
2003-07-01
This report gives an overview and the mathematical formulation of geophysical inverse problems. General principles of statistical estimation are explained. The maximum likelihood and least square fit methods, the Backus-Gilbert method and general approaches for solving inverse problems are discussed. General formulations of linearized inverse problems, singular value decomposition and properties of pseudo-inverse solutions are given
Study of the characteristics of crust stress field in East China by inversion of stress tensor
International Nuclear Information System (INIS)
Huilan, Z.; Rugang, D.
1991-12-01
This paper combines the search procedure with the optimization procedure to inverse the average stress tensor, and applies this method to study the crustal stress field using data of the solution of P wave first motion. By dealing with the data of Haicheng, Tangshan, Xingtai, Anyang, Liyang, Taiwan, Fujian and Guangdong areas, we obtain the characteristics of crust stress field of East China. The directions of the principal pressure stress always possess a small dip angle, but the azimuths vary from NEE (in north part of East China) to SEE (in the south part). This frame probably is related to the push-extrusive effects of the northwestern Pacific plate from NEE and the Philippine plate from SEE. (author). 5 refs, 8 figs, 4 tabs
Heers, Marcel; Chowdhury, Rasheda A; Hedrich, Tanguy; Dubeau, François; Hall, Jeffery A; Lina, Jean-Marc; Grova, Christophe; Kobayashi, Eliane
2016-01-01
Distributed inverse solutions aim to realistically reconstruct the origin of interictal epileptic discharges (IEDs) from noninvasively recorded electroencephalography (EEG) and magnetoencephalography (MEG) signals. Our aim was to compare the performance of different distributed inverse solutions in localizing IEDs: coherent maximum entropy on the mean (cMEM), hierarchical Bayesian implementations of independent identically distributed sources (IID, minimum norm prior) and spatially coherent sources (COH, spatial smoothness prior). Source maxima (i.e., the vertex with the maximum source amplitude) of IEDs in 14 EEG and 19 MEG studies from 15 patients with focal epilepsy were analyzed. We visually compared their concordance with intracranial EEG (iEEG) based on 17 cortical regions of interest and their spatial dispersion around source maxima. Magnetic source imaging (MSI) maxima from cMEM were most often confirmed by iEEG (cMEM: 14/19, COH: 9/19, IID: 8/19 studies). COH electric source imaging (ESI) maxima co-localized best with iEEG (cMEM: 8/14, COH: 11/14, IID: 10/14 studies). In addition, cMEM was less spatially spread than COH and IID for ESI and MSI (p < 0.001 Bonferroni-corrected post hoc t test). Highest positive predictive values for cortical regions with IEDs in iEEG could be obtained with cMEM for MSI and with COH for ESI. Additional realistic EEG/MEG simulations confirmed our findings. Accurate spatially extended sources, as found in cMEM (ESI and MSI) and COH (ESI) are desirable for source imaging of IEDs because this might influence surgical decision. Our simulations suggest that COH and IID overestimate the spatial extent of the generators compared to cMEM.
Stability studies of oxytetracycline in methanol solution
Wang, Wei; Wu, Nan; Yang, Jinghui; Zeng, Ming; Xu, Chenshan; Li, Lun; Zhang, Meng; Li, Liting
2018-02-01
As one kind of typical tetracycline antibiotics, antibiotic residues of oxytetracycline have been frequently detected in many environmental media. In this study, the stability of oxytetracycline in methanol solution was investigated by high-performance liquid chromatography combined with UV-vis (HPLC-UV). The results show that the stability of oxytetracycline in methanol solution is highly related to its initial concentration and the preserved temperature. Under low temperature condition, the solution was more stable than under room temperature preservation. Under the same temperature preservation condition, high concentrations of stock solutions are more stable than low concentrations. The study provides a foundation for preserving the oxytetracycline-methanol solution.
Kamynin, V. L.; Bukharova, T. I.
2017-01-01
We prove the estimates of stability with respect to perturbations of input data for the solutions of inverse problems for degenerate parabolic equations with unbounded coefficients. An important feature of these estimates is that the constants in these estimates are written out explicitly by the input data of the problem.
DEFF Research Database (Denmark)
Mosegaard, Klaus
2012-01-01
For non-linear inverse problems, the mathematical structure of the mapping from model parameters to data is usually unknown or partly unknown. Absence of information about the mathematical structure of this function prevents us from presenting an analytical solution, so our solution depends on our......-heuristics are inefficient for large-scale, non-linear inverse problems, and that the 'no-free-lunch' theorem holds. We discuss typical objections to the relevance of this theorem. A consequence of the no-free-lunch theorem is that algorithms adapted to the mathematical structure of the problem perform more efficiently than...... pure meta-heuristics. We study problem-adapted inversion algorithms that exploit the knowledge of the smoothness of the misfit function of the problem. Optimal sampling strategies exist for such problems, but many of these problems remain hard. © 2012 Springer-Verlag....
Experimental study of population inversion in laser plasmas
International Nuclear Information System (INIS)
Bocher, J.L.; Busquet, M.; Combis, P.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.
1986-01-01
Thin and thick composite targets of various materials (Al, CH, Au) have been irradiated on both circular and linear focal spots with the OCTAL laser facility at wavelengths 1.06 μm and 0.35 μm and laser irradiances 5 10 12 w/cm 2 to 5 10 14 w/cm 2 . X ray spectra in the range 5 - 8 A and 15 - 300 A recorded respectively by means of flat TlaP and grazing incidence spectrographs gave some experimental evidence of population inversion in aluminum plasma
Experimental study of population inversion in laser plasmas
Energy Technology Data Exchange (ETDEWEB)
Bocher, J.L.; Busquet, M.; Combis, P.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.
1986-10-01
Thin and thick composite targets of various materials (Al, CH, Au) have been irradiated on both circular and linear focal spots with the OCTAL laser facility at wavelengths 1.06 ..mu..m and 0.35 ..mu..m and laser irradiances 5 10/sup 12/ w/cm/sup 2/ to 5 10/sup 14/ w/cm/sup 2/. X-ray spectra in the range 5 - 8 A and 15 - 300 A recorded respectively by means of flat TlaP and grazing incidence spectrographs gave some experimental evidence of population inversion in aluminum plasma.
Experimental study of population inversion in laser plasmas
International Nuclear Information System (INIS)
Bocher, J.L.; Busquet, M.; Combis, M.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.
1986-06-01
Thin and thick composite targets of various material (Al, CH, Au) have been irradiated on both circular and linear focal spot with the laser Octal facility at wavelength 1.06 μm and 0.35 μm and laser irradiances (5.10 12 .W/cm 2 to 5.10 14 .W/cm 2 ). X-ray spectra, in the ranges 5-8 A and 15 - 300 A, recorded respectively by means of flat TIAP and grazing incidence spectrographs show an experimental evidence of population inversion in aluminium plasmas
Study on Rayleigh Wave Inversion for Estimating Shear-wave Velocity Profile
Directory of Open Access Journals (Sweden)
T.A. Sanny
2003-05-01
Full Text Available Rayleigh wave or ground roll is a noise in seismic body waves. However, how to use this noise for soil characterization is very interesting since Rayleigh wave phase velocity is a function of compression-wave velocity, shear-wave velocity, density and layer thickness. In layered-medium Rayleigh wave velocity also depends on wavelength or frequency, and this phenomenon is called dispersion. Inversion procedure to get shear-wave velocity profile needs a priori information about the solution of the problem to limit the unknown parameters. The Lagrange multiplier method was used to solve the constrained optimization problems or well known as a smoothing parameter in inversion problems. The advantage of our inversion procedure is that it can guarantee the convergence of solution even though the field data is incomplete, insufficient, and inconsistent. The addition of smoothing parameter can reduce the time to converge. Beside numerical stability, the statistical stability is also involved in inversion procedure. In field experiment we extracted ground roll data from seismic refraction record. The dispersion curves had been constructed by applying f-k analysis and f-k dip filtering. The dispersion curves show the dependence of Rayleigh wave phase velocities in layered media to frequency. The synthetic models also demonstrate the stability and the speed of inversion procedure.
THE DIDACTIC ANALYSIS OF STUDIES ON THE INVERSE PROBLEMS FOR THE DIFFERENTIAL EQUATIONS
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В С Корнилов
2017-12-01
Full Text Available In article results of the didactic analysis of the organization and carrying out seminar classes in the inverse problems for the differential equations for students of higher educational institutions of the physical and mathematical directions of preparation are discussed. Such analysis includes a general characteristic of mathematical content of seminar occupations, the analysis of structure of seminar occupation, the analysis of realization of the developing and educational purposes, allocation of didactic units and informative means which have to be acquired by students when training each section of content of training in the inverse problems and other important psychology and pedagogical aspects. The attention to establishment of compliance to those of seminar occupations to lecture material and identification of functions in teaching and educational process which are carried out at the solution of the inverse problems, and also is paid to need to show various mathematical receptions and methods of their decision. Such didactic analysis helps not only to reveal such inverse problems at which solution students can collectively join in creative process of search of their decision, but also effectively organize control of assimilation of knowledge and abilities of students on the inverse problems for the differential equations.
Inversion of the pahse diagram in polymer blends studied by small-angle neutron scattering
International Nuclear Information System (INIS)
Jinnai, Hiroshi; Hasegawa, Hirokazu; Hashimoto, Takeji; Han, C.C.
1993-01-01
The miscibility of an amorphous mixture of normal (protonated) polybutadiend (HPB) and perdeuterated polybutadiene (DPB) has been extensively studied and was characterized by an upper critical solution temperature (UCST). In this study the miscibility of HPB and DPB as a function of temperature was studied by small-angle neutron scattering (SANS). The vinyl component of the DPB was held constant at 16%, while the vinyl frantion of the HPB was varied from 17-80%. The binary interaction parameter, χ, was obtained. The mixtures of DPB and HPB with 17-39% vinyl show UCST behaviors; i.e., χ increases with decreasing temperature. The mixture of DPB and HPB with 52% vinyl was found to have almost no temperature dependence. However, the mixture of DPB and HPB with 65-80% show a lower critical solution temperature (LCST) behavior; i.e., χ increases with increasing temperature. This inversion of the phase diagram from UCST to LCST has never been observed. (author)
International Nuclear Information System (INIS)
Yuece, Cem
2003-01-01
In this paper, the problem of the charged harmonic plus an inverse harmonic oscillator with time-dependent mass and frequency in a time-dependent electromagnetic field is investigated. It is reduced to the problem of the inverse harmonic oscillator with time-independent parameters and the exact wave function is obtained
Comparative study of direct and inverse problems of cracked beams
Directory of Open Access Journals (Sweden)
Mahieddine Chettah
2018-01-01
Full Text Available In recent decades, the analysis and evaluation of the cracked structures were hot spots in several engineering fields and has been the subject of great interest with important and comprehensive surveys covering various methodologies and applications, in order to obtain reliable and effective methods to maintain the safety and performance of structures on a proactive basis. The presence of a crack, not only causes a local variation in the structural parameters (e.g., the stiffness of a beam at its location, but it also has a global effect which affects the overall dynamic behavior of the structure (such as the natural frequencies. For this reason, the dynamic characterization of the cracked structures can be used to detect damage from non-destructive testing. The objective of this paper is to compare the accuracy and ability of two methods to correctly predict the results for both direct problem to find natural frequencies and inverse problem to find crack’s locations and depths of a cracked simply supported beam. Several cases of crack depths and crack locations are investigated. The crack is supposed to remain open. The Euler–Bernoulli beam theory is employed to model the cracked beam and the crack is represented as a rotational spring with a sectional flexibility. In the first method, the transfer matrix method is used; the cracked beam is modeled as two uniform sub-segments connected by a rotational spring located at the cracked section. In the second method which is based on the Rayleigh’s method, the mode shape of the cracked beam is constructed by adding a cubic polynomial function to that of the undamaged beam. By applying the compatibility conditions at crack’s location and the corresponding boundary conditions, the general forms of characteristic equations for this cracked system are obtained. The two methods are then utilized to determine the locations and depths by using any two natural frequencies of a cracked simply
Ingram, WT
2012-01-01
Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen
Cholet, Cybèle; Charlier, Jean-Baptiste; Moussa, Roger; Steinmann, Marc; Denimal, Sophie
2017-07-01
The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection-diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection-diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs) in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space - between the two reaches located in the unsaturated zone (R1), and in the zone that is both unsaturated and saturated (R2) - as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions) and localized infiltration in the secondary conduit network (tributaries) in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit-matrix exchanges, inducing a complex water mixing effect in the saturated zone
Directory of Open Access Journals (Sweden)
C. Cholet
2017-07-01
Full Text Available The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection–diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection–diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space – between the two reaches located in the unsaturated zone (R1, and in the zone that is both unsaturated and saturated (R2 – as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions and localized infiltration in the secondary conduit network (tributaries in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit–matrix exchanges, inducing a complex water mixing effect
Intersections, ideals, and inversion
International Nuclear Information System (INIS)
Vasco, D.W.
1998-01-01
Techniques from computational algebra provide a framework for treating large classes of inverse problems. In particular, the discretization of many types of integral equations and of partial differential equations with undetermined coefficients lead to systems of polynomial equations. The structure of the solution set of such equations may be examined using algebraic techniques.. For example, the existence and dimensionality of the solution set may be determined. Furthermore, it is possible to bound the total number of solutions. The approach is illustrated by a numerical application to the inverse problem associated with the Helmholtz equation. The algebraic methods are used in the inversion of a set of transverse electric (TE) mode magnetotelluric data from Antarctica. The existence of solutions is demonstrated and the number of solutions is found to be finite, bounded from above at 50. The best fitting structure is dominantly one dimensional with a low crustal resistivity of about 2 ohm-m. Such a low value is compatible with studies suggesting lower surface wave velocities than found in typical stable cratons
Intersections, ideals, and inversion
Energy Technology Data Exchange (ETDEWEB)
Vasco, D.W.
1998-10-01
Techniques from computational algebra provide a framework for treating large classes of inverse problems. In particular, the discretization of many types of integral equations and of partial differential equations with undetermined coefficients lead to systems of polynomial equations. The structure of the solution set of such equations may be examined using algebraic techniques.. For example, the existence and dimensionality of the solution set may be determined. Furthermore, it is possible to bound the total number of solutions. The approach is illustrated by a numerical application to the inverse problem associated with the Helmholtz equation. The algebraic methods are used in the inversion of a set of transverse electric (TE) mode magnetotelluric data from Antarctica. The existence of solutions is demonstrated and the number of solutions is found to be finite, bounded from above at 50. The best fitting structure is dominantly onedimensional with a low crustal resistivity of about 2 ohm-m. Such a low value is compatible with studies suggesting lower surface wave velocities than found in typical stable cratons.
Neutron scattering study of dilute supercritical solutions
International Nuclear Information System (INIS)
Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.
1994-01-01
Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope 36 Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast
International Nuclear Information System (INIS)
Piskunov, N.E.
1985-01-01
Mathematical formulation of the inverse problem of determination of magnetic field geometry from the polarization profiles of spectral lines is gven. The solving algorithm is proposed. A set of model calculations has shown the effectiveness of the algorithm, the high precision of magnetic star model parameters obtained and also the advantages of the inverse problem method over the commonly used method of interpretation of effective field curves
International Nuclear Information System (INIS)
Tsuchihashi, Toshio; Maki, Toshio; Suzuki, Takeshi
1997-01-01
The fast inversion recovery (fast IR) pulse sequence was evaluated. We compared the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence in which inversion time (TI) was established as equal to the water null point for the purpose of the water-suppressed T 2 -weighted image, with the fast short TI inversion recovery (fast STIR) pulse sequence in which TI was established as equal to the fat null point for purpose of fat suppression. In the fast FLAIR pulse sequence, the water null point was increased by making TR longer. In the FLAIR pulse sequence, the longitudinal magnetization contrast is determined by TI. If TI is increased, T 2 -weighted contrast improves in the same way as increasing TR for the SE pulse sequence. Therefore, images should be taken with long TR and long TI, which are longer than TR and longer than the water null point. On the other hand, the fat null point is not affected by TR in the fast STIR pulse sequence. However, effective TE was affected by variation of the null point. This increased in proportion to the increase in effective TE. Our evaluation indicated that the fast STIR pulse sequence can control the extensive signals from fat in a short time. (author)
A Study of H-Reflexes in Subjects with Acute Ankle Inversion Injuries
1996-12-09
stress to the injured ankle at heel- strike .(57) Any increased inversion stress by way of joint loading in the presence of compromised joint...the present study, may play a role in decreasing the degree of calcaneal inversion just prior to heel- strike and minimize the stress on the lateral...Presentation: * Significant edema/ecchymosis on lateral and medial aspects of ankle. * Possible pitting edema on forefoot (several days post- injury
Study of temperature inversion symmetry for the twisted Wess-Zumino model
International Nuclear Information System (INIS)
Oikonomou, V K
2007-01-01
The temperature inversion symmetry, for a non-interacting supersymmetric ensemble, at finite volume, is studied. It is found that the scaled free energy, f(ξ), is antisymmetric under temperature inversion transformation, i.e. f(ξ) = -ξ d (1/ξ). This occurs for antiperiodic bosons and periodic fermions in the compact dimension. In contrast, for periodic bosons and antiperiodic fermions, f(ξ = ξ d (1/ξ)
INVERSION OF FULL ACOUSTIC WAVEFIELD IN LOCAL HELIOSEISMOLOGY: A STUDY WITH SYNTHETIC DATA
International Nuclear Information System (INIS)
Cobden, L. J.; Warner, M. R.; Tong, C. H.
2011-01-01
We present the first results from the inversion of full acoustic wavefield in the helioseismic context. In contrast to time-distance helioseismology, which involves analyzing the travel times of seismic waves propagating into the solar interior, wavefield tomography models both the travel times and amplitude variations present in the entire seismic record. Unlike the use of ray-based, Fresnel-zone, Born, or Rytov approximations in previous time-distance studies, this method does not require any simplifications to be made to the sensitivity kernel in the inversion. In this study, the acoustic wavefield is simulated for all iterations in the inversion. The sensitivity kernel is therefore updated while lateral variations in sound-speed structure in the model emerge during the course of the inversion. Our results demonstrate that the amplitude-based inversion approach is capable of resolving sound-speed structures defined by relatively sharp vertical and horizontal boundaries. This study therefore provides the foundation for a new type of subsurface imaging in local helioseismology that is based on the inversion of the entire seismic wavefield.
Solute redistribution studies in oxidised zirconium alloys
Energy Technology Data Exchange (ETDEWEB)
Khera, S K; Kale, G B; Gadiyar, H S [Bhabha Atomic Research Centre, Bombay (India). Metallurgy Div.
1977-01-01
Electron microprobe studies on solute distribution in oxide layers and in the regions near oxide metal interface have been carried out in the case of zircaloy-2 and zirconium binary alloys containing niobium, tin, iron, copper, chromium and nickel and oxidised in steam at 550 deg C. In the case of alloys having higher oxidation rates, the oxide of solute element was found to dissolve in ZrO/sub 2/ without any composition variation. However, for solute addition with limited solubility like Cr, Cu and Fe, solute enrichment at metal/oxide interface and depletion of the same matrix has been observed. The intensity profiles for nickel distribution were also found to be identical to Fe or Cr distribution. The mode of solute distribution has been discussed in relation to oxidation behaviour of these alloys.
International Nuclear Information System (INIS)
Barysz, Maria; Mentel, Lukasz; Leszczynski, Jerzy
2009-01-01
The two-component Hamiltonian of the infinite-order two-component (IOTC) theory is obtained by a unitary block-diagonalizing transformation of the Dirac-Hamiltonian. Once the IOTC spin orbitals are calculated, they can be back transformed into four-component solutions. The transformed four component solutions are then used to evaluate different moments of the electron density distribution. This formally exact method may, however, suffer from certain approximations involved in its numerical implementation. As shown by the present study, with sufficiently large basis set of Gaussian functions, the Dirac values of these moments are fully recovered in spite of using the approximate identity resolution into eigenvectors of the p 2 operator.
An inverse problem for evolution inclusions
Ton, Bui An
2002-01-01
An inverse problem, the determination of the shape and a convective coefficient on a part of the boundary from partial measurements of the solution, is studied using 2-person optimal control techniques.
Analytical solution for the inverse kinematics of a redundant 7DoF manipulator with link offsets
CSIR Research Space (South Africa)
Singh, GK
2010-10-01
Full Text Available This work addresses the inverse kinematics problem for the 7 Degrees of Freedom Barrett Whole Arm Manipulator with link offsets. The presence of link offsets gives rise to the possibility of the in-elbow & out-elbow poses for a given end...
Czech Academy of Sciences Publication Activity Database
Domesová, Simona; Beres, Michal
2017-01-01
Roč. 15, č. 2 (2017), s. 258-266 ISSN 1336-1376 R&D Projects: GA MŠk LQ1602 Institutional support: RVO:68145535 Keywords : Bayesian statistics * Cross-Entropy method * Darcy flow * Gaussian random field * inverse problem Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics http://advances.utc.sk/index.php/AEEE/article/view/2236
Prinari, Barbara; Demontis, Francesco; Li, Sitai; Horikis, Theodoros P.
2018-04-01
The inverse scattering transform (IST) with non-zero boundary conditions at infinity is developed for an m × m matrix nonlinear Schrödinger-type equation which, in the case m = 2, has been proposed as a model to describe hyperfine spin F = 1 spinor Bose-Einstein condensates with either repulsive interatomic interactions and anti-ferromagnetic spin-exchange interactions (self-defocusing case), or attractive interatomic interactions and ferromagnetic spin-exchange interactions (self-focusing case). The IST for this system was first presented by Ieda et al. (2007) , using a different approach. In our formulation, both the direct and the inverse problems are posed in terms of a suitable uniformization variable which allows to develop the IST on the standard complex plane, instead of a two-sheeted Riemann surface or the cut plane with discontinuities along the cuts. Analyticity of the scattering eigenfunctions and scattering data, symmetries, properties of the discrete spectrum, and asymptotics are derived. The inverse problem is posed as a Riemann-Hilbert problem for the eigenfunctions, and the reconstruction formula of the potential in terms of eigenfunctions and scattering data is provided. In addition, the general behavior of the soliton solutions is analyzed in detail in the 2 × 2 self-focusing case, including some special solutions not previously discussed in the literature.
International Nuclear Information System (INIS)
Golbahar Haghighi, M.R.; Eghtesad, M.; Necsulescu, D.S.; Malekzadeh, P.
2010-01-01
As a first endeavor, an approach for the two- and three-dimensional temperature control of functionally graded (FG) plates by using the inverse solution and the proportional-differential (PD) controller is provided. For this purpose, firstly, having the desired temperatures at different locations and times, heat fluxes at the boundaries of the plates are estimated by inverse solution techniques offline. Then, the estimated heat fluxes as feedforward control inputs are combined with a PD controller to introduce a hybrid feedforward-feedback control input to the FG domain in the presence of disturbance and noise. In order to show the efficiency and accuracy of the proposed (inverse + PD) controller in two- and three-dimensional domains, different distinct examples, which include different boundary conditions, material properties and disturbance sources are presented. It is shown that the presented approach can adjust heat fluxes for control of the temperature accurately; also, the PD controller gains do not need to be re-adjusted for different problems.
Energy Technology Data Exchange (ETDEWEB)
Golbahar Haghighi, M.R. [Department of Mechanical Engineering, School of Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Eghtesad, M. [Department of Mechanical Engineering, School of Engineering, Shiraz University, Shiraz 71348-51154 (Iran, Islamic Republic of); Necsulescu, D.S. [Department of Mechanical Engineering, Faculty of Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5 (Canada); Malekzadeh, P., E-mail: malekzadeh@pgu.ac.i [Department of Mechanical Engineering, School of Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Center of Excellence for Computational Mechanics, Shiraz University, Shiraz (Iran, Islamic Republic of)
2010-01-15
As a first endeavor, an approach for the two- and three-dimensional temperature control of functionally graded (FG) plates by using the inverse solution and the proportional-differential (PD) controller is provided. For this purpose, firstly, having the desired temperatures at different locations and times, heat fluxes at the boundaries of the plates are estimated by inverse solution techniques offline. Then, the estimated heat fluxes as feedforward control inputs are combined with a PD controller to introduce a hybrid feedforward-feedback control input to the FG domain in the presence of disturbance and noise. In order to show the efficiency and accuracy of the proposed (inverse + PD) controller in two- and three-dimensional domains, different distinct examples, which include different boundary conditions, material properties and disturbance sources are presented. It is shown that the presented approach can adjust heat fluxes for control of the temperature accurately; also, the PD controller gains do not need to be re-adjusted for different problems.
On semi-inverse solutions for the time-dependent flows of a second-grade fluid
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available This paper deals with analytical solutions for the time-dependent equations arising in a second-grade fluid. The solutions have been developed by assuming certain forms of the stream function. Expressions for velocity components are obtained for flows in plane polar, axisymmetric cylindrical, and axisymmetric spherical polar coordinates. The obtained solutions are compared with existing results.
Nezhad, Mohsen Motahari; Shojaeefard, Mohammad Hassan; Shahraki, Saeid
2016-02-01
In this study, the experiments aimed at analyzing thermally the exhaust valve in an air-cooled internal combustion engine and estimating the thermal contact conductance in fixed and periodic contacts. Due to the nature of internal combustion engines, the duration of contact between the valve and its seat is too short, and much time is needed to reach the quasi-steady state in the periodic contact between the exhaust valve and its seat. Using the methods of linear extrapolation and the inverse solution, the surface contact temperatures and the fixed and periodic thermal contact conductance were calculated. The results of linear extrapolation and inverse methods have similar trends, and based on the error analysis, they are accurate enough to estimate the thermal contact conductance. Moreover, due to the error analysis, a linear extrapolation method using inverse ratio is preferred. The effects of pressure, contact frequency, heat flux, and cooling air speed on thermal contact conductance have been investigated. The results show that by increasing the contact pressure the thermal contact conductance increases substantially. In addition, by increasing the engine speed the thermal contact conductance decreases. On the other hand, by boosting the air speed the thermal contact conductance increases, and by raising the heat flux the thermal contact conductance reduces. The average calculated error equals to 12.9 %.
International Nuclear Information System (INIS)
Aboanber, A E; Nahla, A A
2002-01-01
A method based on the Pade approximations is applied to the solution of the point kinetics equations with a time varying reactivity. The technique consists of treating explicitly the roots of the inhour formula. A significant improvement has been observed by treating explicitly the most dominant roots of the inhour equation, which usually would make the Pade approximation inaccurate. Also the analytical inversion method which permits a fast inversion of polynomials of the point kinetics matrix is applied to the Pade approximations. Results are presented for several cases of Pade approximations using various options of the method with different types of reactivity. The formalism is applicable equally well to non-linear problems, where the reactivity depends on the neutron density through temperature feedback. It was evident that the presented method is particularly good for cases in which the reactivity can be represented by a series of steps and performed quite well for more general cases
A comparative study of surface waves inversion techniques at strong motion recording sites in Greece
Panagiotis C. Pelekis,; Savvaidis, Alexandros; Kayen, Robert E.; Vlachakis, Vasileios S.; Athanasopoulos, George A.
2015-01-01
Surface wave method was used for the estimation of Vs vs depth profile at 10 strong motion stations in Greece. The dispersion data were obtained by SASW method, utilizing a pair of electromechanical harmonic-wave source (shakers) or a random source (drop weight). In this study, three inversion techniques were used a) a recently proposed Simplified Inversion Method (SIM), b) an inversion technique based on a neighborhood algorithm (NA) which allows the incorporation of a priori information regarding the subsurface structure parameters, and c) Occam's inversion algorithm. For each site constant value of Poisson's ratio was assumed (ν=0.4) since the objective of the current study is the comparison of the three inversion schemes regardless the uncertainties resulting due to the lack of geotechnical data. A penalty function was introduced to quantify the deviations of the derived Vs profiles. The Vs models are compared as of Vs(z), Vs30 and EC8 soil category, in order to show the insignificance of the existing variations. The comparison results showed that the average variation of SIM profiles is 9% and 4.9% comparing with NA and Occam's profiles respectively whilst the average difference of Vs30 values obtained from SIM is 7.4% and 5.0% compared with NA and Occam's.
Nguyen, Dinh-Liem; Klibanov, Michael V.; Nguyen, Loc H.; Kolesov, Aleksandr E.; Fiddy, Michael A.; Liu, Hui
2017-09-01
We analyze in this paper the performance of a newly developed globally convergent numerical method for a coefficient inverse problem for the case of multi-frequency experimental backscatter data associated to a single incident wave. These data were collected using a microwave scattering facility at the University of North Carolina at Charlotte. The challenges for the inverse problem under the consideration are not only from its high nonlinearity and severe ill-posedness but also from the facts that the amount of the measured data is minimal and that these raw data are contaminated by a significant amount of noise, due to a non-ideal experimental setup. This setup is motivated by our target application in detecting and identifying explosives. We show in this paper how the raw data can be preprocessed and successfully inverted using our inversion method. More precisely, we are able to reconstruct the dielectric constants and the locations of the scattering objects with a good accuracy, without using any advanced a priori knowledge of their physical and geometrical properties.
Grellier , Emilie
2008-01-01
Vehicle routing problems in inverse logistics : modelling and solving with hybrid methods; Optimisation des tournées de véhicules dans le cadre de la logistique inverse : modélisation et résolution par des méthodes hybrides
Studies of population inversion and gains for xuv laser development in a recombining plasma column
International Nuclear Information System (INIS)
Milchberg, H.M.
1985-01-01
An experimental study is presented of population inversions and gains in CO 2 laser produced plasmas in a number of different solid and gas targets, with and without the presence of a magnetic field. Population inversions and gains were measured in hydrogenic carbon, CVI, and in the Li-like sequence CIV, OVI, FVII, and NeVIII. The Li-like species were easily produced in gas targets and, in general, 4d-3d population inversions were seen to increase with a combination of higher target pressure and the presence of an external magnetic field. Ratios of the 4d-3d sublevel populations ranged up to approx.10, for OVI. Inversions in CIV and FVII, in cases where solid targets were used, were less sensitive to the presence of the magnetic field. Gains in the CVI 182.17 A (3-2) line were measured using solid carbon targets, and increased in the presence of a magnetic field. The effect of placing aluminum blades near the target, for plasma cooling and faster recombination, was inconclusive. In general, gains determined by measuring an on-axis enhancement of the 182.17 A line were consistent with absolute measurements of CVI excitation-level populations. Gains of 2-4 cm -1 were measured. Axially oriented carbon-fiber targets were irradiated by the CO 2 laser, and it was found that population inversions and gain resulted only when there was no magnetic field present
Rheological study of chitosan in solution
International Nuclear Information System (INIS)
Silva, Italo Guimaraes Medeiros da; Alves, Keila dos Santos; Balaban, Rosangela de Carvalho
2009-01-01
Chitosan is an abundant biopolymer with remarkable physicochemical and biological properties, usually employed in a wide range of applications. It acts as a cationic polyelectrolyte in aqueous acid solutions, leading to unique characteristics. In this work, chitosan was characterized by 1 H NMR and its rheological behavior were studied as function of chitosan sample, shear rate, polymer concentration, ionic strength, time and temperature. In order to calculate rheological parameters and to understand the macromolecular dynamic in solution, the Otswald-de Waele model was fitted. (author)
International Nuclear Information System (INIS)
Li Guoli; Song Gang; Wu Yican
2007-01-01
Inverse treatment planning for radiation therapy is a multi-objective optimization process. The hybrid multi-objective optimization algorithm is studied by combining the simulated annealing(SA) and genetic algorithm(GA). Test functions are used to analyze the efficiency of algorithms. The hybrid multi-objective optimization SA algorithm, which displacement is based on the evolutionary strategy of GA: crossover and mutation, is implemented in inverse planning of external beam radiation therapy by using two kinds of objective functions, namely the average dose distribution based and the hybrid dose-volume constraints based objective functions. The test calculations demonstrate that excellent converge speed can be achieved. (authors)
A STUDY ON DYNAMIC LOAD HISTORY RECONSTRUCTION USING PSEUDO-INVERSE METHODS
Santos, Ariane Rebelato Silva dos; Marczak, Rogério José
2017-01-01
Considering that the vibratory forces generally cannot be measured directly at the interface of two bodies, an inverse method is studied in the present work to recover the load history in such cases. The proposed technique attempts to reconstruct the dynamic loads history by using a frequency domain analysis and Moore-Penrose pseudo-inverses of the frequency response function (FRF) of the system. The methodology consists in applying discrete dynamic loads on a finite element model in the time...
Waite, A. J.; Swart, P. K.
2011-12-01
As aragonite is the metastable polymorph of calcium carbonate, it lends itself to monotropic inversion to the more stable polymorph, calcite. This inversion is possible through an increase in the temperature and pressure conditions to which the sample is exposed and, although first noted nearly a century ago, has been primarily discussed in the context of sample roasting prior to analyses in paleoclimatological studies. Over the last several decades, however, researchers have found evidence to suggest that the friction associated with the sampling of biogenic carbonates via milling/drilling also induces inversion. Furthermore, this inversion may be associated with a shift in measured oxygen isotopic values and ultimately have significant implications for the interpretation of paleoclimatic reconstructions. Despite this, the isotopic heterogeneity of biogenic aragonite skeletons makes the effects of inversion challenging to test and the subject remains underrepresented in the literature. Here we present a first order study into the effects of milling on both the mineralogy and isotopic compositions measured in sclerosponges, corals, and molluscs. X-Ray diffraction analysis of samples hand ground with a mortar and pestle reveal 100% aragonitic skeletons. Conversely, samples milled with a computerized micromill show measurable inversion to calcite. On average, percent inversion of aragonite to calcite for individual specimens was 15% for sclerosponges, 16% for corals, and 9% for molluscs. Isotopic data from these specimens show that the higher the percentage of aragonite inverted to calcite, the more depleted the measured oxygen isotopic values. In the largest of the datasets (sclerosponges), it is evident that the range of oxygen isotope values from milled samples (-0.02 to +0.84%) exceeds the range in values for those samples which were hand ground and showed no inversion (+0.53 to +0.90%). This, coupled with the strong correlation between the two variables
International Nuclear Information System (INIS)
Papoular, R.J.; Zheludev, A.; Ressouche, E.; Schweizer, J.
1995-01-01
When density distributions in crystals are reconstructed from 3D diffraction data, a problem sometimes occurs when the spatial resolution in one given direction is very small compared to that in perpendicular directions. In this case, a 2D projected density is usually reconstructed. For this task, the conventional Fourier inversion method only makes use of those structure factors measured in the projection plane. All the other structure factors contribute zero to the reconstruction of a projected density. On the contrary, the maximum-entropy method uses all the 3D data, to yield 3D-enhanced 2D projected density maps. It is even possible to reconstruct a projection in the extreme case when not one structure factor in the plane of projection is known. In the case of poor resolution along one given direction, a Fourier inversion reconstruction gives very low quality 3D densities 'smeared' in the third dimension. The application of the maximum-entropy procedure reduces the smearing significantly and reasonably well resolved projections along most directions can now be obtained from the MaxEnt 3D density. To illustrate these two ideas, particular examples based on real polarized neutron diffraction data sets are presented. (orig.)
DEFF Research Database (Denmark)
Donner, Stefanie; Krüger, Frank; Rössler, Dirk
2014-01-01
In this study, we suggest a novel approach for the retrieval of regional moment tensors for earthquakes with small to moderate magnitudes. The first modification is the combined inversion of broadband and short‐period waveform data. The broadband waveforms are inverted in a frequency range suitable.......1). In this area, several factors exacerbate the difficulty of performing inversion for moment tensors, for example, a heterogeneous station network and large azimuthal gaps. We have demonstrated that our approach supplies reliable moment tensors when inversion from broadband data alone fails. In one case, we...... successfully retrieved a stable solution from short‐period waveform data alone. Thus, our approach enables successful determination of seismic moment tensors wherever a sparse network of broadband stations has thus far prevented it....
Fymat, A. L.; Smith, C. B.
1979-01-01
It is shown that the inverse analytical solutions, provided separately by Fymat and Box-McKellar, for reconstructing particle size distributions from remote spectral transmission measurements under the anomalous diffraction approximation can be derived using a cosine and a sine transform, respectively. Sufficient conditions of validity of the two formulas are established. Their comparison shows that the former solution is preferable to the latter in that it requires less a priori information (knowledge of the particle number density is not needed) and has wider applicability. For gamma-type distributions, and either a real or a complex refractive index, explicit expressions are provided for retrieving the distribution parameters; such expressions are, interestingly, proportional to the geometric area of the polydispersion.
Chudnovsky, D V
1978-09-01
For systems of nonlinear equations having the form [L(n) - ( partial differential/ partial differentialt), L(m) - ( partial differential/ partial differentialy)] = 0 the class of meromorphic solutions obtained from the linear equations [Formula: see text] is presented.
A gEUD-based inverse planning technique for HDR prostate brachytherapy: Feasibility study
Energy Technology Data Exchange (ETDEWEB)
Giantsoudi, D. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78229 (United States); Department of Radiation Oncology, Francis H. Burr Proton Therapy Center, Boston, Massachusetts 02114 (United States); Baltas, D. [Department of Medical Physics and Engineering, Strahlenklinik, Klinikum Offenbach GmbH, 63069 Offenbach (Germany); Nuclear and Particle Physics Section, Physics Department, University of Athens, 15701 Athens (Greece); Karabis, A. [Pi-Medical Ltd., Athens 10676 (Greece); Mavroidis, P. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78299 and Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, 17176 (Sweden); Zamboglou, N.; Tselis, N. [Strahlenklinik, Klinikum Offenbach GmbH, 63069 Offenbach (Germany); Shi, C. [St. Vincent' s Medical Center, 2800 Main Street, Bridgeport, Connecticut 06606 (United States); Papanikolaou, N. [Department of Radiological Sciences, University of Texas Health Sciences Center, San Antonio, Texas 78299 (United States)
2013-04-15
Purpose: The purpose of this work was to study the feasibility of a new inverse planning technique based on the generalized equivalent uniform dose for image-guided high dose rate (HDR) prostate cancer brachytherapy in comparison to conventional dose-volume based optimization. Methods: The quality of 12 clinical HDR brachytherapy implants for prostate utilizing HIPO (Hybrid Inverse Planning Optimization) is compared with alternative plans, which were produced through inverse planning using the generalized equivalent uniform dose (gEUD). All the common dose-volume indices for the prostate and the organs at risk were considered together with radiobiological measures. The clinical effectiveness of the different dose distributions was investigated by comparing dose volume histogram and gEUD evaluators. Results: Our results demonstrate the feasibility of gEUD-based inverse planning in HDR brachytherapy implants for prostate. A statistically significant decrease in D{sub 10} or/and final gEUD values for the organs at risk (urethra, bladder, and rectum) was found while improving dose homogeneity or dose conformity of the target volume. Conclusions: Following the promising results of gEUD-based optimization in intensity modulated radiation therapy treatment optimization, as reported in the literature, the implementation of a similar model in HDR brachytherapy treatment plan optimization is suggested by this study. The potential of improved sparing of organs at risk was shown for various gEUD-based optimization parameter protocols, which indicates the ability of this method to adapt to the user's preferences.
Study of influence of various factors on electrochemical signal of lead in water solutions
Zhikharev, Yu N.; Andrianova, L. I.; Ogudova, E. V.
2018-05-01
The conditions for obtaining a reproducible signal of lead in water solutions of indifferent electrolytes on various substrates (working electrodes) for analytical purposes were studied. Attention was also paid to studying the regularities of the initial stage of formation of lead sediments by the method of inversion voltammetry. The possibility of using different working electrodes to obtain stable current-potential curves is shown depending on the conditions of electrolysis, pH of the medium, the electrolysis potential and impurities.
International Nuclear Information System (INIS)
Jamema, S.V.; Deshpande, D.D.; Kirisits, C.; Trnkova, P.; Poetter, R.; Mahantshetty, U.; Shrivastava, S.K.; Dinshaw, K.A.
2008-01-01
In the recent past, inverse planning algorithms were introduced for intracavitary brachytherapy planning (ICBT) for cervical cancer. The loading pattern of these algorithms in comparison with traditional systems may not be similar. The purpose of this study was to objectively compare the loading patterns of traditional systems with the inverse optimization. Based on the outcome of the comparison, an attempt was made to obtain a loading pattern that takes into account the experience made with the inverse optimization
International Nuclear Information System (INIS)
Li, Xuewei; Kong, Li; Cheng, Jingjing; Wu, Lei
2015-01-01
The multi-exponential inversion of a NMR relaxation signal plays a key role in core analysis and logging interpretation in the formation of porous media. To find an efficient metod of inverting high-resolution relaxation time spectra rapidly, this paper studies the effect of inversion which is based on the discretization of the original echo in a time domain by using a simulation model. This paper analyzes the ill-condition of discrete equations on the basis of the NMR inversion model and method, determines the appropriate number of discrete echoes and acquires the optimal distribution of discrete echo points by the Lloyd–Max optimal quantization method, in considering the inverse precision and computational complexity comprehensively. The result shows that this method can effectively improve the efficiency of the relaxation time spectra inversion while guaranteeing inversed accuracy. (paper)
Serroukh, Sonia; Huber, Patrick; Lallam, Abdelaziz
2018-01-19
Inverse liquid chromatography is a technique for studying solid/liquid interaction and most specifically for the determination of solute adsorption isotherm. For the first time, the adsorption behaviour of microfibrillated cellulose was assessed using inverse liquid chromatography. We showed that microfibrillated cellulose could adsorb 17 mg/g of tetrasulfonated optical brightening agent in typical papermaking conditions. The adsorbed amount of hexasulfonated optical brightening agent was lower (7 mg/g). The packing of the column with microfibrillated cellulose caused important axial dispersion (D a = 5e-7 m²/s). Simulation of transport phenomena in the column showed that neglecting axial dispersion in the analysis of the chromatogram caused significant error (8%) in the determination of maximum adsorbed amount. We showed that conventional chromatogram analysis technique such as elution by characteristic point could not be used to fit our data. Using a bi-Langmuir isotherm model improved the fitting, but did not take into account axial dispersion, thus provided adsorption parameters which may have no physical significance. Using an inverse method with a single Langmuir isotherm, and fitting the transport equation to the chromatogram was shown to provide a satisfactory fitting to the chromatogram data. In general, the inverse method could be recommended to analyse inverse liquid chromatography data for column packing with significant axial dispersion (D a > 1e-7 m²/s). Copyright © 2017 Elsevier B.V. All rights reserved.
Laurençot, Philippe
2018-03-01
Uniqueness of mass-conserving self-similar solutions to Smoluchowski's coagulation equation is shown when the coagulation kernel K is given by K(x,x_*)=2(x x_*)^{-α } , (x,x_*)\\in (0,∞)^2 , for some α >0.
International Nuclear Information System (INIS)
Bejawada, Venki; Mohapatra, C.; Rao, A.S.; Prasad, K.L.; Murthy, P.K.; Rao, A.K.; Singh, H.P.; Vithal, G.K.; Kumar, Sangita D.
2014-01-01
In order to enrich 10 B, band migration of boric acid-mannitol with hydrochloric acid solution was performed by inverse frontal chromatography on a porous, 25% crosslinked, 38% quaternized 4-vinylpyridine-divinylbenzene resin (py-resin). The work was initiated to replace the existing strong base anion exchange resin type-II (SBA-II) which is used in Boron Enrichment Plant (BEP) of heavy water plant Manuguru. Before its application in BEP, it is mandatory to evaluate py-resin for its performance. The studies showed that maximum of 40% 10 B enrichment observed after 13 m band movement and there was no further improvement, hence profile sampling carried out after 28 m. (author)
Study of actinide paramagnetism in solution
International Nuclear Information System (INIS)
Autillo, Matthieu
2015-01-01
The physiochemical properties of actinide (An) solutions are still difficult to explain, particularly the behavioral differences between An(III) and Ln(III). The study of actinide paramagnetic behavior may be a 'simple' method to analyze the electronic properties of actinide elements and to obtain information on the ligand-actinide interaction. The objective of this PhD thesis is to understand the paramagnetic properties of these elements by magnetic susceptibility measurements and chemical shift studies. Studies on actinide electronic properties at various oxidation states in solution were carried out by magnetic susceptibility measurements in solution according to the Evans method. Unlike Ln(III) elements, there is no specific theory describing the magnetic properties of these ions in solution. To obtain accurate data, the influence of experimental measurement technique and radioactivity of these elements was analyzed. Then, to describe the electronic structure of their low energy states, the experimental results were complemented with quantum chemical calculations from which the influence of the ligand field was studied. Finally, these interpretations were applied to better understand the variations in the magnetic properties of actinide cations in chloride and nitrate media. Information about ligand-actinide interactions may be determined from an NMR chemical shift study of actinide complexes. Indeed, modifications induced by a paramagnetic complex can be separated into two components. The first component, a Fermi contact contribution (δ_c) is related to the degree of covalency in coordination bonds with the actinide ions and the second, a dipolar contribution (δ_p_c) is related to the structure of the complex. The paramagnetic induced shift can be used only if we can isolate these two terms. To achieve this study on actinide elements, we chose to work with the complexes of dipicolinic acid (DPA). Firstly, to characterize the geometrical parameters, a
A novel study on Kepler’s law and inverse square law of gravitation
International Nuclear Information System (INIS)
Zhang, Bingzhan; Zhen, Shengchao; Zhao, Han; Huang, Kang; Deng, Bin; Chen, Ye-Hwa
2015-01-01
The Udwadia–Kalaba equation is a simple, aesthetic, and thought-provoking description of the world at a very fundamental level. It is about the way systems move. In this paper, we creatively apply the Udwadia–Kalaba approach to study heavenly bodies’ movements (especially on Kepler’s law and the inverse square law of gravitation). In an alternative way, we show that a heavenly body’s motion orbit can be an ellipse, a circle, a hyperbola, or a parabola and show the conservation of angular momentum. Furthermore, by applying the Udwadia–Kalaba approach, we use the constraint of motion orbit (ellipse, circle, hyperbola, or parabola) and the conservation of angular momentum constraint (or energy conservation constraint) and easily verify that any heavenly body’s motion complies with the inverse square law of gravitation. That is, we study Kepler’s law and Newton’s inverse square law in an analytical way, which makes the dynamicist more clear about the way heavenly bodies move and also makes the celestial mechanician more clear about the analytical mechanics (the Udwadia–Kalaba approach). Furthermore, for the students of dynamics and celestial physics, a different unique perspective is provided for them to study. At the end, we present the detailed process of applying the Udwadia–Kalaba approach to two imaginary cases to show its simplicity and efficiency. (paper)
Blajer, W.; Dziewiecki, K.; Kołodziejczyk, K.; Mazur, Z.
