Adaptive cyclically dominating game on co-evolving networks: numerical and analytic results
Choi, Chi Wun; Xu, Chen; Hui, Pak Ming
2017-10-01
A co-evolving and adaptive Rock (R)-Paper (P)-Scissors (S) game (ARPS) in which an agent uses one of three cyclically dominating strategies is proposed and studied numerically and analytically. An agent takes adaptive actions to achieve a neighborhood to his advantage by rewiring a dissatisfying link with a probability p or switching strategy with a probability 1 - p. Numerical results revealed two phases in the steady state. An active phase for p pc has three separate clusters of agents using only R, P, and S, respectively with terminated adaptive actions. A mean-field theory based on the link densities in co-evolving network is formulated and the trinomial closure scheme is applied to obtain analytical solutions. The analytic results agree with simulation results on ARPS well. In addition, the different probabilities of winning, losing, and drawing a game among the agents are identified as the origin of the small discrepancy between analytic and simulation results. As a result of the adaptive actions, agents of higher degrees are often those being taken advantage of. Agents with a smaller (larger) degree than the mean degree have a higher (smaller) probability of winning than losing. The results are informative for future attempts on formulating more accurate theories.
Results from Numerical General Relativity
Baker, John G.
2011-01-01
For several years numerical simulations have been revealing the details of general relativity's predictions for the dynamical interactions of merging black holes. I will review what has been learned of the rich phenomenology of these mergers and the resulting gravitational wave signatures. These wave forms provide a potentially observable record of the powerful astronomical events, a central target of gravitational wave astronomy. Asymmetric radiation can produce a thrust on the system which may accelerate the single black hole resulting from the merger to high relative velocity.
Ocean wave prediction using numerical and neural network models
Digital Repository Service at National Institute of Oceanography (India)
Mandal, S.; Prabaharan, N.
This paper presents an overview of the development of the numerical wave prediction models and recently used neural networks for ocean wave hindcasting and forecasting. The numerical wave models express the physical concepts of the phenomena...
Aspects of the numerical analysis of neural networks
Ellacott, S. W.
This article starts with a brief introduction to neural networks for those unfamiliar with the basic concepts, together with a very brief overview of mathematical approaches to the subject. This is followed by a more detailed look at three areas of research which are of particular interest to numerical analysts.The first area is approximation theory. If K is a compact set in n, for some n, then it is proved that a semilinear feedforward network with one hidden layer can uniformly approximate any continuous function in C(K) to any required accuracy. A discussion of known results and open questions on the degree of approximation is included. We also consider the relevance of radial basis functions to neural networks.The second area considered is that of learning algorithms. A detailed analysis of one popular algorithm (the delta rule) will be given, indicating why one implementation leads to a stable numerical process, whereas an initially attractive variant (essentially a form of steepest descent) does not. Similar considerations apply to the backpropagation algorithm. The effect of filtering and other preprocessing of the input data will also be discussed systematically.Finally some applications of neural networks to numerical computation are considered.
Flow focusing in unsaturated fracture networks: A numerical investigation
Energy Technology Data Exchange (ETDEWEB)
Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S.; Liu, Hui-Hai
2003-04-17
A numerical modeling study is presented to investigate flow-focusing phenomena in a large-scale fracture network, constructed using field data collected from the unsaturated zone of Yucca Mountain, Nevada, the proposed repository site for high-level nuclear waste. The two-dimensional fracture network for an area of 100 m x 150 m contains more than 20,000 fractures. Steady-state unsaturated flow in the fracture network is investigated for different boundary conditions and rock properties. Simulation results indicate that flow paths are generally vertical, and that horizontal fractures mainly provide pathways between neighboring vertical paths. In addition to fracture properties, flow-focusing phenomena are also affected by rock-matrix permeability, with lower matrix permeability leading to a high degree of flow focusing. The simulation results further indicate that the average spacing between flow paths in a layered system tends to increase and flow tends to becomes more focused, with depth.