2011-05-01
Underactuated systems are featured by fewer control inputs than the degrees-of-freedom, m strategy that forces such a system to complete a set of m specified motion tasks is a challenging task, and the explicit solution existence is conditioned to differential flatness of the problem. The flatness-based solution denotes that all the 2 n states and m control inputs can be algebraically expressed in terms of the m specified outputs and their time derivatives up to a certain order, which is in practice attainable only for simple systems. In this contribution the problem is posed in a more practical way as a set of index-three differential-algebraic equations, and the solution is obtained numerically. The formulation is then illustrated by a two-degree-of-freedom underactuated system composed of two rotating discs connected by a torsional spring, in which the pre-specified motion of one of the discs is actuated by the torque applied to the other disc, n = 2 and m = 1. Experimental verification of the inverse simulation control methodology is reported.
Seismic signal simulation and study of underground nuclear sources by moment inversion
International Nuclear Information System (INIS)
Crusem, R.
1986-09-01
Some problems of underground nuclear explosions are examined from the seismological point of view. In the first part a model is developed for mean seismic propagation through the lagoon of Mururoa atoll and for calculation of synthetic seismograms (in intermediate fields: 5 to 20 km) by summation of discrete wave numbers. In the second part this ground model is used with a linear inversion method of seismic moments for estimation of elastic source terms equivalent to the nuclear source. Only the isotrope part is investigated solution stability is increased by using spectral smoothing and a minimal phase hypothesis. Some examples of applications are presented: total energy estimation of a nuclear explosion, simulation of mechanical effects induced by an underground explosion [fr
A FTIR study water in membrane of nitrocellulose prepared by phase inversion
International Nuclear Information System (INIS)
Benosmane, N.; Boutemeur, B.; Hamdi, M.
2004-01-01
Full text.Cellulose derivates were the first biopolymers used to produce synthesis membranes for technical applications, in this study the state of water in asymmetric membrane of nitrocellulose, prepared by the phase inversion process, was investigated using infrared spectroscopy (FTIR), after membrane preparation by the wet inversion process in acetone, the spectre FTIR of wet asymmetric membrane of nitrocellulose after immersion in water (after one week) is compared to the spectre of dried asymmetric membrane of nitrocellulose, the difference in spectre of dried and wet membrane indicate a weakly hydrogen-bonded to the polymer hydroxyl groups between water and hydroxyl groups in surface of membrane, the results demonstrate the amount of water species present in the surface of asymmetric membrane and heterogeneous of surface
Inversion domain boundaries in GaN studied by X-ray microprobe
Energy Technology Data Exchange (ETDEWEB)
Martinez-Criado, Gema; Tucoulou, Remi; Cloetens, Peter; Sans, Juan Angel; Susini, Jean [European Synchrotron Radiation Facility, Experiments Division, Grenoble (France); Somogyi, Andrea [Experiments Division, Synchrotron SOLEIL, Gif-sur-Yvette (France); Alen, Benito [Microelectronics Institute Madrid, CNM-CSIC, Madrid (Spain); Miskys, Claudio [Walter Schottky Institute, Technical University Munich, Garching (Germany)
2010-02-15
In this study, we report on the application of synchrotron spectro-microscopic techniques to the examination of inversion domain boundaries formed intentionally in a GaN-based lateral polarity heterostructure. Using X-ray sub-microbeams, no evidence of field-driven electrodiffusion effects has been observed on spatially separated inversion domain boundaries. In addition, XANES data around the Ga K-edge strongly supported hexagonal Ga site configurations, suggesting high local order reconstruction. Based on inner-shell excited luminescence on the micrometer scale, the uniform spectral distribution of the radiative centers was discussed. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Energy Technology Data Exchange (ETDEWEB)
Koshelev, A. S., E-mail: alexsander.coshelev@yandex.ru; Arapov, A. V.; Ovchinnikov, M. A. [Russian Federal Nuclear Center–All-Russian Research Institute of Experimental Physics (Russian Federation)
2016-12-15
The file-evaluation results of a reactimeter based on the inverse solution to the kinetics equation (ISKE) are presented, which were obtained using an operating hardware-measuring complex with a KNK-4 neutron detector working in the current mode. The processing of power-recording files of the BR-1M, BR-K1, and VIR-2M reactors of the Russian Federal Nuclear Center—All-Russian Research Institute of Experimental Physics, which was performed with the use of Excel simulation of the ISKE formalism, demonstrated the feasibility of implementation of the reactivity monitoring (during the operation of these reactors at stationary power) beginning from the level of ~5 × 10{sup –4}β{sub eff}.
International Nuclear Information System (INIS)
Giraldo, Liliana; Moreno, Juan Carlos
2006-01-01
We report the preparation of an activated carbon obtained by impregnation of mineral carbon samples with a phosphoric acid solution (50%).The obtained material, exhibits a superficial area of 586 m 2 .g -1 and a total pore volume of 0.37 cm 3 g -1 . With respect to the chemical properties, the activated carbon shows an increased number of acidic sites (0.92 meq g -l ) compared to basic sites (0.63 meq g-1) which yields a material with almost neutral characteristics (PHpzc: 7.4). At a pH: 4.0 the amount of Pb 2 + absorbed and the immersion enthalpy values for the activated carbon reached a maximum with values of 15.7 mg -1 y 27.6 Jg -1 respectively. It was established that similar behaviour occurs for the two properties, absorption and immersion enthalpy, as a function of pH. In addition, a second order function that relates the adsorption constant and immersion enthalpy, and the adsorption constant and pH of the solution are presented
International Nuclear Information System (INIS)
Burkhard, N.R.
1979-01-01
The gravity inversion code applies stabilized linear inverse theory to determine the topography of a subsurface density anomaly from Bouguer gravity data. The gravity inversion program consists of four source codes: SEARCH, TREND, INVERT, and AVERAGE. TREND and INVERT are used iteratively to converge on a solution. SEARCH forms the input gravity data files for Nevada Test Site data. AVERAGE performs a covariance analysis on the solution. This document describes the necessary input files and the proper operation of the code. 2 figures, 2 tables
Mechanistic studies of the metabolic chiral inversion of (R)-ibuprofen in humans
International Nuclear Information System (INIS)
Baillie, T.A.; Adams, W.J.; Kaiser, D.G.; Olanoff, L.S.; Halstead, G.W.; Harpootlian, H.; Van Giessen, G.J.
1989-01-01
The metabolic chiral inversion of R-(-)-ibuprofen has been studied in human subjects by means of specific deuterium labeling and stereoselective gas chromatography-mass spectrometry methodology. After simultaneous p.o. administration of a mixture of R-(-)-ibuprofen (300 mg) and R-(-)-[3,3,3-2H3]ibuprofen (304 mg) to four adult male volunteers, the enantiomeric composition and deuterium content of the drug in serum, and of the drug and its principal metabolites in urine, were followed over a period of 24 hr. The results of these analyses indicated that: (1) conversion of R-(-)- to S-(+)-ibuprofen takes place with complete retention of deuterium at the beta-methyl (C-3) position; (2) chiral inversion of R-(-)-[2H3]ibuprofen is not subject to a discernible deuterium isotope effect; and (3) replacement of the beta-methyl hydrogen atoms by deuterium has no effect on any of the serum pharmacokinetic parameters for R-(-)- or S-(+)-ibuprofen. These data indicate that the process whereby R-(-)-ibuprofen undergoes metabolic inversion in human subjects does not involve 2,3-dehydroibuprofen as an intermediate, and that the underlying mechanism cannot, therefore, entail a desaturation/reduction sequence
Variational approach to direct and inverse problems of atmospheric pollution studies
Penenko, Vladimir; Tsvetova, Elena; Penenko, Alexey
2016-04-01
We present the development of a variational approach for solving interrelated problems of atmospheric hydrodynamics and chemistry concerning air pollution transport and transformations. The proposed approach allows us to carry out complex studies of different-scale physical and chemical processes using the methods of direct and inverse modeling [1-3]. We formulate the problems of risk/vulnerability and uncertainty assessment, sensitivity studies, variational data assimilation procedures [4], etc. A computational technology of constructing consistent mathematical models and methods of their numerical implementation is based on the variational principle in the weak constraint formulation specifically designed to account for uncertainties in models and observations. Algorithms for direct and inverse modeling are designed with the use of global and local adjoint problems. Implementing the idea of adjoint integrating factors provides unconditionally monotone and stable discrete-analytic approximations for convection-diffusion-reaction problems [5,6]. The general framework is applied to the direct and inverse problems for the models of transport and transformation of pollutants in Siberian and Arctic regions. The work has been partially supported by the RFBR grant 14-01-00125 and RAS Presidium Program I.33P. References: 1. V. Penenko, A.Baklanov, E. Tsvetova and A. Mahura . Direct and inverse problems in a variational concept of environmental modeling //Pure and Applied Geoph.(2012) v.169: 447-465. 2. V. V. Penenko, E. A. Tsvetova, and A. V. Penenko Development of variational approach for direct and inverse problems of atmospheric hydrodynamics and chemistry, Izvestiya, Atmospheric and Oceanic Physics, 2015, Vol. 51, No. 3, p. 311-319, DOI: 10.1134/S0001433815030093. 3. V.V. Penenko, E.A. Tsvetova, A.V. Penenko. Methods based on the joint use of models and observational data in the framework of variational approach to forecasting weather and atmospheric composition
International Nuclear Information System (INIS)
Hou, Y H; Liu, Z W; Yu, H Y; Zhong, X C; Qiu, W Q; Zeng, D C; Wen, L S; Zhao, Y J
2010-01-01
Partially inverse spinel CoFe 2 O 4 , which may be prepared through various heat treatments, differs remarkably from the ideal inverse spinel in many properties. The structure of partially inverse spinel CoFe 2 O 4 as well as its electronic and magnetic properties through a systemic theoretical calculation of (Co 1-x Fe x ) Tet (Co x Fe 2-x ) Oct O 4 (x = 0, 0.25, 0.5, 0.75 and 1.0) have been investigated by the generalized gradient approximation (GGA) + U approach. It is found that the Co and Fe ions prefer their high spin configurations with higher spin moments at octahedral sites in all the studied cases, in line with experimental observations. The Co ions at the octahedral sites favour being far away from each other in the partial inverse spinels, which also show half metallicity at certain inversion degrees.
Pulse radiolysis study of aqueous cyanamide solutions
International Nuclear Information System (INIS)
Draganic, I.G.; Draganic, Z.D.; Sehested, K.
1978-01-01
The radiolysis of oxygen-free, aqueous solutions of cyanamide was studied by fast kinetic spectrophotometry. Computer simulation of the reaction mechanisms was used to evaluate the experimental data. Four different species are identified: (1) the radical anion (NH 2 CN) - absorbing light in the UV with lambda/sub max/ 240 = 1500 M -1 cm -1 ; the disappearance is a second-order process with 2k = 1.3 x 10 9 M -1 s -1 ; (2) the hydrogen adduct, NH 2 C(H) double bond N (or NH 2 C double bond NH), with lambda/sub max/ 300 nm and epsilon 300 = 150 M -1 cm -1 decaying by second-order kinetics with 2k = 3.1 x 10 9 M -1 s -1 ; (3) the hydroxyl radical preferentially adds to the cyano group, NH 2 C(OH) double bond N (or NH 2 C double bond NOH). This species rearranges in the submicrosecond scale to NH 2 C ( double bond O) NH (lambda/sub max/ 325 nm and epsilon/sub 325 = 1900 M -1 cm -1 ) and disappears by a second-order process with 2k = 6.3 x 10 9 M -1 s -1 . (4) It is estimated that about 10% of OH radicals attack the substituent group and by H abstraction produce the NHCN radical (lambda/sub max/ 370 nm and epsilon 370 = 1800 M -1 cm -1 ); it disappears by a pseudo-first-order process attributed to a hydrolysis reaction. At increasing acidities, protonation of this radical takes place, NHCN + H + → + NH 2 CN; the protonated form decays faster and absorbs more strongly. In a cyanamide solution containing S 2 O 8 2- , the SO - 4 . radicals react with cyanamide, k = 1 x 10 8 M -1 s -1 , producing + NH 2 CN radicals. The dependence of the optical density at 325 nm on the dose rate and solute concentration are quantitatively consistent with the assumption that the OH radicals react with the NH 2 C(=O)NH species with k = 4 x 10 9 M -1 s -1
Structural study of concentrated micellar solutions
International Nuclear Information System (INIS)
Zemb, Thomas
1985-01-01
This research thesis reports the study of the structure of concentrated soap-water binary micelles with a comparison of measurements of light, neutrons and X-ray scattering, and the relaxation induced by paramagnetic ions adsorbed at the interface. In the first part, the author discusses the specific sensitivity ranges of different experimental techniques, outlines the resolution which can be obtained with scattering experiments, and proposes a critical analysis of results published in the relevant literature. In a second part, the author discusses the compared results of the application of various techniques (magnetic resonance, X-light and neutron scattering) on the two most used model systems: sodium octanoate and sodium dodecyl sulfate (SDS) in solution. Then, the author addresses the case of ternary systems: study of the influence of the presence of a co-surfactant on the structure, study of the effect of interfacial charge on the micellar structure, use of the same previous quantitative methods to study the disturbances brought to the structure due to the presence of reactants [fr
International Nuclear Information System (INIS)
Dordevic, S.V.
2012-01-01
Inverse Fourier Transform of optical conductivity is used for studies of quasiparticle relaxation in Heavy Fermions in time domain. We demonstrate the usefulness of the procedure on model spectra and then use it to study quasiparticle relaxation in two Heavy Fermions YbFe 4 Sb 12 and CeRu 4 Sb 12 . Optical conductivity in time domain reveals details of quasiparticle relaxation close to the Fermi level, not readily accessible from the spectra in the frequency domain. In particular, we find that the relaxation of heavy quasiparticles does not start instantaneously, but typically after a few hundred femto-seconds.
Calculation of the inverse data space via sparse inversion
Saragiotis, Christos
2011-01-01
The inverse data space provides a natural separation of primaries and surface-related multiples, as the surface multiples map onto the area around the origin while the primaries map elsewhere. However, the calculation of the inverse data is far from trivial as theory requires infinite time and offset recording. Furthermore regularization issues arise during inversion. We perform the inversion by minimizing the least-squares norm of the misfit function by constraining the $ell_1$ norm of the solution, being the inverse data space. In this way a sparse inversion approach is obtained. We show results on field data with an application to surface multiple removal.
Decoloration studies of some fluorescent dye solutions
International Nuclear Information System (INIS)
Zafar-uz-Zaman, M.; Ditta, A.
1997-01-01
Rhenium-186-(Sn)-l, l hydroxy ethylene diphosphonate (/sup 186/Re-HEDP) has been used for the palliation of metastatic bone pain. /sup 186/Re- has excellent physical properties that may be useful for the formulation of radiotherapeutic agents. It has a short half-life (90.6 hrs) with moderate energy particles (E /sub max/=1.07 MeV) that penetrate over a short range of tissue and gamma ray of 137 keV which is well suited to image. A number of samples of natural rhenium (metal) power were irradiated in PARR-I research reactor at a thermal neutrons flux of the order lx10/sup 14/ n.cm /sup -2/.s/sup -1/ for various time intervals in order to optimize the production yield of /sup 186/Re. The data indicated that 60 mCi/mg of radioactivity could be obtained for an irradiation time of 24 hours. The irradiated target was converted to its ammonium salt which was used for preparation of /sup 186/Re-HEDP complex. Labeling studies of dissolution salt of HEDP with /sup 186/Re were performed by varying the amounts of rhenium, HEDP and Sn. These studies were also carried out at different pH of the solutions. The quality control of /sup 186/Re-HEDP complex was checked by radio chromatographic techniques. These investigations indicated that the complex of optimum yield (approx. 95%) could be obtained by using amounts of Re (0.15 mg), HEDP (10 mg), stannous chloride dihydrate (4mg) and pH range of 4-6. The effect of antioxidant genetic acid was studied on the stability of the complex which was found to be stable up to five days in the presence of 3 mg of genetic acid. The biodistribution studies in rats showed optimum uptake by bone after 2.5 hours. (author)
Kolgotin, Alexei; Müller, Detlef; Chemyakin, Eduard; Romanov, Anton
2016-12-01
Multiwavelength Raman/high spectral resolution lidars that measure backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm can be used for the retrieval of particle microphysical parameters, such as effective and mean radius, number, surface-area and volume concentrations, and complex refractive index, from inversion algorithms. In this study, we carry out a correlation analysis in order to investigate the degree of dependence that may exist between the optical data taken with lidar and the underlying microphysical parameters. We also investigate if the correlation properties identified in our study can be used as a priori or a posteriori constraints for our inversion scheme so that the inversion results can be improved. We made the simplifying assumption of error-free optical data in order to find out what correlations exist in the best case situation. Clearly, for practical applications, erroneous data need to be considered too. On the basis of simulations with synthetic optical data, we find the following results, which hold true for arbitrary particle size distributions, i.e., regardless of the modality or the shape of the size distribution function: surface-area concentrations and extinction coefficients are linearly correlated with a correlation coefficient above 0.99. We also find a correlation coefficient above 0.99 for the extinction coefficient versus (1) the ratio of the volume concentration to effective radius and (2) the product of the number concentration times the sum of the squares of the mean radius and standard deviation of the investigated particle size distributions. Besides that, we find that for particles of any mode fraction of the particle size distribution, the complex refractive index is uniquely defined by extinction- and backscatter-related Ångström exponents, lidar ratios at two wavelengths, and an effective radius.
Larin, S.V.; Lyulin, S.V.; Lyulin, A.V.; Darinskii, A.A.
2009-01-01
Complexes of fully ionized third-generation dendrimers with oppositely charged linear polyelectrolyte chains are studied by the Brownian dynamics method. A freely jointed model of a dendrimer and a linear chain is used. Electrostatic interactions are considered within the Debye-Hückel approximation
Pavlenko, Daniil
2012-01-01
Developing the algorithm of estimation of the rotational parameters of the artificial satellite by its light curve, we face the necessity to compute test light curves for various initially given types of rotation and specific features of lighting of the satellite. In the present study the algorithm of creation of such light curves with the simulation method and the obtained result are described.
Convex blind image deconvolution with inverse filtering
Lv, Xiao-Guang; Li, Fang; Zeng, Tieyong
2018-03-01
Blind image deconvolution is the process of estimating both the original image and the blur kernel from the degraded image with only partial or no information about degradation and the imaging system. It is a bilinear ill-posed inverse problem corresponding to the direct problem of convolution. Regularization methods are used to handle the ill-posedness of blind deconvolution and get meaningful solutions. In this paper, we investigate a convex regularized inverse filtering method for blind deconvolution of images. We assume that the support region of the blur object is known, as has been done in a few existing works. By studying the inverse filters of signal and image restoration problems, we observe the oscillation structure of the inverse filters. Inspired by the oscillation structure of the inverse filters, we propose to use the star norm to regularize the inverse filter. Meanwhile, we use the total variation to regularize the resulting image obtained by convolving the inverse filter with the degraded image. The proposed minimization model is shown to be convex. We employ the first-order primal-dual method for the solution of the proposed minimization model. Numerical examples for blind image restoration are given to show that the proposed method outperforms some existing methods in terms of peak signal-to-noise ratio (PSNR), structural similarity (SSIM), visual quality and time consumption.
International Nuclear Information System (INIS)
Grant, Walter; Carol, Mark; Geis, Paul; Boyer, Arthur L.
1995-01-01
Purpose/Objective: To demonstrate the feasibility of inverse planning for multiple fixed-field conformal therapy with a prototype simulated annealing technique and to deliver the treatment plan with an engineering prototype dynamic multileaf collimator. Methods and Materials: A version of the NOMOS inverse-planning algorithm was used to compute weighting distributions over the areas of multiple fixed-gantry fields. The algorithm uses simulated annealing and a cost function based on physical dose. The algorithm is a modification of a NOMOS Peacock planning implementation being used clinically. The computed weighting distributions represented the relative intensities over small 0.5 cm x 1.0 cm areas of the fields. The inverse planning was carried out using a Sun Model 20 computer using four processors. Between five and nine fixed-gantry beams were used in the plans. The weighting distributions were rendered into leaf-setting sequences using an algorithm developed for use with a Varian experimental dynamic-multileaf collimator. The sequences were saved as computer files in a format that was used to drive the Varian control system. X-ray fields having 6-MV and 18-MV energies were planned and delivered using tumor target and sensitive structure volumes segmented from clinical CT scans. Results: The resulting beam-modulation sequences could be loaded into the accelerator control systems and initiated. Each fixed-gantry angle beam was delivered in 30 s to 50 s. The resulting dose distributions were measured in quasi-anatomical phantoms using film. Dose distributions that could achieve significant tissue-sparing were demonstrated. There was good agreement between the delivered dose distributions and the planned distributions. Conclusion: The prototype inverse-planning system under development by NOMOS can be integrated with the prototype dynamic-delivery system being developed by Varian Associates. Should these commercial entities chose to offer compatible FDA
Study of actinides fission induced by multi-nucleon transfer reactions in inverse kinematics
International Nuclear Information System (INIS)
Derkx, X.
2010-10-01
The study of actinide fission encounters two major issues. On one hand, measurements of the fission fragment distributions and the fission probabilities allow a better understanding of the fission process itself and the discrimination among the models of nuclear structure and dynamics. On the other hand, new measurements are required to improve nuclear data bases, which are a key component for the design of new generation reactors and radio-toxic waste incinerators. This thesis is in line with different French and American experimental projects using the surrogate method, i.e. transfer reactions leading to the same compound nuclei as in neutron irradiation, allowing the study of fission of actinides which are inaccessible by conventional techniques, whereas they are important for applications. The experiment is based on multi-nucleon transfer reactions between a 238 U beam and a 12 C target, using the inverse kinematics technique to measure, for each transfer channel, the complete isotopic distributions of the fission fragments with the VAMOS spectrometer. The work presented in this dissertation is focused on the identification of the transfer channels and their properties, as their angular distributions and the distributions of the associated excitation energy, using the SPIDER telescope to identify the target recoil nuclei. This work of an exploratory nature aims to generalize the surrogate method to heavy transfers and to measure, for the first time, the fission probabilities in inverse kinematics. The obtained results are compared with available direct kinematics and neutron irradiation measurements. (author)
Inverse association of leptin levels with renal cell carcinoma: results from a case-control study.
Spyridopoulos, Themistoklis N; Petridou, Eleni Th; Dessypris, Nick; Terzidis, Agapios; Skalkidou, Alkistis; Deliveliotis, Charalambos; Chrousos, George P
2009-01-01
Leptin is primarily produced in adipose tissue and appears to play a modulatory role between metabolism and immunity. Given that obesity, a state of chronic inflammation, is an established risk factor for Renal Cell Carcinoma (RCC), we investigated the association between plasma leptin levels and RCC risk. This case-control study included 70 patients with newly diagnosed, histologically confirmed RCC and 280 age-, gender- and district of residence-matched controls. Anthropometric data, socio-demographic variables, medical history, lifestyle habits and dietary data were derived from a personal interview. Serum leptin and adiponectin levels were determined using standard commercial kits. Adjusted odds ratios for RCC risk were derived through multiple logistic regression analyses. Leptin levels were inversely associated with RCC risk (OR: 0.53, CI: 0.28- 0.99, p = 0.05), even after controlling for potential confounding factors, such as Body Mass Index (BMI), recent weight change, history of diabetes mellitus and other obesity related hormones, notably adiponectin. The precise mechanism linking obesity with RCC remains unclear; however, the inverse association of leptin with RCC might be attributed, at least in part, to hormonal cross-talk with complex neuron-endocrine and immune circuits. These findings, if confirmed in prospective and interventional studies, might further elucidate the underlying mechanisms.
Numerical and Experimental Studies of Transient Natural Convection with Density Inversion
Mizutani, Satoru; Ishiguro, Tatsuji; Kuwahara, Kunio
1996-11-01
In beer manufacturing process, we cool beer in storage tank down from 8 to -1 ^circC. The understanding of cooling process is very important for designing a fermentation tank. In this paper, flow and temperature distribution in a rectangular enclosure was studied. The unsteady incompressible Navier-Stokes equations were integrated by using the multi-directional third-order upwind finite difference method(MUFDM). A parabolic density-temperature relationship was assumed in water which has the maximum density at 3.98 ^circC. Cooling down from 8 to 0 ^circC of water in 10 cm cubical enclosure (Ra=10^7) was numerically done by keeping a vertical side wall at 0 ^circC. Vortex was caused by density inversion of water which was cooled bellow 4 ^circC, and it rose near the cold wall and reached water surface after 33 min from the start of cooling. Finally, cooling proceeded from upper surface. At the aim of verifing the accuracy of the numerical result, temperature distribution under the same condition was experimentally visualized using temperature sensitive liquid crystal. The results will be presented by using video movie. Comparison between the computation and the experiment showed that the present direct simulation based on the MUFDM was powerful tool for the understanding of the natural convection with density inversion and the application of cooling phenomenon to the design of beer storage tanks.
Gatto, Emilia Mabel; Melcon, Carlos; Parisi, Virginia L; Bartoloni, Leonardo; Gonzalez, Claudio D
2015-09-15
Yerba mate tea is a very common beverage in some countries of South America. We conducted a case-control study on an individual basis using hospital records to investigate the association between Parkinson's disease (PD) and yerba mate intake. A case was defined as an age of ≥ 40 years with ≥ 1 year of PD. Each case was individually matched by two controls. Exposure was measured by yerba mate consumption, coffee, tea, and alcohol intake and smoking status. The sample consisted of 223 PD patients (mean age 68 years and mean disease duration 7.3 years) and 406 controls. There was an inverse association between yerba mate "bombilla" consumption and PD (OR 0.64, 95% CI: 0.54-0.76, p=0.00001). A multivariate analysis with a logistic regression adjusted by sex, alcohol intake and smoking provided the following results: yerba mate (OR 0.63, 95% CI: 0.53-0.76), tea (OR 0.60, 95% CI: 0.42-0.86), coffee (OR 0.51, 95% CI: 0.35-0.73). We found an inverse association between yerba mate consumption and PD. These results led us to hypothesize that yerba mate may have a potential protective role in the development of PD. Copyright © 2015 Elsevier B.V. All rights reserved.
NMR studies of DNA structures in solution
International Nuclear Information System (INIS)
Rinkel, L.J.
1987-01-01
This thesis describes the conformational analysis of some polynucleotides in aqueous solution. A new graphical method is presented as an aid in the pseudorotational analysis of the sugar rings in DNA by means of sums of proton-proton coupling constants. (Auth.)
Gallovič, František; Imperatori, Walter; Mai, Paul Martin
2015-01-01
Earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1-D velocity models and a flat Earth surface. However, heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena, introducing complex 3-D effects on ground motions. Here we investigate how the use of imprecise Green's functions - achieved by including 3-D velocity perturbations and topography - affect slip-inversion results. We create sets of synthetic seismograms, including 3-D heterogeneous Earth structure and topography, and then invert these synthetics using Green's functions computed for a horizontally layered 1-D Earth model. We apply a linear inversion, regularized by smoothing and positivity constraint, and examine in detail how smoothing effects perturb the solution. Among others, our tests and resolution analyses demonstrate how imprecise Green's functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing. The investigation is extended to recordings of the 2009 Mw6.3 L'Aquila earthquake, considering both strong motion and high-rate GPS stations. We interpret the inversion results taking into account the lessons learned from the synthetic tests. The retrieved slip model resembles previously published solutions using geodetic data, showing a large-slip asperity southeast of the hypocenter. In agreement with other studies, we find evidence for fast but subshear rupture propagation in updip direction, followed by a delayed propagation along strike. We conjecture that rupture was partially inhibited by a deep localized velocity-strengthening patch that subsequently experienced afterslip.
Gallovič, František
2015-01-01
Earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1-D velocity models and a flat Earth surface. However, heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena, introducing complex 3-D effects on ground motions. Here we investigate how the use of imprecise Green\\'s functions - achieved by including 3-D velocity perturbations and topography - affect slip-inversion results. We create sets of synthetic seismograms, including 3-D heterogeneous Earth structure and topography, and then invert these synthetics using Green\\'s functions computed for a horizontally layered 1-D Earth model. We apply a linear inversion, regularized by smoothing and positivity constraint, and examine in detail how smoothing effects perturb the solution. Among others, our tests and resolution analyses demonstrate how imprecise Green\\'s functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing. The investigation is extended to recordings of the 2009 Mw6.3 L\\'Aquila earthquake, considering both strong motion and high-rate GPS stations. We interpret the inversion results taking into account the lessons learned from the synthetic tests. The retrieved slip model resembles previously published solutions using geodetic data, showing a large-slip asperity southeast of the hypocenter. In agreement with other studies, we find evidence for fast but subshear rupture propagation in updip direction, followed by a delayed propagation along strike. We conjecture that rupture was partially inhibited by a deep localized velocity-strengthening patch that subsequently experienced afterslip.
International Nuclear Information System (INIS)
Namatame, Hirofumi; Taniguchi, Masaki
1994-01-01
Photoelectron spectroscopy is regarded as the most powerful means since it can measure almost perfectly the occupied electron state. On the other hand, inverse photoelectron spectroscopy is the technique for measuring unoccupied electron state by using the inverse process of photoelectron spectroscopy, and in principle, the similar experiment to photoelectron spectroscopy becomes feasible. The development of the experimental technology for inverse photoelectron spectroscopy has been carried out energetically by many research groups so far. At present, the heightening of resolution of inverse photoelectron spectroscopy, the development of inverse photoelectron spectroscope in which light energy is variable and so on are carried out. But the inverse photoelectron spectroscope for vacuum ultraviolet region is not on the market. In this report, the principle of inverse photoelectron spectroscopy and the present state of the spectroscope are described, and the direction of the development hereafter is groped. As the experimental equipment, electron guns, light detectors and so on are explained. As the examples of the experiment, the inverse photoelectron spectroscopy of semimagnetic semiconductors and resonance inverse photoelectron spectroscopy are reported. (K.I.)
Pericentric Inversion of Human Chromosome 9 Epidemiology Study in Czech Males and Females.
Šípek, A; Panczak, A; Mihalová, R; Hrčková, L; Suttrová, E; Sobotka, V; Lonský, P; Kaspříková, N; Gregor, V
2015-01-01
Pericentric inversion of human chromosome 9 [inv(9)] is a relatively common cytogenetic finding. It is largely considered a clinically insignificant variant of the normal human karyotype. However, numerous studies have suggested its possible association with certain pathologies, e.g., infertility, habitual abortions or schizophrenia. We analysed the incidence of inv(9) and the spectrum of clinical indications for karyotyping among inv(9) carriers in three medical genetics departments in Prague. In their cytogenetic databases, among 26,597 total records we identified 421 (1.6 %) cases of inv(9) without any concurrent cytogenetic pathology. This study represents the world's largest epidemiological study on inv(9) to date. The incidence of inv(9) calculated in this way from diagnostic laboratory data does not differ from the incidence of inv(9) in three specific populationbased samples of healthy individuals (N = 4,166) karyotyped for preventive (amniocentesis for advanced maternal age, gamete donation) or legal reasons (children awaiting adoption). The most frequent clinical indication in inv(9) carriers was "idiopathic reproductive failure" - 37.1 %. The spectra and percentages of indications in individuals with inv(9) were further statistically evaluated for one of the departments (N = 170) by comparing individuals with inv(9) to a control group of 661 individuals with normal karyotypes without this inversion. The proportion of clinical referrals for "idiopathic reproductive failure" among inv(9) cases remains higher than in controls, but the difference is not statistically significant for both genders combined. Analysis in separated genders showed that the incidence of "idiopathic reproductive failure" could differ among inv(9) female and male carriers.
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction
Vasilieva, A. V.; Grigoryeva, N. A.; Mistonov, A. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Lukashin, A. V.; Tretyakov, Yu D.; Petukhov, A. V.; Byelov, D.; Chernyshov, D.; Okorokov, A. I.; Bouwman, W. G.; Grigoriev, S. V.
2010-10-01
Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a0 = 650 ± 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length Ltran is 2.4 ± 0.1 μm, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length Llong is 3.4 ± 0.2 μm, and the structure mosaic is of order of 10°.
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction
International Nuclear Information System (INIS)
Vasilieva, A V; Okorokov, A I; Grigoriev, S V; Grigoryeva, N A; Mistonov, A A; Sapoletova, N A; Napolskii, K S; Eliseev, A A; Lukashin, A V; Tretyakov, Yu D; Petukhov, A V; Byelov, D; Chernyshov, D; Bouwman, W G
2010-01-01
Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a 0 = 650 ± 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length L tran is 2.4 ± 0.1 μm, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length L long is 3.4 ± 0.2 μm, and the structure mosaic is of order of 10 0 .
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction
Energy Technology Data Exchange (ETDEWEB)
Vasilieva, A V; Okorokov, A I; Grigoriev, S V [Petersburg Nuclear Physics Institute, Gatchina, 188350, St. Petersburg (Russian Federation); Grigoryeva, N A; Mistonov, A A [Department of Physics, St. Petersburg State University, 198504, St. Petersburg (Russian Federation); Sapoletova, N A; Napolskii, K S; Eliseev, A A; Lukashin, A V; Tretyakov, Yu D [Department of Materials Science, Moscow State University, 119899, Moscow (Russian Federation); Petukhov, A V; Byelov, D [Debye Institute, Utrecht University, 3584 CH Utrecht (Netherlands); Chernyshov, D [SNBL European Synchrotron Radiation Facility (ESRF), 38043 Grenoble (France); Bouwman, W G, E-mail: vasilieva@lns.pnpi.spb.r [Delft Technical University, 2629 JB Delft (Netherlands)
2010-10-01
Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a{sub 0} = 650 {+-} 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length L{sub tran} is 2.4 {+-} 0.1 {mu}m, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length L{sub long} is 3.4 {+-} 0.2 {mu}m, and the structure mosaic is of order of 10{sup 0}.
Study on orthorhombic parameters for 3D elastic full waveform inversion
Oh, Juwon
2015-08-21
For a better understanding of the influence of the parameterizations on the multi-parameter full waveform inversion (FWI) for 3D elastic orthorhombic media, we analyze the virtual sources for each cij parameter. Because the virtual sources for cij parameters can be regarded as bases of the virtual sources for other parameterizations, the insights developed here explains many of the scattering phenomena of the different parameters. The resulting radiation patterns provide insights on which parameter set is the best in the multi-parameter FWI for 3D elastic orthorhombic media. In this study, we analyze the virtual source for each cij parameter as a linear combination of several moment tensors. After that, we analyze the strain fields deformed by incident waves as momenta of the virtual source and their influences on sensitivity kernels of each cij parameter.
Study on orthorhombic parameters for 3D elastic full waveform inversion
Oh, Juwon; Alkhalifah, Tariq Ali
2015-01-01
For a better understanding of the influence of the parameterizations on the multi-parameter full waveform inversion (FWI) for 3D elastic orthorhombic media, we analyze the virtual sources for each cij parameter. Because the virtual sources for cij parameters can be regarded as bases of the virtual sources for other parameterizations, the insights developed here explains many of the scattering phenomena of the different parameters. The resulting radiation patterns provide insights on which parameter set is the best in the multi-parameter FWI for 3D elastic orthorhombic media. In this study, we analyze the virtual source for each cij parameter as a linear combination of several moment tensors. After that, we analyze the strain fields deformed by incident waves as momenta of the virtual source and their influences on sensitivity kernels of each cij parameter.
The Study on the Alteration of Simulated HLLW Glass in Aqueous Media by Inverse Gas Chromatography
International Nuclear Information System (INIS)
Zhang, Zhentao; Gan, Xueying; Yuan, Wenyi; Wang, Lei; Xing, Haiqing; Balard, Henri
2008-01-01
There exist webs of fissures inside the glass block accessible to underground water and theses fissures will influence the alteration of the glass significantly. It is very necessary to study the fissure surface properties of the glass under deep geological conditions. The alteration tests were conducted using the simulated high level radioactive glass powder immersed in Beishan (candidate disposal site) underground water with S/V ratio of 8000 m -1 at 150 deg. C and 90 deg. C for different periods. After immersion, the glass powder was filtered and dried at 120 deg. C for 3 hours. The surface properties of the dried glass powder were evaluated by inverse chromatography. The results showed that the specific surface area of the glass increases abruptly at the beginning of immersion and then increase slowly afterwards. At higher immersion temperature, the secondary phase is condensing crystals; at the lower immersion temperature, the secondary phases were loosely 'islands' with cracks or fissures. (authors)
A neutron spectrometer for studying giant resonances with (p,n) reactions in inverse kinematics
International Nuclear Information System (INIS)
Stuhl, L.; Krasznahorkay, A.; Csatlós, M.; Algora, A.; Gulyás, J.; Kalinka, G.; Timár, J.; Kalantar-Nayestanaki, N.; Rigollet, C.; Bagchi, S.; Najafi, M.A.
2014-01-01
A neutron spectrometer, the European Low-Energy Neutron Spectrometer (ELENS), has been constructed to study exotic nuclei in inverse-kinematics experiments. The spectrometer, which consists of plastic scintillator bars, can be operated in the neutron energy range of 100 keV–10 MeV. The neutron energy is determined using the time-of-flight technique, while the position of the neutron detection is deduced from the time-difference information from photomultipliers attached to both ends of each bar. A novel wrapping method has been developed for the plastic scintillators. The array has a larger than 25% detection efficiency for neutrons of approximately 500 keV in kinetic energy and an angular resolution of less than 1°. Details of the design, construction and experimental tests of the spectrometer will be presented
Anatomy-based inverse planning dose optimization in HDR prostate implant: A toxicity study
International Nuclear Information System (INIS)
Mahmoudieh, Alireza; Tremblay, Christine; Beaulieu, Luc; Lachance, Bernard; Harel, Francois; Lessard, Etienne; Pouliot, Jean; Vigneault, Eric
2005-01-01
Background and purpose: The aim of this study is to evaluate the acute and late complications in patients who have received HDR implant boost using inverse planning, and to determine dose volume correlations. Patients and methods: Between September 1999 and October 2002, 44 patients with locally advanced prostate cancer (PSA ≥10 ng/ml, and/or Gleason score ≥7, and/or Stage T2c or higher) were treated with 40-45 Gy external pelvic field followed by 2-3 fraction of inverse-planned HDR implant boost (6-9.5 Gy /fraction). Median follow-up time was 1.7 years with 81.8% of patients who had at least 12 months of follow up (range 8.6-42.5. Acute and late morbidity data were collected and graded according to RTOG criteria. Questionnaires were used to collect prostate related measures of quality of life, and international prostate symptom score (IPSS) before and after treatment. Dose-volume histograms for prostate, urethra, bladder, penis bulb and rectum were analyzed. Results: The median patient age was 64 years. Of these, 32% were in the high risk group, and 61% in the intermediate risk group. 3 patients (7%) had no adverse prognostic factors. A single grade 3 GU acute toxicity was reported but no grade 3-4 acute GI toxicity. No grade 3-4 late GU or GI toxicity was reported. Acute (late) grade 2 urinary and rectal symptoms were reported in 31.8 (11.4%) and 4.6% (4.6%) of patients, respectively. A trend for predicting acute GU toxicity is seen for total HDR dose of more than 18 Gy (OR=3.6, 95%CI=[0.96-13.5], P=0.058). The evolution of toxicity is presented for acute and late GU/GI toxicity. Erectile dysfunction occurs in approximately 27% of patients who were not on hormonal deprivation, but may be taking sildenafil. The IPSS peaked on averaged 6 weeks post-implant and returned to the baseline at a median of 6 months. Conclusions: Inverse-planned HDR brachytherapy is a viable option to deliver higher dose to the prostate as a boost without increasing GU or rectal
Generalized inverses theory and computations
Wang, Guorong; Qiao, Sanzheng
2018-01-01
This book begins with the fundamentals of the generalized inverses, then moves to more advanced topics. It presents a theoretical study of the generalization of Cramer's rule, determinant representations of the generalized inverses, reverse order law of the generalized inverses of a matrix product, structures of the generalized inverses of structured matrices, parallel computation of the generalized inverses, perturbation analysis of the generalized inverses, an algorithmic study of the computational methods for the full-rank factorization of a generalized inverse, generalized singular value decomposition, imbedding method, finite method, generalized inverses of polynomial matrices, and generalized inverses of linear operators. This book is intended for researchers, postdocs, and graduate students in the area of the generalized inverses with an undergraduate-level understanding of linear algebra.
Directory of Open Access Journals (Sweden)
T Sundaram
2013-01-01
Full Text Available Context: Possible benefits of inverse planning. Aims: To analyze possible benefits of inverse planning intensity modulated radiation therapy (IMRT over field-in-field 3D conformal radiation therapy (FIF-3DCRT and to evaluate the differences if any, between low (6 Million Volts and high energy (15 Million Volts IMRT plans. Materials and Methods: Ten patients with squamous cell carcinoma of oropharynx, previously treated with 6 MV step and shoot IMRT were studied. V 100 , V 33 , V 66 , mean dose and normal tissue complication probabilities (NTCP were evaluated for parotid glands. Maximum dose and NTCP were the parameters for spinal cord. Statistical Analysis Used: A two-tailed t-test was applied to analyze statistical significance between the different techniques. Results: For combined parotid gland, a reduction of 4.374 Gy, 9.343 Gy and 7.883 Gy were achieved for D 100 , D 66 and D 33 , respectively in 6 MV-IMRT when compared with FIF-3DCRT. Spinal cord sparing was better in 6 MV-IMRT (40.963 ± 2.650, with an average reduction of maximum spinal cord dose by 7.355 Gy from that using the FIF-3DCRT technique. The uncomplicated tumor control probabilities values were higher in IMRT plans thus leading to a possibility of dose escalation. Conclusions: Though low-energy IMRT is the preferred choice for treatment of oropharyngeal cancers, FIF-3DCRT must be given due consideration as a second choice for its well established advantages over traditional conventioan technique.
Acute puerperal uterine inversion
International Nuclear Information System (INIS)
Hussain, M.; Liaquat, N.; Noorani, K.; Bhutta, S.Z; Jabeen, T.
2004-01-01
Objective: To determine the frequency, causes, clinical presentations, management and maternal mortality associated with acute puerperal inversion of the uterus. Materials and Methods: All the patients who developed acute puerperal inversion of the uterus either in or outside the JPMC were included in the study. Patients of chronic uterine inversion were not included in the present study. Abdominal and vaginal examination was done to confirm and classify inversion into first, second or third degrees. Results: 57036 deliveries and 36 acute uterine inversions occurred during the study period, so the frequency of uterine inversion was 1 in 1584 deliveries. Mismanagement of third stage of labour was responsible for uterine inversion in 75% of patients. Majority of the patients presented with shock, either hypovolemic (69%) or neurogenic (13%) in origin. Manual replacement of the uterus under general anaesthesia with 2% halothane was successfully done in 35 patients (97.5%). Abdominal hysterectomy was done in only one patient. There were three maternal deaths due to inversion. Conclusion: Proper education and training regarding placental delivery, diagnosis and management of uterine inversion must be imparted to the maternity care providers especially to traditional birth attendants and family physicians to prevent this potentially life-threatening condition. (author)
International Nuclear Information System (INIS)
Rosenwald, J.-C.
2008-01-01
The lecture addressed the following topics: Optimizing radiotherapy dose distribution; IMRT contributes to optimization of energy deposition; Inverse vs direct planning; Main steps of IMRT; Background of inverse planning; General principle of inverse planning; The 3 main components of IMRT inverse planning; The simplest cost function (deviation from prescribed dose); The driving variable : the beamlet intensity; Minimizing a 'cost function' (or 'objective function') - the walker (or skier) analogy; Application to IMRT optimization (the gradient method); The gradient method - discussion; The simulated annealing method; The optimization criteria - discussion; Hard and soft constraints; Dose volume constraints; Typical user interface for definition of optimization criteria; Biological constraints (Equivalent Uniform Dose); The result of the optimization process; Semi-automatic solutions for IMRT; Generalisation of the optimization problem; Driving and driven variables used in RT optimization; Towards multi-criteria optimization; and Conclusions for the optimization phase. (P.A.)
International Nuclear Information System (INIS)
Chung, Hwan Hoon; Kim, Yun Hwan; Kang, Chang Ho; Park, Bum Jin; Chung, Kyoo Byung; Suh, Won Hyuck
2000-01-01
To determine the most useful sonographic technique to evaluate pleural effusion and ascites by comparing conventional, tissue harmonic and pulse inversion harmonic images. 12 patients having pleural effusion and 14 patients having ascites were included in this study. 18 patients were male and 8 patients were female. Average age was 54.8 yrs (25-77). We compared images which had been taken at the same section with 3 above mentioned sonographic techniques. Evaluation was done by 3 radiologists in consensus and grades were given to 3 techniques from 1 to 3. Evaluating points were 1) normal structures that border the fluid such as liver, peritoneal lining, pleura, 2) septation in fluid, 3) debris floating in fluid, and 4) artifacts. Pulse inversion harmonic image was the best in image quality for normal structures, followed by tissue harmonic and conventional image (p<0.05). Pulse inversion harmonic image was better than conventional image to evaluate septation in fluid (p<0.05), but there were no statistically significant difference between pulse inversion and tissue harmonic images, and tissue harmonic and conventional images. Tissue harmonic image was better than pulse inversion harmonic and conventional images to evaluate debris floating in fluid (p<0.05) but there was no statistically significant difference between these two latter techniques. Artifacts were most prominent on conventional image followed by tissue harmonic and pulse inversion harmonic image (p<0.05). Pulse inversion harmonic image was the best sonographic technique to evaluate pleural effusion or ascites, However, Tissue harmonic image was the best for evaluation of debris.
Energy Technology Data Exchange (ETDEWEB)
Chung, Hwan Hoon; Kim, Yun Hwan; Kang, Chang Ho; Park, Bum Jin; Chung, Kyoo Byung; Suh, Won Hyuck [Korea University College of Medicine, Seoul (Korea, Republic of)
2000-12-15
To determine the most useful sonographic technique to evaluate pleural effusion and ascites by comparing conventional, tissue harmonic and pulse inversion harmonic images. 12 patients having pleural effusion and 14 patients having ascites were included in this study. 18 patients were male and 8 patients were female. Average age was 54.8 yrs (25-77). We compared images which had been taken at the same section with 3 above mentioned sonographic techniques. Evaluation was done by 3 radiologists in consensus and grades were given to 3 techniques from 1 to 3. Evaluating points were 1) normal structures that border the fluid such as liver, peritoneal lining, pleura, 2) septation in fluid, 3) debris floating in fluid, and 4) artifacts. Pulse inversion harmonic image was the best in image quality for normal structures, followed by tissue harmonic and conventional image (p<0.05). Pulse inversion harmonic image was better than conventional image to evaluate septation in fluid (p<0.05), but there were no statistically significant difference between pulse inversion and tissue harmonic images, and tissue harmonic and conventional images. Tissue harmonic image was better than pulse inversion harmonic and conventional images to evaluate debris floating in fluid (p<0.05) but there was no statistically significant difference between these two latter techniques. Artifacts were most prominent on conventional image followed by tissue harmonic and pulse inversion harmonic image (p<0.05). Pulse inversion harmonic image was the best sonographic technique to evaluate pleural effusion or ascites, However, Tissue harmonic image was the best for evaluation of debris.
International Nuclear Information System (INIS)
Huang, C.-H.; Wu, H.-H.
2006-01-01
In the present study an inverse hyperbolic heat conduction problem is solved by the conjugate gradient method (CGM) in estimating the unknown boundary heat flux based on the boundary temperature measurements. Results obtained in this inverse problem will be justified based on the numerical experiments where three different heat flux distributions are to be determined. Results show that the inverse solutions can always be obtained with any arbitrary initial guesses of the boundary heat flux. Moreover, the drawbacks of the previous study for this similar inverse problem, such as (1) the inverse solution has phase error and (2) the inverse solution is sensitive to measurement error, can be avoided in the present algorithm. Finally, it is concluded that accurate boundary heat flux can be estimated in this study
Stability study of pre-stack seismic inversion based on the full Zoeppritz equation
Liang, Lifeng; Zhang, Hongbing; Guo, Qiang; Saeed, Wasif; Shang, Zuoping; Huang, Guojiao
2017-10-01
Pre-stack seismic inversion is highly important and complicated. Its result is non-unique, and the process is unstable because pre-stack seismic inversion is an ill-posed problem that simultaneously obtains the results of multiple parameters. Combining the full Zoeppritz equation and additional assumptions with edge-preserving regularization (EPR) can help mitigate the problem. To achieve this combination, we developed an inversion method by constructing a new objective function, which includes the EPR and the Markov random field. The method directly gains reflectivity R PP by the full Zoeppritz equation instead of its approximations and effectively controls the stability of simultaneous inversion by two additional assumptions: the sectional constant V S/V P and the generalized Gardner equation. Thus, the simultaneous inversion of multiple parameters is directed toward to V P, ΔL S (the fitting deviation of V S) and density, and the generalized Gardner equation is regarded as a constraint from which the fitting relationship is derived. We applied the fast simulated annealing algorithm to solve the nonlinear optimization problem. The test results on 2D synthetic data indicated that the stability of simultaneous inversion for V P, ΔL S and density is better than these for V P, V S, and density. The inverted result of density gradually worsens as the deviation ΔL D (the fitting deviation of the density) increases. Moreover, the inverted results were acceptable when using the fitting relationships with error, although they showed varying degrees of influence. We constructed time-varying and space-varying fitting relationships using the logging data in pre-stack inversion of the field seismic data. This improved the inverted results of the simultaneous inversion for complex geological models. Finally, the inverted results of the field data distinctly revealed more detailed information about the layers and matched well with the logging data along the wells over most
International Nuclear Information System (INIS)
Egelhof, P.
1997-02-01
The investigation of light-ion induced direct reactions with exotic beams in inverse kinematics gives access to a wide field of nuclear structure studies in the region far off stability. The present contribution will focus on the investigation of few-nucleon transfer reactions, which turn out to be most favourably studied with good-quality low-energy radioactive beams, as provided by the new generation of radioactive beam facilities presently planned or under construction at Caen, Grenoble, Munich, and elsewhere. An overview on the physics motivation, basically concerning nuclear structure and nuclear astrophysics questions, is given. Of particular interest are the nuclear shell model in the region far off stability, the two-body residual interaction in nuclei, the structure of halo nuclei, as well as the understanding of the r-process scenario. The experimental conditions, along with the experimental concept, for such measurements are discussed with particular emphasis on the kinematical conditions, the observables, as well as the appropriate detection schemes. The concept of a large solid angle TPC ionization chamber as an active target for experiments with low-energy radioactive beams is presented. It turns out to be a highly effective detection scheme, well suited for the present experimental conditions, at least for light exotic beams up to Z∼20. (orig.)
Liu, Feng-Cheng; Huang, Wen-Yen; Lin, Te-Yu; Shen, Chih-Hao; Chou, Yu-Ching; Lin, Cheng-Li; Lin, Kuen-Tze; Kao, Chia-Hung
2015-11-01
The effects of the inflammatory mediators involved in systemic lupus erythematous (SLE) on subsequent Parkinson disease have been reported, but no relevant studies have focused on the association between the 2 diseases. This nationwide population-based study evaluated the risk of Parkinson disease in patients with SLE.We identified 12,817 patients in the Taiwan National Health Insurance database diagnosed with SLE between 2000 and 2010 and compared the incidence rate of Parkinson disease among these patients with that among 51,268 randomly selected age and sex-matched non-SLE patients. A Cox multivariable proportional-hazards model was used to evaluate the risk factors of Parkinson disease in the SLE cohort.We observed an inverse association between a diagnosis of SLE and the risk of subsequent Parkinson disease, with the crude hazard ratio (HR) being 0.60 (95% confidence interval 0.45-0.79) and adjusted HR being 0.68 (95% confidence interval 0.51-0.90). The cumulative incidence of Parkinson disease was 0.83% lower in the SLE cohort than in the non-SLE cohort. The adjusted HR of Parkinson disease decreased as the follow-up duration increased and was decreased among older lupus patients with comorbidity.We determined that patients with SLE had a decreased risk of subsequent Parkinson disease. Further research is required to elucidate the underlying mechanism.
Incomplete Hippocampal Inversion: a comprehensive MRI study of over 2000 subjects
Directory of Open Access Journals (Sweden)
Claire eCury
2015-12-01
Full Text Available The incomplete-hippocampal-inversion (IHI, also known as malrotation, is an atypical anatomical pattern of the hippocampus, which has been reported in healthy subjects in different studies. However, extensive characterization of IHI in a large sample has not yet been performed. Furthermore, it is unclear whether IHI are restricted to the medial-temporal lobe or are associated with more extensive anatomical changes. Here, we studied the characteristics of IHI in a community-based sample of 2008 subjects of the IMAGEN database and their association with extra-hippocampal anatomical variations. The presence of IHI was assessed on T1-weighted anatomical magnetic resonance imaging (MRI using visual criteria. We assessed the association of IHI with other anatomical changes throughout the brain using automatic morphometry of cortical sulci. We found that IHI were much more frequent in the left hippocampus (left: 17%, right: 6%, χ2-test, p<10-28. Compared to subjects without IHI, subjects with IHI displayed morphological changes in several sulci located mainly in the limbic lobe. Our results demonstrate that IHI are a common left-sided phenomenon in normal subjects and that they are associated with morphological changes outside the medial temporal lobe.
Energy Technology Data Exchange (ETDEWEB)
Pei, Yi Gang; Li, Fang; Long, Xue Ying; Liu, Hui; Wang, Xiao Yi; Liu, Jin Kang; Li, Wen Zheng [Dept. of Radiology, Xiangya Hospital, Central South University, Changsha (China); Shen, Hao [GE Healthcare, Waukesha (United States)
2016-02-15
To determine whether an optimal blood suppression inversion time (BSP TI) can boost arterial visibility and whether the optimal BSP TI is related to breathing rate (BR) and heart rate (HR) for hypertension subjects in spatial labeling with multiple inversion pulses (SLEEK). This prospective study included 10 volunteers and 93 consecutive hypertension patients who had undergone SLEEK at 1.5T MRI system. Firstly, suitable BSP TIs for displaying clearly renal artery were determined in 10 volunteers. Secondly, non-contrast enhanced magnetic resonance angiography with the suitable BSP TIs were performed on those hypertension patients. Then, renal artery was evaluated and an optimal BSP TI to increase arterial visibility was determined for each patient. Patients' BRs and HRs were recorded and their relationships with the optimal BSP TI were analyzed. The optimal BSP TI was negatively correlated with BR (r1 = -0.536, P1 < 0.001; and r2 = -0.535, P2 < 0.001) and HR (r1 = -0.432, P1 = 0.001; and r2 = -0.419, P2 = 0.001) for 2 readers (κ = 0.93). For improving renal arterial visibility, BSP TI = 800 ms could be applied as the optimal BSP TI when the 95% confidence interval were 17-19/min (BR1) and 74-82 bpm (HR1) for reader#1 and 17-19/min (BR2) and 74-83 bpm (HR2) for reader#2; BSP TI = 1100 ms while 14-15/min (BR1, 2) and 71-76 bpm (HR1, 2) for both readers; and BSP TI = 1400 ms when 13-16/min (BR1) and 63-68 bpm (HR1) for reader#1 and 14-15/min (BR2) and 64-70 bpm (HR2) for reader#2. In SLEEK, BSP TI is affected by patients' BRs and HRs. Adopting the optimal BSP TI based on BR and HR can improve the renal arterial visibility and consequently the working efficiency.
Experimental study of ERT monitoring ability to measure solute dispersion.
Lekmine, Grégory; Pessel, Marc; Auradou, Harold
2012-01-01
This paper reports experimental measurements performed to test the ability of electrical resistivity tomography (ERT) imaging to provide quantitative information about transport parameters in porous media such as the dispersivity α, the mixing front velocity u, and the retardation factor R(f) associated with the sorption or trapping of the tracers in the pore structure. The flow experiments are performed in a homogeneous porous column placed between two vertical set of electrodes. Ionic and dyed tracers are injected from the bottom of the porous media over its full width. Under such condition, the mixing front is homogeneous in the transverse direction and shows an S-shape variation in the flow direction. The transport parameters are inferred from the variation of the concentration curves and are compared with data obtained from video analysis of the dyed tracer front. The variations of the transport parameters obtained from an inversion performed by the Gauss-Newton method applied on smoothness-constrained least-squares are studied in detail. While u and R(f) show a relatively small dependence on the inversion procedure, α is strongly dependent on the choice of the inversion parameters. Comparison with the video observations allows for the optimization of the parameters; these parameters are found to be robust with respect to changes in the flow condition and conductivity contrast. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.
Inverse-kinematics study of 78Kr + 40Ca at 10 AMeV
Directory of Open Access Journals (Sweden)
Henry E.
2015-01-01
Full Text Available The CHIMERA multi-detector array at LNS Catania has been used to study the inverse-kinematics reaction of 78Kr + 40Ca at a bombarding energy of 10 A MeV. Analysis of the experimental data focused on a class of selected events consistent with the complete fusion and subsequent binary split of the of the reacting system. This class of events features a broad A, Z distribution of fission fragments centered about symmetric fission while exhibiting relative velocities significantly higher than given by Viola systematics. The center-of-mass angular distribution (dσ/dΘ of the fission fragments exhibit an unexpected anisotropy inconsistent with a compound-nucleus reaction and indicates a dynamic fusion-fission like process. The observed angular distribution features an asymmetric forward-backward peaking most prevalent for mass-asymmetric events. Furthermore, the more massive fragment of mass-asymmetric events appears to emerge preferentially in the forward direction, along the beam axis, in analogy to dynamic fragmentation of projectile-like fragments. Analysis of the angular distribution of alpha particles emitted from these fission fragments suggests the events are associated mostly with central collisions.
Polyphased Inversions of an Intracontinental Rift: Case Study of the Marrakech High Atlas, Morocco
Leprêtre, R.; Missenard, Y.; Barbarand, J.; Gautheron, C.; Jouvie, I.; Saddiqi, O.
2018-03-01
The High and Middle Atlas intraplate belts in Morocco correspond to Mesozoic rifted basins inverted during the Cenozoic during Africa/Eurasia convergence. The Marrakech High Atlas lies at a key location between Atlantic and Tethyan influences during the Mesozoic rifting phase but represents today high reliefs. Age and style of deformation and the mechanisms underlying the Cenozoic inversion are nevertheless still debated. To solve this issue, we produced new low-temperature thermochronology data (fission track and [U-Th]/He on apatite). Two cross sections were investigated in the western and eastern Marrakech High Atlas. Results of inverse modeling allow recognizing five cooling events attributed to erosion since Early Jurassic. Apart from a first erosional event from Middle/Late Jurassic to Early Cretaceous, four stages can be related to the convergence processes between Africa and Europe since the Late Cretaceous. Our data and thermal modeling results suggest that the inversion processes are guided at first order by the fault network inherited from the rifting episodes. The sedimentary cover and the Neogene lithospheric thinning produced a significant thermal weakening that facilitated the inversion of this ancient rift. Our data show that the Marrakech High Atlas has been behaving as a giant pop-up since the beginning of Cenozoic inversion stages.
Gijsbers, L.; Geleijnse, J.M.; Soedamah-Muthu, S.S.
2011-01-01
Observational studies suggest an inverse association between dairy intake and incident type 2 diabetes, but the quantity of dairy is not known. Previous meta-analyses did not take into account the type of dairy product. Therefore, we examined dose-response associations between the intake of total
Digital Repository Service at National Institute of Oceanography (India)
Muraleedharan, P.M.; Mohankumar, K.; Sivakumar, K.U.
The thermal inversion characteristics during active and break cycles of two consecutive and contrasting monsoon years were studied using GPS radiosonde profiles in Goa (15 degrees 46′ N; 73 degrees 08′ E), located on the west coast of India...
Wilson, M G; Sharma, S; Carré, F; Charron, P; Richard, P; O'Hanlon, R; Prasad, S K; Heidbuchel, H; Brugada, J; Salah, O; Sheppard, M; George, K P; Whyte, G; Hamilton, B; Chalabi, H
2012-11-01
Preparticipation screening programmes for underlying cardiac pathologies are now commonplace for many international sporting organisations. However, providing medical clearance for an asymptomatic athlete without a family history of sudden cardiac death (SCD) is especially challenging when the athlete demonstrates particularly abnormal repolarisation patterns, highly suggestive of an inherited cardiomyopathy or channelopathy. Deep T-wave inversions of ≥ 2 contiguous anterior or lateral leads (but not aVR, and III) are of major concern for sports cardiologists who advise referring team physicians, as these ECG alterations are a recognised manifestation of hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Subsequently, inverted T-waves may represent the first and only sign of an inherited heart muscle disease, in the absence of any other features and before structural changes in the heart can be detected. However, to date, there remains little evidence that deep T-wave inversions are always pathognomonic of either a cardiomyopathy or an ion channel disorder in an asymptomatic athlete following long-term follow-up. This paper aims to provide a systematic review of the prevalence of T-wave inversion in athletes and examine T-wave inversion and its relationship to structural heart disease, notably HCM and ARVC with a view to identify young athletes at risk of SCD during sport. Finally, the review proposes clinical management pathways (including genetic testing) for asymptomatic athletes demonstrating significant T-wave inversion with structurally normal hearts.
Carbon Market and Integrated Waste Solutions : a Case Study of ...
International Development Research Centre (IDRC) Digital Library (Canada)
Carbon Market and Integrated Waste Solutions : a Case Study of Indonesia ... dual purpose of helping developing countries achieve sustainable development ... with a view to devising integrated waste management solutions in urban centres ... and disseminate them through national, regional and international networks.
A Simulation Tool for the Study of Symmetric Inversions in Bacterial Genomes
Dias, Ulisses; Dias, Zanoni; Setubal, João C.
We present the tool SIB that simulates genomic inversions in bacterial chromosomes. The tool simulates symmetric inversions but allows the appearance of nonsymmetric inversions by simulating small syntenic blocks frequently observed on bacterial genome comparisons. We evaluate SIB by comparing its results to real genome alignments. We develop measures that allow quantitative comparisons between real pairwise alignments (in terms of dotplots) and simulated ones. These measures allow an evaluation of SIB in terms of dendrograms. We evaluate SIB by comparing its results to whole chromosome alignments and maximum likelihood trees for three bacterial groups (the Pseudomonadaceae family and the Xanthomonas and Shewanella genera). We demonstrate an application of SIB by using it to evaluate the ancestral genome reconstruction tool MGR.
Analysis of a spectrum of a positron annihilation half life through inverse problem studies
International Nuclear Information System (INIS)
Monteiro, Roberto Pellacani G.; Viterbo, Vanessa C.; Braga, Joao Pedro; Magalhaes, Wellington F. de; Braga, A.P.
2002-01-01
Inversion of positron annihilation lifetime spectroscopy, based on a neural network Hopfield model and singular value decomposition (SVD) associated to Tikhonov regularization is presented in this work. From a previous reported density function for lysozyme in water a simulated spectrum, without spectrometer resolution effects, was generated. The precision of the inverted density function was analyzed taking into account the number of neurons and the learning time of the Hopfield network and the maximum position and areas for the spectral peaks in the SVD method considering noise and noiseless data. A fair agreement was obtained when comparing the inversion results with direct exact results. (author)
A Generalization of the Spherical Inversion
Ramírez, José L.; Rubiano, Gustavo N.
2017-01-01
In the present article, we introduce a generalization of the spherical inversion. In particular, we define an inversion with respect to an ellipsoid, and prove several properties of this new transformation. The inversion in an ellipsoid is the generalization of the elliptic inversion to the three-dimensional space. We also study the inverse images…
Inversion of full acoustic wavefield in local helioseismology: A study with synthetic data
Cobden, L.J.; Tong, C.H.; Warner, M.R.
We present the first results from the inversion of full acoustic wavefield in the helioseismic context. In contrast to time-distance helioseismology, which involves analyzing the travel times of seismic waves propagating into the solar interior, wavefield tomography models both the travel times and
Experimental study of geo-acoustic inversion uncertainty due to ocean sound-speed fluctuations.
Siderius, M.; Nielsen, P.L.; Sellschopp, J.; Snellen, M.; Simons, D.G.
2001-01-01
Acoustic data measured in the ocean fluctuate due to the complex time-varying properties of the channel. When measured data are used for model-based, geo-acoustic inversion, how do acoustic fluctuations impact estimates for the seabed properties? In May 1999 SACLANT Undersea Research Center and
A structured approach to forensic study of explosions: The TNO Inverse Explosion Analysis tool
Voort, M.M. van der; Wees, R.M.M. van; Brouwer, S.D.; Jagt-Deutekom, M.J. van der; Verreault, J.
2015-01-01
Forensic analysis of explosions consists of determining the point of origin, the explosive substance involved, and the charge mass. Within the EU FP7 project Hyperion, TNO developed the Inverse Explosion Analysis (TNO-IEA) tool to estimate the charge mass and point of origin based on observed damage
Inverse source problems for eddy current equations
International Nuclear Information System (INIS)
Rodríguez, Ana Alonso; Valli, Alberto; Camaño, Jessika
2012-01-01
We study the inverse source problem for the eddy current approximation of Maxwell equations. As for the full system of Maxwell equations, we show that a volume current source cannot be uniquely identified by knowledge of the tangential components of the electromagnetic fields on the boundary, and we characterize the space of non-radiating sources. On the other hand, we prove that the inverse source problem has a unique solution if the source is supported on the boundary of a subdomain or if it is the sum of a finite number of dipoles. We address the applicability of this result for the localization of brain activity from electroencephalography and magnetoencephalography measurements. (paper)
Kong, Changduk; Lim, Semyeong
2011-12-01
Recently, the health monitoring system of major gas path components of gas turbine uses mostly the model based method like the Gas Path Analysis (GPA). This method is to find quantity changes of component performance characteristic parameters such as isentropic efficiency and mass flow parameter by comparing between measured engine performance parameters such as temperatures, pressures, rotational speeds, fuel consumption, etc. and clean engine performance parameters without any engine faults which are calculated by the base engine performance model. Currently, the expert engine diagnostic systems using the artificial intelligent methods such as Neural Networks (NNs), Fuzzy Logic and Genetic Algorithms (GAs) have been studied to improve the model based method. Among them the NNs are mostly used to the engine fault diagnostic system due to its good learning performance, but it has a drawback due to low accuracy and long learning time to build learning data base if there are large amount of learning data. In addition, it has a very complex structure for finding effectively single type faults or multiple type faults of gas path components. This work builds inversely a base performance model of a turboprop engine to be used for a high altitude operation UAV using measured performance data, and proposes a fault diagnostic system using the base engine performance model and the artificial intelligent methods such as Fuzzy logic and Neural Network. The proposed diagnostic system isolates firstly the faulted components using Fuzzy Logic, then quantifies faults of the identified components using the NN leaned by fault learning data base, which are obtained from the developed base performance model. In leaning the NN, the Feed Forward Back Propagation (FFBP) method is used. Finally, it is verified through several test examples that the component faults implanted arbitrarily in the engine are well isolated and quantified by the proposed diagnostic system.
International Nuclear Information System (INIS)
Tsuchihashi, Toshio; Yoshizawa, Satoshi; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Ken; Fujita, Isao
1998-01-01
A technique that increases slice thickness so that it becomes wider than the excitation width of the 180deg inversion pulse and in which TR is partitioned twice has been investigated with regard to fast FLAIR. This is a technique that reduces the flow artifact of CSF. It is thought that, with this technique, the flow artifact is reduced because the CSF that flows onto the slice reaches the null point. The cross talk effect of the 180deg inversion pulse appears as a high CSF signal. As a result, the number of slices needs to be partitioned two or three times before imaging. Thus the imaging time is doubled or tripled. Considering the cross talk effect of the 180deg inversion pulse and the imaging time needed for this technique, the optimal imaging technique would be one that uses an inversion pulse that is four times slice thickness plus slice space and for which the number of slices is partitioned twice. Furthermore, the null point of CSF was dependent on dividing TR in half. (author)
Czech Academy of Sciences Publication Activity Database
Wernersson, Erik; Kjellander, R.; Lyklema, J.
2010-01-01
Roč. 114, č. 4 (2010), s. 1849-1866 ISSN 1932-7447 Institutional research plan: CEZ:AV0Z40550506 Keywords : charge inversion * colloid * aqueous interface Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.520, year: 2010
Analytic study of nonperturbative solutions in open string field theory
International Nuclear Information System (INIS)
Bars, I.; Kishimoto, I.; Matsuo, Y.
2003-01-01
We propose an analytic framework to study the nonperturbative solutions of Witten's open string field theory. The method is based on the Moyal star formulation where the kinetic term can be split into two parts. The first one describes the spectrum of two identical half strings which are independent from each other. The second one, which we call midpoint correction, shifts the half string spectrum to that of the standard open string. We show that the nonlinear equation of motion of string field theory is exactly solvable at zeroth order in the midpoint correction. An infinite number of solutions are classified in terms of projection operators. Among them, there exists only one stable solution which is identical to the standard butterfly state. We include the effect of the midpoint correction around each exact zeroth order solution as a perturbation expansion which can be formally summed to the complete exact solution
Fluoride removal from aqueous solution by pumice: case study on ...
African Journals Online (AJOL)
EJIRO
conditions, the fluoride removal efficiency from Kuhbonan water by 2.8 mg/L fluoride was 74.64%. Eventually ... industrial wastewater containing fluoride is a key ..... solution using silica ceramic: Adsorption kinetics and equilibrium studies.
Children's strategies to solving additive inverse problems: a preliminary analysis
Ding, Meixia; Auxter, Abbey E.
2017-03-01
Prior studies show that elementary school children generally "lack" formal understanding of inverse relations. This study goes beyond lack to explore what children might "have" in their existing conception. A total of 281 students, kindergarten to third grade, were recruited to respond to a questionnaire that involved both contextual and non-contextual tasks on inverse relations, requiring both computational and explanatory skills. Results showed that children demonstrated better performance in computation than explanation. However, many students' explanations indicated that they did not necessarily utilize inverse relations for computation. Rather, they appeared to possess partial understanding, as evidenced by their use of part-whole structure, which is a key to understanding inverse relations. A close inspection of children's solution strategies further revealed that the sophistication of children's conception of part-whole structure varied in representation use and unknown quantity recognition, which suggests rich opportunities to develop students' understanding of inverse relations in lower elementary classrooms.
International Nuclear Information System (INIS)
Pozdnyakov, Yu.A.; Terenetskij, K.O.
1981-01-01
The approximate method for solution of the inverse scattering problem (ISP) at fixed energy for complex spherically symmetric potentials decreasing faster 1/r is considered. The method is based on using a generalized WKB approximation. For the designed potential V(r) a sufficiently ''close'' reference potential V(r) has been chosen. For both potentials S-matrix elements (ME) have been calculated and inversion procedure has been carried out. S-ME have been calculated for integral-valued and intermediate angular moment values. S-ME are presented in a graphical form for being restored reference, and restored potentials for proton scattering with Esub(p)=49.48 MeV energy on 12 C nuclei. The restoration is the better the ''closer'' the sought-for potential to the reference one. This allows to specify the potential by means of iterations: the restored potential can be used as a reference one, etc. The operation of a restored potential smoothing before the following iteration is introduced. Drawbacks and advantages of the ISP solution method under consideration are pointed out. The method application is strongly limited by the requirement that the energy should be higher than a certain ''critical'' one. The method is applicable in a wider region of particle energies (in the low-energies direction) than the ordinary WKB method. The method is more simple in realization conformably to complex potentials. The investigations carried out of the proposed ISP solution method at fixed energy for complex spherically-symmetric potentials allow to conclude that the method can be successFully applied to specify the central part of interaction of nucleons, α-particles and heavy ions of average and high energies with atomic nuclei [ru
STUDY OF ESTIMATE CONCENTRATION OF WATER CONSTITUENTS AT BADUNG STRAIT BALI USING INVERSE MODEL
Directory of Open Access Journals (Sweden)
I Ketut Swardika
2012-11-01
Full Text Available An algorithm was employed to retrieve the concentrations of three water constituents, chlorophyll-a,suspended matter and colored dissolved organic matter (CDOM from MODIS (Moderate-ResolutionImaging Spectrometer in wide range covering from oligotrophic case-1 to turbid case-2 waters at theBadung Strait Bali. The algorithm is a neural network (NN which is used to parameterize the inverse of aradiative transfer model. It’s used in this study as a multiple nonlinear regression technique. The NN is a feedforward back propagation model with two hidden layers. The NN was trained with computed radiancecovering the range of chlorophyll-a from 0.001 to 64.0 ?g/l, inorganic suspended matter from 0.01 to 50.0mg/l, and CDOM absorption at 440nm from 0.001 to 5.0 m-1. Inputs to the NN are the radiance of the fivespectral channels which were under discussion for MODIS. The outputs are the three water constituentconcentrations. The NN algorithm was tested using in-situ data set on May, September, November 2005 atthe Badung Strait Bali and the north sea of Sumbawa Island and applied to MODIS. The coefficient ofdetermination (R2 between chlorophyll-a concentrations derived from simulation and in-situ data is 0.327,for suspended matter R2 is 0.408. No in-situ measurements of CDOM available for validation. Also, in-situdata were compared with the corresponding distribution obtained by the NASA standard OC4 (OC3M forMODIS chlorophyll-a algorithm and giving R2 0.188. This study gives better accuracy compare withstandard algorithm. How ever both studies are giving over estimate chlorophyll-a concentration. Since thereare no standard MODIS products available for suspended matter and CDOM, the result of the retrieval by theNN for these two variables could only be assessed by a general knowledge of their concentrations anddistribution patterns
Arahman, Nasrul; Maimun, Teuku; Mukramah, Syawaliah
2017-01-01
The composition of polymer solution and the methods of membrane preparation determine the solidification process of membrane. The formation of membrane structure prepared via non-solvent induced phase separation (NIPS) method is mostly determined by phase separation process between polymer, solvent, and non-solvent. This paper discusses the phase separation process of polymer solution containing Polyethersulfone (PES), N-methylpirrolidone (NMP), and surfactant Tetronic 1307 (Tet). Cloud point experiment is conducted to determine the amount of non-solvent needed on induced phase separation. Amount of water required as a non-solvent decreases by the addition of surfactant Tet. Kinetics of phase separation for such system is studied by the light scattering measurement. With the addition of Tet., the delayed phase separation is observed and the structure growth rate decreases. Moreover, the morphology of fabricated membrane from those polymer systems is analyzed by scanning electron microscopy (SEM). The images of both systems show the formation of finger-like macrovoids through the cross-section.
Inverse Kinematic Analysis Of A Quadruped Robot
Directory of Open Access Journals (Sweden)
Muhammed Arif Sen
2017-09-01
Full Text Available This paper presents an inverse kinematics program of a quadruped robot. The kinematics analysis is main problem in the manipulators and robots. Dynamic and kinematic structures of quadruped robots are very complex compared to industrial and wheeled robots. In this study inverse kinematics solutions for a quadruped robot with 3 degrees of freedom on each leg are presented. Denavit-Hartenberg D-H method are used for the forward kinematic. The inverse kinematic equations obtained by the geometrical and mathematical methods are coded in MATLAB. And thus a program is obtained that calculate the legs joint angles corresponding to desired various orientations of robot and endpoints of legs. Also the program provides the body orientations of robot in graphical form. The angular positions of joints obtained corresponding to desired different orientations of robot and endpoints of legs are given in this study.
Polarimetry as a tool for the study of solutions of chiral solutes.
Orlova, Anna V; Andrade, Renato R; da Silva, Clarissa O; Zinin, Alexander I; Kononov, Leonid O
2014-01-13
Optical rotation of aqueous solutions of D-levoglucosan was studied experimentally in the 0.03-4.0 mol L(-1) concentration range and a nonlinear concentration dependence of specific optical rotation (SR) was revealed. Discontinuities observed in the concentration plot of SR (at 0.1, 0.3, 0.5, 1.0, and 2.0 mol L(-1)) are well correlated with those found by static and dynamic light scattering and identify concentration ranges in which different solution domains (supramers) may exist. The average SR experimental value for a D-levoglucosan aqueous solution ([α]D(28) -58.5±8.7 deg dm(-1) cm(-3) g(-1)) was found to be in good agreement with values obtained by theoretical calculation (TD-DFT/GIAO) of SR for 15 different conformers revealed by conformational sampling at the PCM/B3LYP/6-311++G(2d,2p)//B3LYP/6-31+G(d,p) level, which were shown to be strongly affected by the solvation microenvironment (0, 1, 2, and 3 explicit solvent molecules considered) due to local geometrical changes induced in the solute molecule. This exceptionally high sensitivity of SR makes polarimetry a unique method capable of sensing changes in the structure of supramers detected in this study. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Study of Tip-loss Using an Inverse 3D Navier-Stokes Method
DEFF Research Database (Denmark)
Mikkelsen, Robert; Sørensen, Jens Nørkær; Shen, Wen Zhong
2003-01-01
the 3D Navier-Stokes equations combined with the actuator line technique where blade loading is applied using an inverse method. The numerical simulations shows that the method captures the tip-correction when comparing with the theories of Prandtl and Goldstein, however, the accuracy of the obtained...... results reveal that further refinements still is needed. Keywords: Tip-loss; Actuator line; 3D Navier-Stokes methods....
Application of tomographic inversion in studying airglow in the mesopause region
Directory of Open Access Journals (Sweden)
T. Nygrén
Full Text Available It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with different elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the first inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to find out the limitations of the method.
Key words. Tomography · Airglow · Mesopause · Gravity waves
Studies of Protein Solution Properties Using Osmotic Pressure Measurements
Agena, S.; Bogle, David; Pusey, Marc; Agena, S.
1998-01-01
Examination of the protein crystallization process involves investigation of the liquid and solid state and a protein's properties in these states. Liquid state studies such as protein self association in solution by light scattering methods or other methods have been used to examine a protein Is properties and therefore its crystallization process and conditions. Likewise can osmotic pressure data be used to examine protein properties and various published osmotic pressure studies were examined by us to correlate osmotic pressure to protein solution properties. The solution behavior of serum albumin, alpha - chymotrypsin, beta - lactoglobulin and ovalbumin was examined over a range of temperatures, pH values and different salt types and concentrations. Using virial expansion and a local composition model the non ideal solution behavior in form of the activity coefficients (thermodynamic) was described for the systems. This protein activity coefficient data was related to a protein's solubility behavior and this process and the results will be presented.
Jakob, Andreas; Mazurek, Martin; Heer, Walter
2003-03-01
Based on the results from detailed structural and petrological characterisation and on up-scaled laboratory values for sorption and diffusion, blind predictions were made for the STT1 dipole tracer test performed in the Swedish Äspö Hard Rock Laboratory. The tracers used were nonsorbing, such as uranine and tritiated water, weakly sorbing 22Na +, 85Sr 2+, 47Ca 2+and more strongly sorbing 86Rb +, 133Ba 2+, 137Cs +. Our model consists of two parts: (1) a flow part based on a 2D-streamtube formalism accounting for the natural background flow field and with an underlying homogeneous and isotropic transmissivity field and (2) a transport part in terms of the dual porosity medium approach which is linked to the flow part by the flow porosity. The calibration of the model was done using the data from one single uranine breakthrough (PDT3). The study clearly showed that matrix diffusion into a highly porous material, fault gouge, had to be included in our model evidenced by the characteristic shape of the breakthrough curve and in line with geological observations. After the disclosure of the measurements, it turned out that, in spite of the simplicity of our model, the prediction for the nonsorbing and weakly sorbing tracers was fairly good. The blind prediction for the more strongly sorbing tracers was in general less accurate. The reason for the good predictions is deemed to be the result of the choice of a model structure strongly based on geological observation. The breakthrough curves were inversely modelled to determine in situ values for the transport parameters and to draw consequences on the model structure applied. For good fits, only one additional fracture family in contact with cataclasite had to be taken into account, but no new transport mechanisms had to be invoked. The in situ values for the effective diffusion coefficient for fault gouge are a factor of 2-15 larger than the laboratory data. For cataclasite, both data sets have values comparable to
Inverse kinematics problem in robotics using neural networks
Choi, Benjamin B.; Lawrence, Charles
1992-01-01
In this paper, Multilayer Feedforward Networks are applied to the robot inverse kinematic problem. The networks are trained with endeffector position and joint angles. After training, performance is measured by having the network generate joint angles for arbitrary endeffector trajectories. A 3-degree-of-freedom (DOF) spatial manipulator is used for the study. It is found that neural networks provide a simple and effective way to both model the manipulator inverse kinematics and circumvent the problems associated with algorithmic solution methods.
Czech Academy of Sciences Publication Activity Database
Fojtíková, Lucia; Zahradník, J.
2014-01-01
Roč. 85, č. 6 (2014), s. 1265-1274 ISSN 0895-0695 R&D Projects: GA ČR GAP210/12/2336 Institutional support: RVO:67985891 Keywords : weak events * sparse networks * focal mechanism * waveform inversion Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.156, year: 2014 http://srl.geoscienceworld.org/content/85/6/1265.full
Directory of Open Access Journals (Sweden)
Joel Sereno
2010-01-01
Full Text Available Inverse kinematics is the process of converting a Cartesian point in space into a set of joint angles to more efficiently move the end effector of a robot to a desired orientation. This project investigates the inverse kinematics of a robotic hand with fingers under various scenarios. Assuming the parameters of a provided robot, a general equation for the end effector point was calculated and used to plot the region of space that it can reach. Further, the benefits obtained from the addition of a prismatic joint versus an extra variable angle joint were considered. The results confirmed that having more movable parts, such as prismatic points and changing angles, increases the effective reach of a robotic hand.
Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study
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A. M. Michalak
2010-07-01
Full Text Available A series of synthetic data experiments is performed to investigate the ability of a regional atmospheric inversion to estimate grid-scale CO2 fluxes during the growing season over North America. The inversions are performed within a geostatistical framework without the use of any prior flux estimates or auxiliary variables, in order to focus on the atmospheric constraint provided by the nine towers collecting continuous, calibrated CO2 measurements in 2004. Using synthetic measurements and their associated concentration footprints, flux and model-data mismatch covariance parameters are first optimized, and then fluxes and their uncertainties are estimated at three different temporal resolutions. These temporal resolutions, which include a four-day average, a four-day-average diurnal cycle with 3-hourly increments, and 3-hourly fluxes, are chosen to help assess the impact of temporal aggregation errors on the estimated fluxes and covariance parameters. Estimating fluxes at a temporal resolution that can adjust the diurnal variability is found to be critical both for recovering covariance parameters directly from the atmospheric data, and for inferring accurate ecoregion-scale fluxes. Accounting for both spatial and temporal a priori covariance in the flux distribution is also found to be necessary for recovering accurate a posteriori uncertainty bounds on the estimated fluxes. Overall, the results suggest that even a fairly sparse network of 9 towers collecting continuous CO2 measurements across the continent, used with no auxiliary information or prior estimates of the flux distribution in time or space, can be used to infer relatively accurate monthly ecoregion scale CO2 surface fluxes over North America within estimated uncertainty bounds. Simulated random transport error is shown to decrease the quality of flux estimates in under-constrained areas at the ecoregion scale, although the uncertainty bounds remain realistic. While these synthetic
BOOK REVIEW: Inverse Problems. Activities for Undergraduates
Yamamoto, Masahiro
2003-06-01
into the nature of inverse problems and the appropriate mode of thought, chapter 1 offers historical vignettes, most of which have played an essential role in the development of natural science. These vignettes cover the first successful application of `non-destructive testing' by Archimedes (page 4) via Newton's laws of motion up to literary tomography, and readers will be able to enjoy a wide overview of inverse problems. Therefore, as the author asks, the reader should not skip this chapter. This may not be hard to do, since the headings of the sections are quite intriguing (`Archimedes' Bath', `Another World', `Got the Time?', `Head Games', etc). The author embarks on the technical approach to inverse problems in chapter 2. He has elegantly designed each section with a guide specifying course level, objective, mathematical and scientifical background and appropriate technology (e.g. types of calculators required). The guides are designed such that teachers may be able to construct effective and attractive courses by themselves. The book is not intended to offer one rigidly determined course, but should be used flexibly and independently according to the situation. Moreover, every section closes with activities which can be chosen according to the students' interests and levels of ability. Some of these exercises do not have ready solutions, but require long-term study, so readers are not required to solve all of them. After chapter 5, which contains discrete inverse problems such as the algebraic reconstruction technique and the Backus - Gilbert method, there are answers and commentaries to the activities. Finally, scripts in MATLAB are attached, although they can also be downloaded from the author's web page (http://math.uc.edu/~groetsch/). This book is aimed at students but it will be very valuable to researchers wishing to retain a wide overview of inverse problems in the midst of busy research activities. A Japanese version was published in 2002.
International Nuclear Information System (INIS)
Desesquelles, P.
1997-01-01
Computer Monte Carlo simulations occupy an increasingly important place between theory and experiment. This paper introduces a global protocol for the comparison of model simulations with experimental results. The correlated distributions of the model parameters are determined using an original recursive inversion procedure. Multivariate analysis techniques are used in order to optimally synthesize the experimental information with a minimum number of variables. This protocol is relevant in all fields if physics dealing with event generators and multi-parametric experiments. (authors)
Introduction to Schroedinger inverse scattering
International Nuclear Information System (INIS)
Roberts, T.M.
1991-01-01
Schroedinger inverse scattering uses scattering coefficients and bound state data to compute underlying potentials. Inverse scattering has been studied extensively for isolated potentials q(x), which tend to zero as vertical strokexvertical stroke→∞. Inverse scattering for isolated impurities in backgrounds p(x) that are periodic, are Heaviside steps, are constant for x>0 and periodic for x<0, or that tend to zero as x→∞ and tend to ∞ as x→-∞, have also been studied. This paper identifies literature for the five inverse problems just mentioned, and for four other inverse problems. Heaviside-step backgrounds are discussed at length. (orig.)
A study of densitometry comparison among three radiographic processing solutions
International Nuclear Information System (INIS)
Changizi, V.; Jazayeri, E.; Talaeepour, A.
2006-01-01
The radiographic image accuracy depends on the X-ray film information visibility. Good visibility is found by good contrast. Radiation exposure parameters (kVp, mAs) and film processing conditions have impact on contrast. In dentistry radiography machines, exposure time and processing procedure are set by radiographer. No optimized exposure time and processing conditions may lead to incorrect diagnosis and re-exposure of the patient. Therefore, we studied the performance of the three different available processing solutions with dental X-ray film. Materials and Methods: Dental intraoral E-speed films, size 2 (Kodak company, USA) were used in this study. These films were developed in a manual processor using three different brands of processing solution: 1) Taifsaz (Iran), 2) Darutasvir (Iran) and 3) Agfa (Germany) for temperatures of 25 d ig C , 28 d ig C and 30 d ig C at the three different exposure times, 0.2 s, 0.25 s and 0.35 s. Performance was evaluated with respect to base plus fog, relative contrast and relative speed. Results: Darutasvir processing solution as the cheapest one showed higher base plus fog density at 25 d ig C and 30 d ig C than that of Taifsaz and Agfa solutions. Also, Darutasvir solution was found to have better relative contrast than that of the others, except for 30 d ig C at 0.25 s. Relative speed was higher in Darutsavir solution than Agfa for 25 d ig C at three exposure times used in this study, for 28 d ig C at 0.2 s and for 30 d ig C at 0.35 s. Taifsaz Processing solution was in the second order with respect to tested conditions. Conclusion: Comparison among available X-ray film processing solutions for different temperatures at different exposure times can help to maintain image quality while patient exposure and film cost are kept considerably low
Pulse radiolysis studies of iron(I) in aqueous solutions
International Nuclear Information System (INIS)
Nenadovic, M.T.; Micic, O.I.; Muk, A.A.
1980-01-01
The absorption spectrum and decay kinetics of the products of the reactions of iron(II) ions with hydrated electrons and hydrogen atoms have been studied in aqueous solution using pulse-radiolysis techniques. Iron(I) is formed by reaction with hydrated electrons and its absorption spectrum is reported and discussed. The formation of molecular hydrogen by reaction of Fe + with water is suppressed by other solutes present in the solutions. In acidic solutions containing [SO 4 ] 2- , the intermediates formed in the reaction with H atoms decay by a first-order process and produce molecular hydrogen, but the rate of their decay does not depend only on the oxonium ion concentration but also on intermolecular rearrangement in the [FeSO 4 -H] complex. (author)
Study on Product Innovative Design Process Driven by Ideal Solution
Zhang, Fuying; Lu, Ximei; Wang, Ping; Liu, Hui
Product innovative design in companies today relies heavily on individual members’ experience and creative ideation as well as their skills of integrating creativity and innovation tools with design methods agilely. Creative ideation and inventive ideas generation are two crucial stages in product innovative design process. Ideal solution is the desire final ideas for given problem, and the striving reaching target for product design. In this paper, a product innovative design process driven by ideal solution is proposed. This design process encourages designers to overcome their psychological inertia, to foster creativity in a systematic way for acquiring breakthrough creative and innovative solutions in a reducing sphere of solution-seeking, and results in effective product innovative design rapidly. A case study example is also presented to illustrate the effectiveness of the proposed design process.
Crises Solutions for SMEs Case Study: ERP Cloud vs Classic Solution
Directory of Open Access Journals (Sweden)
Gabriela GHEORGHE
2012-11-01
Full Text Available Information Technology has responded to the crisis by change and innovation. The phenomenon of cloud computing represents a huge chance for a country like Romania, as a technologically low economy has, from the start, a handicap. Cloud technologies redefine concepts such as saving time and money, flexibility, scalability and global access, transforming them into business advantages. This case study wishes to argument the software provider’s decision to change his strategy, choosing an “all inclusive” solution.
Direct and inverse source problems for a space fractional advection dispersion equation
Aldoghaither, Abeer
2016-05-15
In this paper, direct and inverse problems for a space fractional advection dispersion equation on a finite domain are studied. The inverse problem consists in determining the source term from final observations. We first derive the analytic solution to the direct problem which we use to prove the uniqueness and the unstability of the inverse source problem using final measurements. Finally, we illustrate the results with a numerical example.
Directory of Open Access Journals (Sweden)
Zhang Yuesheng
2010-04-01
Full Text Available Abstract Background Inverse associations between cruciferous vegetable intake and lung cancer risk have been consistently reported. However, associations within smoking status subgroups have not been consistently addressed. Methods We conducted a hospital-based case-control study with lung cancer cases and controls matched on smoking status, and further adjusted for smoking status, duration, and intensity in the multivariate models. A total of 948 cases and 1743 controls were included in the analysis. Results Inverse linear trends were observed between intake of fruits, total vegetables, and cruciferous vegetables and risk of lung cancer (ORs ranged from 0.53-0.70, with P for trend Conclusions Our findings are consistent with the smoking-related carcinogen-modulating effect of isothiocyanates, a group of phytochemicals uniquely present in cruciferous vegetables. Our data support consumption of a diet rich in cruciferous vegetables may reduce the risk of lung cancer among smokers.