Numerical homogenization: survey, new results, and perspectives
Directory of Open Access Journals (Sweden)
Gloria Antoine
2012-09-01
Full Text Available These notes give a state of the art of numerical homogenization methods for linear elliptic equations. The guideline of these notes is analysis. Most of the numerical homogenization methods can be seen as (more or less different discretizations of the same family of continuous approximate problems, which H-converges to the homogenized problem. Likewise numerical correctors may also be interpreted as approximations of Tartar’s correctors. Hence the convergence analysis of these methods relies on the H-convergence theory. When one is interested in convergence rates, the story is different. In particular one first needs to make additional structure assumptions on the heterogeneities (say periodicity for instance. In that case, a crucial tool is the spectral interpretation of the corrector equation by Papanicolaou and Varadhan. Spectral analysis does not only allow to obtain convergence rates, but also to devise efficient new approximation methods. For both qualitative and quantitative properties, the development and the analysis of numerical homogenization methods rely on seminal concepts of the homogenization theory. These notes contain some new results. Ces notes de cours dressent un état de l’art des méthodes d’homogénéisation numérique pour les équations elliptiques linéaires. Le fil conducteur choisi est l’analyse. La plupart des méthodes d’homogénéisation numérique s’interprète comme des discrétisations (plus ou moins différentes d’une même famille de problèmes continus approchés qui H-converge vers le problème homogénéisé. De même, le concept de correcteur numérique s’interprète comme une approximation des correcteurs introduits par Tartar. Ainsi l’analyse de convergence repose essentiellement sur la théorie de la H-convergence. Si on s’intéresse aux estimations quantitatives d’erreur, il faut faire des hypothèses supplémentaires de structure sur les hétérogénéités (périodicité par
Numerical Analysis on the Optimization of Hydraulic Fracture Networks
Directory of Open Access Journals (Sweden)
Zhaobin Zhang
2015-10-01
Full Text Available The clear understanding of hydraulic fracture network complexity and the optimization of fracture network configuration are important to the hydraulic fracturing treatment of shale gas reservoirs. For the prediction of hydraulic fracture network configuration, one of the problems is the accurate representation of natural fractures. In this work, a real natural fracture network is reconstructed from shale samples. Moreover, a virtual fracture system is proposed to simulate the large number of small fractures that are difficult to identify. A numerical model based on the displacement discontinuity method is developed to simulate the fluid-rock coupling system. A dimensionless stress difference that is normalized by rock strength is proposed to quantify the anisotropy of crustal stress. The hydraulic fracturing processes under different stress conditions are simulated. The most complex fracture configurations are obtained when the maximum principle stress direction is perpendicular to the principle natural fracture direction. In contrast, the worst results are obtained when these two directions are parallel to each other. Moreover, the side effects of the unfavorable geological conditions caused by crustal stress anisotropy can be partly suppressed by increasing the viscous effect of the fluid.
Magnetic Guarding: Experimental and Numerical Results
Heinrich, Jonathon; Font, Gabriel; Garrett, Michael; Rose, D.; Genoni, T.; Welch, D.; McGuire, Thomas
2017-10-01
The magnetic field topology of Lockheed Martin's Compact Fusion Reactor (CFR) concept requires internal magnetic field coils. Internal coils for similar devices have leveraged levitating coils or coils with magnetically guarded supports. Magnetic guarding of supports has been investigated for multipole devices (theoretically and experimentally) without conclusive results. One outstanding question regarding magnetic guarding of supports is the magnitude and behavior of secondary plasma drifts resulting from magnetic guard fields (grad-B drifts, etc). We present magnetic-implicit PIC modeling results and preliminary proof of concept experimental results on magnetic guarding of internal-supports and the subsequent reduction in total plasma losses.
A numerical study of equilibrium states in tidal network morphodynamics
Xu, Fan; Coco, Giovanni; Zhou, Zeng; Tao, Jianfeng; Zhang, Changkuan
2017-09-01
The long-term morphodynamic evolution of tidal networks on tidal flats is investigated using a two-dimensional numerical model. We explore the physical processes related to the development of the morphology and the presence of equilibrium configurations. Tidal networks are simulated over a rectangular domain representing a tidal platform, a different setting compared to estuaries (subject to riverine influence) and lagoons (offshore bars constricting the flow). In the early and middle phases of the tidal network evolution, large sediment patches with rhombus-like shape form and gradually migrate in the flood direction, even though the overall sediment flux is ebb-directed. A cross-section-averaged "equilibrium" state is asymptotically approached after about 500 years. The area and peak discharge of the lower flat cross-sections at year 500 approximately show a 1:1 relationship, which is in agreement with field observations. We also show that model results are consistent with the Q-A relationship (peak discharge Q versus cross-sectional area A), which is obtained under the assumption of a constant Chézy friction.