Yavari, Fatemeh; Mahdavi, Shirin; Towhidkhah, Farzad; Ahmadi-Pajouh, Mohammad-Ali; Ekhtiari, Hamed; Darainy, Mohammad
2016-04-01
Despite several pieces of evidence, which suggest that the human brain employs internal models for motor control and learning, the location of these models in the brain is not yet clear. In this study, we used transcranial direct current stimulation (tDCS) to manipulate right cerebellar function, while subjects adapt to a visuomotor task. We investigated the effect of this manipulation on the internal forward and inverse models by measuring two kinds of behavior: generalization of training in one direction to neighboring directions (as a proxy for inverse models) and localization of the hand position after movement without visual feedback (as a proxy for forward model). The experimental results showed no effect of cerebellar tDCS on generalization, but significant effect on localization. These observations support the idea that the cerebellum is a possible brain region for internal forward, but not inverse model formation. We also used a realistic human head model to calculate current density distribution in the brain. The result of this model confirmed the passage of current through the cerebellum. Moreover, to further explain some observed experimental results, we modeled the visuomotor adaptation process with the help of a biologically inspired method known as population coding. The effect of tDCS was also incorporated in the model. The results of this modeling study closely match our experimental data and provide further evidence in line with the idea that tDCS manipulates FM's function in the cerebellum.
Evaluation of an artificial intelligence guided inverse planning system: Clinical case study
International Nuclear Information System (INIS)
Yan Hui; Yin Fangfang; Willett, Christopher
2007-01-01
Purpose: An artificial intelligence (AI) guided method for parameter adjustment of inverse planning was implemented on a commercial inverse treatment planning system. For evaluation purpose, four typical clinical cases were tested and the results from both plans achieved by automated and manual methods were compared. Methods and materials: The procedure of parameter adjustment mainly consists of three major loops. Each loop is in charge of modifying parameters of one category, which is carried out by a specially customized fuzzy inference system. A physician prescribed multiple constraints for a selected volume were adopted to account for the tradeoff between prescription dose to the PTV and dose-volume constraints for critical organs. The searching process for an optimal parameter combination began with the first constraint, and proceeds to the next until a plan with acceptable dose was achieved. The initial setup of the plan parameters was the same for each case and was adjusted independently by both manual and automated methods. After the parameters of one category were updated, the intensity maps of all fields were re-optimized and the plan dose was subsequently re-calculated. When final plan arrived, the dose statistics were calculated from both plans and compared. Results: For planned target volume (PTV), the dose for 95% volume is up to 10% higher in plans using the automated method than those using the manual method. For critical organs, an average decrease of the plan dose was achieved. However, the automated method cannot improve the plan dose for some critical organs due to limitations of the inference rules currently employed. For normal tissue, there was no significant difference between plan doses achieved by either automated or manual method. Conclusion: With the application of AI-guided method, the basic parameter adjustment task can be accomplished automatically and a comparable plan dose was achieved in comparison with that achieved by the manual
Evaluation of an artificial intelligence guided inverse planning system: clinical case study.
Yan, Hui; Yin, Fang-Fang; Willett, Christopher
2007-04-01
An artificial intelligence (AI) guided method for parameter adjustment of inverse planning was implemented on a commercial inverse treatment planning system. For evaluation purpose, four typical clinical cases were tested and the results from both plans achieved by automated and manual methods were compared. The procedure of parameter adjustment mainly consists of three major loops. Each loop is in charge of modifying parameters of one category, which is carried out by a specially customized fuzzy inference system. A physician prescribed multiple constraints for a selected volume were adopted to account for the tradeoff between prescription dose to the PTV and dose-volume constraints for critical organs. The searching process for an optimal parameter combination began with the first constraint, and proceeds to the next until a plan with acceptable dose was achieved. The initial setup of the plan parameters was the same for each case and was adjusted independently by both manual and automated methods. After the parameters of one category were updated, the intensity maps of all fields were re-optimized and the plan dose was subsequently re-calculated. When final plan arrived, the dose statistics were calculated from both plans and compared. For planned target volume (PTV), the dose for 95% volume is up to 10% higher in plans using the automated method than those using the manual method. For critical organs, an average decrease of the plan dose was achieved. However, the automated method cannot improve the plan dose for some critical organs due to limitations of the inference rules currently employed. For normal tissue, there was no significant difference between plan doses achieved by either automated or manual method. With the application of AI-guided method, the basic parameter adjustment task can be accomplished automatically and a comparable plan dose was achieved in comparison with that achieved by the manual method. Future improvements to incorporate case
Preliminary study on lithium-salt aqueous solution blanket
International Nuclear Information System (INIS)
Yoshida, Hiroshi; Naruse, Yuji; Yamaoka, Mitsuaki; Ohara, Atsushi; Ono, Kiyoshi; Kobayashi, Shigetada.
1992-06-01
Aqueous solution blanket using lithium salts such as LiNO 3 and LiOH have been studied in the US-TIBER program and ITER conceptual design activity. In the JAERI/LANL collaboration program for the joint operation of TSTA (Tritium Systems Test Assembly), preliminary design work of blanket tritium system for lithium ceramic blanket, aqueous solution blanket and liquid metal blanket, have been performed to investigate technical feasibility of tritium demonstration tests using the TSTA. Detail study of the aqueous solution blanket concept have not been performed in the Japanese fusion program, so that this study was carried out to investigate features of its concept and to evaluated its technical problems. The following are the major items studied in the present work: (i) Neutronics of tritium breeding ratio and shielding performance Lithium concentration, Li-60 enrichment, beryllium or lead, composition of structural material/beryllium/solution, heavy water, different lithium-salts (ii) Physicochemical properties of salts Solubility, corrosion characteristics and compatibility with structural materials, radiolysis (iii) Estimation of radiolysis in ITER aqueous solution blanket. (author)
Study of the 6Li + p → 3He + 4He reaction in inverse kinematics
International Nuclear Information System (INIS)
Betsou, C.; Pakou, A.; Aslanoglou, X.; Nicolis, N.G.; Sgouros, O.; Soukeras, V.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernandez-Garcia, J.P.; Figuera, P.; Fisichella, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Strano, E.; Torresi, D.; Pierroutsakou, D.; Rusek, K.; Stiliaris, E.
2015-01-01
Angular distribution measurements were performed for the 6 Li + p → 3 He + 4 He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8 MeV/u. The detection of both recoils ( 3 He and 4 He) over the laboratory angle range θ lab = 16 circle to 34 circle allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame (θ c.m. ∝ 40 circle to 140 circle ). The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations. (orig.)
Optimization for nonlinear inverse problem
International Nuclear Information System (INIS)
Boyadzhiev, G.; Brandmayr, E.; Pinat, T.; Panza, G.F.
2007-06-01
The nonlinear inversion of geophysical data in general does not yield a unique solution, but a single model, representing the investigated field, is preferred for an easy geological interpretation of the observations. The analyzed region is constituted by a number of sub-regions where the multi-valued nonlinear inversion is applied, which leads to a multi-valued solution. Therefore, combining the values of the solution in each sub-region, many acceptable models are obtained for the entire region and this complicates the geological interpretation of geophysical investigations. In this paper are presented new methodologies, capable to select one model, among all acceptable ones, that satisfies different criteria of smoothness in the explored space of solutions. In this work we focus on the non-linear inversion of surface waves dispersion curves, which gives structural models of shear-wave velocity versus depth, but the basic concepts have a general validity. (author)
Biological and analytical studies of peritoneal dialysis solutions
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N. Hudz
2018-04-01
Full Text Available The purpose of our work was to conduct biological and analytical studies of the peritoneal dialysis (PD solutions containing glucose and sodium lactate and establish correlations between cell viability of the Vero cell line and values of analytical indexes of the tested solutions. The results of this study confirm the cytotoxicity of the PD solutions even compared with the isotonic solution of sodium chloride, which may be due to the low pH of the solutions, presence of glucose degradation products (GDPs and high osmolarity of the solutions, and unphysiological concentrations of glucose and sodium lactate. However, it is not yet known what factors or their combination and to what extent cause the cytotoxicity of PD solutions. In the neutral red (NR test the weak, almost middle (r = -0.496 and 0.498, respectively and unexpected correlations were found between reduced viability of monkey kidney cells and increased pH of the PD solutions and between increased cell viability and increased absorbance at 228 nm of the tested PD solutions. These two correlations can be explained by a strong correlation (r = -0.948 between a decrease in pH and an increase in the solution absorbance at 228 nm. The opposite effect was observed in the MTT test. The weak, but expected correlations (r = 0.32 and -0.202, respectively were found between increased cell viability and increased pH in the PD solutions and between decreased cell viability and increased absorbance at 228 nm of the tested PD solutions. The middle and weak correlations (r = 0.56 and 0.29, respectively were detected between increased cell viability and increased lactate concentration in the NR test and MTT test. The data of these correlations can be partially explained by the fact that a correlation with a coefficient r = -0.34 was found between decreased pH in the solutions and increased lactate concentration. The very weak correlations (0.138 and 0.196, respectively were found between increased cell
Study of free acidity determinations in aqueous solution
International Nuclear Information System (INIS)
Kergreis, A.
1966-04-01
The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author) [fr
An experimental study on gold precipitation from leach solutions of ...
African Journals Online (AJOL)
This paper presents the results of the study dedicated to the determination of the optimum parameters for the electrolytic gold precipitation from thiourea leach solutions. The leaching was carried out using technogenic gold-bearing raw materials (gold-bearing sands) of the Far East of the Russian Federation. The study ...
Equilibrium Sorption Studies of Hg (II) Ions from Aqueous Solution ...
African Journals Online (AJOL)
The potential of swamp arum (Lasimorpha senegalensis) seeds as a low-cost adsorbent for the removal of Hg (II) ions from aqueous solution was investigated in this study. The influence of initial metal concentration on the percent adsorption of Hg (II) ions onto powdered swamp arum seeds was studied in a batch system ...
Rb-intercalated C60 compounds studied by Inverse Photoemission Spectroscopy
International Nuclear Information System (INIS)
Finazzi, M.; Brambilla, A; Biagioni, P.; Cattoni, A.; Duo, L.; Ciccacci, F.; Braicovich, L.; Giovanelli, L.; Goldoni, A.
2004-01-01
Full text: Since the discovery of superconductivity in alkali-doped solid C 60 , the electronic structure of the host material (C 60 ) and the doped compounds (A x C 60 , where A is an alkali metal), has been the subject of a considerable amount of work, both theoretical and experimental. The spectroscopic investigations of the alkali-doped C 60 compounds has been mainly focussed on the valence states, while much less information is available on the unoccupied states. In particular, inverse photoemission data on the complete set of stable Rb x C 60 compounds was, so far, still missing. We have performed Inverse Photoemission (IPE) spectroscopy on Rb x C 60 compounds (x = 1, 3, 4, 6). IPE spectra were obtained using a band-pass photon detector (hv = 9.4 eV, FWHM = 0.7 eV) and scanning the kinetic energy of the electrons impinging on the sample. Rb was evaporated on C 60 films (thickness = 6-12 atomic layers) grown in situ on a Cu(100) substrate. The temperature of the substrate was kept equal to T = 100 deg C, which is lower than the C 60 sublimation temperature. The amount of Rb was checked by measuring the intensity of the C1s and Rb3d photoemission lines. After the required amount of Rb had been deposited, the samples were annealed to distillate the desired stable phase
Model study of the compact gravity reconstruction; Juryoku inversion `CGR` no model kento
Energy Technology Data Exchange (ETDEWEB)
Ishii, Y; Muraoka, A [Sogo Geophysical Exploration Co. Ltd., Tokyo (Japan)
1996-05-01
An examination was made on gravity inversion using a compact gravity reconstruction (CGR) method in gravity tomography analysis. In a model analysis, an analytical region of 100m{times}50m was divided into cells of 10m{times}10m, on the assumption that two density anomalous bodies with a density difference of 1.0g/cm{sup 3} existed with one shallow and the other deep density distribution. The result of the analysis revealed that, in a linear analysis by a general inverse matrix, blurs and blotting were plenty with a tendency of making gravity anomaly attributable to an anomalous distribution of shallow density; that CGR provided a large effect in making a clear contrast of an anomalous part; that, where structures of shallow and deep density anomalies existed, the analysis by CGR was inferior in the restoration of a deep structure with errors enlarged; that, if a gravity traverse was taken long compared with the distribution depth of density anomalies, the analytical precision of a deep part was improved; that an analytical convergence was better with the restriction of density difference given on the large side than on the small side; and so on. 3 refs., 10 figs.
An analytic study of the magnetohydrodynamic stability of inverse shear profiles
International Nuclear Information System (INIS)
Gimblett, C.G.; Hastie, R.J.; Hender, T.C.
1996-01-01
This paper reports on the ideal magnetohydrodynamic (MHD) stability of tokamak field profiles that have a non-monotonic safety factor q(r). An analytic criterion is obtained for these open-quote open-quote inverse shear close-quote close-quote profiles by expanding in inverse aspect ratio and assuming that the minimum in q is slightly less than the m/n value of the mode under examination (m and n being the principal poloidal and toroidal mode numbers of the instability). Three terms are identified as controlling the stability of this open-quote open-quote double kink close-quote close-quote; two of them are stabilizing and due, respectively, to field line bending and the interaction of average favorable curvature with the pressure gradient. The possibility of instability comes from the third term which is due to toroidal coupling and is ballooning in character. The analytic results are compared with those from a fully toroidal stability code
International Nuclear Information System (INIS)
Musleh, Rola M.; Helu, Amal
2014-01-01
In this article we consider statistical inferences about the unknown parameters of the Inverse Weibull distribution based on progressively type-II censoring using classical and Bayesian procedures. For classical procedures we propose using the maximum likelihood; the least squares methods and the approximate maximum likelihood estimators. The Bayes estimators are obtained based on both the symmetric and asymmetric (Linex, General Entropy and Precautionary) loss functions. There are no explicit forms for the Bayes estimators, therefore, we propose Lindley's approximation method to compute the Bayes estimators. A comparison between these estimators is provided by using extensive simulation and three criteria, namely, Bias, mean squared error and Pitman nearness (PN) probability. It is concluded that the approximate Bayes estimators outperform the classical estimators most of the time. Real life data example is provided to illustrate our proposed estimators. - Highlights: • We consider progressively type-II censored data from the Inverse Weibull distribution (IW). • We derive MLEs, approximate MLEs, LS and Bayes estimate methods of scale and shape parameters of the IW. • Bayes estimator of shape parameter cannot be expressed in closed forms. • We suggest using Lindley's approximation. • We conclude that the Bayes estimates outperform the classical methods
Jiang, Hua; Lu, Wenke; Zhang, Guoan
2013-07-01
In this paper, we propose a low insertion loss and miniaturization wavelet transform and inverse transform processor using surface acoustic wave (SAW) devices. The new SAW wavelet transform devices (WTDs) use the structure with two electrode-widths-controlled (EWC) single phase unidirectional transducers (SPUDT-SPUDT). This structure consists of the input withdrawal weighting interdigital transducer (IDT) and the output overlap weighting IDT. Three experimental devices for different scales 2(-1), 2(-2), and 2(-3) are designed and measured. The minimum insertion loss of the three devices reaches 5.49dB, 4.81dB, and 5.38dB respectively which are lower than the early results. Both the electrode width and the number of electrode pairs are reduced, thus making the three devices much smaller than the early devices. Therefore, the method described in this paper is suitable for implementing an arbitrary multi-scale low insertion loss and miniaturization wavelet transform and inverse transform processor using SAW devices. Copyright © 2013 Elsevier B.V. All rights reserved.
Limitations of Dower's inverse transform for the study of atrial loops during atrial fibrillation.
Guillem, María S; Climent, Andreu M; Bollmann, Andreas; Husser, Daniela; Millet, José; Castells, Francisco
2009-08-01
Spatial characteristics of atrial fibrillatory waves have been extracted by using a vectorcardiogram (VCG) during atrial fibrillation (AF). However, the VCG is usually not recorded in clinical practice and atrial loops are derived from the 12-lead electrocardiogram (ECG). We evaluated the suitability of the reconstruction of orthogonal leads from the 12-lead ECG for fibrillatory waves in AF. We used the Physikalisch-Technische Bundesanstalt diagnostic ECG database, which contains 15 simultaneously recorded signals (12-lead ECG and three Frank orthogonal leads) of 13 patients during AF. Frank leads were derived from the 12-lead ECG by using Dower's inverse transform. Derived leads were then compared to true Frank leads in terms of the relative error achieved. We calculated the orientation of AF loops of both recorded orthogonal leads and derived leads and measured the difference in estimated orientation. Also, we investigated the relationship of errors in derivation with fibrillatory wave amplitude, frequency, wave residuum, and fit to a plane of the AF loops. Errors in derivation of AF loops were 68 +/- 31% and errors in the estimation of orientation were 35.85 +/- 20.43 degrees . We did not find any correlation among these errors and amplitude, frequency, or other parameters. In conclusion, Dower's inverse transform should not be used for the derivation of orthogonal leads from the 12-lead ECG for the analysis of fibrillatory wave loops in AF. Spatial parameters obtained after this derivation may differ from those obtained from recorded orthogonal leads.
Bayesian seismic AVO inversion
Energy Technology Data Exchange (ETDEWEB)
Buland, Arild
2002-07-01
A new linearized AVO inversion technique is developed in a Bayesian framework. The objective is to obtain posterior distributions for P-wave velocity, S-wave velocity and density. Distributions for other elastic parameters can also be assessed, for example acoustic impedance, shear impedance and P-wave to S-wave velocity ratio. The inversion algorithm is based on the convolutional model and a linearized weak contrast approximation of the Zoeppritz equation. The solution is represented by a Gaussian posterior distribution with explicit expressions for the posterior expectation and covariance, hence exact prediction intervals for the inverted parameters can be computed under the specified model. The explicit analytical form of the posterior distribution provides a computationally fast inversion method. Tests on synthetic data show that all inverted parameters were almost perfectly retrieved when the noise approached zero. With realistic noise levels, acoustic impedance was the best determined parameter, while the inversion provided practically no information about the density. The inversion algorithm has also been tested on a real 3-D dataset from the Sleipner Field. The results show good agreement with well logs but the uncertainty is high. The stochastic model includes uncertainties of both the elastic parameters, the wavelet and the seismic and well log data. The posterior distribution is explored by Markov chain Monte Carlo simulation using the Gibbs sampler algorithm. The inversion algorithm has been tested on a seismic line from the Heidrun Field with two wells located on the line. The uncertainty of the estimated wavelet is low. In the Heidrun examples the effect of including uncertainty of the wavelet and the noise level was marginal with respect to the AVO inversion results. We have developed a 3-D linearized AVO inversion method with spatially coupled model parameters where the objective is to obtain posterior distributions for P-wave velocity, S
An inverse problem in a parabolic equation
Directory of Open Access Journals (Sweden)
Zhilin Li
1998-11-01
Full Text Available In this paper, an inverse problem in a parabolic equation is studied. An unknown function in the equation is related to two integral equations in terms of heat kernel. One of the integral equations is well-posed while another is ill-posed. A regularization approach for constructing an approximate solution to the ill-posed integral equation is proposed. Theoretical analysis and numerical experiment are provided to support the method.
Energy Technology Data Exchange (ETDEWEB)
Uesaka, S [Kyoto University, Kyoto (Japan). Faculty of Engineering; Watanabe, T; Sassa, K [Kyoto University, Kyoto (Japan)
1997-05-27
Algorithm is constructed and a program developed for a full-wave inversion (FWI) method utilizing the elastic wave equation in seismic exploration. The FWI method is a method for obtaining a physical property distribution using the whole observed waveforms as the data. It is capable of high resolution which is several times smaller than the wavelength since it can handle such phenomena as wave reflection and dispersion. The method for determining the P-wave velocity structure by use of the acoustic wave equation does not provide information about the S-wave velocity since it does not consider S-waves or converted waves. In an analysis using the elastic wave equation, on the other hand, not only P-wave data but also S-wave data can be utilized. In this report, under such circumstances, an inverse analysis algorithm is constructed on the basis of the elastic wave equation, and a basic program is developed. On the basis of the methods of Mora and of Luo and Schuster, the correction factors for P-wave and S-wave velocities are formulated directly from the elastic wave equation. Computations are performed and the effects of the hypocenter frequency and vibration transmission direction are examined. 6 refs., 8 figs.
Szabó, Norbert Péter
2018-03-01
An evolutionary inversion approach is suggested for the interpretation of nuclear and resistivity logs measured by direct-push tools in shallow unsaturated sediments. The efficiency of formation evaluation is improved by estimating simultaneously (1) the petrophysical properties that vary rapidly along a drill hole with depth and (2) the zone parameters that can be treated as constant, in one inversion procedure. In the workflow, the fractional volumes of water, air, matrix and clay are estimated in adjacent depths by linearized inversion, whereas the clay and matrix properties are updated using a float-encoded genetic meta-algorithm. The proposed inversion method provides an objective estimate of the zone parameters that appear in the tool response equations applied to solve the forward problem, which can significantly increase the reliability of the petrophysical model as opposed to setting these parameters arbitrarily. The global optimization meta-algorithm not only assures the best fit between the measured and calculated data but also gives a reliable solution, practically independent of the initial model, as laboratory data are unnecessary in the inversion procedure. The feasibility test uses engineering geophysical sounding logs observed in an unsaturated loessy-sandy formation in Hungary. The multi-borehole extension of the inversion technique is developed to determine the petrophysical properties and their estimation errors along a profile of drill holes. The genetic meta-algorithmic inversion method is recommended for hydrogeophysical logging applications of various kinds to automatically extract the volumetric ratios of rock and fluid constituents as well as the most important zone parameters in a reliable inversion procedure.
Thermal measurements and inverse techniques
Orlande, Helcio RB; Maillet, Denis; Cotta, Renato M
2011-01-01
With its uncommon presentation of instructional material regarding mathematical modeling, measurements, and solution of inverse problems, Thermal Measurements and Inverse Techniques is a one-stop reference for those dealing with various aspects of heat transfer. Progress in mathematical modeling of complex industrial and environmental systems has enabled numerical simulations of most physical phenomena. In addition, recent advances in thermal instrumentation and heat transfer modeling have improved experimental procedures and indirect measurements for heat transfer research of both natural phe
Measurements of transuranium trace amounts in solution. Bibliographic study
International Nuclear Information System (INIS)
Billon, A.; Gaudez, M.T.
1986-01-01
A critical study based on the data of the literature published up to 1984 has been carried out on the measurements of transuranian traces in solution. The general technical aspects of the dosage of transuranian traces in solution and of their speciations were initially reviewed. The second part is devoted to the detailed review of various methods in use in the laboratories. This work has been carried out in the framework of the MIRAGE (migration of radionuclides in the biosphere) Community project. 85 refs
Physicochemical studies on ion-pair amphiphiles: Solution and ...
Indian Academy of Sciences (India)
Administrator
Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700 032. 2 ... ing systems, drug delivery, nanoparticle synthesis, ... to study the phase behaviours and the interfacial ..... Sections: A, coacervate formation (0⋅10–0⋅19 mol dm ... marked zone – clear solution with precipitate; cross marked.
A study of liposome formation using a solution (isoperibol) calorimeter.
Barriocanal, L; Taylor, K M G; Buckton, G
2004-12-09
A solution (isoperibol) calorimeter has been employed to study the process of formation of phospholipid vesicles from natural and synthetic phospholipid films. Phospholipid films were hydrated in the solution calorimeter at temperatures exceeding the main phospholipid phase transition temperature, with continuous agitation to ensure conversion of the hydrating bilayers into multilamellar liposomes. It was seen that retention of chloroform in phospholipid films altered the apparent enthalpy change of vesicle formation to a far greater extent than would be expected from the contribution of the enthalpy of solution of chloroform; this indicates that chloroform alters the hydration process of the lipid. The overall measured enthalpy change for the formation of egg phosphatidylcholine vesicles was exothermic, whilst that for dimyristoylphosphatidylcholine was endothermic. This difference, it is suggested, results from the influence of the hydrocarbon chains mostly on the hydration process and also on the process of vesicle formation.
Rb-intercalated C{sub 60} compounds studied by Inverse Photoemission Spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Finazzi, M; Brambilla, A; Biagioni, P; Cattoni, A; Duo, L; Ciccacci, F; Braicovich, L [INFM and Dip di Fisica del Politecnico di Milano, Milano (Italy); Giovanelli, L; Goldoni, A [ELETTRA Basovizza (Italy)
2004-07-01
Full text: Since the discovery of superconductivity in alkali-doped solid C{sub 60}, the electronic structure of the host material (C{sub 60}) and the doped compounds (A{sub x}C{sub 60}, where A is an alkali metal), has been the subject of a considerable amount of work, both theoretical and experimental. The spectroscopic investigations of the alkali-doped C{sub 60} compounds has been mainly focussed on the valence states, while much less information is available on the unoccupied states. In particular, inverse photoemission data on the complete set of stable Rb{sub x}C{sub 60} compounds was, so far, still missing. We have performed Inverse Photoemission (IPE) spectroscopy on Rb{sub x}C{sub 60} compounds (x = 1, 3, 4, 6). IPE spectra were obtained using a band-pass photon detector (hv = 9.4 eV, FWHM = 0.7 eV) and scanning the kinetic energy of the electrons impinging on the sample. Rb was evaporated on C{sub 60} films (thickness = 6-12 atomic layers) grown in situ on a Cu(100) substrate. The temperature of the substrate was kept equal to T = 100 deg C, which is lower than the C{sub 60} sublimation temperature. The amount of Rb was checked by measuring the intensity of the C1s and Rb3d photoemission lines. After the required amount of Rb had been deposited, the samples were annealed to distillate the desired stable phase.
Fast downscaled inverses for images compressed with M-channel lapped transforms.
de Queiroz, R L; Eschbach, R
1997-01-01
Compressed images may be decompressed and displayed or printed using different devices at different resolutions. Full decompression and rescaling in space domain is a very expensive method. We studied downscaled inverses where the image is decompressed partially, and a reduced inverse transform is used to recover the image. In this fashion, fewer transform coefficients are used and the synthesis process is simplified. We studied the design of fast inverses, for a given forward transform. General solutions are presented for M-channel finite impulse response (FIR) filterbanks, of which block and lapped transforms are a subset. Designs of faster inverses are presented for popular block and lapped transforms.
International Nuclear Information System (INIS)
Murgulescu, Sanda; Calusaru, A.
1977-01-01
When a solution containing ferric ions passes on cationic resin in U(IV) form, the substitution of uranium by iron is preceded by oxydation of U(IV) to U(VI). During the contact of U(VI) in solution with U(IV) in resin, an exchange reaction occurs, in which 235 U is slightly concentrated in solution and 238 U in resin phase. Since increase of temperature accelerates the exchange reaction, the apparent thermodynamic values of the exchange reaction were calculated, by taking into account the variation of the apparent equilibrium constant as a function of the reciprocal value of the temperature. The corresponding thermodynamic values in both pure aqueous and water-glycerine solution are: ΔH 0 =6.45 cal.mol -1 and ΔS 0 =21.6x10 -3 cal. 0 K -1 . The use of glycerine containing solutions offers the important advantage to increase the stability versus hydrolysis of the ferric ions even at higher temperature
Kinetic Uptake Studies of Powdered Materials in Solution
Directory of Open Access Journals (Sweden)
Mohamed H. Mohamed
2015-06-01
Full Text Available Challenges exist for the study of time dependent sorption processes for heterogeneous systems, especially in the case of dispersed nanomaterials in solvents or solutions because they are not well suited to conventional batch kinetic experiments. In this study, a comparison of batch versus a one-pot setup in two variable configurations was evaluated for the study of uptake kinetics in heterogeneous (solid/solution systems: (i conventional batch method; (ii one-pot system with dispersed adsorbent in solution with a semi-permeable barrier (filter paper or dialysis tubing for in situ sampling; and (iii one-pot system with an adsorbent confined in a semi-permeable barrier (dialysis tubing or filter paper barrier with ex situ sampling. The sorbent systems evaluated herein include several cyclodextrin-based polyurethane materials with two types of phenolic dyes: p-nitrophenol and phenolphthalein. The one-pot kinetics method with in situ (Method ii or ex situ (Method iii sampling described herein offers significant advantages for the study of heterogeneous sorption kinetics of highly dispersed sorbent materials with particles sizes across a range of dimensions from the micron to nanometer scale. The method described herein will contribute positively to the development of advanced studies for heterogeneous sorption processes where an assessment of the relative uptake properties is required at different experimental conditions. The results of this study will be advantageous for the study of nanomaterials with significant benefits over batch kinetic studies for a wide range of heterogeneous sorption processes.
Directory of Open Access Journals (Sweden)
Curtiss P Schneider
Full Text Available Much work has been performed on understanding the effects of additives on protein thermodynamics and degradation kinetics, in particular addressing the Hofmeister series and other broad empirical phenomena. Little attention, however, has been paid to the effect of additive-additive interactions on proteins. Our group and others have recently shown that such interactions can actually govern protein events, such as aggregation. Here we use dendrimers, which have the advantage that both size and surface chemical groups can be changed and therein studied independently. Dendrimers are a relatively new and broad class of materials which have been demonstrated useful in biological and therapeutic applications, such as drug delivery, perturbing amyloid formation, etc. Guanidinium modified dendrimers pose an interesting case given that guanidinium can form multiple attractive hydrogen bonds with either a protein surface or other components in solution, such as hydrogen bond accepting counterions. Here we present a study which shows that the behavior of such macromolecule species (modified PAMAM dendrimers is governed by intra-solvent interactions. Attractive guanidinium-anion interactions seem to cause clustering in solution, which inhibits cooperative binding to the protein surface but at the same time, significantly suppresses nonnative aggregation.
Picosecond pulse radiolysis study of primary reactions in solutions
International Nuclear Information System (INIS)
El-Omar, Abdel Karim
2013-01-01
Following the discovery of ionizing radiations and their chemical effects, it was important to study and comprehend the formation mechanisms of short lived free radicals and molecular products. In order to perform such studies, researchers and research groups worked on developing tools allowing both formation and detection of those species at short time scales. Nowadays, pulse radiolysis imposed itself as a fundamental and efficient tool allowing scientists to probe chemical effects as well as reaction mechanisms in studied media. The Laboratoire de Chimie Physique d'Orsay 'LCP' is an interdisciplinary laboratory hosting the platform of fast kinetics known as 'ELYSE'. Due to its femtosecond laser and its picosecond electron accelerator, we have the possibility to study chemical effects of ionizing radiations interaction with media at ultrashort times up to ∼5 ps.Knowing that we are interested in primary reactions induced in aqueous media by ionizing radiations, ELYSE represents the essential tool in performing our studies. The obtained results concern:- First direct determination of hydroxyl radical 'HO*' radiolytic yield as function of time at picosecond time scale;- Direct effect of ionizing radiation in highly concentrated aqueous solutions as well as investigation of the ultrafast electron transfer reaction between solute molecules and positive holes 'H 2 O*+' formed upon water radiolysis;- Study at room temperature of electron transfer reaction between solvated electron (electron donor) and organic solutes (electron acceptors) en viscous medium;- Study at room temperature of electron's solvation dynamics in ethylene glycol and 2-propanol. (author)
Interactions of acidic solutions with sediments: a case study
International Nuclear Information System (INIS)
Peterson, S.R.; Serne, R.J.; Felmy, A.R.; Erikson, R.L.; Krupka, K.M.; Gee, G.W.
1984-01-01
A methodology is presented for investigating the chemical interactions of acidic solutions with sediments. The MINTEQ geochemical computer code was used to predict solid-phase reactions that might occur when acidic solutions contact neutral sediments which, in turn, may control the concentrations of certain dissolved components. Results of X-ray diffraction analysis of laboratory samples of sediments that have been contacted with acidic uranium mill tailings solutions suggest gypsum and jarosite precipitated. These same mineralogical changes were identified in sediment samples collected from a drained uranium mill evaporation pond (Lucky Mc mine in Wyoming) with a 10-year history of acid attack. Geochemical modeling predicted that these same phases and several amorphous solids not identifiable by X-ray diffraction should have precipitated in the contacted sediments. An equilibrium conceptual model consisting of an assemblage of minerals and amorphous solid phases was then developed to represent a sediment column through which uranium mill tailings solutions were percolated. The MINTEQ code was used to predict effluent solution concentrations resulting from the reactions of the tailings solution with the assemblage of solid phases in the conceptual model. The conceptual model successfully predicted the concentrations of several of the macro-constituents (e.g., Ca, SO 4 , Al, Fe, and Mn), but was not successful in modeling the concentrations of trace elements. The lack of success in predicting the observed trace metal concentrations suggests that other mechanisms, such as adsorption, must be included in future models. The geochemical modeling methodology coupled with the laboratory and field studies should be applicable to a variety of waste disposal problems
Study of solute segregation at interfaces using Auger electron spectroscopy
International Nuclear Information System (INIS)
White, C.L.
1984-01-01
Interfacial segregation, often confined to within a few atomic distances of the interface, can strongly influence the processing and properties of metals and ceramics. The thinness of such solute-enriched regions can cause them to be particularly suitable for study using surface sensitive microanalytical techniques such as Auger electron spectroscopy (AES). The application of AES to studies of interfacial segregation in metals and ceramics is briefly reviewed, and several examples are presented. 43 references, 14 figures
Reiter, P; Blazhev, A A; Nardelli, S; Stora, T; Tengborn, E A; Kruecken, R; Voulot, D; Korten, W; Srebrny, J; Clement, E; Lo bianco, G; Sorlin, O H; Habs, D; Fraile prieto, L M; Chapman, R; Nilsson, T; Diriken, J V J; Jenkins, D G; Wady, P T; Kroell, T; Patronis, N; Angus, L J; Iwanicki, J S
We plan to study states in $^{46}$ Ar via the (t,p) two-neutron transfer reaction in inverse kinematics in order to identify and characterize excited states and to gain insights into the onset of deformation and the possible occurrence of shape-coexistence in this region where the N = 28 shell closure may be weakening. The experiment will be performed using accelerated beams from REX-ISOLDE and the T-REX particle detector set-up inside MINIBALL. We request a total of 30 shifts + 3 shifts for beam commissioning.
Directory of Open Access Journals (Sweden)
Deepthi Nagulapally
2015-01-01
Full Text Available The Inverse Piezoelectric Effect (IPE is thought to contribute to possible device failure of GaN High Electron Mobility Transistors (HEMTs. Here we focus on a simulation study to probe the possible mitigation of the IPE by reducing the internal electric fields and related elastic energy through the use of high-k materials. Inclusion of a HfO2 “cap layer” above the AlGaN barrier particularly with a partial mesa structure is shown to have potential advantages. Simulations reveal even greater reductions in the internal electric fields by using “field plates” in concert with high-k oxides.
International Nuclear Information System (INIS)
Maslennikov, A.; Peretroukhine, V.; Masson, M.; Lecomte, M.
1999-01-01
Recovery of technetium from aqueous formate buffer solutions of ionic strength μ = 1.0 was studied in the pH interval from 1.6 to 7.5 at graphite cathode in an electrolytic cell with separated compartments was studied, using cyclic voltammetry (CV) and inverse stripping voltammetry (ISV) techniques. It has been shown that Tc electrodeposition process becomes possible at the potentials of graphite cathode E cath. 1/2 = -0.72±0.02 V/SCE and was pH independent in the interval pH = 3.46-7.32. Mechanism of electrodeposition, including Tc(VII)/Tc(IV) reduction in the solution followed by Tc(IV) hydrolysis at the electrode surface with formation of hydrated Tc oxide cathodic deposit has been proposed. The further precision of the Tc(VII) electrochemical reduction mechanism in formate buffer media and optimization of the electrodeposition process seems to be possible using additional analytical facilities except electrochemical methods. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Kim, Dong Su; Kim, Tae Ho; Kim, Kyeong Hyeon; Yoon, Do Kun; Suh, Tae Suk [Dept. of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Kang, Seong Hee [Dept. of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of); Cho, Min Seok [Dept. of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of); Noh, Yu Yoon [Dept. of Radiation Oncology, Eulji University Hospital, Daejeon (Korea, Republic of)
2017-04-15
The inverse geometry computed tomography (IGCT) composed of multiple source and small size detector has several merits such as reduction of scatter effect and large volumetric imaging within one rotation without cone-beam artifact, compared to conventional cone-beam computed tomography (CBCT). By using this multi-source characteristics, we intend to present a selective and multiple interior region-of-interest (ROI) imaging method by using a designed source on-off sequence of IGCT. ROI-IGCT showed comparable image quality and has the capability to provide multi ROI image within a rotation. In this regard, it seems to be useful for diagnostic or image guidance for radiotherapy. ROI-IGCT showed comparable image quality and has the capability to provide multi ROI image within a rotation. Projection of ROI-IGCT is performed by selective irradiation, hence unnecessary imaging dose to non-interest region can be reduced. In this regard, it seems to be useful for diagnostic or image guidance for radiotherapy.
Gavara, R; Catalá, R; Hernández-Muñoz, P
1997-01-01
Scalping of aroma components in polymers used for food packaging was determined by solubility experiments. Aromas were selected from different families: esters, alcohols, hydrocarbons and ketones. Polymers were a linear low density polyethylene (LLDPE), an ionomer and a new thermosealable polyester (PET). Polymers were selected from thermosealable materials because of their resistance to fats and oils. Sorption isotherms (low sorbate activity range) for every system aroma (vapour)/polymer were determined by inverse gas chromatography. Isotherms were found to be linear. Hence, solubility coefficients (S) as defined by Henry's law were calculated from the isotherm slopes. According to S values, PET appears to be the best choice to minimize aroma scalping by sorption in the packaging inner layer, Ionomers improve the barrier to aroma when compared with LLDPE except for polar sorbates. Sorption of aroma components was shown to be selective, e.g. limonene was preferentially sorbed in LLDPE. The value of S for the limonene/LLDPE system was 2.5 times the value of S for ethyl caproate/LLDPE. This selectivity may lead to an imbalance in the flavour and may be more important than the prevention of overall scalping.
Inverse kinematics technique for the study of fission-fragment isotopic yields at GANIL energies
International Nuclear Information System (INIS)
Delaune, O.
2012-01-01
The characteristics of the fission-products distributions result of dynamical and quantum properties of the deformation process of the fissioning nucleus. These distributions have also an interest for the conception of new nuclear power plants or for the transmutation of the nuclear wastes. Up to now, our understanding of the nuclear fission remains restricted because of experimental limitations. In particular, yields of the heavy fission products are difficult to get with precision. In this work, an innovative experimental technique is presented. It is based on the use of inverse kinematics coupled to the use of a spectrometer, in which a 238 U beam at 6 or 24 A MeV impinges on light targets. Several actinides, from 238 U to 250 Cf, are produced by transfer or fusion reactions, with an excitation energy ranges from ten to few hundreds MeV depending on the reaction and the beam energy. The fission fragments of these actinides are detected by the VAMOS spectrometer or the LISE separator. The isotopic yields of fission products are completely measured for different fissioning systems. The neutron excess of the fragments is used to characterise the isotopic distributions. Its evolution with excitation energy gives important insights on the mechanisms of the compound-nucleus formation and its deexcitation. Neutron excess is also used to determine the multiplicity of neutrons evaporated by the fragments. The role of the proton and neutron shell effects into the formation of fission fragments is also discussed. (author) [fr
Mossin, Mats H; Aaby, Jens B; Dalgård, Christine; Lykkedegn, Sine; Christesen, Henrik T; Bilenberg, Niels
2017-07-01
To examine the association between cord 25-hydroxyvitamin D 2+3 (25(OH)D) and attention deficit hyperactivity disorder symptoms in toddlers, using Child Behaviour Checklist for ages 1.5-5. In a population-based birth cohort, a Child Behaviour Checklist for ages 1.5-5 questionnaire was returned from parents of 1233 infants with mean age 2.7 (standard deviation 0.6) years. Adjusted associations between cord 25(OH)D and Child Behaviour Checklist-based attention deficit hyperactivity disorder problems were analysed by multiple regression. Results The median cord 25(OH)D was 44.1 (range: 1.5-127.1) nmol/L. Mean attention deficit hyperactivity disorder problem score was 2.7 (standard deviation 2.1). In adjusted analyses, cord 25(OH)D levels >25 nmol/L and >30 nmol/L were associated with lower attention deficit hyperactivity disorder scores compared to levels ⩽25 nmol/L ( p = 0.035) and ⩽30 nmol/L ( p = 0.043), respectively. The adjusted odds of scoring above the 90th percentile on the Child Behaviour Checklist-based attention deficit hyperactivity disorder problem scale decreased by 11% per 10 nmol/L increase in cord 25(OH)D. An inverse association between cord 25(OH)D and attention deficit hyperactivity disorder symptoms in toddlers was found, suggesting a protective effect of prenatal vitamin D.
Corrosion and impedance studies on magnesium alloy in oxalate solution
International Nuclear Information System (INIS)
Fekry, A.M.; Tammam, Riham H.
2011-01-01
Highlights: → Corrosion behavior of AZ91E alloy was investigated in 0.1 M Na 2 C 2 O 4 containing different additives as Br - , Cl - or Silicate. → The corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na 2 C 2 O 4 ). This was confirmed by scanning electron microscope (SEM) observations. → For the other added ions Br - or Cl - , the corrosion rate is higher than the blank. - Abstract: Corrosion behavior of AZ91E alloy was investigated in oxalate solution using potentiodynamic polarization and electrochemical impedance measurements (EIS). The effect of oxalate concentration was studied, where the corrosion rate increases with increasing oxalate concentration. The effect of added ions (Br - , Cl - or SiO 3 2- ) on the electrochemical behavior of magnesium alloy in 0.1 M Na 2 C 2 O 4 solution at 298 K, was investigated. It was found that the corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na 2 C 2 O 4 ). This was confirmed by scanning electron microscope (SEM) observations. However, for the other added ions Br - or Cl - , the corrosion rate is higher than the blank.
Corrosion and impedance studies on magnesium alloy in oxalate solution
Energy Technology Data Exchange (ETDEWEB)
Fekry, A.M., E-mail: hham4@hotmail.com [Chemistry Department, Faculty of Science, Cairo University, Gamaa Street, Giza 12613 (Egypt); Tammam, Riham H. [Chemistry Department, Faculty of Science, Cairo University, Gamaa Street, Giza 12613 (Egypt)
2011-06-15
Highlights: > Corrosion behavior of AZ91E alloy was investigated in 0.1 M Na{sub 2}C{sub 2}O{sub 4} containing different additives as Br{sup -}, Cl{sup -} or Silicate. > The corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na{sub 2}C{sub 2}O{sub 4}). This was confirmed by scanning electron microscope (SEM) observations. > For the other added ions Br{sup -} or Cl{sup -}, the corrosion rate is higher than the blank. - Abstract: Corrosion behavior of AZ91E alloy was investigated in oxalate solution using potentiodynamic polarization and electrochemical impedance measurements (EIS). The effect of oxalate concentration was studied, where the corrosion rate increases with increasing oxalate concentration. The effect of added ions (Br{sup -}, Cl{sup -} or SiO{sub 3}{sup 2-}) on the electrochemical behavior of magnesium alloy in 0.1 M Na{sub 2}C{sub 2}O{sub 4} solution at 298 K, was investigated. It was found that the corrosion rate of 0.1 M oxalate solution containing silicate ion is lower than the blank (0.1 M Na{sub 2}C{sub 2}O{sub 4}). This was confirmed by scanning electron microscope (SEM) observations. However, for the other added ions Br{sup -} or Cl{sup -}, the corrosion rate is higher than the blank.
The philosophical aspect of learning inverse problems of mathematical physics
Directory of Open Access Journals (Sweden)
Виктор Семенович Корнилов
2018-12-01
Full Text Available The article describes specific questions student learning inverse problems of mathematical physics. When teaching inverse problems of mathematical physics to the understanding of the students brought the information that the inverse problems of mathematical physics with a philosophical point of view are the problems of determining the unknown causes of known consequences, and the search for their solutions have great scientific and educational potential. The reasons are specified in the form of unknown coefficients, right side, initial conditions of the mathematical model of inverse problems, and as a consequence are functionals of the solution of this mathematical model. In the process of learning the inverse problems of mathematical physics focuses on the philosophical aspects of the phenomenon of information and identify cause-effect relations. It is emphasized that in the process of logical analysis applied and humanitarian character, students realize that information is always related to the fundamental philosophical questions that the analysis applied and the humanitarian aspects of the obtained results the inverse problem of mathematical physics allows students to make appropriate inferences about the studied process and to, ultimately, new information, to study its properties and understand its value. Philosophical understanding of the notion of information opens up to students a new methodological opportunities to comprehend the world and helps us to reinterpret existing science and philosophy of the theory related to the disclosure of the interrelationship of all phenomena of reality.
A study of precipitation from pure solutions of uranyl nitrate
International Nuclear Information System (INIS)
Decrop, J.; Holder, J.; Sauteron, J.
1961-01-01
After its purification by extraction of the uranyl nitrate from the organic solvent, uranium has to be converted into solid form again: uranium trioxide (UO 3 ). It can be done either by thermal decomposition of uranyl nitrate or by precipitation of uranium, followed by filtration and calcination. Only the second method has been studied for now at the Bouchet plant. This paper reports the bench-scale and pilot-scale experiments of the studies of the precipitation of pure solutions of uranyl nitrate using ammonia (gaseous or in solution) or ammonium carbonate. These have been carried out at the Bouchet plant. It investigates the chemical aspect (pH, precipitates chemical composition) and the technical aspect of the different ways of precipitation (conditions of precipitation, decantation and filtration of precipitates). (M.P.)
Transmuted Generalized Inverse Weibull Distribution
Merovci, Faton; Elbatal, Ibrahim; Ahmed, Alaa
2013-01-01
A generalization of the generalized inverse Weibull distribution so-called transmuted generalized inverse Weibull dis- tribution is proposed and studied. We will use the quadratic rank transmutation map (QRTM) in order to generate a flexible family of probability distributions taking generalized inverse Weibull distribution as the base value distribution by introducing a new parameter that would offer more distributional flexibility. Various structural properties including explicit expression...
Support Minimized Inversion of Acoustic and Elastic Wave Scattering
Safaeinili, Ali
Inversion of limited data is common in many areas of NDE such as X-ray Computed Tomography (CT), Ultrasonic and eddy current flaw characterization and imaging. In many applications, it is common to have a bias toward a solution with minimum (L^2)^2 norm without any physical justification. When it is a priori known that objects are compact as, say, with cracks and voids, by choosing "Minimum Support" functional instead of the minimum (L^2)^2 norm, an image can be obtained that is equally in agreement with the available data, while it is more consistent with what is most probably seen in the real world. We have utilized a minimum support functional to find a solution with the smallest volume. This inversion algorithm is most successful in reconstructing objects that are compact like voids and cracks. To verify this idea, we first performed a variational nonlinear inversion of acoustic backscatter data using minimum support objective function. A full nonlinear forward model was used to accurately study the effectiveness of the minimized support inversion without error due to the linear (Born) approximation. After successful inversions using a full nonlinear forward model, a linearized acoustic inversion was developed to increase speed and efficiency in imaging process. The results indicate that by using minimum support functional, we can accurately size and characterize voids and/or cracks which otherwise might be uncharacterizable. An extremely important feature of support minimized inversion is its ability to compensate for unknown absolute phase (zero-of-time). Zero-of-time ambiguity is a serious problem in the inversion of the pulse-echo data. The minimum support inversion was successfully used for the inversion of acoustic backscatter data due to compact scatterers without the knowledge of the zero-of-time. The main drawback to this type of inversion is its computer intensiveness. In order to make this type of constrained inversion available for common use, work
Hot 56Mn reactions in permanganate solutions: a quasi solution state study [Paper No. NC-6
International Nuclear Information System (INIS)
Dedgaonkar, V.G.; Mitra, S.
1982-01-01
Neutron activation of aqueous solutions of transition metal and ammonium permanganates over the concentration range 1-10 -3 M has been performed. Retentions for concentrated solutions were much higher than the solid state values, and upon dilution, a limiting value of approx. 4 per cent was attained. Activation of 1-10 -1 M permanganate quasi solutions containing either alumina or a polystyrene cation exchanger allowed continuous extraction of the recoil species before their recombination. (author)
Upper air thermal inversion and their impact on the summer monsoon rainfall over Goa - A case study
Swathi, M. S.; Muraleedharan, P. M.; Ramaswamy, V.; Rameshkumar, M. R.; Aswini, Anirudhan
2018-04-01
Profiles of periodic GPS Radiosonde ascends collected from a station at the west coast of India (Goa) during summer monsoon months (June to September) of 2009 and 2013 have been used to analyze the thermal inversion statistics at various heights and their repercussions on the regional weather is studied. The interaction of contrasting air masses over the northern Arabian Sea often produces a two layer structure in the lower 5000 m close to the coastal station with warm and dusty air (Summer Shamal) occupying the space above the cool and moist Low Level Jet (LLJ) by virtue of their density differences. The warm air intrusion creates low lapse rate pockets above LLJ and modifies the gravitational stability strong enough to inhibit convection. It is observed that the inversion occurring in the lower 3000 m layer with an optimum layer thickness of 100-200 m has profound influence on the weather beneath it. We demonstrated the validity of the proposed hypothesis by analyzing the collocated data from radiosonde, lidar and the rain gauge during 16th July 2013 as a case study. The lidar depolarization ratio provides evidence to support the two layer structure in the lidar backscatter image. The presence of dust noticed in the two layer interface hints the intrusion of warm air that makes the atmosphere stable enough to suppress convection. The daily rainfall record of 2013 surprisingly coincides with the patterns of a regional break like situation centered at 16th July 2013 in Goa.
[Immortal time bias in pharmacoepidemiological studies: definition, solutions and examples].
Faillie, Jean-Luc; Suissa, Samy
2015-01-01
Among the observational studies of drug effects in chronic diseases, many of them have found effects that were exaggerated or wrong. Among bias responsible for these errors, the immortal time bias, concerning the definition of exposure and exposure periods, is relevantly important as it usually tends to wrongly attribute a significant benefit to the study drug (or exaggerate a real benefit). In this article, we define the mechanism of immortal time bias, we present possible solutions and illustrate its consequences through examples of pharmacoepidemiological studies of drug effects. © 2014 Société Française de Pharmacologie et de Thérapeutique.
The Neuroelectromagnetic Inverse Problem and the Zero Dipole Localization Error
Directory of Open Access Journals (Sweden)
Rolando Grave de Peralta
2009-01-01
Full Text Available A tomography of neural sources could be constructed from EEG/MEG recordings once the neuroelectromagnetic inverse problem (NIP is solved. Unfortunately the NIP lacks a unique solution and therefore additional constraints are needed to achieve uniqueness. Researchers are then confronted with the dilemma of choosing one solution on the basis of the advantages publicized by their authors. This study aims to help researchers to better guide their choices by clarifying what is hidden behind inverse solutions oversold by their apparently optimal properties to localize single sources. Here, we introduce an inverse solution (ANA attaining perfect localization of single sources to illustrate how spurious sources emerge and destroy the reconstruction of simultaneously active sources. Although ANA is probably the simplest and robust alternative for data generated by a single dominant source plus noise, the main contribution of this manuscript is to show that zero localization error of single sources is a trivial and largely uninformative property unable to predict the performance of an inverse solution in presence of simultaneously active sources. We recommend as the most logical strategy for solving the NIP the incorporation of sound additional a priori information about neural generators that supplements the information contained in the data.
Coefficient Inverse Problem for Poisson's Equation in a Cylinder
Solov'ev, V. V.
2011-01-01
The inverse problem of determining the coefficient on the right-hand side of Poisson's equation in a cylindrical domain is considered. The Dirichlet boundary value problem is studied. Two types of additional information (overdetermination) can be specified: (i) the trace of the solution to the
Neutron studies of paramagnetic fullerenols’ assembly in aqueous solutions
Lebedev, V. T.; Szhogina, A. A.; Suyasova, M. V.
2018-03-01
Recent results on structural studies of aqueous solutions of water-soluble derivatives of endofullerenes encapsulating 4f- and 3d-elements have been presented. Neutron small angle scattering experiments allowed recognize subtle features of fullerenols assembly as dependent on chemical nature (atomic number) of interior atom, pH-factor and temperature of solutions. It was observed a fractal-type fullerenols’ ordering at the scale of correlation radii ∼ 10-20 nm when molecules with iron atoms are integrated into branched structures at low concentrations (C ≤ 1 % wt.) and organized into globular aggregates at higher amounts (C > 1 % wt.). On the other hand, for Lanthanides captured in carbon cages the supramolecular structures are mostly globular and have larger gyration radii ∼ 30 nm. They demonstrated a good stability in acidic (pH ∼ 3) and neutral (pH ∼ 7) media that is important for forthcoming medical applications.
Parameter estimation and inverse problems
Aster, Richard C; Thurber, Clifford H
2005-01-01
Parameter Estimation and Inverse Problems primarily serves as a textbook for advanced undergraduate and introductory graduate courses. Class notes have been developed and reside on the World Wide Web for faciliting use and feedback by teaching colleagues. The authors'' treatment promotes an understanding of fundamental and practical issus associated with parameter fitting and inverse problems including basic theory of inverse problems, statistical issues, computational issues, and an understanding of how to analyze the success and limitations of solutions to these probles. The text is also a practical resource for general students and professional researchers, where techniques and concepts can be readily picked up on a chapter-by-chapter basis.Parameter Estimation and Inverse Problems is structured around a course at New Mexico Tech and is designed to be accessible to typical graduate students in the physical sciences who may not have an extensive mathematical background. It is accompanied by a Web site that...
Wu, Xingwei; Li, Cong; Wang, Yong; Wang, Zhiwei; Feng, Chunlei; Ding, Hongbin
2015-09-01
The hydrocarbon impurities formation is inevitable due to wall erosion in a long pulse high performance scenario with carbon-based plasma facing materials in fusion devices. The standard procedure to determine the chemical erosion yield in situ is by means of inverse photon efficiency D/XB. In this work, the conversion factor between CH4 flux and photon flux of CH A → X transition (effective inverse photon efficiency PE-1) was measured directly using a cascaded arc plasma simulator with argon/methane. This study shows that the measured PE-1 is different from the calculated D/XB. We compared the photon flux measured by optical emission spectroscopy (OES) and calculated by electron impact excitation of CH(X) which was diagnosed by cavity ring-down spectroscopy (CRDS). It seems that charge exchange and dissociative recombination processes are the main channels of CH(A) production and removal which lead to the inconsistency of PE -1 and D/XB at lower temperature. Meanwhile, the fraction of excited CH(A) produced by dissociative recombination processes was investigated, and we found it increased with Te in the range from 4% to 13% at Te definition instead of D/XB since the electron impact excitation is not the only channel of CH(A) production. These results have an effect on evaluating the yield of chemical erosion in divertor of fusion device.
Energy Technology Data Exchange (ETDEWEB)
Aguilo Valentin, Miguel Alejandro [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-07-01
This study presents a new nonlinear programming formulation for the solution of inverse problems. First, a general inverse problem formulation based on the compliance error functional is presented. The proposed error functional enables the computation of the Lagrange multipliers, and thus the first order derivative information, at the expense of just one model evaluation. Therefore, the calculation of the Lagrange multipliers does not require the solution of the computationally intensive adjoint problem. This leads to significant speedups for large-scale, gradient-based inverse problems.
Study of reactive solutes transport and PAH migration in unsaturated soils
International Nuclear Information System (INIS)
Gujisaite, V.; Simonnot, M.O.; Gujisaite, V.; Morel, J.L.; Ouvrard, S.; Simonnot, M.O.; Gaudet, J.P.
2005-01-01
-silty uncontaminated soil or a sand and a model porous medium constituted of sand in which coal tar particles are dispersed. In a second time, column experiments will be carried out with a PAH contaminated soil from a former coking plant and with a multi-polluted industrial soil (PAH, heavy metals) to study PAH migration. For each studied soil, we will also determine the water retention curve in order to find the best operating conditions for our experiments with unsaturated flow. Modelling of solutes transfer in soils is also needed to improve understanding of the fate of contaminants and for risk assessment. However, it is difficult to take into account at the same time flow and interactions in models. Different models and numerical codes have been developed for solute transport. We have chosen to use the CXTFIT code, in order to model our results. This code allows indeed modelling of reactive solute transport in unsaturated porous media as well as under saturated conditions. It is usually used to estimate solute transport parameters using a nonlinear least-squares parameter optimization method. It may be used to solve the inverse problem by fitting a variety of mathematical solutions of theoretical transport models, based upon the one-dimensional convection-dispersion equation (CDE), to experimental results. The program may also be used to solve the direct or forward problem to determine concentrations as a function of time and/or position. This study at a bench scale will enable us at first to develop a methodology under unsaturated conditions and also to better understand the dominating mechanisms which control PAH transfer and availability in natural soils, especially by quantifying the impact of parameters like soil water content, water flow or the presence of plants. This is a first step before the change of scale (lysimeter). Modelling of the observed processes will also enable us to predict long term fate of PAH in soils
Wong, Shiu F; Grisham, Jessica R
2017-12-01
The inference-based approach (IBA) is a cognitive account of the genesis and maintenance of obsessive-compulsive disorder (OCD). According to the IBA, individuals with OCD are prone to using inverse reasoning, in which hypothetical causes form the basis of conclusions about reality. Several studies have provided preliminary support for an association between features of the IBA and OCD symptoms. However, there are currently no studies that have investigated the proposed causal relationship of inverse reasoning in OCD. In a non-clinical sample (N = 187), we used an interpretive cognitive bias procedure to train a bias towards using inverse reasoning (n = 64), healthy sensory-based reasoning (n = 65), or a control condition (n = 58). Participants were randomly allocated to these training conditions. This manipulation allowed us to assess whether, consistent with the IBA, inverse reasoning training increased compulsive-like behaviours and self-reported OCD symptoms. Results indicated that compared to a control condition, participants trained in inverse reasoning reported more OCD symptoms and were more avoidant of potentially contaminated objects. Moreover, change in inverse reasoning bias was a small but significant mediator of the relationship between training condition and behavioural avoidance. Conversely, training in a healthy (non-inverse) reasoning style did not have any effect on symptoms or behaviour relative to the control condition. As this study was conducted in a non-clinical sample, we were unable to generalise our findings to a clinical population. Findings generally support the IBA model by providing preliminary evidence of a causal role for inverse reasoning in OCD. Copyright © 2017 Elsevier Ltd. All rights reserved.
Inverse diffusion theory of photoacoustics
International Nuclear Information System (INIS)
Bal, Guillaume; Uhlmann, Gunther
2010-01-01
This paper analyzes the reconstruction of diffusion and absorption parameters in an elliptic equation from knowledge of internal data. In the application of photoacoustics, the internal data are the amount of thermal energy deposited by high frequency radiation propagating inside a domain of interest. These data are obtained by solving an inverse wave equation, which is well studied in the literature. We show that knowledge of two internal data based on well-chosen boundary conditions uniquely determines two constitutive parameters in diffusion and Schrödinger equations. Stability of the reconstruction is guaranteed under additional geometric constraints of strict convexity. No geometric constraints are necessary when 2n internal data for well-chosen boundary conditions are available, where n is spatial dimension. The set of well-chosen boundary conditions is characterized in terms of appropriate complex geometrical optics solutions
A Study on the Stability of Diluted Bee Venom Solution
Directory of Open Access Journals (Sweden)
Mi-Suk Kang
2003-06-01
Full Text Available Objective : The purpose of this study was to investigate the stability of bee venom according to the keeping method and period. Method : The author observed microbial contamination of bee venom in nutrient agar, broth, YPD agar and YPD media and antibacterial activity for S. aureus, E. coli manufactured 12, 6 and 3 months ago as the two type of room temperature and 4℃ cold storage. Result : 1. 1:3,000 and 1:4,000 diluted bee venom solution did not show microbial contamination both room temperature and cold storage within twelve months. 2. There was antibacterial activity of diluted bee venom for S. aureus in cold storage within twelve months and there was no antibacterial activity of diluted bee venom for S. aureus in twelve months, room temperature storage. 3. We could not observe the zone of inhibition around paper disc of all for E.coli. in 1:3,000, 1:30,000 and 1:3,000,000 diluted bee venom solution, respectively. According to results, we expect that diluted bee venom solution is stable both cold and room temperature storage within twelve months.
Diffuse neutron scattering study of metallic interstitial solid solutions
International Nuclear Information System (INIS)
Barberis, P.
1991-10-01
We studied two interstitial solid solutions (Ni-C(1at%) and Nb-O(2at%) and two stabilized zirconia (ZrO2-CaO(13.6mol%) and ZrO2-Y2O3(9.6mol%) by elastic diffuse neutron scattering. We used polarized neutron scattering in the case of the ferromagnetic Ni-based sample, in order to determine the magnetic perturbation induced by the C atoms. Measurements were made on single crystals in the Laboratoire Leon Brillouin (CEA-CNRS, Saclay, France). An original algorithm to deconvolve time-of-flight spectra improved the separation between elastically and inelastically scattered intensities. In the case of metallic solutions, we used a simple non-linear model, assuming that interstitials are isolated and located in octahedral sites. Results are: - in both compounds, nearest neighbours are widely displaced away from the interstitial, while next nearest neighbours come slightly closer. - the large magnetic perturbation induced by carbon in Nickel decreases with increasing distance on the three first neighbour shells and is in good agreement with the total magnetization variation. - no chemical order between solute atoms could be evidenced. Stabilized zirconia exhibit a strong correlation between chemical order and the large displacements around vacancies and dopants. (Author). 132 refs., 38 figs., 13 tabs
Multi-objective optimization of inverse planning for accurate radiotherapy
International Nuclear Information System (INIS)
Cao Ruifen; Pei Xi; Cheng Mengyun; Li Gui; Hu Liqin; Wu Yican; Jing Jia; Li Guoli
2011-01-01
The multi-objective optimization of inverse planning based on the Pareto solution set, according to the multi-objective character of inverse planning in accurate radiotherapy, was studied in this paper. Firstly, the clinical requirements of a treatment plan were transformed into a multi-objective optimization problem with multiple constraints. Then, the fast and elitist multi-objective Non-dominated Sorting Genetic Algorithm (NSGA-II) was introduced to optimize the problem. A clinical example was tested using this method. The results show that an obtained set of non-dominated solutions were uniformly distributed and the corresponding dose distribution of each solution not only approached the expected dose distribution, but also met the dose-volume constraints. It was indicated that the clinical requirements were better satisfied using the method and the planner could select the optimal treatment plan from the non-dominated solution set. (authors)
An experimental study on MRI signal intensity of albumin solution
International Nuclear Information System (INIS)
Ahn, In Oak; Chang, Kee Hyun; Han, Moon Hee; Song, Chi Sung; Yeon, Kyung Mo
1990-01-01
This in vitro study attempted to correlate magnetic resonance (MR) signal intensity with concentration of albumin solution in magnetic field strength of 2.0 Tesla (T) and 0.5T. MR imaging of bovine serum albumin solutions of various concentrations ranging from 0 to 40 g/dl was performed on both 2.0T and 0.5T MR units. The relative (with respect to normal saline) signal intensities of each albumin solution were measured in T1-weighted, proton density-weighted and T2-weighted MR images, correlated with albumin concentration on each pulse sequence, and compared between 2.0T and 0.5T. Additionally, the albumin concentrations showing signal intensities identical to those of white matter, cortical gray matter and cerebrospinal fluid (CSF) of normal brain MRI were determined by visual comparison of those images. 1. On T1-weighted (SE 400-500 msec/30 msec) images under 2.0T and 0.5T field strength, the signal intensity increased with increasing albumin concentrations up to about 30-35 g/dl and the decreased. For the solutions ranging from 0 to about 5 g/dl concentration, the signal intensities appeared isointense to normal saline on visual inspection. 2. On proton density-weighted (SE 2000-2500 msec/30 msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations up to about 7.5-10 g/dl, and then gradually decreased. 3. On T2-weighted (SE 2000-2500 msec/80-100 msec) images under 2.0T and 0.5T field strength, the signal intensity slightly increased with increasing albumin concentrations up to about 7.5-10 g/dl, and then gradually decreased. Above the concentration of about 25-30 g/dl, the signal intensity appeared lower than that of normal saline on visual inspection. 4. Compared with the signal intensities of normal brain structures on T1-weighted images under 2.0T and 0.5T field strength, the signal intensities of the albumin solution below 2.5-5 g/dl concentration were similar to that of CSF, and those of
Pulse radiolysis for the study of lead salt solutions
International Nuclear Information System (INIS)
Breitenkamp, M.
1976-01-01
The Pb + ions are produced from Pb 2 + in lead perchlorate solutions by reduction with hydrated electrons, and the absorption spectrum of this ion has been measured together with a time differential observation in the micro- and millisecond range of the disparation of these ions from the solution in the presence of different substances. For these studies the method of pulsed radiolysis has been applied, detecting the short lifed intermediate reaction products by optical absorption and electric conductivity measurements. First an attempt has been made to produce the Pb + ions also by reduction of Pb 2 + with H-atoms. If Pb + and H is produced simultaneously in an aqueous solution the reaction Pb + + H -> PbH + can occur. The absorption spectrum of the short lifed species PbH + has been studied together with the second order evanescence. In addition Pb 2 + has been reduced by i-propanol radicals at high Pb 2 + concentrations. The second order evanescence has been observed and the rate constant of the reaction 2Pb + -> Pb + Pb 2 + has been measured. The Pb 2 + ions can also be reduced by CO 2- radicals, which are formed in the presence of formiate. The observations can be interpreted by the assumption of the primary reaction Pb 2 + + CO 2- -> PbCO 2+ . the spectrum of the product PbCO 2+ has been measured. A second order reaction of PbCO 2+ is observed with a resulting unstable particle of the structure Pb 2 CO 2 2 + . Finally the oxidation of Pb + by the OH-radical and by hydrogen peroxide has been studied. (orig./HK) [de
International Nuclear Information System (INIS)
Apelblat, Alexander; Korin, Eli; Manzurola, Emanuel
2013-01-01
Highlights: • Over a wide range of concentrations and temperatures sound velocities were measured in aqueous solutions of citric acid. • Compressibility properties of citric acid solutions are thermodynamically characterized. • Changes in the structure of water when citric acid is dissolved are discussed. -- Abstract: Sound velocities in aqueous solutions of citric acid were measured from 15 °C to 50 °C in 5 °C intervals, within the 0.1 mol · kg −1 to 5.0 mol · kg −1 concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions
Thermal decomposition studies of aqueous and nitric solutions of hydroxyurea
International Nuclear Information System (INIS)
Shekhar Kumar; Pranay Kumar Sinha; Kamachi Mudali, U.; Natarajan, R.
2012-01-01
Hydroxyurea and its derivatives are important nonsalt forming reductants in partitioning of uranium and plutonium in the nuclear fuel reprocessing operations. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of aqueous and nitric solutions of hydroxyurea at elevated temperatures. Authors studied thermal decomposition of hydroxyurea-nitric acid system and resultant pressurization at various concentrations of nitric acid in an adiabatic calorimeter in closed-vent conditions. During these experiments, pressurization was observed. In this paper, results of these experiments have been discussed. (author)
Zhou, Ting; Zeng, Jing; Liu, Shan; Zhao, Ting; Wu, Jie; Lai, Wenshi; He, Mingzhi; Xu, Beining; Qu, Shanshan; Xu, Ling; Tan, Wen
2015-10-01
The chiral inversion has been a concerned issue during the research and development of a chiral drug. In this study, a sensitive chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for determination of salbutamol enantiomers in human plasma and urine. The chiral inversion mechanism of R-salbutamol was fully investigated for the first time by studying the effects of physicochemical factors, including pH, temperature and time. A fitted model to predict the chiral inversion ratio of R-salbutamol was proposed using a Box-Behnken design. All the samples were separated on an Astec Chirobiotic T column and detected by a tandem mass spectrometer in multiple reaction monitoring mode. Lower limit of quantification of 0.100ng/mL was achieved under the optimized conditions. The method was fully validated and successfully applied to the clinical pharmacokinetic study of R-salbutamol in healthy volunteers. Chiral inversion of R-salbutamol to S-salbutamol has been detected in urine samples. The results indicated that pH and temperature were two dominant factors that caused the chiral inversion of R-salbutamol, which should be taken into consideration during the analysis of chiral drugs. The chiral inversion of R-salbutamol determined in this study was confirmed resulted from the gastric acid in stomach rather than caused by the analysis conditions. Moreover, the calculated results of the fitted model matched very well with the enantioselective pharmacokinetic study of R-salbutamol, and the individual difference of the chiral inversion ratio of R-salbutamol was related to the individual gastric environment. On the basis of the results, this study provides important and concrete information not only for the chiral analysis but also for the metabolism research of chiral drugs. Copyright © 2015 Elsevier B.V. All rights reserved.
Martella, Andrea; Sijben, Huub; Rufer, Arne C; Grether, Uwe; Fingerle, Juergen; Ullmer, Christoph; Hartung, Thomas; IJzerman, Adriaan P; van der Stelt, Mario; Heitman, Laura H
2017-10-01
The endocannabinoid system, and in particular the cannabinoid type 2 receptor (CB2R), raised the interest of many medicinal chemistry programs for its therapeutic relevance in several (patho)physiologic processes. However, the physico-chemical properties of tool compounds for CB2R (e.g., the radioligand [ 3 H]CP55,940) are not optimal, despite the research efforts in developing effective drugs to target this system. At the same time, the importance of drug-target binding kinetics is growing since the kinetic binding profile of a ligand may provide important insights for the resulting in vivo efficacy. In this context we synthesized and characterized [ 3 H]RO6957022, a highly selective CB2R inverse agonist, as a radiolabeled tool compound. In equilibrium and kinetic binding experiments [ 3 H]RO6957022 showed high affinity for human CB2R with fast association ( k on ) and moderate dissociation ( k off ) kinetics. To demonstrate the robustness of [ 3 H]RO6957022 binding, affinity studies were carried out for a wide range of CB2R reference ligands, spanning the range of full, partial, and inverse agonists. Finally, we used [ 3 H]RO6957022 to study the kinetic binding profiles (i.e., k on and k off values) of selected synthetic and endogenous (i.e., 2-arachidonoylglycerol, anandamide, and noladin ether) CB2R ligands by competition association experiments. All tested ligands, and in particular the endocannabinoids, displayed distinct kinetic profiles, shedding more light on their mechanism of action and the importance of association rates in the determination of CB2R affinity. Altogether, this study shows that the use of a novel tool compound, i.e., [ 3 H]RO6957022, can support the development of novel ligands with a repertoire of kinetic binding profiles for CB2R. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.
Approximate inverse preconditioning of iterative methods for nonsymmetric linear systems
Energy Technology Data Exchange (ETDEWEB)
Benzi, M. [Universita di Bologna (Italy); Tuma, M. [Inst. of Computer Sciences, Prague (Czech Republic)
1996-12-31
A method for computing an incomplete factorization of the inverse of a nonsymmetric matrix A is presented. The resulting factorized sparse approximate inverse is used as a preconditioner in the iterative solution of Ax = b by Krylov subspace methods.
Djoussé, Luc; Hopkins, Paul N.; Arnett, Donna K.; Pankow, James S.; Borecki, Ingrid; North, Kari E.; Ellison, R. Curtis
2010-01-01
Background and Aims While a diet rich in anti-oxidant has been favorably associated with coronary disease and hypertension, limited data have evaluated the influence of such diet on subclinical disease. Thus, we sought to examine whether chocolate consumption is associated with calcified atherosclerotic plaque in the coronary arteries (CAC). Methods In a cross-sectional design, we studied 2,217 participants of the NHLBI Family Heart Study. Chocolate consumption was assessed by a semi-quantitative food-frequency questionnaire and CAC was measured by cardiac CT. We defined prevalent CAC using an Agatston score of at least 100 and fitted generalized estimating equations to calculate prevalence odds ratios of CAC. Results There was an inverse association between frequency of chocolate consumption and prevalent CAC. Odds ratios (95% CI) for CAC were 1.0 (reference), 0.94 (0.66-1.35), 0.78 (0.53-1.13), and 0.68 (0.48-0.97) for chocolate consumption of 0, 1-3 times per month, once per week, and 2+ times per week, respectively (p for trend 0.022), adjusting for age, sex, energy intake, waist-hip ratio, education, smoking, alcohol consumption, ratio of total-to-HDL-cholesterol, non-chocolate candy, and diabetes mellitus. Controlling for additional confounders did not alter the findings. Exclusion of subjects with coronary heart disease or diabetes mellitus did not materially change the odds ratio estimates but did modestly decrease the overall significance (p = 0.07). Conclusions These data suggest that chocolate consumption might be inversely associated with prevalent CAC. PMID:20655129
Inverse and Ill-posed Problems Theory and Applications
Kabanikhin, S I
2011-01-01
The text demonstrates the methods for proving the existence (if et all) and finding of inverse and ill-posed problems solutions in linear algebra, integral and operator equations, integral geometry, spectral inverse problems, and inverse scattering problems. It is given comprehensive background material for linear ill-posed problems and for coefficient inverse problems for hyperbolic, parabolic, and elliptic equations. A lot of examples for inverse problems from physics, geophysics, biology, medicine, and other areas of application of mathematics are included.
Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution
Energy Technology Data Exchange (ETDEWEB)
Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-05-15
It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4}. On the other hand, the inner oxide layers are composed of Cr{sub 2}O{sub 3}, (Ni{sub 1-x}Ni{sub x})(Cr{sub 1-y}Fe{sub y}){sub 2}O{sub 4}, and FeCr{sub 2}O{sub 4}. Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications
Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution
International Nuclear Information System (INIS)
Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon
2013-01-01
It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe 3 O 4 and NiFe 2 O 4 . On the other hand, the inner oxide layers are composed of Cr 2 O 3 , (Ni 1-x Ni x )(Cr 1-y Fe y ) 2 O 4 , and FeCr 2 O 4 . Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. It is revealed that Inconel-600 specimen is more
OBJECTIVES: The aim of this study was to examine whether magnesium intake is associated with coronary artery calcification (CAC) and abdominal aortic calcification (AAC). BACKGROUND: Animal and cell studies suggest that magnesium may prevent calcification within atherosclerotic plaques underlying c...
Pisso, I. J.; Lopez-Aparicio, S.; Schneider, P.; Schmidbauer, N.; Vogt, M.
2017-12-01
Norway has set the target of cutting greenhouse gas (GHG) emissions by at least 40% compared to 1990 levels by 2030. This goal will require the implementation of policy measures aiming at strong reductions of GHGs emissions, especially in the urban environment. The implementation of urban policy measures is still a challenging task and it requires control and verification for success. The URGE project aims at assessing the emission flux of GHGs including comprehensive uncertainty estimates based on inverse transport modelling techniques and optimized use of measurements. The final goal is to establish a coherent and consistent GHG urban emission inventory. This will be carried out in a case study in Oslo (Norway), where CO2 will be the priority compound. The overall outcome of the project will provide support in the development of strategies to effectively reduce GHG emissions in the urban environment. The overall goal will be reached through establishing the baseline urban CO2 emission inventory for Oslo; determining the optimal measurement locations based on transport modelling (with flexpart-wrf); designing and carrying out a pilot measurement campaign of the CO2-rich air downwind of the city plume combining state-of-the-art instruments (Picarro) and small sensors; assessing the feasibility of determining the background concentration surrounding the city with satellite measurements (OCO2); and providing optimised estimates of the emissions and their uncertainties via inverse modelling (source-receptor relationship). One of our main interests is the interoperability and exchange of information with similar activities in other urban areas. We will present the overall project and the preliminary results of the network design. We will discuss the data exchange formats, the algorithms and data structures that could be used for results and methodology intercomparisons as well as the suitability to apply the same techniques to other atmospheric compounds.
International Nuclear Information System (INIS)
Chihao Luan; Urry, D.W.
1991-01-01
As previously shown, the polypentapeptide of elastin, (Val 1 -Pro 2 -Gly 3 -Val 4 -Gly 5 ) n or simply poly(VPGVG), undergoes an inverse temperature transition which is seen macroscopically as a phase separation with a dense viscoelastic phase of about 60% water, 40% peptide by weight and which is characterized molecularly by increase in intra- and intermolecular order as evidenced by formation of specific hydrophobic contacts. Furthermore, from an extensive study of polypentapeptides of the composition poly[f x (VPGXG), f v (VPGVG)], where f x + f v = 1 and X is any of the amino acid residues with apolar (hydrophobic) side chains, it has been shown that the temperature of the transition decreases and the heat of the transition increases with increased hydrophobicity. In the present paper differential scanning calorimetry has been utilized to determine the effect of D 2 O on the temperature and heats of the inverse temperature transitions for poly(VPGVG), poly(IPGVG), poly(LPGVG), and poly(VPAVG) and in the latter case in the presence of 0.5 and 1.0 N NaCl and of 1,2, and 3 M urea. In all cases, the effect of D 2 O as compared to H 2 O is to lower the transition temperature about 2 C and to increase the heat of the transition about 10%, and this occurs also in the presence of NaCl, which itself lowers the temperature and increases the heat, and in the presence of urea, which itself raises the temperature and decreases the heat of the transition. It is concluded that the effect of replacement of H 2 O by D 2 O by D 2 O in these polypeptides is to effect a small but consistent increase in the expression of hydrophobicity
Directory of Open Access Journals (Sweden)
Widawski Artur
2015-06-01
Full Text Available Sosnowiec is located in the Katowice Region, which is the most urbanized and industrialized region in Poland. Urban areas of such character favor enhancement of pollution concentration in the atmosphere and the consequent emergence of smog. Local meteorological and circulation conditions significantly influence not only on the air pollution level but also change air temperature considerably in their centers and immediate vicinities. The synoptic situation also plays the major role in dispersal and concentration of air pollutants and changes in temperature profile. One of the most important are the near-ground (100 m inversions of temperature revealed their highest values on clear winter days and sometimes stay still for the whole day and night. Air temperature inversions in Sosnowiec occur mainly during anticyclone stagnation (Ca-anticyclone centre and Ka-anticyclonic ridge and in anticyclones with air advection from the south and southwest (Sa and SWa which cause significantly increase of air pollution values. The detailed evaluation of the influence of circulation types on the appearance of a particular concentration of pollutants carried out in this work has confirmed the predominant influence of individual circulation types on the development of air pollution levels at the Katowice region. This paper presents research case study results of the thermal structure of the near-ground atmospheric layer (100 m and air pollution parameters (PM10, SO2, NO, NO2 changes in selected days of 2005 year according to regional synoptic circulation types. The changes in urban environment must be taken into account in analyses of multiyear trends of air temperature and air conditions on the regional and global scales.
Reactivity in inverse micelles
International Nuclear Information System (INIS)
Brochette, Pascal
1987-01-01
This research thesis reports the study of the use of micro-emulsions of water in oil as reaction support. Only the 'inverse micelles' domain of the ternary mixing (water/AOT/isooctane) has been studied. The main addressed issues have been: the micro-emulsion disturbance in presence of reactants, the determination of reactant distribution and the resulting kinetic theory, the effect of the interface on electron transfer reactions, and finally protein solubilization [fr
AWS certified solutions architect official study guide associate exam
Baron, Joe; Bixler, Tim; Gaut, Biff; Kelly, Kevin E; Senior, Sean; Stamper, John
2017-01-01
This is your opportunity to take the next step in your career by expanding and validating your skills on the AWS cloud. AWS has been the frontrunner in cloud computing products and services, and the AWS Certified Solutions Architect Official Study Guide for the Associate exam will get you fully prepared through expert content, and real-world knowledge, key exam essentials, chapter review questions, access to Sybex's interactive online learning environment, and much more. This official study guide, written by AWS experts, covers exam concepts, and provides key review on exam topics, including: * Mapping Multi-Tier Architectures to AWS Services, such as web/app servers, firewalls, caches and load balancers * Understanding managed RDBMS through AWS RDS (MySQL, Oracle, SQL Server, Postgres, Aurora) * Understanding Loose Coupling and Stateless Systems * Comparing Different Consistency Models in AWS Services * Understanding how AWS CloudFront can make your application more cost efficient, faster and secure * Implem...
Archiving Primary Data: Solutions for Long-Term Studies.
Mills, James A; Teplitsky, Céline; Arroyo, Beatriz; Charmantier, Anne; Becker, Peter H; Birkhead, Tim R; Bize, Pierre; Blumstein, Daniel T; Bonenfant, Christophe; Boutin, Stan; Bushuev, Andrey; Cam, Emmanuelle; Cockburn, Andrew; Côté, Steeve D; Coulson, John C; Daunt, Francis; Dingemanse, Niels J; Doligez, Blandine; Drummond, Hugh; Espie, Richard H M; Festa-Bianchet, Marco; Frentiu, Francesca; Fitzpatrick, John W; Furness, Robert W; Garant, Dany; Gauthier, Gilles; Grant, Peter R; Griesser, Michael; Gustafsson, Lars; Hansson, Bengt; Harris, Michael P; Jiguet, Frédéric; Kjellander, Petter; Korpimäki, Erkki; Krebs, Charles J; Lens, Luc; Linnell, John D C; Low, Matthew; McAdam, Andrew; Margalida, Antoni; Merilä, Juha; Møller, Anders P; Nakagawa, Shinichi; Nilsson, Jan-Åke; Nisbet, Ian C T; van Noordwijk, Arie J; Oro, Daniel; Pärt, Tomas; Pelletier, Fanie; Potti, Jaime; Pujol, Benoit; Réale, Denis; Rockwell, Robert F; Ropert-Coudert, Yan; Roulin, Alexandre; Sedinger, James S; Swenson, Jon E; Thébaud, Christophe; Visser, Marcel E; Wanless, Sarah; Westneat, David F; Wilson, Alastair J; Zedrosser, Andreas
2015-10-01
The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers. Copyright © 2015 Elsevier Ltd. All rights reserved.
Experimental and theoretical study of solid solution stability under irradiation
International Nuclear Information System (INIS)
Cauvin, Richard.
1981-08-01
The behavior of dilute alloys (Al-Zn, Al-Ag, Al-Si, Al-Ge and Al-Mg) under 1 MeV electron irradiation has been studied in a high voltage electron microscope. A phenomenon of homogeneous precipitation induced by irradiation in undersaturated solid solutions (Al-Zn, Al-Ag and Al-Si) has been discovered; the observed precipitates are either coherent or incoherent, but never associated with point defect sinks. The solubility limit is a function of irradiation temperature and flux; but, under irradiation, it does not behave as a true thermal solubility limit (without irradiation). The existing theories (kinetic or strictly thermodynamic) do not account for this phenomenon. It is shown that the irreversibility of the mutual recombination between trapped vacancies and mixed interstitials is the driving force of this homogeneous precipitation. Using a dilute solid solution model, we show that, under irradiation, the homogeneous stationary state, stable from a strictly thermodynamic point of view, can be unstable when the recombination reaction is taken into account. The solubility limit under irradiation is calculated with a nucleation-growth model taking account for this effect; it is proportional to the thermal solubility limit without irradiation. This model explains all the experimental observations [fr
On two-spectra inverse problems
Guliyev, Namig J.
2018-01-01
We consider a two-spectra inverse problem for the one-dimensional Schr\\"{o}dinger equation with boundary conditions containing rational Herglotz--Nevanlinna functions of the eigenvalue parameter and provide a complete solution of this problem.
Vermeulen, A.C.; Geus, John W.; Stol, R.J.; Bruyn, P.L. de
Acidified aluminum nitrate solutions were titrated with alkali (NaOH or KOH) over a temperature range of 24°C to 90°C. A homogeneous distribution of added base was achieved by: (i) in situ decomposition of urea (90°C); and (ii) a novel method involving injection through a capillary submerged in the
Studies on Benzo-DODA encapsulated polymeric beads for separation of Pu from acidic solution
International Nuclear Information System (INIS)
Singh, K.K.; Panja, S.; Kumar, M.; Ruhela, R.; Tripathi, S.C.; Singh, A.K.; Hubli, R.C.; Bajaj, P.N.
2014-01-01
High level liquid waste (HLLW) generated during the reprocessing of spent fuel contains a few mg of Pu per litre of waste volume. Therefore, there is a need for selective separation of Pu from above solution as well as other such acidic waste streams. The widely used technology for separation and recovery of metal ions from radioactive wastes is liquid-liquid extraction.Though, such technologies play major role in all the bulk separation processes, they have marked limitations involving the losses of extractant in aqueous phase, third phase problems at higher metal loading, etc. These limitations have necessitated the exploration of advance, more efficient and technically feasible alternatives. In this regard it is thought that solid-liquid based Extractant Encapsulated Polymeric Beads (EEPBs) may solve some of the problems. Benzodioxodiamide (BenzoDODA) is a recently reported extractant for the separation of plutonium from radioactive waste, containing nitric acid. BenzoDODA extractant encapsulated polymeric beads were prepared by phase inversion technique and found to be quite stable as no significant structural deformation or leaching out of the extractant was observed in 4.0 M HNO 3 solution, up to studied equilibration time of 8 days. These beads have been characterized by FT-IR, TGA and SEM techniques to gain insight into their structure and morphology. Morphology and porosity of the beads, as studied by the SEM analysis, indicate that the surface of the beads is quite rough, and has enough porosity. Thermo gravimetric analysis of the synthesized composite beads shows a weight loss of ∼74% during the heating from room temperature to 120℃, due to the loss of water present in the swollen beads. Such high water content also confirms that the beads have enough porosity for efficient exchange of metal ions.The synthesized beads were evaluated, for their ability to absorb Pu from acidic solution. The kinetics measurement showed that about 45 min of
Cakir, Suleyman Sami; Ozcan, Levent; Besiroglu, Huseyin; Dursun, Murat; Polat, Emre Can; Otunctemur, Alper; Ozbek, Emin
2018-01-16
Visceral adiposity index (VAI) is a novel indicator for the assessment of visceral obesity. In this study, we aimed to evaluate the relationship between VAI and premature ejaculation (PE). A total of 300 men were included in the study. Hundred and fifty men with PE and 150 men without PE (control). All men were evaluated for PE by premature ejaculation diagnostic tool (PEDT). VAI levels were calculated using body mass index (BMI), high density lipoprotein and triglyceride (TG) levels. Mean age of the study groups was 34.3 ± 5.2 (30-60) years and the mean age of the controls were 35.9 ± 5.3 (30-60) years. The men with PE had lower BMI, TG levels, waist circumference (WC) and higher high-density lipoprotein-cholesterol (HDL-C) levels. Mean VAI level was 4.13 ± 0.7 in study group and 5.72 ± 1.6 in control group, respectively. VAI levels were statistically higher in men without PE (p correlation between VAI and PE. VAI is superior index for the evaluation and calculation the relationship between obesity and PE.
Inverse association between atopy and melanoma: A case-control study
Marasigan, V. (Vivien); M.-A. Morren (Marie-Anne); J. Lambert; Medaer, K. (Karen); Fieuws, S. (Steffen); T.E.C. Nijsten (Tamar); Garmyn, M. (Marjan)
2017-01-01
textabstractHeightened cutaneous immune surveillance in atopic patients may inhibit development of melanoma. The aim of this study was to analyse the association between atopy and melanoma (development and outcome). A total of 188 cases of melanoma and 596 healthy controls were interviewed by
Gelder, van B.M.; Buijsse, B.; Tijhuis, M.J.; Kalmijn, S.; Giampaoli, S.; Nissinen, A.; Kromhout, D.
2007-01-01
Objective: To investigate whether coffee consumption is associated with 10-year cognitive decline in elderly men, as results of previous studies obtained hitherto have been controversial and prospective information on this association has been lacking. Design, subjects and setting: Six hundred and
Implicit structural inversion of gravity data using linear programming, a validation study
Zon, A.T. van; Roy Chowdhury, K.
2010-01-01
In this study, a regional scale gravity data set has been inverted to infer the structure (topography) of the top of the basement underlying sub-horizontal strata. We apply our method to this real data set for further proof of concept, validation and benchmarking against results from an earlier
Approximation of Bayesian Inverse Problems for PDEs
Cotter, S. L.; Dashti, M.; Stuart, A. M.
2010-01-01
Inverse problems are often ill posed, with solutions that depend sensitively on data.n any numerical approach to the solution of such problems, regularization of some form is needed to counteract the resulting instability. This paper is based on an approach to regularization, employing a Bayesian formulation of the problem, which leads to a notion of well posedness for inverse problems, at the level of probability measures. The stability which results from this well posedness may be used as t...
Electrochemical Studies of Lead Telluride Behavior in Acidic Nitrate Solutions
Directory of Open Access Journals (Sweden)
Rudnik E.
2015-04-01
Full Text Available Electrochemistry of lead telluride stationary electrode was studied in nitric acid solutions of pH 1.5-3.0. E-pH diagram for Pb-Te-H2O system was calculated. Results of cyclic voltammetry of Pb, Te and PbTe were discussed in correlation with thermodynamic predictions. Anodic dissolution of PbTe electrode at potential approx. -100÷50 mV (SCE resulted in tellurium formation, while above 300 mV TeO2 was mainly produced. The latter could dissolve to HTeO+2 under acidic electrolyte, but it was inhibited by increased pH of the bath.
Study of the flow development of polymer solutions through capillaries
International Nuclear Information System (INIS)
Perez-Gonzalez, J.; De Vargas, L.; Tejero, M.
1991-01-01
Flow experiments through capillaries with semirigid and rigid polymers in aqueous solutions were carried out in order to study the dependence of the flow development on the molecular conformation and the length to diameter ratio (L/D), of the capillary at relatively low shear rates. It was found that the apparent viscosity has a strong dependence upon the ratio L/D for a given shear rate, although an asymptotic value is reached. This dependence was reflected in the non-linearity of Bagley's plots. The asymptotic value was attained at lower L/D values for semirigid molecules than for rigid ones, showing the influence of the molecular conformation on the flow field development due to the different modes of relaxation for each type of molecule. (Author)
Bronchography in dogs. Comparative study with two barium sulphate solutions
International Nuclear Information System (INIS)
Thibaut, J.; Gallardo, P.; Vargas, L.; Deppe, R.; Born, R.
1998-01-01
Two solutions of barium sulphate, 60 and 30% w/v, were compared with the ''overflow'' Bronchographic method. Two groups of eight healthy adult does of both sexes, weighing 7 to 18 kg were used for the study. The dogs were anaesthetised with thiopentone sodium 2% (20 mg/kg iv). After intubation, each dog received contrast medium by a catheter connected to a syringe, in a 9 mi dose. Two series of two x-rays plates were taken in left lateral recumbent, 3 and 6 min after administering the contrast medium and in ventrodorsal projection, 30 sec. later. The x-ray plates obtained were analysed and compared intra and inter group considering the advance speed of the contrast medium, the radiographic density and outlines. Adverse reactions were controlled
A study on caregiver burden: stressors, challenges, and possible solutions.
Bialon, Laura Nelson; Coke, Sallie
2012-05-01
The purpose of this qualitative study was to explore factors impacting caregiver burden and to explore possible solutions for family caregivers of terminally ill patients. The majority of caregivers reported experiencing role conflict and inadequate stress management. Caregivers who worked outside the home, those who cared for two parents concurrently, those with the least amount of outside assistance, and caregivers who spent a longer period of time caregiving reported the highest levels of health problems and overall burden. Caregivers stated a need for more support from Hospice agencies, more education on caregiver training, and more public education about Hospice services. Faith played a positive role in alleviating caregiver burden. Early identification, intervention, education and coordination of services may help to alleviate caregiver burden, which will improve quality of life for both patient and caregiver.
NMR studies of phase behaviour in polyacrylonitrile solutions
International Nuclear Information System (INIS)
Golightly, J.A.
1998-10-01
The aim of the thesis was to study the phase behaviour of aqueous polyacrylonitrile/NaSCN solutions using a variety of nuclear magnetic resonance techniques. Polyacrylonitrile (PAN) is the basis of the acrylic fibre industry, as such fibres contain at least 85% PAN. Despite this industrial importance, the available literature describing the phase behaviour of PAN in solution is far from comprehensive. Bulk 1 H NMR relaxation measurements were carried out over a wide range of concentrations and temperatures to probe the molecular dynamics of the PAN and water molecules. The relaxation data was found to be biexponential decay for all samples, the relative amplitudes of which were shown to be equal to the ratio of PAN protons to water protons. Both species were found to be in the regime of rapid molecular motion. Bulk 1 H NMR self diffusion measurements, using the PFGSTE technique, exhibited a bi-exponential decay of the echo amplitudes. By careful selection of the observation time, Δ, it was possible to independently probe the water and PAN translational diffusion. A background gradient, resulting from inhomogeneities of the magnetic field, complicated the analysis of the data and a novel polynomial least squares fitting procedure was devised to overcome this effect. The measured attenuation of the water diffusion coefficients (D∼10 -6 -10 -5 cm 2 s -1 ) with increasing PAN volume fraction was modelled according to various theories, including free volume and scaling laws. The study of the PAN diffusion coefficient (D∼10 -7 -10 -6 cm 2 s -1 ) was limited by the experimental constraints of the NMR spectrometer. A 1 H NMR one-dimensional imaging technique was used to study the non-solvent induced phase separation (coagulation) of a PAN solution. The time dependence of the measured profiles allowed observation of the coagulation process. A diffusion model was developed to fit the experimental data using a semi-infinite diffusion framework. The fitting parameters
Inverse Kinematics of a Serial Robot
Directory of Open Access Journals (Sweden)
Amici Cinzia
2016-01-01
Full Text Available This work describes a technique to treat the inverse kinematics of a serial manipulator. The inverse kinematics is obtained through the numerical inversion of the Jacobian matrix, that represents the equation of motion of the manipulator. The inversion is affected by numerical errors and, in different conditions, due to the numerical nature of the solver, it does not converge to a reasonable solution. Thus a soft computing approach is adopted to mix different traditional methods to obtain an increment of algorithmic convergence.
Cooling solutions in an operational data centre: A case study
International Nuclear Information System (INIS)
Fakhim, B.; Behnia, M.; Armfield, S.W.; Srinarayana, N.
2011-01-01
The rapid growth in data centres - large computing infrastructures containing vast quantities of data processing and storage equipment - has resulted in their consumption of up to 100 times more energy per square metre than office accommodation. The decrease in processing server sizes and the more efficient use of space and server processing are challenging data centre facilities to provide more power and cooling, significantly increasing energy demands. Energy consumption of data centres can be severely and unnecessarily high due to inadequate localised cooling and densely packed server rack layouts. However, as heat dissipation in data centres rises by orders of magnitude, inefficiencies such as air recirculation causing hot spots and flow short-circuiting will have a significant impact on the thermal manageability and energy efficiency of the cooling infrastructure. Therefore, an efficient thermal management of high-powered electronic equipment is a significant challenge for cooling of data centres. To highlight the importance of some of these issues, in this project, an operational data centre has been studied. Field measurements of temperature have been performed. Numerical analysis of flow and temperature fields is conducted in order to evaluate the thermal behaviour of the data centre. A number of undesirable hot spots have been identified. To rectify the problem, a few practical design and remedial solutions to improve the cooling effectiveness have been proposed and examined to allow a reduced air-conditioning power requirement. The findings lead to a better understanding of the cooling issues and the respective proposed solutions allow an improved design for future data centres. - Highlights: → Study of flow and temperature distribution in an operational data centre. → Both field measurements and numerical simulations are conducted. → Numerical simulations are validated by field measurements. → Various modifications to improve the thermal
Djoussé, Luc; Hopkins, Paul N; North, Kari E; Pankow, James S; Arnett, Donna K; Ellison, R Curtis
2011-04-01
Epidemiologic studies have suggested beneficial effects of flavonoids on cardiovascular disease. Cocoa and particularly dark chocolate are rich in flavonoids and recent studies have demonstrated blood pressure lowering effects of dark chocolate. However, limited data are available on the association of chocolate consumption and the risk of coronary heart disease (CHD). We sought to examine the association between chocolate consumption and prevalent CHD. We studied in a cross-sectional design 4970 participants aged 25-93 years who participated in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study. Chocolate intake was assessed through a semi-quantitative food frequency questionnaire. We used generalized estimating equations to estimate adjusted odds ratios. Compared to subjects who did not report any chocolate intake, odds ratios (95% CI) for CHD were 1.01 (0.76-1.37), 0.74 (0.56-0.98), and 0.43 (0.28-0.67) for subjects consuming 1-3 times/month, 1-4 times/week, and 5+ times/week, respectively (p for trend Consumption of non-chocolate candy was associated with a 49% higher prevalence of CHD comparing 5+/week vs. 0/week [OR = 1.49 (0.96-2.32)]. These data suggest that consumption of chocolate is inversely related with prevalent CHD in a general United States population. Published by Elsevier Ltd.
Study on corrosion of carbon steel in DEA aqueous solutions
Yang, Jun Han; Xie, Jia Lin; Zhang, Li
2018-02-01
Corrosion of carbon steel in the CO2 capture process using diethanolamine (DEA) aqueous solutions was investigated. The effects of the mass concentrations of DEA, solution temperature and CO2 loading on the corrosion rate of carbon steel were demonstrated. The experimental results provided comprehensive information on the appropriate concentration range of DEA aqueous solutions under which low corrosion of carbon steel can be achieved.
Radiolysis studies of uranyl nitrate solution in nitric acid medium
International Nuclear Information System (INIS)
Siri, Sandra; Mondino, Angel V.
2005-01-01
The radiolysis of acidic uranyl nitrate solutions was investigated using Co-60 gamma radiation. Hydrogen peroxide was determined as a function of increasing dose. The UV-vis absorption spectra of the irradiated solutions were measured and the spectral changes were analyzed. The increasing dose increases the absorbance intensities, possibly by an increment in nitrate concentration produced by radiolysis, which can originate the formation of different uranyl complexes in solution. (author)
Study of the 66Ni(t,d)67Ni Transfer Reaction in Inverse Kinematics
Callens, Maarten
The nickel isotopes with 28 protons are an interesting series in the study of nuclear structure. In the framework of the shell model nickel has a closed proton shell and the number of neutrons ranges from the magic numbers 20 to 50. The neutron-rich isotope $^{78}$Ni, is a waiting point in the nucleosynthesis r-process. In this process an intense neutron flux such as in supernovae results in the rapid capture of neutrons. The reaction sequence halts at $^{78}$Ni and waits for this nucleus to decay [Hea05]. For several decades the nickel isotopes have been studied extensively, particularly how the nuclear structure evolves when moving to the exotic boundaries of the nuclear chart. A remarkable feature was observed in $^{68}$Ni. This nucleus with 40 neutrons exhibits properties that are characteristic for doubly magic nuclei. Such as the energy of the first 2$^+$ state lies significantly higher than in neighbouring even-A isotopes, and is also higher than the energy of the second 0$^+$ state. Moreover also the ...
UV laser interaction with a fluorescent dye solution studied using pulsed digital holography.
Amer, Eynas; Gren, Per; Sjödahl, Mikael
2013-10-21
A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously, a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent perpendicularly resulting in a gain through stimulated laser induced fluorescence (LIF) emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Two digital holograms without and with the pump beam were recorded. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to the stimulated LIF. In addition numerical data of the local temperature rise was calculated from the corresponding phase maps using Radon inversion. It was concluded that about 15% of the pump beam energy is transferred to the dye solution as heat while the rest is consumed in the radiative process. The results show that pulsed digital holography is a promising technique for quantitative study of fluorescent species.
Alkerwi, Ala'a; Baydarlioglu, Burcu; Sauvageot, Nicolas; Stranges, Saverio; Lemmens, Paul; Shivappa, Nitin; Hébert, James R
2017-10-01
Relationships between food consumption/nutrient intake and tobacco smoking have been described in the literature. However, little is known about the association between smoking and overall diet quality. This study examined the associations between eight diet quality indices, namely, the Diet Quality Index-International (DQI-I), Recommendation Compliance Index (RCI), Dietary Approach to Stop Hypertension (DASH) score, Energy Density Score (EDS), Dietary Diversity Score (DDS), Recommended Food Score (RFS), non-Recommended Food Score (non-RFS), and Dietary Inflammatory Index (DII), and smoking status with a focus on smoking intensity. Analyses were based on a sample of 1352 participants in the Observation of Cardiovascular Risk Factors in Luxembourg (ORISCAV-LUX) survey, a nationwide population-based cross-sectional study of adults aged 18-69 years. Nutritional data from food frequency questionnaire (FFQ) were used to compute selected diet quality indices. Participants were classified as never smoker, former smoker (≥12 months cessation period), occasional or light smokers (≤1 cig/d), moderate smokers (≤20 cig/d) and heavy smokers (>20 cig/d). Descriptive and linear regression analyses were performed, after adjustment for several potential covariates. Compared to the other groups, heavy smokers had significantly higher prevalence of dyslipidemia (83%), obesity (34%), and elevated glycemic biomarkers. About 50% of former smokers had hypertension. Diet quality of heavy smokers was significantly poorer than those who never smoked independent of several socioeconomic, lifestyle, and biologic confounding factors (all p diet, as expressed by higher DII scores (P diet quality. The implication is that efforts aimed at tobacco control should target heavy smokers and intervention on smoking cessation should take into account diet quality of smokers and their nutritional habits, to increase effectiveness and relevance of public health messages. Copyright © 2016
International Nuclear Information System (INIS)
Ni Jianming; Chen Shuang; Liu Jianjun; Huang Gang; Shen Tianzhen; Chen Xingrong
2010-01-01
Background and purpose: Although diffusion characteristics of white matter (WM) and its aging effects have been well described in the literature, diffusion characteristics of grey matter (GM), especially the cortical GM, have not been fully evaluated. In the present study, we used the fluid-inversion prepared diffusion imaging (FLIPD) technique to determine if there are age-related water diffusivity changes in GM. Materials and methods: 120 healthy volunteers were recruited for our study. They were divided into three age groups: group one (20-39 years old), group two (40-59 years old) and group three (60 years or older). All patients were evaluated with MRI using FLIPD at 3.0 T. Apparent diffusion coefficient (ADC) values of the frontal GM, cingulate cortex and thalami were determined bilaterally by region-of-interest analysis. Results: Group three had significantly higher ADC values in both thalami and the left frontal GM compared to group two or group one. No ADC value difference was found among the three groups in the right frontal GM and bilateral cingulate cortex. There was a significant positive correlation between individual ADC values and age in both thalami and left frontal GM. For the cingulate cortex and the right frontal GM, ADC values did not correlate significantly with advancing age. Conclusion: Statistically significant age-related diffusion changes were observed in both thalami and the left frontal cortex. The data reported here may serve as a reference for future studies.
Directory of Open Access Journals (Sweden)
Lane Athene J
2008-04-01
Full Text Available Abstract Background In a cross-sectional community based study, as part of a randomised controlled trial of eradication of Helicobacter pylori infection, the association between blood pressure and symptoms of gastro-oesophageal reflux was examined. Methods Linear regression was used to examine the association between systolic and diastolic blood pressure and the frequency of heartburn and acid regurgitation in 4,902 of 10,537 participants aged 20–59 years. Results In multivariable analyses, adjusted mean systolic blood pressure was 4.2 (95% confidence interval 1.5 to 7.0 mm Hg lower in participants with daily acid regurgitation compared to those with less frequent symptoms. Similarly, for diastolic blood pressure, a reduction of 2.1 (0.0 to 4.3 mm Hg wasobserved. Conclusion People who experience daily symptoms of gastro-oesophageal reflux have lower blood pressure than people with less frequent or no symptoms. It is possible that factors influencing nitric oxide concentrations both at the lower oesophageal sphincter and within the vasculature may be involved. This hypothesis requires confirmation. Trials registration number ISRCTN44816925
Fast Component Pursuit for Large-Scale Inverse Covariance Estimation.
Han, Lei; Zhang, Yu; Zhang, Tong
2016-08-01
The maximum likelihood estimation (MLE) for the Gaussian graphical model, which is also known as the inverse covariance estimation problem, has gained increasing interest recently. Most existing works assume that inverse covariance estimators contain sparse structure and then construct models with the ℓ 1 regularization. In this paper, different from existing works, we study the inverse covariance estimation problem from another perspective by efficiently modeling the low-rank structure in the inverse covariance, which is assumed to be a combination of a low-rank part and a diagonal matrix. One motivation for this assumption is that the low-rank structure is common in many applications including the climate and financial analysis, and another one is that such assumption can reduce the computational complexity when computing its inverse. Specifically, we propose an efficient COmponent Pursuit (COP) method to obtain the low-rank part, where each component can be sparse. For optimization, the COP method greedily learns a rank-one component in each iteration by maximizing the log-likelihood. Moreover, the COP algorithm enjoys several appealing properties including the existence of an efficient solution in each iteration and the theoretical guarantee on the convergence of this greedy approach. Experiments on large-scale synthetic and real-world datasets including thousands of millions variables show that the COP method is faster than the state-of-the-art techniques for the inverse covariance estimation problem when achieving comparable log-likelihood on test data.
Electrochemically driven emulsion inversion
Johans, Christoffer; Kontturi, Kyösti
2007-09-01
It is shown that emulsions stabilized by ionic surfactants can be inverted by controlling the electrical potential across the oil-water interface. The potential dependent partitioning of sodium dodecyl sulfate (SDS) was studied by cyclic voltammetry at the 1,2-dichlorobenzene|water interface. In the emulsion the potential control was achieved by using a potential-determining salt. The inversion of a 1,2-dichlorobenzene-in-water (O/W) emulsion stabilized by SDS was followed by conductometry as a function of added tetrapropylammonium chloride. A sudden drop in conductivity was observed, indicating the change of the continuous phase from water to 1,2-dichlorobenzene, i.e. a water-in-1,2-dichlorobenzene emulsion was formed. The inversion potential is well in accordance with that predicted by the hydrophilic-lipophilic deviation if the interfacial potential is appropriately accounted for.
A study on the structure of thorium salt solutions
International Nuclear Information System (INIS)
Magini, M.; Cabrini, A.; Di Bartolomeo, A.
1975-01-01
The structure of highly hydrolyzed thorium salt solutions has been investigated by large and small angle X-ray scattering techniques. The diffraction data obtained with large angle measurements show the presence in solution of microcrystalline particles with the thorium oxide structure. Particles larger than those were discovered by small angle measurements. A possible shape of these colloidal particles has been discussed
Struggling with solutions : a case study of using organisation concepts
Benders, Jos; Slomp, Jannes
2009-01-01
Engineers contribute to the constant flow of new tools and organisation concepts. These tend to be presented as solutions to existing organisational problems. These solutions may become problems themselves, however. We present a longitudinal case of how a truck manufacturer struggled with various
International Nuclear Information System (INIS)
Zhang Peng; Hugo, Geoffrey D.; Yan Di
2008-01-01
Purpose: Real-time target tracking (RT-TT) and four-dimensional inverse planning (4D-IP) are two potential methods to manage respiratory target motion. In this study, we evaluated each method using the cumulative dose-volume criteria in lung cancer radiotherapy. Methods and Materials: Respiration-correlated computed tomography scans were acquired for 4 patients. Deformable image registration was applied to generate a displacement mapping for each phase image of the respiration-correlated computed tomography images. First, the dose distribution for the organs of interest obtained from an idealized RT-TT technique was evaluated, assuming perfect knowledge of organ motion and beam tracking. Inverse planning was performed on each phase image separately. The treatment dose to the organs of interest was then accumulated from the optimized plans. Second, 4D-IP was performed using the probability density function of respiratory motion. The beam arrangement, prescription dose, and objectives were consistent in both planning methods. The dose-volume and equivalent uniform dose in the target volume, lung, heart, and spinal cord were used for the evaluation. Results: The cumulative dose in the target was similar for both techniques. The equivalent uniform dose of the lung, heart, and spinal cord was 4.6 ± 2.2, 11 ± 4.4, and 11 ± 6.6 Gy for RT-TT with a 0-mm target margin, 5.2 ± 3.1, 12 ± 5.9, and 12 ± 7.8 Gy for RT-TT with a 2-mm target margin, and 5.3 ± 2.3, 11.9 ± 5.0, and 12 ± 5.6 Gy for 4D-IP, respectively. Conclusion: The results of our study have shown that 4D-IP can achieve plans similar to those achieved by RT-TT. Considering clinical implementation, 4D-IP could be a more reliable and practical method to manage patient respiration-induced motion
Chen, Qing; Yang, Huan; Zhou, Niya; Sun, Lei; Bao, Huaqiong; Tan, Lu; Chen, Hongqiang; Ling, Xi; Zhang, Guowei; Huang, Linping; Li, Lianbing; Ma, Mingfu; Yang, Hao; Wang, Xiaogang; Zou, Peng; Peng, Kaige; Liu, Taixiu; Cui, Zhihong; Ao, Lin; Roenneberg, Till; Zhou, Ziyuan; Cao, Jia
2016-01-01
Study Objectives: To investigate the association between sleep duration and semen parameters as well as reproductive hormone levels. Methods: We designed a cohort of male college students in Chongqing, China. A total of 796 subjects were recruited in 2013 and 656 (82.4%) were followed up in 2014. Each time, semen and peripheral blood samples were collected for semen quality and reproductive hormone measurement. Sleep duration was estimated by revised Munich Chronotype Questionnaire. In 2014, sleep quality was also measured by Pittsburgh Sleep Quality Index (PSQI). Results: There was a substantial inverse U-shaped association between sleep duration and two semen parameters (semen volume and total sperm number), with 7.0–7.5 h/day of sleep showing highest parameters. Either longer or shorter sleep was associated with decreased semen parameters in a dose-response manner (P = 0.002 and 0.001, respectively). Sleeping > 9.0 h was associated with a 21.5% (95% confidence interval 9.2, 32.2) reduction in semen volume and 39.4% (23.3, 52.1) reduction in total sperm number; sleeping ≤ 6.5 h was associated with 4.6% (−10.5, 22.3) and 25.7% (−1.2, 60.1) reduction. Increase of the two parameters was found in those who changed sleep duration toward 7.0–7.5 h/day from 2013 to 2014. The U-shaped association was independent from PSQI and was replicated in another dataset of 1,346 males. No association found between sleep duration and reproductive hormone. Conclusions: Either restricted or excessive sleep may impair semen quality. Further research is needed to validate this finding. Citation: Chen Q, Yang H, Zhou N, Sun L, Bao H, Tan L, Chen H, Ling X, Zhang G, Huang L, Li L, Ma M, Yang H, Wang X, Zou P, Peng K, Liu T, Cui Z, Ao L, Roenneberg T, Zhou Z, Cao J. Inverse u-shaped association between sleep duration and semen quality: longitudinal observational study (MARHCS) in Chongqing, China. SLEEP 2016;39(1):79–86. PMID:26350472
QENS and NMR studies of 3-picoline-water solutions
Almasy, L; Bokor, M; Cser, L; Tompa, K; Zanotti, J M; Jancso, G
2002-01-01
Quasi-elastic neutron scattering measurements were performed on aqueous solutions of 3-picoline (3-methylpyridine) at room temperature. H-D substitution on both the solute and the water was used to separate the dynamics of the two species. The analysis of the translational diffusive motion at different concentrations shows that at high picoline content the diffusion coefficient of water decreases strongly and becomes similar to that of the solute, indicating strong coupling between the motions of the solute and the solvent. Activation energies characteristic of the dynamic behavior of the methyl group were determined from sup 1 H spin-lattice relaxation rate measurements for H sub 2 O and D sub 2 O solutions of 3-picoline above 310 K. (orig.)
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Ben-Shian Huang
2016-07-01
Full Text Available This study was conducted to determine the risk of chronic kidney disease (CKD among women with endometriosis in Taiwan. We conducted a retrospective cohort study using the National Health Insurance Research Database of Taiwan. A total of 27,973 women with a diagnosis of endometriosis and 27,973 multivariable-matched controls (1:1 from 2000 to 2010 were selected. Cox regression and computed hazard ratios (HR with 95% confidence intervals (95% CI were used to determine the risk of CKD among women with endometriosis. The incidence rates (IR, per 10,000 person-years of CKD among women with and without endometriosis were 4.64 and 7.01, respectively, with a significantly decreased risk of CKD (crude HR 0.65, 95% CI 0.53–0.81; adjusted HR 0.69, 95% CI 0.56–0.86 among women with endometriosis. The IR of CKD progressively increased with age, but the trend of lower CKD risk among women with endometriosis was consistent. However, the lower risk of CKD in women with endometriosis was no longer statistically significant after adjusting for menopausal status (adjusted HR 0.85, 95% CI 0.65–1.10. The results suggest that endometriosis is inversely associated with CKD, but this effect was mediated by menopause. The possible mechanism of this association is worthy of further evaluation.
International Nuclear Information System (INIS)
Safronov, A.N.
2007-01-01
Full text: The pion-nucleon dynamics is one of the most fundamental problems in nuclear and particle physics. It is now widely believed that QCD is fundamental theory of strong interactions. On this basis all hadron-hadron interactions are completely determined by the underlying quark-gluon dynamics. However, due to the formidable mathematical problems raised by the non-perturbative character of QCD at low and intermediate energies, we are still far from a quantitative understanding hadron-hadron interactions from this point of view. Recently the relativistic approaches to constructing effective interaction operators between strongly interacting composite particles has been proposed on the basis of analytic S-matrix theory and methods for solving the inverse quantum scattering problem. The kernel of Marchenko equation in theory of inverse scattering problem can be expressed in terms of the discontinuity of the partial wave amplitude on dynamic cut in the complex s=k 2 plane, k being the relative momentum of colliding particles. The discontinuities of partial-wave amplitudes are determined by model-independent quantities (renormalized vertex constants and amplitudes of sub-processes involving on-mass-shell particles off physical region) and can be calculated by methods of relativistic quantum field theory within various dynamical approaches. In particular, effective field theory can be used to calculate the discontinuities across dynamical cuts closest to physical region. In present work a new manifestly Poincare-invariant approach to solving the inverse scattering problem is developed with allowance for inelasticity effects. The equations of the N/D method are used as dynamical equations in this approach. With the help of N/D-equations it was earlier shown that solution of a scattering problem in case of nonzero angular momentum does not exist for arbitrary discontinuity of partial-wave amplitude. The method is elaborated allowing to determine contributions of
Application of Solution NMR Spectroscopy to Study Protein Dynamics
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Christoph Göbl
2012-03-01
Full Text Available Recent advances in spectroscopic methods allow the identification of minute fluctuations in a protein structure. These dynamic properties have been identified as keys to some biological processes. The consequences of this structural flexibility can be far‑reaching and they add a new dimension to the structure-function relationship of biomolecules. Nuclear Magnetic Resonance (NMR spectroscopy allows the study of structure as well as dynamics of biomolecules in a very broad range of timescales at atomic level. A number of new NMR methods have been developed recently to allow the measurements of time scales and spatial fluctuations, which in turn provide the thermodynamics associated with the biological processes. Since NMR parameters reflect ensemble measurements, structural ensemble approaches in analyzing NMR data have also been developed. These new methods in some instances can even highlight previously hidden conformational features of the biomolecules. In this review we describe several solution NMR methods to study protein dynamics and discuss their impact on important biological processes.
Nonlinear problems in fluid dynamics and inverse scattering: Nonlinear waves and inverse scattering
Ablowitz, Mark J.
1994-12-01
Research investigations involving the fundamental understanding and applications of nonlinear wave motion and related studies of inverse scattering and numerical computation have been carried out and a number of significant results have been obtained. A class of nonlinear wave equations which can be solved by the inverse scattering transform (IST) have been studied, including the Kadaomtsev-Petviashvili (KP) equation, the Davey-Stewartson equation, and the 2+1 Toda system. The solutions obtained by IST correspond to the Cauchy initial value problem with decaying initial data. We have also solved two important systems via the IST method: a 'Volterra' system in 2+1 dimensions and a new one dimensional nonlinear equation which we refer to as the Toda differential-delay equation. Research in computational chaos in moderate to long time numerical simulations continues.
Inverse problems in ordinary differential equations and applications
Llibre, Jaume
2016-01-01
This book is dedicated to study the inverse problem of ordinary differential equations, that is it focuses in finding all ordinary differential equations that satisfy a given set of properties. The Nambu bracket is the central tool in developing this approach. The authors start characterizing the ordinary differential equations in R^N which have a given set of partial integrals or first integrals. The results obtained are applied first to planar polynomial differential systems with a given set of such integrals, second to solve the 16th Hilbert problem restricted to generic algebraic limit cycles, third for solving the inverse problem for constrained Lagrangian and Hamiltonian mechanical systems, fourth for studying the integrability of a constrained rigid body. Finally the authors conclude with an analysis on nonholonomic mechanics, a generalization of the Hamiltonian principle, and the statement an solution of the inverse problem in vakonomic mechanics.
Autenrieth, Christine S; Kirchberger, Inge; Heier, Margit; Zimmermann, Anja-Kerstin; Peters, Annette; Döring, Angela; Thorand, Barbara
2013-07-01
Physical activity is suggested to play a key role in the prevention of several chronic diseases. However, data on the association between physical activity and multimorbidity are lacking. Using data from 1007 men and women aged 65-94 years who participated in the population-based KORA (Cooperative Health Research in the Region of Augsburg)-Age project conducted in Augsburg/Germany and two adjacent counties in 2008/09, 13 chronic conditions were identified, and physical activity scores were calculated based on the self-reported physical activity scale for the elderly (PASE). Multivariable sex-specific logistic regression was applied to determine the association of the continuous physical activity score with multimorbidity (≥ 2 out of 13 diseases). Physical activity (mean PASE score±SD) was higher in men (125.1 ± 59.2) than in women (112.2 ± 49.2). Among men, the odds ratio (OR) for multimorbidity was 0.73 (95% CI: 0.60-0.90) for a 1 standard deviation increase of the PASE score. No significant results could be observed for women (OR: 1.05; 95% CI: 0.83-1.33). We demonstrated an inverse association between physical activity and multimorbidity among men. Further prospective studies have to confirm the temporality of effects. Copyright © 2013 Elsevier Inc. All rights reserved.
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Roberta de Oliveira Santos
2017-07-01
Full Text Available Abstract Background The association of obesity and dietary patterns has been well documented in scientific literature; however, information on the impact of meal patterns on obesity is scarce. The objective of this study was to investigate the association of adherence to lunch patterns and body mass index (BMI in a representative sample of individuals aged 20 years or older in Sao Paulo. Methods Data for 933 participants were retrieved from the Health Survey of São Paulo (ISA-Capital 2008, a cross-sectional population-based survey. The usual dietary intake of individuals with at least one 24-h recall was estimated by the Multiple Source Method. The definition of lunch was self-reported by the participant. Five lunch patterns were derived from twenty-two food groups by exploratory factor analysis: Traditional, Western, Sweetened juice, Salad, and Meats. To estimate the effect of lunch patterns on BMI, we used a generalized linear model with link identity and inverse Gaussian distribution. Analyses were adjusted by age, gender, household income per capita, physical activity levels, smoking status, alcohol consumption, total energy intake, and misreporting status. Results The greater adherence to the traditional pattern at the lunch meal was associated with lower BMI, only in insufficiently active individuals (ß = −0.78; 95% CI -1.57; −0.02. Conclusions The traditional Brazilian lunch pattern might protect the insufficiently active individuals against obesity.
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Xiujuan Wang
2006-01-01
Full Text Available Bottom-simulating reflectors (BSRs were observed beneath the seafloor in the northern continental margin of the South China Sea (SCS. Acoustic impedance profile was derived by Constrained Sparse Spike Inversion (CSSI method to provide information on rock properties and to estimate gas hydrate or free gas saturations in the sediments where BSRs are present. In general, gas hydrate-bearing sediments have positive impedance anomalies and free gas-bearing sediments have negative impedance anomalies. Based on well log data and Archie's equation, gas hydrate saturation can be estimated. But in regions where well log data is not available, a quantitative estimate of gas hydrate or free gas saturation is inferred by fitting the theoretical acoustic impedance to sediment impedance obtained by CSSI. Our study suggests that gas hydrate saturation in the Taixinan Basin is about 10 - 20% of the pore space, with the highest value of 50%, and free gas saturation below BSR is about 2 - 3% of the pore space, that can rise to 8 - 10% at a topographic high. The free gas is non-continuous and has low content in the southeastern slope of the Dongsha Islands. Moreover, BSR in the northern continental margin of the SCS is related to the presence of free gas. BSR is strong where free gas occurs.
A study on CT attenuation and MR signal intensity of protein solution
International Nuclear Information System (INIS)
Kim, Joung Hae; Choi, Dae Seob; Kim, Soon; Lee, Hyeon Kyeong; Oh, Hyeon Hee; Kim, Seung Hyeon; Lee, Sung Woo; Chang, Kee Hyun; Chung, Jun Ho
2001-01-01
To correlate CT attenuation and MR signal intensity with concentration of protein solution. CT and MR examinations of a phantom containing bovine serum albumin solutions of various concentrations ranging from 0 to 55% were performed. CT Hounsfield units(HUs), MR signal intensities, and apparent diffusion coefficients (ADCs) of each albumin solution were measured, and CT HUs and MR signal intensities of the solutions were compared with those of cerebrospinal fluid (CSF), white matter, and cortical gray matter. CT HU increased gradually with increasing albumin concentration. On T1-weighted images(T1WI), signal intensity increased with increasing albumin concentrations of up to 35% but then decreased. On T2-weighted images(T2Wl), gradually decreasing signal intensity and increasing albumin concentration were observed Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images (DWls) showed that signal intensity peaked at a concentration of 10% and then gradually decreased. The ADC of the solution gradually decreased as concentration increased. Compared with those of normal brain structures, the CT HUs of solutions at concentrations of over 20% were higher than those of white and gray matter. At T1WI, the signal intensities of 10-45% solutions were similar to or higher than that of the gray matter. At T2Wl, the signal intensities of solutions above 25, 35, and 40% were lower than those of CSF, gray matter, and white matter, respectively. FLAIR images showed that the signal intensities of 5-35% solutions were higher than that of gray matter. The CT attenuation of albumin solution increased gradually with increasing concentration. MR signal intensities peaked at 35% concentration on T1WI and at 10% on FLAIR and DW images, respectively, and then gradually decreased. T2Wl and ADC map images showed gradually decreasing signal intensity and ADC as albumin concentration increased
Kyrke-Smith, Teresa M.; Gudmundsson, G. Hilmar; Farrell, Patrick E.
2018-04-01
Given high-resolution satellite-derived surface elevation and velocity data, ice-sheet models generally estimate mechanical basal boundary conditions using surface-to-bed inversion methods. In this work, we address the sensitivity of results from inversion methods to the accuracy of the bed elevation data on Pine Island Glacier. We show that misfit between observations and model output is reduced when high-resolution bed topography is used in the inverse model. By looking at results with a range of detail included in the bed elevation, we consider the separation of basal drag due to the bed topography (form drag) and that due to inherent bed properties (skin drag). The mean value of basal shear stress is reduced when more detailed topography is included in the model. This suggests that without a fully resolved bed a significant amount of the basal shear stress recovered from inversion methods may be due to the unresolved bed topography. However, the spatial structure of the retrieved fields is robust as the bed accuracy is varied; the fields are instead sensitive to the degree of regularisation applied to the inversion. While the implications for the future temporal evolution of PIG are not quantified here directly, our work raises the possibility that skin drag may be overestimated in the current generation of numerical ice-sheet models of this area. These shortcomings could be overcome by inverting simultaneously for both bed topography and basal slipperiness.
Dielectric relaxation studies of dilute solutions of amides
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Malathi, M.; Sabesan, R.; Krishnan, S
2003-11-15
The dielectric constants and dielectric losses of formamide, acetamide, N-methyl acetamide, acetanilide and N,N-dimethyl acetamide in dilute solutions of 1,4-dioxan/benzene have been measured at 308 K using 9.37 GHz, dielectric relaxation set up. The relaxation time for the over all rotation {tau}{sub (1)} and that for the group rotation {tau}{sub (2)} of (the molecules were determined using Higasi's method. The activation energies for the processes of dielectric relaxation and viscous flow were determined by using Eyring's rate theory. From relaxation time behaviour of amides in non-polar solvent, solute-solvent and solute-solute type of molecular association is proposed.
Small angle neutron scattering (SANS) study of gastric mucin solutions
Hong, Z.; Bansil, R.; Waigh, T.; Turner, B.; Bhaskar, K. R.; Afdhal, N.; Lal, J.
2002-03-01
We report the first results from a SANS study of purified porcine gastric mucin solutions in D2O. The ability of this glycoprotein to protect the stomach epithelium from acid damage, may be due to a pH dependent conformational transition which leads to gelation at low pH Cao et. al. (Biophysical. J. 76, 1250, 1999). SANS measurements were made over the concentration range of 1 -15 mg/ml at pH 7, 4 and 2. The data indicate that at pH 7 the excluded volume exponent is 1.7, characteristic of swollen chains whereas at pH 2 this exponent increases to 2, indicating theta or poor solvent conditions, consistent with the hydrophobic interactions increasing at lower pH. From a Guinier analysis of the 1mg/ml data at low q's (0.003- 0.007 Å-1) we estimate the cross section radius of the effective cylinder to be 23nm and its length as 96nm in an unbuffered sample, i.e. close to pH 7. In the intermediate q-range (0.01 -0.1Å-1) at pH 7 a fit to the Debye chain gives radius of gyration Rg of 16nm. Mucin is best modelled as an elongated micelle with a cylindrical or worm-like chain to represent the protein core and the sugar chains forming the corona. Results of such calculations will be presented.
Interactive Tutoring in Blended Studies: Hindrances and Solutions
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Asim Ismail Ilyas (Al-Titinchy
2016-01-01
Full Text Available This paper distinguishes between traditional teaching known as lecturing (the teacher centered approach; and tutoring (the contemporary technology-oriented interactive teaching/learning approach. It is based on the implementation of tutoring strategies of ‘blended studies’ at the Arab Open University. It investigates the application of modern interactive teaching/learning strategies, specifying some hindering factors in the AOU-Jordan Branch context. The factors include four variables: tutors, students, course material and assessment. The paper is based on qualitative research in terms of a real teaching/leaning context, using both observation and conversation with learners, besides the use of some quantitative data retrieved from a questionnaire in which learners’ views are sought regarding a number of relevant matters. A number of suggested solutions related to each of the hindering factors are presented, which if applied, may secure shifting the balance of the teaching/learning process to a more interactive technology-based tutoring level, which in turn will enhance learners’ opportunities for the attainment of better academic standards, and secure a higher degree of achievement of the shared educational goals of learners and the educational institution they study in.
Static and dynamic light scattering studies on dilute polyrotaxane solutions
Kume, Tetsuya; Araki, Jun; Sakai, Yasuhiro; Mayumi, Koichi; Kidowaki, Masatoshi; Yokoyama, Hideaki; Ito, Kohzo
2009-08-01
Static and dynamic light scattering measurements were performed for dilute polyrotaxane solutions in different types of solvent systems, i.e. dimethylacetamide (DMAc) or dimethylformamide (DMF) containing 1-6 wt% lithium chloride (LiCl), 1 M aqueous sodium hydroxide (NaOH) and dimethylsulfoxide (DMSO). No aggregation of the polyrotaxane in DMF/LiCl was confirmed in the present study. Radius of gyration of the dissolved polyrotaxane was largest in NaOHaq., followed by values in amide solvents/LiCl and that in DMSO, and was probably dominated not by Coulombic repulsion but by the mutual affinity between solvent and polyrotaxane. Ratio of radius of gyration to hydrodynamic radius suggested the flexible random-coiled conformation in DMSO and relatively more extended, semi-flexible ones in amide solvents/LiCl and NaOHaq. The obtained values of second virial coefficient and weight average molecular weight seemed to be affected by a potential change in differential refractive index increments, caused by selective macrocationization or ionization.
Static and dynamic light scattering studies on dilute polyrotaxane solutions
International Nuclear Information System (INIS)
Kume, Tetsuya; Sakai, Yasuhiro; Mayumi, Koichi; Kidowaki, Masatoshi; Yokoyama, Hideaki; Ito, Kohzo; Araki, Jun
2009-01-01
Static and dynamic light scattering measurements were performed for dilute polyrotaxane solutions in different types of solvent systems, i.e. dimethylacetamide (DMAc) or dimethylformamide (DMF) containing 1-6 wt% lithium chloride (LiCl), 1 M aqueous sodium hydroxide (NaOH) and dimethylsulfoxide (DMSO). No aggregation of the polyrotaxane in DMF/LiCl was confirmed in the present study. Radius of gyration of the dissolved polyrotaxane was largest in NaOHaq., followed by values in amide solvents/LiCl and that in DMSO, and was probably dominated not by Coulombic repulsion but by the mutual affinity between solvent and polyrotaxane. Ratio of radius of gyration to hydrodynamic radius suggested the flexible random-coiled conformation in DMSO and relatively more extended, semi-flexible ones in amide solvents/LiCl and NaOHaq. The obtained values of second virial coefficient and weight average molecular weight seemed to be affected by a potential change in differential refractive index increments, caused by selective macrocationization or ionization.
Radiolytic studies of the cumyloxyl radical in aqueous solutions
International Nuclear Information System (INIS)
Neta, P.; Dizdaroglu, M.; Simic, M.G.
1984-01-01
Formation and reactions of the cumyloxyl radical in aqueous solutions were studied by steady-state and pulse radiolytic techniques. Cumene hydroperoxide reacts with esub(aq)sup(-) (k = 4.4x10 9 M -1 s -1 ) to yield the cumyloxyl radical. The spectrum recorded after the pulse indicates formation of a species absorbing at 250 nm. This product was identified as acetophenone, which is formed by the fragmentation of the cumyloxyl radical. By comparison of the pseudo-first-order rates of esub(aq)sup(-) decay at 600 nm with the rate of production of acetophenone at 245 nm at increasing concentrations of cumene hydroperoxide, it was possible to derive a rate constant of 1.0x10 7 s -1 for the cleavage of cumyloxyl to acetophenone and methyl radical. This value is higher than that measured previously in organic solvents (1x10 6 s -1 ), as expected. HPLC analysis of the radiation products acetophenone and cumyl alcohol permitted determination of rate constants for hydrogen abstraction by the cumyloxyl radical, in competition with the fragmentation. The rate constants for H abstraction from i-PrOH, EtOH, and MeOH by CmO were found to be 9.9x10 6 , 3.8x10 6 , and 8.5x10 5 M -1 s -1 , respectively
Isopiestic studies of aqueous solutions at elevated temperatures
International Nuclear Information System (INIS)
Holmes, H.F.; Mesmer, R.E.
1981-01-01
Isopiestic measurements have been made on SrCl 2 (aq) and BaCl 2 (aq) over the temperature range 382.96 to 473.61 K with NaCl(aq) as the reference solution for the calculation of osmotic coefficients. The molalities corresponded to NaCl(aq) molalities ranging from 0.6 to 6.5 mol kg -1 . An ion-interaction model was fitted to the osmotic coefficients of SrCl 2 (aq) and BaCl 2 (aq) with a standard deviation of fit (in the osmotic coefficient) ranging from 0.0007 to 0.0048. Parameters derived from the fit were used to calculate the activity coefficients. The osmotic and activity coefficients decrease with increasing temperature and become less dependent on molality. Previous isopiestic results between 318 and 394 K agree with the present study. Activity coefficients from electrochemical measurements between 283.15 and 343.15 K are not consistent with the isopiestic results. (author)
SFG study of platinum electrodes in perchloric acid solutions
Zheng, W. Q.; Pluchery, O.; Tadjeddine, A.
2002-04-01
Infrared-visible sum-frequency generation (SFG) spectroscopy has been used to study the structure of water molecules (and/or its derivatives OH -, H 3O + etc.) at aqueous electrolyte/electrode interfaces. For Pt(1 1 0) and Pt(1 0 0) electrodes in 0.1 M perchloric acid solution, we did not observe any significant O-H stretching resonance. In striking contrast to the resonant SFG signal, the nonresonant SFG (NRSFG) signal varies sensitively with the applied electrochemical potential, indicating that the interaction of water molecules with platinum electrodes is relatively weak as compared to that of H + and ClO 4- ions. From changes in the NRSFG signal and on the basis of an ionic adsorption model, we can also deduce that the potential of zero charge of Pt(1 1 0) in 0.1 M HClO 4 should be located at about 0.22 V (vs. NHE). This value is in good agreement with that measured recently by electrochemical method.
International Nuclear Information System (INIS)
Mauborgne, Bernard
1979-01-01
Systems of immiscible aqueous solutions composed by a phase rich in mineral salt and by another phase almost totally containing an organic salt, have been studied for years, with quaternary ammonium salts with an organic cation. The objective of this research is to study systems symmetric to the previous ones, i.e. with organic anions such as alkyl phosphates, and then to try to understand mechanisms of extraction of metals in these environments. Based on properties of immiscible aqueous solutions, an original three-phase process of liquid-liquid extraction has been developed, and is used to separate uranium in phosphoric acids with better performance than the existing industrial processes [fr
Haghighatdoost, Fahimeh; Kelishadi, Roya; Qorbani, Mostafa; Heshmat, Ramin; Motlagh, Mohammad Esmaeil; Ardalan, Gelayol; Azadbakht, Leila
2017-04-01
Family dinner is a proxy of family connectedness that may affect mental health. The present study aimed to examine the associations of frequency of family dinner with mental disorders and obesity in a nationally-representative sample of Iranian adolescents. A total of 5528 Iranians adolescents aged 10-18 years were enrolled in 2009-2010 in the third survey of a national surveillance program, entitled Childhood and Adolescence Surveillance and Prevention of Adult Non-communicable disease (CASPIAN-III) study. The frequency of family dinner meal was assessed. Mental health assessments were done as part of the World Health Organization-Global School-based Student Health Survey. The odds of having mental disorders and obesity were assessed by logistic regression. No significant difference was found in dietary intake between family dinner consumers (≥5 times (night)/wk) and skippers (dinner consumers had lower odds for all types of mental disorders (OR = 0.55; 95% CI = 0.47-0.64), anxiety (OR = 0.47; 95% CI = 0.4-0.54), insomnia (OR = 0.6; 95% CI = 0.53-0.7), and confusion (OR = 0.7; 95% CI = 0.6-0.86), as well as the body mass index- z score (OR = 0.78; 95% CI = 0.73-0.84). The current study showed an inverse relationship between the frequency of family dinner consuming and mental disorders and obesity in a nationally-representative sample of Iranian adolescents. Such simple recommendations for consuming family dinner for families may be feasible, sustainable, and effective for health promotion and disease prevention.
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Cristaldi, Alice; Ermolli, Ilaria, E-mail: alice.cristaldi@oaroma.inaf.it [INAF Osservatorio Astronomico di Roma, via Frascati 33, Monte Porzio Catone, I-00078 (Italy)
2017-06-01
Present-day semi-empirical models of solar irradiance (SI) variations reconstruct SI changes measured on timescales greater than a day by using spectra computed in one dimensional atmosphere models (1D models), which are representative of various solar surface features. Various recent studies have pointed out, however, that the spectra synthesized in 1D models do not reflect the radiative emission of the inhomogenous atmosphere revealed by high-resolution solar observations. We aimed to derive observation-based atmospheres from such observations and test their accuracy for SI estimates. We analyzed spectropolarimetric data of the Fe i 630 nm line pair in photospheric regions that are representative of the granular quiet-Sun pattern (QS) and of small- and large-scale magnetic features, both bright and dark with respect to the QS. The data were taken on 2011 August 6, with the CRisp Imaging Spectropolarimeter at the Swedish Solar Telescope, under excellent seeing conditions. We derived atmosphere models of the observed regions from data inversion with the SIR code. We studied the sensitivity of results to spatial resolution and temporal evolution, and discuss the obtained atmospheres with respect to several 1D models. The atmospheres derived from our study agree well with most of the 1D models we compare our results with, both qualitatively and quantitatively (within 10%), except for pore regions. Spectral synthesis computations of the atmosphere obtained from the QS observations return an SI between 400 and 2400 nm that agrees, on average, within 2.2% with standard reference measurements, and within −0.14% with the SI computed on the QS atmosphere employed by the most advanced semi-empirical model of SI variations.
Reinwald, Michael; Bernauer, Moritz; Igel, Heiner; Donner, Stefanie
2016-10-01
With the prospects of seismic equipment being able to measure rotational ground motions in a wide frequency and amplitude range in the near future, we engage in the question of how this type of ground motion observation can be used to solve the seismic source inverse problem. In this paper, we focus on the question of whether finite-source inversion can benefit from additional observations of rotational motion. Keeping the overall number of traces constant, we compare observations from a surface seismic network with 44 three-component translational sensors (classic seismometers) with those obtained with 22 six-component sensors (with additional three-component rotational motions). Synthetic seismograms are calculated for known finite-source properties. The corresponding inverse problem is posed in a probabilistic way using the Shannon information content to measure how the observations constrain the seismic source properties. We minimize the influence of the source receiver geometry around the fault by statistically analyzing six-component inversions with a random distribution of receivers. Since our previous results are achieved with a regular spacing of the receivers, we try to answer the question of whether the results are dependent on the spatial distribution of the receivers. The results show that with the six-component subnetworks, kinematic source inversions for source properties (such as rupture velocity, rise time, and slip amplitudes) are not only equally successful (even that would be beneficial because of the substantially reduced logistics installing half the sensors) but also statistically inversions for some source properties are almost always improved. This can be attributed to the fact that the (in particular vertical) gradient information is contained in the additional motion components. We compare these effects for strike-slip and normal-faulting type sources and confirm that the increase in inversion quality for kinematic source parameters is
Further study of the reactions of fishes to toxic solutions
Energy Technology Data Exchange (ETDEWEB)
Jones, J R.E.
1948-01-01
This paper records some further observations on the reactions of fish to toxic solutions. The method of experimentation resembles that described in a previous paper by the writer (Jones, 1947b). In every case the solution is presented as an alternative to the Aberystwyth tap water, which is well aerated, very soft, of pH 6.8. In experiments with sodium sulphide a supply system is arranged in which dilute sodium sulphide solution, brought to pH 6.8 by the addition of sulphuric acid, is automatically made up as it runs into the observation vessel. Gasterosteus aculeatus l. reacts negatively to a 0.001N solution almost immediately; at greater dilution the reaction time lengthens, at 0.00008N is about 47 min. Over the concentration range tested the reaction time is always shorter than the survival time. Gasterosteus is positive to 0.04N lead nitrate. As a positive reaction is also displayed to equivalent concentrations of calcium nitrate, sodium nitrate and sodium chloride it is possible that the osmotic pressure of the solution is its attractive feature. At 0.01N the positive response to lead nitrate disappears and at 0.004N is replaced by a very definite negative reaction which is maintained down to 0.00002N. The minnow (Phoxinus phoxinus l.) is also negative to dilute lead nitrate and will detect and avoid a 0.000004N solution. Gasterosteus will avoid water more acid than pH 5.6 or more alkaline than pH 11.4. Over the range 5.8-11.2 the fish are indifferent or very vaguely positive. Gasterosteus is negative to 0.04 and 0.01N ammonia solution, positive to 0.001 and 0.0001N. The general result with ammonia is thus the converse of that observed with lead nitrate.
Simon, Martin
2015-01-01
This monograph is concerned with the analysis and numerical solution of a stochastic inverse anomaly detection problem in electrical impedance tomography (EIT). Martin Simon studies the problem of detecting a parameterized anomaly in an isotropic, stationary and ergodic conductivity random field whose realizations are rapidly oscillating. For this purpose, he derives Feynman-Kac formulae to rigorously justify stochastic homogenization in the case of the underlying stochastic boundary value problem. The author combines techniques from the theory of partial differential equations and functional analysis with probabilistic ideas, paving the way to new mathematical theorems which may be fruitfully used in the treatment of the problem at hand. Moreover, the author proposes an efficient numerical method in the framework of Bayesian inversion for the practical solution of the stochastic inverse anomaly detection problem. Contents Feynman-Kac formulae Stochastic homogenization Statistical inverse problems Targe...
Forward and inverse kinematics of double universal joint robot wrists
Williams, Robert L., II
1991-01-01
A robot wrist consisting of two universal joints can eliminate the wrist singularity problem found on many individual robots. Forward and inverse position and velocity kinematics are presented for such a wrist having three degrees of freedom. Denavit-Hartenberg parameters are derived to find the transforms required for the kinematic equations. The Omni-Wrist, a commercial double universal joint robot wrist, is studied in detail. There are four levels of kinematic parameters identified for this wrist; three forward and three inverse maps are presented for both position and velocity. These equations relate the hand coordinate frame to the wrist base frame. They are sufficient for control of the wrist standing alone. When the wrist is attached to a manipulator arm; the offset between the two universal joints complicates the solution of the overall kinematics problem. All wrist coordinate frame origins are not coincident, which prevents decoupling of position and orientation for manipulator inverse kinematics.
Indium oxide inverse opal films synthesized by structure replication method
Amrehn, Sabrina; Berghoff, Daniel; Nikitin, Andreas; Reichelt, Matthias; Wu, Xia; Meier, Torsten; Wagner, Thorsten
2016-04-01
We present the synthesis of indium oxide (In2O3) inverse opal films with photonic stop bands in the visible range by a structure replication method. Artificial opal films made of poly(methyl methacrylate) (PMMA) spheres are utilized as template. The opal films are deposited via sedimentation facilitated by ultrasonication, and then impregnated by indium nitrate solution, which is thermally converted to In2O3 after drying. The quality of the resulting inverse opal film depends on many parameters; in this study the water content of the indium nitrate/PMMA composite after drying is investigated. Comparison of the reflectance spectra recorded by vis-spectroscopy with simulated data shows a good agreement between the peak position and calculated stop band positions for the inverse opals. This synthesis is less complex and highly efficient compared to most other techniques and is suitable for use in many applications.
Study of accurate volume measurement system for plutonium nitrate solution
Energy Technology Data Exchange (ETDEWEB)
Hosoma, T. [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works
1998-12-01
It is important for effective safeguarding of nuclear materials to establish a technique for accurate volume measurement of plutonium nitrate solution in accountancy tank. The volume of the solution can be estimated by two differential pressures between three dip-tubes, in which the air is purged by an compressor. One of the differential pressure corresponds to the density of the solution, and another corresponds to the surface level of the solution in the tank. The measurement of the differential pressure contains many uncertain errors, such as precision of pressure transducer, fluctuation of back-pressure, generation of bubbles at the front of the dip-tubes, non-uniformity of temperature and density of the solution, pressure drop in the dip-tube, and so on. The various excess pressures at the volume measurement are discussed and corrected by a reasonable method. High precision-differential pressure measurement system is developed with a quartz oscillation type transducer which converts a differential pressure to a digital signal. The developed system is used for inspection by the government and IAEA. (M. Suetake)
Directory of Open Access Journals (Sweden)
Sijing Chen
2017-03-01
Full Text Available Chromium has long been known as an enhancer of insulin action. However, the role of chromium in the development of type 2 diabetes mellitus (T2DM in humans remains controversial. The current study aimed to examine the associations of plasma chromium levels with T2DM and pre-diabetes mellitus (pre-DM. We conducted a case-control study involving 1471 patients with newly diagnosed T2DM, 682 individuals with newly diagnosed pre-DM, and 2290 individuals with normal glucose tolerance in a Chinese population from 2009 to 2014. Plasma chromium was measured by inductively coupled plasma mass spectrometry. Plasma chromium levels were lower in the T2DM and pre-DM groups than in the control group (median: 3.68 μg/L, 3.61 μg/L, 3.97 μg/L, respectively, p < 0.001. After adjustment for potential confounding factors, the odds ratios (95% confidence interval for T2DM across increasing quartiles of plasma chromium levels were 1 (referent, 0.67 (0.55–0.83, 0.64 (0.51–0.79, and 0.58 (0.46–0.73, respectively (p for trend <0.001. The corresponding odds ratios (95% confidence interval for pre-DM were 1 (referent, 0.70 (0.54–0.91, 0.67 (0.52–0.88, and 0.58 (0.43–0.78, respectively (p for trend < 0.001. Our results indicated that plasma chromium concentrations were inversely associated with T2DM and pre-DM in Chinese adults.
Electroanalytical studies of uranium, neptunium, and plutonium ions in solutions
International Nuclear Information System (INIS)
Yoshida, Zenko; Aoyagi, Hisao; Kihara, Sorin
1989-01-01
Redox behavior of uranium, neptunium, and plutonium ions, whose oxidation states in acid solutions are between (VI) and (III), were investigated by flow-coulometry with a column electrode of glassy carbon fibers as well as ordinary voltammetry with a rotating disc electrode. Based on current-potential curves the electrode processes were elucidated taking their disproportionation and/or complexation reactions into account. The flow-coulometry, which provides rapid and quantitative electrolysis, was applied to such analytical purposes as follows; the determination of uranium and plutonium in the solution or the solid with discerning their oxidation states, the preparation of species in a desired oxidation state, even in an unstable state which cannot be prepared by ordinary procedure, and the separation of trace amount of uranium in solutions by the electrodeposition of its hydroxide
Ethical challenges and solutions regarding delirium studies in palliative care.
Sweet, Lisa; Adamis, Dimitrios; Meagher, David J; Davis, Daniel; Currow, David C; Bush, Shirley H; Barnes, Christopher; Hartwick, Michael; Agar, Meera; Simon, Jessica; Breitbart, William; MacDonald, Neil; Lawlor, Peter G
2014-08-01
Delirium occurs commonly in settings of palliative care (PC), in which patient vulnerability in the unique context of end-of-life care and delirium-associated impairment of decision-making capacity may together present many ethical challenges. Based on deliberations at the Studies to Understand Delirium in Palliative Care Settings (SUNDIPS) meeting and an associated literature review, this article discusses ethical issues central to the conduct of research on delirious PC patients. Together with an analysis of the ethical deliberations at the SUNDIPS meeting, we conducted a narrative literature review by key words searching of relevant databases and a subsequent hand search of initially identified articles. We also reviewed statements of relevance to delirium research in major national and international ethics guidelines. Key issues identified include the inclusion of PC patients in delirium research, capacity determination, and the mandate to respect patient autonomy and ensure maintenance of patient dignity. Proposed solutions include designing informed consent statements that are clear, concise, and free of complex phraseology; use of concise, yet accurate, capacity assessment instruments with a minimally burdensome schedule; and use of PC friendly consent models, such as facilitated, deferred, experienced, advance, and proxy models. Delirium research in PC patients must meet the common standards for such research in any setting. Certain features unique to PC establish a need for extra diligence in meeting these standards and the employment of assessments, consent procedures, and patient-family interactions that are clearly grounded on the tenets of PC. Copyright © 2014 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.
Studies on mixed metal oxides solid solutions as heterogeneous catalysts
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H. R. Arandiyan
2009-03-01
Full Text Available In this work, a series of perovskite-type mixed oxide LaMo xV1-xO3+δ powder catalysts (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0, with 0.5 < δ < 1.5, prepared by the sol-gel process and calcined at 750ºC, provide an attractive and effective alternative means of synthesizing materials with better control of morphology. Structures of resins obtained during the gel formation process by FT-IR spectroscopy and XRD analysis showed that all the LaMo xV1-xO3+δ samples are single phase perovskite-type solid solutions. The surface area (BET between 2.5 - 5.0 m²/g (x = 0.1 and 1.0 respectively increases with increasing Mo ratio in the samples. They show high purity, good chemical homogeneity, and lower calcinations temperatures as compared with the solid-state chemistry route. SEM coupled to EDS and thermogravimetric analysis/differential thermal analyses (TGA/DTA have been carried out in order to evaluate the homogeneity of the catalyst. Finally, the experimental studies show that the calcination temperature and Mo content exhibited a significant influence on catalytic activity. Among the LaMo xV1-xO3+δ samples, LaMo0.7V0.3O4.2 showed the best catalytic activity for the topic reaction and the best activity and stability for ethane reforming at 850ºC under 8 bar.
Critical experiment study on uranyl nitrate solution experiment facility
International Nuclear Information System (INIS)
Zhu Qingfu; Shi Yongqian; Wang Jinrong
2005-01-01
The Uranyl Nitrate Solution Experiment Facility was constructed for the research on nuclear criticality safety. In this paper, the configuration of the facility is introduced; a series of critical experiments on uranyl nitrate solution is described later, which were performed for various uranium concentrations under different conditions, i.e. with or without neutron absorbers in the core and with or without water-reflector outside the core. Critical volume and the minimum 235U critical mass for different uranium concentrations are presented. Finally, theoretical analysis is made on the experimental results. (authors)
Czech Academy of Sciences Publication Activity Database
Dal Moro, Giancarlo; Puzzilli, L.M.
2017-01-01
Roč. 14, č. 4 (2017), s. 431-444 ISSN 1214-9705 Institutional support: RVO:67985891 Keywords : surface wave analysis * Rayleigh wave dispersion * joint inversion * Vs30 Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 0.699, year: 2016
Directory of Open Access Journals (Sweden)
Iqbal Ahmad
2017-06-01
Full Text Available The photoinitiated polymerization of 2-hydroxyethyl methacrylate (HEMA (1-3 M using camphorquinone (CQ \\ triethanolamine (TEOHA system has been studied in the pH range 6.0-9.0. The kinetics of the reaction has been evaluated during the initial stages causing about 5% HEMA conversion to avoid the effects of any variation in the volume of the solution. The change in the concentration of HEMA during polymerization has been determined by a UV spectrometric method at 208 nm with a precision of 3%. The apparent first-order rate constants (kobs for the polymerization of HEMA by CQ in the presence of 0.01 M TEOHA, carried out up to 100 s, range from 3.35-7.78 (1 M, 2.72-6.78 (2 M and 2.33`5.89x104 s-1(3 M. The second-order rate constants for the interaction of TEOHA radicals with HEMA (1-3 M range from 2.33-7.78x10-2 M 1 s-lat pH 6.0-9.0 indicating an increase in the reactivity of TEOHA radicals with an increase in the pH of the solution. There is a linear relation between kobs (1-3 M HEMA and inverse of solution viscosity suggesting the quenching of CQ excited state with an increase in the viscosity of the medium.
On the inverse windowed Fourier transform
Rebollo Neira, Laura; Fernández Rubio, Juan Antonio
1999-01-01
The inversion problem concerning the windowed Fourier transform is considered. It is shown that, out of the infinite solutions that the problem admits, the windowed Fourier transform is the "optimal" solution according to a maximum-entropy selection criterion. Peer Reviewed
Posadas-Sánchez, Rosalinda; Posadas-Romero, Carlos; Cardoso-Saldaña, Guillermo; Vargas-Alarcón, Gilberto; Villarreal-Molina, María Teresa; Pérez-Hernández, Nonanzit; Rodríguez-Pérez, José Manuel; Medina-Urrutia, Aida; Jorge-Galarza, Esteban; Juárez-Rojas, Juan Gabriel; Torres-Tamayo, Margarita
2016-03-01
Serum magnesium is inversely associated to coronary artery calcification (CAC) in patients with chronic kidney disease. There is little information on this association in a general healthy population. The aim of this study was to examine the cross-sectional association of serum magnesium levels with CAC. We included 1276 Mexican-mestizo subjects (50 % women), aged 30-75 years, free of symptomatic cardiovascular disease. CAC was quantified by multidetector computed tomography using the method described by Agatston. Cross-sectional associations of serum magnesium with cardiometabolic factors and subclinical atherosclerosis defined as a CAC score > 0, were examined in logistic regression models adjusted for age, sex, education, smoking status, body mass index, systolic blood pressure, physical activity, elevated abdominal visceral tissue, fasting insulin and glucose, alcohol consumption, menopausal status (women only), low (LDL-C) and high density lipoprotein cholesterol (HDL-C), triglycerides, diuretic use, type 2 diabetes mellitus (DM2), and family history of DM2. After full adjustment, subjects in the highest quartile of serum magnesium had 48 % lower odds of hypertension (p = 0.028), 69 % lower odds of DM2 (p = 0.003), and 42 % lower odds of CAC score > 0 (p = 0.016) compared to those with the lowest serum magnesium. The analyses also showed that a 0.17 mg/dL (1SD) increment in serum magnesium was independently associated with 16 % lower CAC (OR 0.84, 95 % CI 0.724-0.986). In a sample of Mexican-mestizo subjects, low serum magnesium was independently associated to higher prevalence not only of hypertension and DM2, but also to coronary artery calcification, which is a marker of atherosclerosis and a predictor of cardiovascular morbidity and mortality.
Moosa, Shabir; Wojczewski, Silvia; Hoffmann, Kathryn; Poppe, Annelien; Nkomazana, Oathokwa; Peersman, Wim; Willcox, Merlin; Derese, Anselme; Mant, David
2014-06-01
Many low-income and middle-income countries globally are now pursuing ambitious plans for universal primary care, but are failing to deliver adequate care quality because of intractable human resource problems. To understand why migrant nurses and doctors from sub-Saharan Africa did not wish to take up available posts in primary and first-contact care in their home countries. Qualitative study of migrant health workers to Europe (UK, Belgium, and Austria) or southern Africa (Botswana and South Africa) from sub-Saharan Africa. Semi-structured interviews with 66 health workers (24 nurses and 42 doctors) from 18 countries between July 2011 and April 2012. Transcripts were analysed thematically using a framework approach. The reasons given for choosing not to work in primary care were grouped into three main analytic streams: poor working environment, difficult living experiences, and poor career path. Responders described a lack of basic medicines and equipment, an unmanageable workload, and lack of professional support. Many had concerns about personal security, living conditions (such as education for children), and poor income. Primary care was seen as lower status than hospital medicine, with lack of specialist training opportunities and more exposure to corruption. Clinicians are reluctant to work in the conditions they currently experience in primary care in sub-Saharan Africa and these conditions tend to get worse as poverty and need for primary care increases. This inverse primary care law undermines achievement of universal health coverage. Policy experience from countries outside Africa shows that it is not immutable. © British Journal of General Practice 2014.
Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study
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Jan-Michael Y. Carrillo
2014-07-01
Full Text Available Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution. This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions.
The mathematical models of solution mining and case study
International Nuclear Information System (INIS)
Jacobson, R.H.; Waskovsky, J.; Wang Xiwen; Wang Haifeng
1991-01-01
The mathematical model of parameters which describe solution mining and the principle of ore leaching are presented theoretically and thoroughly with the emphasis on in-situ leaching with a biolixiviant, furthermore, the example of bioleach mining, or biomining, in an abandoned underground copper mine is discussed
Rheological study of chitosan acetate solutions containing chitin nanofibrils
Czech Academy of Sciences Publication Activity Database
Mikešová, Jana; Hašek, Jindřich; Tishchenko, Galina; Morganti, P.
2014-01-01
Roč. 112, 4 November (2014), s. 753-757 ISSN 0144-8617 EU Projects: European Commission(XE) 315233 - N-CHITOPACK Institutional support: RVO:61389013 Keywords : rheology * chitosan solutions * chitin nanofibrils Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.074, year: 2014
NMR study of thermoresponsive block copolymer in aqueous solution
Czech Academy of Sciences Publication Activity Database
Spěváček, Jiří; Konefal, Rafal; Čadová, Eva
2016-01-01
Roč. 217, č. 12 (2016), s. 1370-1375 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * NMR * NOESY Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016
Osmotic pressure of ring polymer solutions : A Monte Carlo study
Flikkema, Edwin; Brinke, Gerrit ten
2000-01-01
Using the wall theorem, the osmotic pressure of ring polymers in solution has been determined using an off-lattice topology conserving Monte Carlo algorithm. The ring polymers are modeled as freely-jointed chains with point-like beads, i.e., under conditions corresponding to θ-conditions for the
Spectroscopic study on the stability of morin in aqueous solution
Energy Technology Data Exchange (ETDEWEB)
Bark, Ki Min [Dept. of Chemical Education and Research Institute of Life Science, Gyeongsang National University, Chinju (Korea, Republic of); Im, Seo Eun; Seo, Jung Ja; Park, Ok Hyun; Park, Hyoung Ryun [Dept. of Chemistry, Chonnam National University, Gwangju (Korea, Republic of); Park, Chul Ho [Dept. of Cosmetic Science, Nambu University, Gwangju (Korea, Republic of)
2015-02-15
Morin (3,2,4,5,7-pentahydroxyflavone) is a flavonol conjugated to a resorcinol moiety at the C-2 position, different from many other flavonoids. The UV–vis spectrum of morin in neat water reveals two major absorption bands with maxima at 265 and 387 nm. The substance is stable in acidic solution and neat water. However, its absorption maximum at 387 nm continuously shifts to longer wavelengths and new peaks appeared at wavelengths of 312 nm with increasing pH of the solution. The shape of the absorption spectrum of morin depends on the storage time at a given pH, indicating the occurrence of other successive chemical reactions. The fluorescence spectroscopic results also prove that new conjugated double bonds are formed in the deaerated basic solution at the initial state and decompose with time. This behavior indicates that morin is very unstable, and therefore its decomposition occurs by a sequence of multistep reactions in basic solution. Probable reaction pathways for the reaction are suggested based on the spectroscopic results.
Dynamic nuclear-polarization studies of paramagnetic species in solution
International Nuclear Information System (INIS)
Glad, W.E.
1982-07-01
Dynamic Nuclear Polarization (DNP) was used to measure the electron spin lattice relaxation times, T 1 , of transition metal ions in aqueous solution. Saturation which is induced in the electron spin system is transferred to the solvent proton spins by dipole-dipole interactions. The change in the polarization of the proton spins is much larger than it is in the electron spins. The change in proton polarization is easily measured by proton Nuclear Magnetic Resonance (NMR). In one experimental arrangement the sample solution was continuously flowed through a microwave cavity to the NMR coil. The NMR was observed with a continuous wave NMR spectrometer. In a second arrangement the whole sample tube was moved from within the microwave cavity to the NMR coil in less than 40 ms by a blast of compressed air. The NMR was then observed with a pulse-Fourier-transform spectrometer. With the second arrangement a mean-square microwave magnetic field at the sample of more than 10 G 2 is obtainable with 14 W of microwave power. Measurements of DNP at 9 GHz were made on aqueous solutions of VO 2+ , Mn 2+ , Cr(CN) 6 3- , Cu 2+ and Cu(ethylenediamine) 2 (H 2 0) 2 2+ ions from 3 to 60 0 C. It was also possible to observe DNP on resolved proton resonances from mixed water-acetonitrile solutions of VO 2+ and Cr(CN) 6 3- ions
An inverse problem approach to pattern recognition in industry
Directory of Open Access Journals (Sweden)
Ali Sever
2015-01-01
Full Text Available Many works have shown strong connections between learning and regularization techniques for ill-posed inverse problems. A careful analysis shows that a rigorous connection between learning and regularization for inverse problem is not straightforward. In this study, pattern recognition will be viewed as an ill-posed inverse problem and applications of methods from the theory of inverse problems to pattern recognition are studied. A new learning algorithm derived from a well-known regularization model is generated and applied to the task of reconstruction of an inhomogeneous object as pattern recognition. Particularly, it is demonstrated that pattern recognition can be reformulated in terms of inverse problems defined by a Riesz-type kernel. This reformulation can be employed to design a learning algorithm based on a numerical solution of a system of linear equations. Finally, numerical experiments have been carried out with synthetic experimental data considering a reasonable level of noise. Good recoveries have been achieved with this methodology, and the results of these simulations are compatible with the existing methods. The comparison results show that the Regularization-based learning algorithm (RBA obtains a promising performance on the majority of the test problems. In prospects, this method can be used for the creation of automated systems for diagnostics, testing, and control in various fields of scientific and applied research, as well as in industry.
Study of the dosimetric properties using organometallic polymers in solution
International Nuclear Information System (INIS)
Fernandes, David Moreira
2012-01-01
This work aimed to study the dosimetric characteristics of the polymer of the polymer ''poly-[ 1, l-bis (ethynyl) -4,4-biphenyl (bis-tributylphosphine) Pt (11)]'' (Pt-DEBP) compared to radiation gamma. The Pt-DEBP polymer, containing ten monomer units, was then dissolved in organic solvents as chloroform and toluene. The samples were irradiated at four concentrations (0.0500, 0.0375, 0.0250, 0.0113 mg / mL) in duplicate, with radiation doses ranging from 1 to 90 Gy. The results were evaluated based on spectroscopic techniques such as optical absorption spectroscopy (UV -Vis), fluorescence (emission), time resolved fluorescence (FRT) and Fourier transform infrared (FTIR). For DEBP-Pt solutions in chloroform, there is a shift in the position of the main optical absorption band (πt - π*) to lower wavelength (blue-shift), allied to a decreasing absorption intensity with increasing radiation dose. In fluorescence spectroscopy, there was a shift to longer wavelengths (redshift) allied to an increasing emission intensity with increasing radiation dose. FRT experiments on irradiated samples dissolved in chloroform indicated the presence of a new emitter center. FTIR spectra show the incorporation of chlorine in the polymer chain, justifying the blue-shift observed in the absorption spectra and the new emission center. In addition, the behavior of linear results in the absorption and fluorescence studies was investigated based on the relationship between the wavelength of maximum absorption/emission and the radiation dose. For both cases, a linear behavior was observed in relation to the sample concentration. Repeatability and stability tests were also performed. For the samples dissolved in toluene, there was no significant shift of the spectrum of absorption or fluorescence for all doses. The results show that the Pt-DEBP polymer dissolved in chloroform can be used as a dosimeter for x-ray doses between 1 - 30 Gy based on the changes in absorption and/or emission
Proton magnetic resonance studies in solutions of o- and p-hydroxy benzoic acids in dioxan
International Nuclear Information System (INIS)
Arulmozhi, V.; Srinivasa Rao, A.; Balasubramanian, V.
1990-01-01
High resolution proton(NMR) studies were carried out in solutions of o- and p-hydroxy benzoic acids(OHBA and PHBA) in dioxan (D) for several solute concentrations in the range of 0.01 to 0.10 mole fraction (mf). The spectra corresponding to OH and COOH protons could be distinguished in solutions of OHBA in D whereas solution of PHBA in D show only peak in the range of chemical shifts attributable to OH and COOH protons. In the solution of OHBA in dioxan the chemical shift of the proton of the hydroxyl group increases with increase of solute concentration and attains a maximum at a solute concentration of 0.04 mf and then decreases with further increase of solute concentration. For the carboxyl group, the chemical shift increase with increase of solute concentration and attians a maximum at 0.08 mf solute concentration. In solutions of PHBA in D the chemical shift of the single line observed increases with increase of solute concentration and attains a maximum at a solute concentration of 0.05 mf. The data are interpreted as due to formation of hydrogen bonds between the molecule of OHBA and PHBA and dioxan. The proton magnetic relaxation studies in the above solutions also confirm the above findings. (author). 6 refs., 5 figs
Quantifying uncertainties of seismic Bayesian inversion of Northern Great Plains
Gao, C.; Lekic, V.
2017-12-01
Elastic waves excited by earthquakes are the fundamental observations of the seismological studies. Seismologists measure information such as travel time, amplitude, and polarization to infer the properties of earthquake source, seismic wave propagation, and subsurface structure. Across numerous applications, seismic imaging has been able to take advantage of complimentary seismic observables to constrain profiles and lateral variations of Earth's elastic properties. Moreover, seismic imaging plays a unique role in multidisciplinary studies of geoscience by providing direct constraints on the unreachable interior of the Earth. Accurate quantification of uncertainties of inferences made from seismic observations is of paramount importance for interpreting seismic images and testing geological hypotheses. However, such quantification remains challenging and subjective due to the non-linearity and non-uniqueness of geophysical inverse problem. In this project, we apply a reverse jump Markov chain Monte Carlo (rjMcMC) algorithm for a transdimensional Bayesian inversion of continental lithosphere structure. Such inversion allows us to quantify the uncertainties of inversion results by inverting for an ensemble solution. It also yields an adaptive parameterization that enables simultaneous inversion of different elastic properties without imposing strong prior information on the relationship between them. We present retrieved profiles of shear velocity (Vs) and radial anisotropy in Northern Great Plains using measurements from USArray stations. We use both seismic surface wave dispersion and receiver function data due to their complementary constraints of lithosphere structure. Furthermore, we analyze the uncertainties of both individual and joint inversion of those two data types to quantify the benefit of doing joint inversion. As an application, we infer the variation of Moho depths and crustal layering across the northern Great Plains.
Energy Technology Data Exchange (ETDEWEB)
Kergreis, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires
1966-04-01
The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author) [French] Le but de ce travail est l'etude des principales methodes de determination de l'acidite 'libre'. Dans une premiere partie nous avons defini les differentes sortes d'acidites pouvant exister en solution aqueuse, puis apres avoir etudie quelques reactions d'hydrolyse, nous avons compare la valeur de pH de neutralisation du cation hydrate et celle de precipitation de l'hydroxyde. Dans la seconde partie nous avons aborde l'etuce des dosages de l'acidite d'une solution aqueuse. Apres avoir envisage assez rapidement la determination de l'acidite 'totale', nous traitons du probleme du titrage de l'acidite 'libre'. Nous avons porte notre attention sur certaines methodes: extrapolation du point equivalent, titrimetrie colorimetrique avec ou sans complexant, et enfin utilisation des resines echangeuses d'ions en milieu aqueux et solvant mixte.
An inverse method for radiation transport
Energy Technology Data Exchange (ETDEWEB)
Favorite, J. A. (Jeffrey A.); Sanchez, R. (Richard)
2004-01-01
Adjoint functions have been used with forward functions to compute gradients in implicit (iterative) solution methods for inverse problems in optical tomography, geoscience, thermal science, and other fields, but only once has this approach been used for inverse solutions to the Boltzmann transport equation. In this paper, this approach is used to develop an inverse method that requires only angle-independent flux measurements, rather than angle-dependent measurements as was done previously. The method is applied to a simplified form of the transport equation that does not include scattering. The resulting procedure uses measured values of gamma-ray fluxes of discrete, characteristic energies to determine interface locations in a multilayer shield. The method was implemented with a Newton-Raphson optimization algorithm, and it worked very well in numerical one-dimensional spherical test cases. A more sophisticated optimization method would better exploit the potential of the inverse method.
Wave-equation dispersion inversion
Li, Jing
2016-12-08
We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained from Rayleigh waves recorded by vertical-component geophones. Similar to wave-equation traveltime tomography, the complicated surface wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the phase-velocity and frequency domains. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2-D or 3-D S-wave velocity models. This procedure, denoted as wave-equation dispersion inversion (WD), does not require the assumption of a layered model and is significantly less prone to the cycle-skipping problems of full waveform inversion. The synthetic and field data examples demonstrate that WD can approximately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic data and the inversion of dispersion curves associated with Love waves.
Case studies in the numerical solution of oscillatory integrals
International Nuclear Information System (INIS)
Adam, G.
1992-06-01
A numerical solution of a number of 53,249 test integrals belonging to nine parametric classes was attempted by two computer codes: EAQWOM (Adam and Nobile, IMA Journ. Numer. Anal. (1991) 11, 271-296) and DO1ANF (Mark 13, 1988) from the NAG library software. For the considered test integrals, EAQWOM was found to be superior to DO1ANF as it concerns robustness, reliability, and friendly user information in case of failure. (author). 9 refs, 3 tabs
Volumetric studies of some amino acids in binary aqueous solutions ...
Indian Academy of Sciences (India)
Unknown
0 values of glycine, L-alanine, and L-valine in aqueous MgCl2⋅6H2O solutions at. 298⋅15 K in order to describe the temperature dependence behaviour of partial molar quantities. Group contributions to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (∆Vφ. 0) have been ...
Molecular dynamics simulation studies of caffeine aggregation in aqueous solution.
Tavagnacco, Letizia; Schnupf, Udo; Mason, Philip E; Saboungi, Marie-Louise; Cesàro, Attilio; Brady, John W
2011-09-22
Molecular dynamics simulations were carried out on a system of eight independent caffeine molecules in a periodic box of water at 300 K, representing a solution near the solubility limit for caffeine at room temperature, using a newly developed CHARMM-type force field for caffeine in water. Simulations were also conducted for single caffeine molecules in water using two different water models (TIP3P and TIP4P). Water was found to structure in a complex fashion around the planar caffeine molecules, which was not sensitive to the water model used. As expected, extensive aggregation of the caffeine molecules was observed, with the molecules stacking their flat faces against one another like coins, with their methylene groups staggered to avoid steric clashes. A dynamic equilibrum was observed between large n-mers, including stacks with all eight solute molecules, and smaller clusters, with the calculated osmotic coefficient being in acceptable agreement with the experimental value. The insensitivity of the results to water model and the congruence with experimental thermodynamic data suggest that the observed stacking interactions are a realistic representation of the actual association mechanism in aqueous caffeine solutions.
Björkholm, Eva
2014-01-01
Within the field of technology education, evaluating technical solutions is considered as an important topic. Research indicates that pupils have difficulties in evaluating technical solutions in terms of fitness for purpose, i.e. how effective a technical solution supports its intended function. By using the learning study, which is an iterative…
Orivuori, L; Loss, G; Roduit, C; Dalphin, J-C; Depner, M; Genuneit, J; Lauener, R; Pekkanen, J; Pfefferle, P; Riedler, J; Roponen, M; Weber, J; von Mutius, E; Braun-Fahrländer, C; Vaarala, O
2014-01-01
The role of breastfeeding for the development of atopic diseases in childhood is contradictory. This might be due to differences in the composition of breast milk and levels of antimicrobial and anti-inflammatory components. The objective of this study was to examine whether levels of total immunoglobulin A (IgA) or transforming growth factor-β1 (TGF-β1) in breast milk were associated with the risk of developing atopic dermatitis (AD), atopic sensitization or asthma at early age taking breastfeeding duration into account. The birth cohort study PASTURE conducted in Finland, France, Germany and Switzerland provided 610 breast milk samples collected 2 months after delivery in which soluble IgA (sIgA) and TGF-β1 levels were measured by ELISA. Duration of breastfeeding was assessed using weekly food frequency diaries from month 3 to month 12. Data on environmental factors, AD and asthma were collected by questionnaires from pregnancy up to age 6. Atopic status was defined by specific IgE levels in blood collected at the ages of 4 and 6 years. Multivariate logistic regression models were used for statistical analysis. Soluble IgA and TGF-β1 levels in breast milk differed between countries, and sIgA levels were associated with environmental factors related to microbial load, for example, contact to farm animals or cats during pregnancy, but not with raw milk consumption. sIgA levels were inversely associated with AD up to the of age 2 years (P-value for adjusted linear trend: 0.005), independent of breastfeeding duration. The dose of sIgA ingested in the first year of life was associated with reduced risk of AD up to the age of 2 (aOR, 95% CI: 0.74; 0.55-0.99) and 4 years (0.73; 0.55-0.96). No clear associations between sIgA and atopy or asthma up to age 6 were observed. TGF-β1 showed no consistent association with any investigated health outcome. IgA in breast milk might protect against the development of AD. © 2013 John Wiley & Sons Ltd.
International Nuclear Information System (INIS)
Zhang, Zhaobin; Sun, Libei; Hu, Ying; Jiao, Jian; Hu, Jianying
2013-01-01
Parabens are p-hydroxybenzoic acid esters that have been used extensively as preservatives in foods, cosmetics, drugs and toiletries. These intact esters are commonly detected in human breast cancer tissues and other human samples, thus arousing concern about the involvement of parabens in human breast cancer. In this study, an in vitro nuclear receptor coactivator recruiting assay was developed and used to evaluate the binding activities of parabens, salicylates and benzoates via antagonist competitive binding on the human oestrogen-related receptor γ (ERRγ), which is known as both a diagnostic biomarker and a treatment target of breast cancer. The results showed that all of the test parabens (methyl-, ethyl-, propyl-, butyl- and benzylparaben) possessed clear inverse antagonist activities on ERRγ, with a lowest observed effect level (LOEL) of 10 −7 M and the 50% relative effective concentrations (REC50) varying from 3.09 × 10 −7 to 5.88 × 10 −7 M, whereas the salicylates possessed much lower activities and the benzoates showed no obvious activity. In silico molecular docking analyses showed that parabens fitted well into the active site of ERRγ, with hydrogen bonds forming between the p-hydroxyl group of parabens and the Glu275/Arg316 of ERRγ. As the paraben levels reported in breast cancer tissues are commonly higher than the LOELs observed in this study, parabens may play some role via ERRγ in the carcinogenesis of human breast cancer. In addition, parabens may have significant effects on breast cancer patients who are taking tamoxifen, as ERRγ is regarded as a treatment target for tamoxifen. - Highlights: • An oestrogen-related receptor γ coactivator recruiting assay was developed. • Strong binding activities of parabens with oestrogen-related receptor γ were found. • The paraben levels reported in breast cancer tissues were higher than their LOELs. • Parabens may play some role via ERRγ in the carcinogenesis of human breast cancer.
Inverse treatment planning based on MRI for HDR prostate brachytherapy
International Nuclear Information System (INIS)
Citrin, Deborah; Ning, Holly; Guion, Peter; Li Guang; Susil, Robert C.; Miller, Robert W.; Lessard, Etienne; Pouliot, Jean; Xie Huchen; Capala, Jacek; Coleman, C. Norman; Camphausen, Kevin; Menard, Cynthia
2005-01-01
Purpose: To develop and optimize a technique for inverse treatment planning based solely on magnetic resonance imaging (MRI) during high-dose-rate brachytherapy for prostate cancer. Methods and materials: Phantom studies were performed to verify the spatial integrity of treatment planning based on MRI. Data were evaluated from 10 patients with clinically localized prostate cancer who had undergone two high-dose-rate prostate brachytherapy boosts under MRI guidance before and after pelvic radiotherapy. Treatment planning MRI scans were systematically evaluated to derive a class solution for inverse planning constraints that would reproducibly result in acceptable target and normal tissue dosimetry. Results: We verified the spatial integrity of MRI for treatment planning. MRI anatomic evaluation revealed no significant displacement of the prostate in the left lateral decubitus position, a mean distance of 14.47 mm from the prostatic apex to the penile bulb, and clear demarcation of the neurovascular bundles on postcontrast imaging. Derivation of a class solution for inverse planning constraints resulted in a mean target volume receiving 100% of the prescribed dose of 95.69%, while maintaining a rectal volume receiving 75% of the prescribed dose of <5% (mean 1.36%) and urethral volume receiving 125% of the prescribed dose of <2% (mean 0.54%). Conclusion: Systematic evaluation of image spatial integrity, delineation uncertainty, and inverse planning constraints in our procedure reduced uncertainty in planning and treatment
An application of sparse inversion on the calculation of the inverse data space of geophysical data
Saragiotis, Christos
2011-07-01
Multiple reflections as observed in seismic reflection measurements often hide arrivals from the deeper target reflectors and need to be removed. The inverse data space provides a natural separation of primaries and surface-related multiples, as the surface multiples map onto the area around the origin while the primaries map elsewhere. However, the calculation of the inverse data is far from trivial as theory requires infinite time and offset recording. Furthermore regularization issues arise during inversion. We perform the inversion by minimizing the least-squares norm of the misfit function and by constraining the 1 norm of the solution, being the inverse data space. In this way a sparse inversion approach is obtained. We show results on field data with an application to surface multiple removal. © 2011 IEEE.
Study on the high-spin states and signature inversion of odd-odd nucleus 170Ta
International Nuclear Information System (INIS)
Deng Fuguo; Zhou Hongyu; Sun Huibin; Lu Jingbin; Zhao Guangyi; Yin Lichang; Liu Yunzuo
2002-01-01
The high-spin states of odd-odd nucleus 170 Ta were populated via the 155 Gd( 19 F, 4n) 170 Ta reaction with beam energy of 97 MeV provided by the HI-13 tandem accelerator of China Institute of Atomic Energy. Three rotational bands have been pushed to higher spin states and the signature inversion point of the semidecoupled band based on the πh 9/2 1/2 - [541] direct x νi 13/2 configuration has been observed to be 19.5 ℎ. The systematic features of the signature inversion in semidecoupled bands in odd-odd rare earth nuclei were summarized. The systematic differences of signature inversion, especially the difference in the energy splitting between the yrast hands and the semidecoupled hands in odd-odd rare earth nuclei are pointed out and discussed for the first time. It seems that p-n interaction between the odd proton and odd neutron in the odd-odd nuclei plays an important role
Directory of Open Access Journals (Sweden)
Lei Zhang
2015-01-01
Full Text Available In the concrete dam construction, it is very necessary to strengthen the real-time monitoring and scientific management of concrete temperature control. This paper constructs the analysis and inverse analysis system of temperature stress simulation, which is based on various useful data collected in real time in the process of concrete construction. The system can produce automatically data file of temperature and stress calculation and then achieve the remote real-time simulation calculation of temperature stress by using high performance computing techniques, so the inverse analysis can be carried out based on a basis of monitoring data in the database; it fulfills the automatic feedback calculation according to the error requirement and generates the corresponding curve and chart after the automatic processing and analysis of corresponding results. The system realizes the automation and intellectualization of complex data analysis and preparation work in simulation process and complex data adjustment in the inverse analysis process, which can facilitate the real-time tracking simulation and feedback analysis of concrete temperature stress in construction process and enable you to discover problems timely, take measures timely, and adjust construction scheme and can well instruct you how to ensure project quality.
3rd Annual Workshop on Inverse Problem
2015-01-01
This proceeding volume is based on papers presented on the Third Annual Workshop on Inverse Problems which was organized by the Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, and took place in May 2013 in Stockholm. The purpose of this workshop was to present new analytical developments and numerical techniques for solution of inverse problems for a wide range of applications in acoustics, electromagnetics, optical fibers, medical imaging, geophysics, etc. The contributions in this volume reflect these themes and will be beneficial to researchers who are working in the area of applied inverse problems.
NLSE: Parameter-Based Inversion Algorithm
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.; Aldrin, John C.; Knopp, Jeremy S.
Chapter 11 introduced us to the notion of an inverse problem and gave us some examples of the value of this idea to the solution of realistic industrial problems. The basic inversion algorithm described in Chap. 11 was based upon the Gauss-Newton theory of nonlinear least-squares estimation and is called NLSE in this book. In this chapter we will develop the mathematical background of this theory more fully, because this algorithm will be the foundation of inverse methods and their applications during the remainder of this book. We hope, thereby, to introduce the reader to the application of sophisticated mathematical concepts to engineering practice without introducing excessive mathematical sophistication.
Bayesian probability theory and inverse problems
International Nuclear Information System (INIS)
Kopec, S.
1994-01-01
Bayesian probability theory is applied to approximate solving of the inverse problems. In order to solve the moment problem with the noisy data, the entropic prior is used. The expressions for the solution and its error bounds are presented. When the noise level tends to zero, the Bayesian solution tends to the classic maximum entropy solution in the L 2 norm. The way of using spline prior is also shown. (author)
Bounoua, L.; Imhoff, M.L.; Franks, S.
2008-01-01
Human demand for food influences the water cycle through diversion and extraction of fresh water needed to support agriculture. Future population growth and economic development alone will substantially increase water demand and much of it for agricultural uses. For many semi-arid lands, socio-economic shifts are likely to exacerbate changes in climate as a driver of future water supply and demand. For these areas in particular, where the balance between water supply and demand is fragile, variations in regional climate can have potentially predictable effect on agricultural production. Satellite data and biophysically-based models provide a powerful method to quantify the interactions between local climate, plant growth and water resource requirements. In irrigated agricultural lands, satellite observations indicate high vegetation density while the precipitation amount indicates otherwise. This inconsistency between the observed precipitation and the observed canopy leaf density triggers the possibility that the observed high leaf density is due to an alternate source of water, irrigation. We explore an inverse process approach using observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), climatological data, and the NASA's Simple Biosphere model, SiB2, to quantitatively assess water demand in a semi-arid agricultural land by constraining the carbon and water cycles modeled under both equilibrium (balance between vegetation and prevailing local climate) and nonequilibrium (water added through irrigation) conditions. We postulate that the degree to which irrigated lands vary from equilibrium conditions is related to the amount of irrigation water used. We added water using two distribution methods: The first method adds water on top of the canopy and is a proxy for the traditional spray irrigation. The second method allows water to be applied directly into the soil layer and serves as proxy for drip irrigation. Our approach indicates that over
Studies of the Tc oxidation states in humic acid solutions
International Nuclear Information System (INIS)
Wang Bo; Liu Dejun; Yao Jun
2010-01-01
The oxidation state is an important aspect of the speciation of Tc in groundwater that contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg L -1 and the Tc (Ⅶ) concentration range is about 10 -8 mol l -1 . The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation methods were carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (IPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (Ⅳ) and Tc (Ⅶ) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentrations are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (Ⅶ) is very stable in the Tc (Ⅶ)-humic acid system during a 350 days experimental period, and the Tc (Ⅳ) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (Ⅶ) in aqueous solutions under anaerobic conditions. That is means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)
Studies of Tc oxidation states in humic acid solutions
International Nuclear Information System (INIS)
Wang Bo; Liu Dejun; Yao Jun
2011-01-01
The oxidation state of Tc is an important aspect of the speciation in groundwater which contained organic substances due to it control the precipitation, complexation, sorption and colloid formation behavior of the Tc under HWL geological disposal conditions. In present work, the oxidation states of Tc were investigated using the LaCl 3 coagulation method and solution extraction method in aqueous solutions in which the humic acid concentration range is from 0 to 20 mg/L and the Tc (VII) concentration is about 10 -8 mol/L. The radiocounting of 99 Tc was determined using liquid scintillation spectrometry. The humic acid will influence the radiocounting ratio of 99 Tc apparently, however, the quenching effect can be restrained once keep the volume of the cocktail to about twenty times of the sample volume. The LaCl 3 coagulation method was carried out for the investigation of Tc oxidation states in humic acid aqueous systems at about pH 8. The tetraphenylarsonium chloride (TPA)-chloroform extraction method was used also simultaneously to investigation the concentrations of Tc (IV) and Tc (VII) for the availability of the LaCl 3 precipitation method, and the experimental results demonstrate that tetravalent technetium and pertechnetate concentration are well agreement with the LaCl 3 precipitation method. These two experimental results demonstrated that Tc (VII) is very stable in the Tc (VII)-humic acid system during a 350 days experimental period, and the Tc (IV) concentrations are very lower, that is indicate that there didn't oxidizing reactions between the Fluka humic acid and Tc (VII) in aqueous solutions under anaerobic conditions. That means the presence of humic acids even in anaerobic groundwater is disadvantage for the retardance of radionuclides. (authors)
NMR studies of proton exchange kinetics in aqueous formaldehyde solutions.
Rivlin, Michal; Eliav, Uzi; Navon, Gil
2014-05-01
Aqueous solutions of formaldehyde, formalin, are commonly used for tissue fixation and preservation. Treatment with formalin is known to shorten the tissue transverse relaxation time T2. Part of this shortening is due to the effect of formalin on the water T2. In the present work we show that the shortening of water T2 is a result of proton exchange between water and the major constituent of aqueous solutions of formaldehyde, methylene glycol. We report the observation of the signal of the hydroxyl protons of methylene glycol at 2ppm to high frequency of the water signal that can be seen at low temperatures and at pH range of 6.0±1.5 and, at conditions where it cannot be observed by the single pulse experiment, it can be detected indirectly through the water signal by the chemical exchange saturation transfer (CEST) experiment. The above finding made it possible to obtain the exchange rate between the hydroxyl protons of the methylene glycol and water in aqueous formaldehyde solutions, either using the dispersion of the spin-lattice relaxation rate in the rotating frame (1/T1ρ) or, at the slow exchange regime, from the line width hydroxyl protons of methylene glycol. The exchange rate was ∼10(4)s(-1) at pH 7.4 and 37°C, the activation energy, 50.2kJ/mol and its pH dependence at 1.1°C was fitted to: k (s(-1))=520+6.5×10(7)[H(+)]+3.0×10(9)[OH(-)]. Copyright © 2014. Published by Elsevier Inc.
Ceramic Ultrafiltration of Marine Algal Solutions: A Comprehensive Study
Dramas, Laure
2014-09-01
Algal bloom can significantly impact reverse osmosis desalination process and reduce the drinking water production. In 2008, a major bloom event forced several UAE reverse osmosis plants to stop their production, and in this context, a better understanding of UF membrane fouling caused by algal organic matter (AOM) is needed, in order to adjust the filtration conditions during algal bloom events. Polymeric MF/UF membranes are already widely used for RO pretreatment, but ceramic UF membranes can also be an alternative for the filtration of marine algal solutions. The fouling potential of the Red Sea and the Arabian Sea, sampled at different seasons, along with four algal monocultures grown in laboratory, and one mesocosm experiment in the Red Sea was investigated. Algal solutions induce a stronger and more irreversible fouling than terrestrial humic solution, toward ceramic membrane. During algal bloom events, this fouling is enhanced and becomes even more problematic at the decline phase of the bloom, for a similar initial DOC. Three main mechanisms are involved: the formation of a cake layer at the membrane surface; the penetration of the algal organic matter (AOM) in the pore network of the membrane; the strong adhesion of AOM with the membrane surface. The last mechanism is species-specific and metal-oxide specific. In order to understand the stronger ceramic UF fouling at the decline phase, AOM quality was analyzed every two days. During growth, AOM is getting enriched in High Molecular Weight (HMW) structures (> 200 kDa), which are mainly composed by proteins and polysaccharides, and these compounds seem to be responsible for the stronger fouling at decline phase. In order to prevent the fouling of ceramic membrane, coagulation-flocculation (CF) using ferric chloride was implemented prior to filtration. It permits a high removal of HMW compounds and greatly reduces the fouling potential of the algal solution. During brief algal bloom events, CF should be
Study and Development of an OpenStack solution
Jorba Brosa, Maria
2014-01-01
Estudi i desenvolupament d'una solució de virtualització amb Openstack. Es farà un especial èmfasi en la part de seguretat. Deployment of a solution based in OpenStack for the creation of an Infrastructure service cloud. Implementación de una solución basada en OpenStack para la creación de una infrastructura de servicios cloud. Implementació d'una solució basada en OpenStack per la creació d'una infrastructura de serveis cloud.
Molecular Dynamics Simulation Studies of Caffeine Aggregation in Aqueous Solution
Tavagnacco, Letizia; Schnupf, Udo; Mason, Philip E.; Saboungi, Marie-Louise; Cesàro, Attilio; Brady, John W.
2011-01-01
Molecular dynamics simulations were carried out on a system of eight independent caffeine molecules in a periodic box of water at 300 K, representing a solution near the solubility limit for caffeine at room temperature, using a newly-developed CHARMM-type force field for caffeine in water. Simulations were also conducted for single caffeine molecules in water using two different water models (TIP3P and TIP4P). Water was found to structure in a complex fashion around the planar caffeine molec...
Efficient Solutions for New Homes Case Study: Savannah Gardens
Energy Technology Data Exchange (ETDEWEB)
None
2016-03-15
The Savannah Housing Department is leading sustainable and affordable housing development in Georgia. It partnered with Southface Energy Institute, a member of the U.S. Department of Energy’s Partnership for Home Innovation Building America research team, to seek cost-effective solutions for increasing the energy efficiency of the Savannah Housing Department’s standard single-family home plans in the Savannah Gardens Community. Based on engineering, cost, and constructability analyses, the combined research team chose to pilot two technologies to evaluate efficiency and comfort impacts for homeowners: a heat-pump water heater in an encapsulated attic and an insulated exterior wall sheathing.
Zhang, Dongliang
2013-01-01
To increase the illumination of the subsurface and to eliminate the dependency of FWI on the source wavelet, we propose multiples waveform inversion (MWI) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. These virtual sources are used to numerically generate downgoing wavefields that are correlated with the backprojected surface-related multiples to give the migration image. Since the recorded data are treated as the virtual sources, knowledge of the source wavelet is not required, and the subsurface illumination is greatly enhanced because the entire free surface acts as an extended source compared to the radiation pattern of a traditional point source. Numerical tests on the Marmousi2 model show that the convergence rate and the spatial resolution of MWI is, respectively, faster and more accurate then FWI. The potential pitfall with this method is that the multiples undergo more than one roundtrip to the surface, which increases attenuation and reduces spatial resolution. This can lead to less resolved tomograms compared to conventional FWI. The possible solution is to combine both FWI and MWI in inverting for the subsurface velocity distribution.
The development of computational algorithms for manipulator inverse kinematics
International Nuclear Information System (INIS)
Sasaki, Shinobu
1989-10-01
A solution technique of the inverse kinematics for multi-joint robot manipulators has been considered to be one of the most cumbersome treatment due to non-linearity properties inclusive of trigonometric functions. The most traditional approach is to use the Jacobian matrix on linearization assumptions. This iterative technique, however, is attended with numerical problems having significant influences on the solution characteristics such as initial guess dependence and singularities. Taking these facts into consideration, new approaches have been proposed from different standpoints, which are based on polynomial transformation of kinematic model, the minimization technique in mathematical programming, vector-geometrical concept, and the separation of joint variables associated with the optimization problem. In terms of computer simulations, each approach was identified to be a useful algorithm which leads to theoretically accurate solutions to complicated inverse problems. In this way, the short-term goal of our studies on manipulator inverse problem in the R and D project of remote handling technology was accomplished with success, and consequently the present report sums up the results of basic studies on this matter. (author)
LED Street Lighting Solutions: Flagstaff, Arizona as a Case Study
Hall, Jeffrey C.
2018-01-01
Dark-sky protection in Flagstaff, Arizona extends back to 1958, with the first ordinance in the City banning advertising floodlights. The current ordinance, adopted in 1989, is comprehensive and has played a critical role in maintaining the quality of the night sky for astronomy, tourism, public enjoyment, and other purposes. Flagstaff, like many communities around the world, is now working on a transition from legacy bulb-based technology to LED for its outdoor lighting. The City, Lowell Observatory, the U. S. Naval Observatory, and the Flagstaff Dark Skies Coalition have been working intensively for two years to identify an LED-based street lighting solution that will preserve the City's dark skies while meeting municipal needs. We will soon be installing test fixtures for an innovative solution incorporating narrow-band amber LED and modest amounts of low-CCT white LED. In this talk, I will review the types of LEDs available for outdoor lighting and discuss the plans for Flagstaff's street lighting in the LED era, which we hope will be a model for communities worldwide.
Gamma Radiolysis Studies of Aqueous Solution of Brilliant Green Dye
Directory of Open Access Journals (Sweden)
D. V. Parwate
2011-01-01
Full Text Available The effect of γ–radiation on colour intensity of aqueous solution of Brilliant Green has been investigated at two different concentrations. The degradation of Brilliant Green (BG has also been investigated in presence of suspended ZnO, by adding different amounts of ZnO. Simultaneously the conductance and pH of each solution system were measured before and after γ-irradiation. All the γ–irradiations were performed at a dose rate of 0.60 kGyhr-1 in GC-900. The maximum dose required for the complete degradation of the dye was found to be 0.39 kGy. G(-dye values were found to decrease with increase in gamma dose and were in the range 4.26 - 12.81. The conductance (7.6 - 25.3 μS and pH values increased marginally with dose for both the concentrations. The rate of decolouration was found to be high at lower doses and the efficiency of dye removal was higher at low concentration of the dye. This may be attributed to the presence of reaction by-products from the destruction of parent compound build up and compete for reaction intermediate species. The rate of reaction and rate constants were calculated and it was found that the degradation reaction follows first order kinetics. It was found that the decolouration percentage was more in dye systems in absence of ZnO.
Workflows for Full Waveform Inversions
Boehm, Christian; Krischer, Lion; Afanasiev, Michael; van Driel, Martin; May, Dave A.; Rietmann, Max; Fichtner, Andreas
2017-04-01
Despite many theoretical advances and the increasing availability of high-performance computing clusters, full seismic waveform inversions still face considerable challenges regarding data and workflow management. While the community has access to solvers which can harness modern heterogeneous computing architectures, the computational bottleneck has fallen to these often manpower-bounded issues that need to be overcome to facilitate further progress. Modern inversions involve huge amounts of data and require a tight integration between numerical PDE solvers, data acquisition and processing systems, nonlinear optimization libraries, and job orchestration frameworks. To this end we created a set of libraries and applications revolving around Salvus (http://salvus.io), a novel software package designed to solve large-scale full waveform inverse problems. This presentation focuses on solving passive source seismic full waveform inversions from local to global scales with Salvus. We discuss (i) design choices for the aforementioned components required for full waveform modeling and inversion, (ii) their implementation in the Salvus framework, and (iii) how it is all tied together by a usable workflow system. We combine state-of-the-art algorithms ranging from high-order finite-element solutions of the wave equation to quasi-Newton optimization algorithms using trust-region methods that can handle inexact derivatives. All is steered by an automated interactive graph-based workflow framework capable of orchestrating all necessary pieces. This naturally facilitates the creation of new Earth models and hopefully sparks new scientific insights. Additionally, and even more importantly, it enhances reproducibility and reliability of the final results.
International Nuclear Information System (INIS)
Hadjadj, A.; Julien, R.; Pucheault, J.; Ferradini, C.; Hickel, B.
1982-01-01
In the preceding study of the radiolysis of concentrated aqueous LiCl solutions, one of the hypotheses used to explain the apparent inefficacy of Cl 2- formation by the direct effect was that molecular chlorine, not detectable by spectrophotometry, could be formed during the early stages of water radiolysis. Such an hypothesis is confirmed here for pulse and #betta#-radiolysis of concentrated aqueous neutral LiI solutions. Indeed, it is shown that, 10 ns after the pulse, molecular iodine, detected as I 3- , is formed with a yield that increases with the LiI concentration. The experimental results yields values of 4.8 and 7.3 respectively for the indirect and direct effects of total oxidation G/sub I 2- / + 2G/sub I 3- /. This last high value is discussed
DEFF Research Database (Denmark)
Eriksen, Janus J.; Olsen, Jógvan Magnus H.; Aidas, Kestutis
2011-01-01
to the results stemming from the conformations extracted from the MM conformational search in terms of replicating an experimental reference as well as in achieving the correct sequence of the NMR relative chemical shifts of L-tryptophan in aqueous solution. We find this to be due to missing conformations......In this study, we have applied two different spanning protocols for obtaining the molecular conformations of L-tryptophan in aqueous solution, namely a molecular dynamics simulation and a molecular mechanics conformational search with subsequent geometry re-optimization of the stable conformers...... using a quantum mechanically based method. These spanning protocols represent standard ways of obtaining a set of conformations on which NMR calculations may be performed. The results stemming from the solute–solvent configurations extracted from the MD simulation at 300 K are found to be inferior...
Inverse radiative transfer problems in two-dimensional heterogeneous media
International Nuclear Information System (INIS)
Tito, Mariella Janette Berrocal
2001-01-01
The analysis of inverse problems in participating media where emission, absorption and scattering take place has several relevant applications in engineering and medicine. Some of the techniques developed for the solution of inverse problems have as a first step the solution of the direct problem. In this work the discrete ordinates method has been used for the solution of the linearized Boltzmann equation in two dimensional cartesian geometry. The Levenberg - Marquardt method has been used for the solution of the inverse problem of internal source and absorption and scattering coefficient estimation. (author)
Electrochemical impedance study of copper in phosphate buffered solution
International Nuclear Information System (INIS)
Salimon, J.; Mohamad, M.; Yamin, B.M.; Kalaji, M.
2003-01-01
The processes occurring on the copper electrode surface in phosphate buffered solution were investigated using the Electrochemical Impedance Spectroscopy. The electrochemical behaviors of copper through their charge transfer resistance and double-layer capacitance at the onset of the hydrogen evolution region and the anodic passivation layer formation and diffusion of copper species at anodic potential regions are discussed. The specific adsorption of anions (hydroxide and/or H/sub 2/PO/sub 4/) occurred at potential less negative than -0.9V. Adsorbed hydrogen appeared at hydrogen evolution region at potential range of -1.5 to -1.0 V. The deposition of insoluble copper species occurred at anodic potential regions. (author)
Study of vapour pressure of lithium nitrate solutions in ethanol
Energy Technology Data Exchange (ETDEWEB)
Verevkin, Sergey [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany); Safarov, Javid [Heat and Refrigeration Techniques, Azerbaijan Technical University, H. Javid Avn. 25, AZ1073 Baku (Azerbaijan)]. E-mail: javids@azdata.net; Bich, Eckard [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany); Hassel, Egon [Lehrstuhl fuer Technische Thermodynamik, Fakultaet Maschinenbau und Schiffstechnik, Universitaet Rostock, Albert-Einstein-Str. 2, D-18059 Rostock (Germany); Heintz, Andreas [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany)
2006-05-15
Vapour pressure p of (LiNO{sub 3} + C{sub 2}H{sub 5}OH) solutions at T = (298.15 to 323.15) K were measured, osmotic, activity coefficients ({phi}, {gamma}) and activity of solvent a {sub s} have been evaluated. The experiments were carried out in the molality range m = (0.19125 to 2.21552) mol . kg{sup -1}. The Antoine equation was used for the empirical description of the experimental vapour pressure results and the (Pitzer + Mayorga) model with inclusion of Archer's ionic strength dependence of the third virial coefficient for the calculated osmotic coefficients were used. The parameters of the Archer for the extended Pitzer model was used for the evaluation of activity coefficients.
Viscometric study of high-cis polybutadiene in toluene solution
International Nuclear Information System (INIS)
Mwllo, Ivana L.; Coutinho, Fernanda M.B.; Delpech, Marcia C.; Albino, Fernanda F.M.
2006-01-01
Viscometric measurements, in toluene solution at 30 deg C, were performed with high-cis polybutadiene synthesized by neodymium based catalyst. Six different equations were used to calculate intrinsic viscosities and viscosimetric constant values: Huggins, Kraemer, Martin and Schulz-Blaschke by graphic extrapolation, and Solomon-Ciuta, Deb-Chanterjee and again Schulz- Blaschke, through a single point determination. The molecular weight of the polymers was also determined applying Mark-Houwink-Sakurada equation using the values of intrinsic viscosity obtained by the six equations. The values of intrinsic viscosity and viscosity-average molecular weight obtained by the two methods were compared in order to verify the validity of the single point determination for high-cis polybutadiene. (author)
Schmäck, J.; Klotzsche, A.; Van Der Kruk, J.; Vereecken, H.; Bechtold, M.
2017-12-01
The characterization of peatlands is of particular interest, since areas with peat soils represent global hotspots for the exchange of greenhouse gases. Their effect on global warming depends on several parameters, like mean annual water level and land use. Models of greenhouse gas emissions and carbon accumulation in peatlands can be improved by including small-scale soil properties that e.g. act as gas traps and periodically release gases to the atmosphere during ebullition events. Ground penetrating radar (GPR) is well suited to non- or minimal invasively characterize and improve our understanding of dynamic processes that take place in the critical zone. It uses high frequency electromagnetic waves to image and characterize the dielectric permittivity and electrical conductivity of the critical zone, which can be related to hydrogeological properties like porosity, soil water content, salinity and clay content. In the last decade, the full-waveform inversion of crosshole GPR data has proved to be a powerful tool to improve the image resolution compared to standard ray-based methods. This approach was successfully applied to several different aquifers and was able to provide decimeter-scale resolution images including small-scale high contrast layers that can be related to zones of high porosity, zones of preferential flow or clay lenses. The comparison to independently measured e.g. logging data proved the reliability of the method. Here, for the first time crosshole GPR full-waveform inversion is used to image three peatland plots with different land use that are part of the "Ahlen-Falkenberger Moor peat bog complex" in northwestern Germany. The full-waveform inversion of the acquired data returned higher resolution images than standard ray-based GPR methods, and, is able to improve our understanding of subsurface structures. The comparison of the different plots is expected to provide new insights into gas content and gas trapping structures across different
Zviagin, Vitaly; Richter, Peter; Böntgen, Tammo; Lorenz, Michael; Ziese, Michael; Zahn, Dietrich R. T.; Salvan, Georgeta; Grundmann, Marius; Schmidt-Grund, Rüdiger
2015-01-01
Co$_3$O$_4$, ZnFe$_2$O$_4$, CoFe$_2$O$_4$, ZnCo$_2$O$_4$, and Fe$_3$O$_4$ thin films were fabricated by pulsed laser deposition at high and low temperatures resulting in crystalline single-phase normal, inverse, as well as disordered spinel oxide thin films with smooth surface morphology. The dielectric function, determined by spectroscopic ellipsometry in a wide spectral range from 0.5 eV to 8.5 eV, is compared with the magneto-optical response of the dielectric tensor, investigated by magne...
Energy Technology Data Exchange (ETDEWEB)
Kitatsuji, Yoshihiro; Yoshida, Zenko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kudo, Hiroshi [Tohoku Univ., Graduate School of Science, Sendai, Miyagi (Japan); Kihara, Sorin [Kyoto Inst. of Technolgy, Dept. of Chemistry, Kyoto (Japan)
2002-04-01
A novel electrochemical method on the basis of a controlled electrolysis has been developed for the study of the ion transfer at the interface of two immiscible electrolyte solutions (ITIES). The controlled-potential electrolysis for ITIES (CPEITIES) was applied to the transfer of actinide ions, and Gibbs energies for the transfer of UO{sub 2}{sup 2+} and Am{sup 3+} from aqueous solution (w) to nitrobenzene solution (nb) were determined to be 71.7 and 113 kJ mol{sup -1}, respectively. The ion transfer potentials for the facilitated transfer of UO{sub 2{sup +}} and Am{sup 3+} from w to nb in the presence of bis(diphenylphosphoryl)methane were determined, from which the stability constants of UO{sub 2}(BDPPM){sub 3}{sup 2+} and Am(BDPPM){sub 3}{sup 3+} complexes involved in the facilitated ion transfer reaction, were calculated to be 10{sup 23.9} and 10{sup 27.5}, respectively. On the basis of the results of CPEITIES, a feasibility of a new separation method, i.e., an electrolytic ion transfer separation, of actinide ions is evaluated. (author)
Inverse Kinematic Analysis and Evaluation of a Robot for Nondestructive Testing Application
Directory of Open Access Journals (Sweden)
Zongxing Lu
2015-01-01
Full Text Available The robot system has been utilized in the nondestructive testing field in recent years. However, only a few studies have focused on the application of ultrasonic testing for complex work pieces with the robot system. The inverse kinematics problem of the 6-DOF robot should be resolved before the ultrasonic testing task. A new effective solution for curved-surface scanning with a 6-DOF robot system is proposed in this study. A new arm-wrist separateness method is adopted to solve the inverse problem of the robot system. Eight solutions of the joint angles can be acquired with the proposed inverse kinematics method. The shortest distance rule is adopted to optimize the inverse kinematics solutions. The best joint-angle solution is identified. Furthermore, a 3D-application software is developed to simulate ultrasonic trajectory planning for complex-shape work pieces with a 6-DOF robot. Finally, the validity of the scanning method is verified based on the C-scan results of a work piece with a curved surface. The developed robot ultrasonic testing system is validated. The proposed method provides an effective solution to this problem and would greatly benefit the development of industrial nondestructive testing.
Calorimetric study of interaction of barium hydroxide with diluted solutions of hydrofluoric acid
International Nuclear Information System (INIS)
Kurbanov, A.R.; Sharipov, D.Sh.
1993-01-01
Present article is devoted to calorimetric study of interaction of barium hydroxide with diluted solutions of hydrofluoric acid. The calorimetric study of interaction of barium hydroxide with diluted solutions of hydrofluoric acid was carried out in order to determine the thermal effects of reactions. The results of interaction of Ba(OH) 4 ·8H 2 O with 5, 10, and 20% solution of hydrofluoric acid were considered.
Liu, Yu; Shi, Zhanjie; Wang, Bangbing; Yu, Tianxiang
2018-01-01
As a method with high resolution, GPR has been extensively used in archaeological surveys. However, conventional GPR profile can only provide limited geometry information, such as the shape or location of the interface, but can't give the distribution of physical properties which could help identify the historical remains more directly. A common way for GPR to map parameter distribution is the common-midpoint velocity analysis, but it provides limited resolution. Another research hotspot, the full-waveform inversion, is unstable and relatively dependent on the initial model. Coring method could give direct information in drilling site, while the accurate result is only limited in several boreholes. In this paper, we propose a new scheme to enhance imaging and characterization of archaeological targets by fusion of GPR and coring data. The scheme mainly involves the impedance inversion of conventional common-offset GPR data, which uses well log to compensate GPR data and finally obtains a high-resolution estimation of permittivity. The core analysis result also contributes to interpretation of the inversion result. To test this method, we did a case study at Mudu city site in Suzhou, China. The results provide clear images of the ancient city's moat and wall subsurface and improve the characterization of archaeological targets. It is shown that this method is effective and feasible for archaeological exploration.
Elhakeem, Ahmed; Hannam, Kimberly; Deere, Kevin C; Hartley, April; Clark, Emma M; Moss, Charlotte; Edwards, Mark H; Dennison, Elaine; Gaysin, Tim; Kuh, Diana; Wong, Andrew; Cooper, Cyrus; Cooper, Rachel; Tobias, Jon H
2018-01-01
Abstract Background High impact physical activity (PA) is thought to improve skeletal health, but its relation to other health outcomes are unclear. We investigated associations between PA impact magnitude and body mass index (BMI) in older adults. Methods Data were taken from the Cohort for Skeletal Health in Bristol and Avon (COSHIBA), Hertfordshire Cohort Study, and MRC National Survey of Health and Development. Vertical acceleration peaks from 7-day hip-worn accelerometer recordings were used to classify PA as low (0.5 impact. Cohort-specific associations of low, medium, and higher impact PA with BMI were examined using linear regressions and estimates combined using random-effects meta-analysis. Results A total of 1182 participants (mean age = 72.7 years, 68% female) were included. Low, medium, and higher impact PA were inversely related to BMI in initial models. After adjustment for confounders and other impacts, low, but not medium or higher, impacts were inversely related to BMI (−0.31, p impacts). In adjusted analyses of body composition measured by dual-energy X-ray absorptiometry in COSHIBA, low, but not medium or higher, impacts were inversely related to total body fat mass (−0.19, p impact PA was weakly and positively associated with lean mass (0.05, p = .06). Conclusions Greater exposure to PA producing low magnitude vertical impacts was associated with lower BMI and fat mass at older age. Low impact PA may help reduce obesity risk in older adults. PMID:29028919
Panchapagesan, Sankaran; Alwan, Abeer
2011-01-01
In this paper, a quantitative study of acoustic-to-articulatory inversion for vowel speech sounds by analysis-by-synthesis using the Maeda articulatory model is performed. For chain matrix calculation of vocal tract (VT) acoustics, the chain matrix derivatives with respect to area function are calculated and used in a quasi-Newton method for optimizing articulatory trajectories. The cost function includes a distance measure between natural and synthesized first three formants, and parameter regularization and continuity terms. Calibration of the Maeda model to two speakers, one male and one female, from the University of Wisconsin x-ray microbeam (XRMB) database, using a cost function, is discussed. Model adaptation includes scaling the overall VT and the pharyngeal region and modifying the outer VT outline using measured palate and pharyngeal traces. The inversion optimization is initialized by a fast search of an articulatory codebook, which was pruned using XRMB data to improve inversion results. Good agreement between estimated midsagittal VT outlines and measured XRMB tongue pellet positions was achieved for several vowels and diphthongs for the male speaker, with average pellet-VT outline distances around 0.15 cm, smooth articulatory trajectories, and less than 1% average error in the first three formants. PMID:21476670
EELS study of the inverse martensitic transformation of 2H and 18R Cu-Al-Zn alloys
International Nuclear Information System (INIS)
Espinosa-Magana, F.; Ochoa-Lara, M.T.; Lovey, F.; Flores-Zuniga, H.; Rios-Jara, D.
2010-01-01
Changes in 3d states occupancy associated with the inverse martensitic transformation in two samples of Cu-Al-Zn alloys with 2H and 18R martensitic structures were investigated by electron energy loss spectroscopy (EELS). The Cu L 2,3 white-lines intensities, which reflect the unoccupied density of states in 3d bands, were measured in situ, during the phase transformation in both the martensite and austenite phases. We find that the white-lines intensity decreases during the inverse transformation, when going from martensite to austenite. Even though the initial 3d occupation numbers in 2H and 18R martensitic structures are different, after the transformation, the 3d occupation numbers in the now austenitic structure have decreased in both samples, indicating that some electrons left Cu 3d bands during phase transformation. Interestingly enough, the occupation numbers in the final phases, which have the same structure, reach the same value, indicating that changes in EELS spectra are a consequence of structural changes.
EELS study of the inverse martensitic transformation of 2H and 18R Cu-Al-Zn alloys
Energy Technology Data Exchange (ETDEWEB)
Espinosa-Magana, F., E-mail: francisco.espinosa@cimav.edu.m [Centro de Investigacion en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Ochoa-Lara, M.T. [Centro de Investigacion en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Lovey, F. [Centro Atomico Bariloche, 8300 S.C. de Bariloche (Argentina); Flores-Zuniga, H. [Universidad Autonoma de Zacatecaa, Av. Lopez Velarde 801, Zacatecas, Zac. 98060 (Mexico); Rios-Jara, D. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, San luis Potosi, S.L.P. 78126 (Mexico)
2010-01-01
Changes in 3d states occupancy associated with the inverse martensitic transformation in two samples of Cu-Al-Zn alloys with 2H and 18R martensitic structures were investigated by electron energy loss spectroscopy (EELS). The Cu L{sub 2,3} white-lines intensities, which reflect the unoccupied density of states in 3d bands, were measured in situ, during the phase transformation in both the martensite and austenite phases. We find that the white-lines intensity decreases during the inverse transformation, when going from martensite to austenite. Even though the initial 3d occupation numbers in 2H and 18R martensitic structures are different, after the transformation, the 3d occupation numbers in the now austenitic structure have decreased in both samples, indicating that some electrons left Cu 3d bands during phase transformation. Interestingly enough, the occupation numbers in the final phases, which have the same structure, reach the same value, indicating that changes in EELS spectra are a consequence of structural changes.
Inverse logarithmic potential problem
Cherednichenko, V G
1996-01-01
The Inverse and Ill-Posed Problems Series is a series of monographs publishing postgraduate level information on inverse and ill-posed problems for an international readership of professional scientists and researchers. The series aims to publish works which involve both theory and applications in, e.g., physics, medicine, geophysics, acoustics, electrodynamics, tomography, and ecology.
Inverse Kinematics using Quaternions
DEFF Research Database (Denmark)
Henriksen, Knud; Erleben, Kenny; Engell-Nørregård, Morten
In this project I describe the status of inverse kinematics research, with the focus firmly on the methods that solve the core problem. An overview of the different methods are presented Three common methods used in inverse kinematics computation have been chosen as subject for closer inspection....
Fluoride removal from aqueous solution by pumice: case study on ...
African Journals Online (AJOL)
The fluoride removal from synthetic water by pumice was studied at batch experiments in this study. The effect of pH, contact time, fluoride concentration and adsorbent dose on the fluoride sequestration was investigated. The optimum conditions were studied on Kuhbonan water as a case study. The results showed that ...
Sarode, Ketan Dinkar; Kumar, V Ravi; Kulkarni, B D
2016-05-01
An efficient inverse problem approach for parameter estimation, state and structure identification from dynamic data by embedding training functions in a genetic algorithm methodology (ETFGA) is proposed for nonlinear dynamical biosystems using S-system canonical models. Use of multiple shooting and decomposition approach as training functions has been shown for handling of noisy datasets and computational efficiency in studying the inverse problem. The advantages of the methodology are brought out systematically by studying it for three biochemical model systems of interest. By studying a small-scale gene regulatory system described by a S-system model, the first example demonstrates the use of ETFGA for the multifold aims of the inverse problem. The estimation of a large number of parameters with simultaneous state and network identification is shown by training a generalized S-system canonical model with noisy datasets. The results of this study bring out the superior performance of ETFGA on comparison with other metaheuristic approaches. The second example studies the regulation of cAMP oscillations in Dictyostelium cells now assuming limited availability of noisy data. Here, flexibility of the approach to incorporate partial system information in the identification process is shown and its effect on accuracy and predictive ability of the estimated model are studied. The third example studies the phenomenological toy model of the regulation of circadian oscillations in Drosophila that follows rate laws different from S-system power-law. For the limited noisy data, using a priori information about properties of the system, we could estimate an alternate S-system model that showed robust oscillatory behavior with predictive abilities. Copyright © 2016 Elsevier Inc. All rights reserved.
Studies of Neutron-Rich Nuclei with (d,p) Reactions in Inverse Kinematics at the HRIBF
International Nuclear Information System (INIS)
Grzywacz-Jones, Kate L.; Baktash, Cyrus; Bardayan, Daniel W.; Blackmon, Jeff C.; Catford, Wilton N.; Cizewski, Jolie; Fitzgerald, Ryan; Greife, Uwe; Gross, Carl J.; Johnson, Micah; Kozub, Raymond L.; Liang, J. Felix; Livesay, Jake; Ma, Zhanwen; Moazen, Brian H.; Nesaraja, Caroline D.; Shapira, Dan; Smith, Michael Scott; Thomas, Jeffrey S.; Visser, Dale William
2005-01-01
Two N=51 isotones have been measured using (d,p) reactions in inverse kinematics at the Holifield Radioactive Beam Facility (HRIBF) of Oak Ridge National Laboratory. Additionally, we have performed a test measurement using a stable 124Sn beam in preparation for measurements of the 2H(130,132Sn,p)131,133Sn reactions. Preliminary results for 83Ge and 85Se suggest a 5/2+ ground state and a 1/2+ first excited state for both isotopes, in agreement with systematics for the N=51 isotones. The excitation energy of the first excited state is shown to drop as the proton number is reduced. Proton angular distributions following the 2H(124Sn,p)125Sn reaction show sensitivity to the l-value of the transfered nucleon and spectroscopic factors are in agreement with previous measurements in normal kinematics.
International Nuclear Information System (INIS)
Popov, V.P.; Semenov, A.L.
1987-01-01
The calibration technique is described, and the metrological characteristics of a high-voltage generator of the inverse-quadratic function (HGF), being a functional unit of the diagnostic system of an electrodynamic analyser of a ionic component of a laser plasma, is analysed. The results of HGF testing in the range of time constants of the τ=(5-25)μs function are given. Analysis of metrologic and experimental characteristics shows, that HGF with automatic calibration has quite high accurate parameters. The high accuracy of function generation is provided with the possibility of calibration and adjustment conduction under experimental working conditions. Increase of the generated pulse amplitude to several tens of kilovelts is possible. Besides, the possibility of timely function adjustment to the necessary parameter (τ) increases essentially the HGF functional possibilities
DEFF Research Database (Denmark)
Pedersen, Jesper Grønnegaard; Gryning, Sven-Erik; Kelly, Mark C.
2014-01-01
A range of large-eddy simulations, with differing free atmosphere stratification and zero or slightly positive surface heat flux, is investigated to improve understanding of the neutral and near-neutral, inversion-capped, horizontally homogeneous, barotropic atmospheric boundary layer with emphasis...... on the upper region. We find that an adjustment time of at least 16 h is needed for the simulated flow to reach a quasi-steady state. The boundary layer continues to grow, but at a slow rate that changes little after 8 h of simulation time. A common feature of the neutral simulations is the development...... of a super-geostrophic jet near the top of the boundary layer. The analytical wind-shear models included do not account for such a jet, and the best agreement with simulated wind shear is seen in cases with weak stratification above the boundary layer. Increasing the surface heat flux decreases the magnitude...
Study of the {sup 6}Li + p → {sup 3}He + {sup 4}He reaction in inverse kinematics
Energy Technology Data Exchange (ETDEWEB)
Betsou, C.; Pakou, A.; Aslanoglou, X.; Nicolis, N.G.; Sgouros, O.; Soukeras, V. [The University of Ioannina, Department of Physics and HINP, Ioannina (Greece); Cappuzzello, F. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Acosta, L. [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico Distrito Federal (Mexico); INFN, Catania (Italy); Agodi, C.; Carbone, D.; Cavallaro, M.; Di Pietro, A.; Fernandez-Garcia, J.P.; Figuera, P.; Fisichella, M. [Laboratori Nazionali del Sud, INFN, Catania (Italy); Foti, A. [Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); INFN, Catania (Italy); Keeley, N. [National Centre for Nuclear Research, Otwock (Poland); Marquinez-Duran, G.; Martel, I. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Mazzocco, M.; Strano, E.; Torresi, D. [Universita di Padova, Departimento di Fisica e Astronomia, Padova (Italy); INFN, Padova (Italy); Pierroutsakou, D. [INFN, Napoli (Italy); Rusek, K. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Stiliaris, E. [University of Athens, Institute of Accelerating Systems and Applications and Department of Physics, Athens (Greece)
2015-07-15
Angular distribution measurements were performed for the {sup 6}Li + p → {sup 3}He + {sup 4}He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8 MeV/u. The detection of both recoils ({sup 3}He and {sup 4}He) over the laboratory angle range θ{sub lab} = 16 {sup circle} to 34 {sup circle} allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame (θ{sub c.m.} ∝ 40 {sup circle} to 140 {sup circle}). The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations. (orig.)
Woolcott, Orison O.; Castillo, Oscar A.; Gutierrez, Cesar; Elashoff, Robert M.; Stefanovski, Darko; Bergman, Richard N.
2014-01-01
Objective To determine whether geographical elevation is inversely associated with diabetes, while adjusting for multiple risk factors. Design and Methods This is a cross-sectional analysis of publicly available online data from the Behavioral Risk Factor Surveillance System, 2009. Final dataset included 285,196 US adult subjects. Odds ratios were obtained from multilevel mixed-effects logistic regression analysis. Results Among US adults (≥20 years old), the odds ratio for diabetes were 1.00 between 0−499 m of altitude (reference), 0.95 (95% confidence interval, 0.90 to 1.01) between 500−1,499 m, and 0.88 (0.81 to 0.96) between 1,500−3,500 m, adjusting for age, sex, body mass index, ethnicity, self-reported fruit and vegetable consumption, self-reported physical activity, current smoking status, level of education, income, health status, employment status, and county-level information on migration rate, urbanization, and latitude. The inverse association between altitude and diabetes in the US was found among men [0.84 (0.76 to 0.94)], but not women [1.09 (0.97 to 1.22)]. Conclusions Among US adults, living at high altitude (1,500−3,500 m) is associated with lower odds of having diabetes than living between 0−499 m, while adjusting for multiple risk factors. Our findings suggest that geographical elevation may be an important factor linked to diabetes. PMID:24890677
Ali, Omar; Cerjak, Diana; Kent, Jack W; James, Roland; Blangero, John; Carless, Melanie A; Zhang, Yi
2016-09-01
Epigenetic mechanisms, including DNA methylation, mediate the interaction between gene and environment and may play an important role in the obesity epidemic. We assessed the relationship between DNA methylation and obesity in peripheral blood mononuclear cells (PBMCs) at 485,000 CpG sites across the genome in family members (8-90 y of age) using a discovery cohort (192 individuals) and a validation cohort (1,052 individuals) of Northern European ancestry. After Bonferroni-correction (P α=0.05 = 1.31 × 10 -7 ) for genome-wide significance, we identified 3 loci, cg18181703 (SOCS3), cg04502490 (ZNF771), and cg02988947 (LIMD2), where methylation status was associated with body mass index percentile (BMI%), a clinical index for obesity in children, adolescents, and adults. These sites were also associated with multiple metabolic syndrome (MetS) traits, including central obesity, fat depots, insulin responsiveness, and plasma lipids. The SOCS3 methylation locus was also associated with the clinical definition of MetS. In the validation cohort, SOCS3 methylation status was found to be inversely associated with BMI% (P = 1.75 × 10 -6 ), waist to height ratio (P = 4.18 × 10 -7 ), triglycerides (P = 4.01 × 10 -4 ), and MetS (P = 4.01 × 10 -7 ), and positively correlated with HDL-c (P = 4.57 × 10 -8 ). Functional analysis in a sub cohort (333 individuals) demonstrated SOCS3 methylation and gene expression in PBMCs were inversely correlated (P = 2.93 × 10 -4 ) and expression of SOCS3 was positively correlated with status of MetS (P = 0.012). We conclude that epigenetic modulation of SOCS3, a gene involved in leptin and insulin signaling, may play an important role in obesity and MetS.
Kuzman, Tomislav; Barišić Kutija, Marija; Kordić, Rajko; Popović Suić, Smiljka; Jandroković, Sonja; Škegro, Ivan; Pokupec, Rajko
2013-01-01
The aim of this study was to compare antimicrobial efficacy of rigid contact lens disinfecting solutions. We tested five commercially available solutions: Unique pH (Alcon Laboratories), Boston Advance (Polymer Technology Corp.), Nitilens Conditioner GP (Avizor), Total Care (AMO), Boston Simplus (Bausch&Lomb). Their efficacy to disinfect saline solution experimentally contaminated with American Type Culture Collection (ATCC): Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922...
A study of the electrode/solution interface during electrochemical reactions by digital holography
Directory of Open Access Journals (Sweden)
SHENHAO CHEN
2006-10-01
Full Text Available Digital holography was used to study in situ the dynamic changes of the electrode/solution interface and the solution near the electrode during the anodic process of iron in a sulfuric acid solution. The effects of chloride, bromide and iodine ions on this process were also investigated. The magnetic field also has effects on the process. The effects are discussed in combination with SEM results.
Solutions to Faculty Work Overload: A Study of Job Sharing
Freeman, Brenda J.; Coll, Kenneth M.
2009-01-01
This study investigated the opinions of a national sample of counselor education chairs and college of education deans regarding the advantages and disadvantages of faculty job sharing. Results showed favorable responses toward faculty job sharing from approximately half the sample, despite limited experience with job sharing. The study found few…
Column studies for biosorption of dyes from aqueous solutions on ...
African Journals Online (AJOL)
Biosorption is becoming a promising alternative to replace or supplement the present dye removal processes from dye wastewaters. Based on the results of batch studies on biosorption of the dyes on powdered fungal biomass, Aspergillus niger, an immobilised fungal biomass was used in column studies for removal of four ...
Bayesian inversion of refraction seismic traveltime data
Ryberg, T.; Haberland, Ch
2018-03-01
We apply a Bayesian Markov chain Monte Carlo (McMC) formalism to the inversion of refraction seismic, traveltime data sets to derive 2-D velocity models below linear arrays (i.e. profiles) of sources and seismic receivers. Typical refraction data sets, especially when using the far-offset observations, are known as having experimental geometries which are very poor, highly ill-posed and far from being ideal. As a consequence, the structural resolution quickly degrades with depth. Conventional inversion techniques, based on regularization, potentially suffer from the choice of appropriate inversion parameters (i.e. number and distribution of cells, starting velocity models, damping and smoothing constraints, data noise level, etc.) and only local model space exploration. McMC techniques are used for exhaustive sampling of the model space without the need of prior knowledge (or assumptions) of inversion parameters, resulting in a large number of models fitting the observations. Statistical analysis of these models allows to derive an average (reference) solution and its standard deviation, thus providing uncertainty estimates of the inversion result. The highly non-linear character of the inversion problem, mainly caused by the experiment geometry, does not allow to derive a reference solution and error map by a simply averaging procedure. We present a modified averaging technique, which excludes parts of the prior distribution in the posterior values due to poor ray coverage, thus providing reliable estimates of inversion model properties even in those parts of the models. The model is discretized by a set of Voronoi polygons (with constant slowness cells) or a triangulated mesh (with interpolation within the triangles). Forward traveltime calculations are performed by a fast, finite-difference-based eikonal solver. The method is applied to a data set from a refraction seismic survey from Northern Namibia and compared to conventional tomography. An inversion test
Luo, Wei-Ping; Fang, Yu-Jing; Lu, Min-Shan; Zhong, Xiao; Chen, Yu-Ming; Zhang, Cai-Xia
2015-04-14
The colour of the edible portion of vegetables and fruit reflects the presence of specific micronutrients and phytochemicals. No existing studies have examined the relationship between the intake of vegetable and fruit colour groups and the risk of colorectal cancer. The present study, therefore, aimed to investigate these associations in a Chinese population. A case-control study was conducted between July 2010 and July 2014 in Guangzhou, China, in which 1057 consecutively recruited cases of colorectal cancer were frequency-matched to 1057 controls by age (5-year interval), sex and residence (rural/urban). A validated FFQ was used to collect dietary information during face-to-face interviews. Vegetables and fruit were classified into four groups according to the colour of their primarily edible parts: green; orange/yellow; red/purple; white. Unconditional logistic regression models were used to estimate the OR and 95 % CI. A higher consumption of orange/yellow, red/purple and white vegetables and fruit was inversely associated with the risk of colorectal cancer, with adjusted OR of 0·16 (95 % CI 0·12, 0·22) for orange/yellow, 0·23 (95 % CI 0·17, 0·31) for red/purple and 0·53 (95 % CI 0·40, 0·70) for white vegetables and fruit when the highest and lowest quartiles were compared. Total vegetable intake and total fruit intake have also been found to be inversely associated with colorectal cancer risk. However, the intake of green vegetable and fruit was not associated with colorectal cancer risk. The results of the present study, therefore, suggest that a greater intake of orange/yellow, red/purple and white vegetables and fruit is inversely associated with the risk of colorectal cancer.
Batch Adsorption Study of Methylene Blue in Aqueous Solution ...
African Journals Online (AJOL)
PROF HORSFALL
of methylene blue (azo dye) from the synthetic industrial wastewater was investigated in a batch system. Rice husk and coconut shell were ... the textiles, rubber, paper, plastics, cosmetic, and .... wastewater by. Fenton's oxidation: Kinetic study.
Inverse problems in linear transport theory
International Nuclear Information System (INIS)
Dressler, K.
1988-01-01
Inverse problems for a class of linear kinetic equations are investigated. The aim is to identify the scattering kernel of a transport equation (corresponding to the structure of a background medium) by observing the 'albedo' part of the solution operator for the corresponding direct initial boundary value problem. This means to get information on some integral operator in an integrodifferential equation through on overdetermined boundary value problem. We first derive a constructive method for solving direct halfspace problems and prove a new factorization theorem for the solutions. Using this result we investigate stationary inverse problems with respect to well posedness (e.g. reduce them to classical ill-posed problems, such as integral equations of first kind). In the time-dependent case we show that a quite general inverse problem is well posed and solve it constructively. (orig.)
Stability studies of lincomycin hydrochloride in aqueous solution and intravenous infusion fluids.
Czarniak, Petra; Boddy, Michael; Sunderland, Bruce; Hughes, Jeff D
2016-01-01
The purpose of this study was to evaluate the chemical stability of Lincocin(®) (lincomycin hydrochloride) in commonly used intravenous fluids at room temperature (25°C), at accelerated-degradation temperatures and in selected buffer solutions. The stability of Lincocin(®) injection (containing lincomycin 600 mg/2 mL as the hydrochloride) stored at 25°C±0.1°C in sodium lactate (Hartmann's), 0.9% sodium chloride, 5% glucose, and 10% glucose solutions was investigated over 31 days. Forced degradation of Lincocin(®) in hydrochloric acid, sodium hydroxide, and hydrogen peroxide was performed at 60°C. The effect of pH on the degradation rate of lincomycin hydrochloride stored at 80°C was determined. Lincomycin hydrochloride w as found to maintain its shelf life at 25°C in sodium lactate (Hartmann's) solution, 0.9% sodium chloride solution, 5% glucose solution, and 10% glucose solution, with less than 5% lincomycin degradation occurring in all intravenous solutions over a 31-day period. Lincomycin hydrochloride showed less rapid degradation at 60°C in acid than in basic solution, but degraded rapidly in hydrogen peroxide. At all pH values tested, lincomycin followed first-order kinetics. It had the greatest stability near pH 4 when stored at 80°C (calculated shelf life of 4.59 days), and was least stable at pH 2 (calculated shelf life of 0.38 days). Lincocin(®) injection was chemically found to have a shelf life of at least 31 days at 25°C when added to sodium lactate (Hartmann's) solution, 0.9% sodium chloride solution, 5% glucose solution, and 10% glucose solution. Solutions prepared at approximately pH 4 are likely to have optimum stability.
Performance study of ultrafiltration membrane with bovine serum albumin as feed solution
International Nuclear Information System (INIS)
Syahril Ahmad
2009-01-01
Bovine serum albumin solutions at different temperature, pH, flow rate and operation pressure have been used as feed solution for studying performance of ultrafiltration membrane. Polysulfone membranes used for this experiment were in form of hollow fibers that have Molecular Weight Cut Off (MWCO) 60 kDa. Observation was focused on flux parameter and rejection coefficient towards protein during the process. Result shows that temperature, pH of BSA feed solution, flow rate and operation pressure can affect the flux and rejection coefficient of membrane. High temperature feed solution tend to decrease the flux but increase rejection coefficient. Rejection coefficient of membrane will increase while flux decreasing at pH of feed solution near to protein isoelectric point. High pressure of feed solution will increase flux but decrease rejection of membrane. Rejection of membrane will decrease and flux will increase when the process operated in slow flow rate. (author)