A numerical study of equilibrium states in tidal network morphodynamics
Xu, Fan; Coco, Giovanni; Zhou, Zeng; Tao, Jianfeng; Zhang, Changkuan
2017-12-01
The long-term morphodynamic evolution of tidal networks on tidal flats is investigated using a two-dimensional numerical model. We explore the physical processes related to the development of the morphology and the presence of equilibrium configurations. Tidal networks are simulated over a rectangular domain representing a tidal platform, a different setting compared to estuaries (subject to riverine influence) and lagoons (offshore bars constricting the flow). In the early and middle phases of the tidal network evolution, large sediment patches with rhombus-like shape form and gradually migrate in the flood direction, even though the overall sediment flux is ebb-directed. A cross-section-averaged "equilibrium" state is asymptotically approached after about 500 years. The area and peak discharge of the lower flat cross-sections at year 500 approximately show a 1:1 relationship, which is in agreement with field observations. We also show that model results are consistent with the Q-A relationship (peak discharge Q versus cross-sectional area A), which is obtained under the assumption of a constant Chézy friction.
A network landscape model: stability analysis and numerical tests
Bonacini, E.; Groppi, M.; Monaco, R.; Soares, A. J.; Soresina, C.
2017-07-01
A Network Landscape Model (NLM) for the evaluation of the ecological trend of an environmental system is here presented and investigated. The model consists in a network of dynamical systems, where each node represents a single Landscape Unit (LU), endowed by a system of ODEs for two variables relevant to the production of bio-energy and to the percentage of green areas, respectively. The main goal of the paper consists in testing the relevance of connectivity between the LUs. For this purpose we consider first the Single LU Model (SLM) and investigate its equilibria and their stability, in terms of two bifurcation parameters. Then the network dynamics is theoretically investigated by means of a bifurcation analysis of a proper simplified differential system, that allows to understand how the coupling between different LUs modifies the asymptotic scenarios for the single LU model. Numerical simulations of NLM are performed, with reference to an environmental system in Northern Italy, and results are discussed in connection with SLM.
[Numerical analysis on network characteristics of communities in herb-pairs network].
Cao, Jia; Xin, Juan-juan; Wang, Yun
2015-06-01
To interpret the traditional Chinese medicine (TCM) theory by the network technology, in order to promote the modernization and programming of studies on compatibility of TCMs. In this paper, efforts were made to express the direct interactions between drugs through the herb-pair network, analyze the community characteristics of the network and its relations with blood-Qi theory, and study the expression of blood-Qi theory on the herb-pair network through prescriptions. According to the findings, the herb-pairs network showed a strong community structure characteristics; Each community is composed of a series of herb pairs with close correlations, and either blood efficacy or Qi efficacy but not both of them. Based on that, the 386 single TCM ingredients involved by the herb-pair network were divided into three types of communities: Blood (B) community, Qi (Q) community and uncertain community. According to the statistical results of 262 prescriptions mapped onto the three types of communities, if a prescription contains single herbs of the Q community, the probability that it contains single herbs o the B community is 99.84%; Meanwhile, there are 140 prescriptions containing single herbs of both the Q community and the B community. The result is completely coincident with the TCM Blood-Qi theory that single herbs belong to both Q and B communities or the B community, because Qi regulation leads to blood regulation, but not vice versa. For example, a patient with hemorrhage due to trauma or blood-heat, Qi tonifying prescriptions may aggravate hemorrhage. In this paper, authors found high-recognition macroscopic network numerical characteristics to network data reference for judging rationality of new prescriptions, and proved human blood and Qi relations from the perspective of data analysis.
Numerical study on the perception-based network formation model
Jo, Hang-Hyun
2015-01-01
In order to understand the evolution of social networks in terms of perception-based strategic link formation, we numerically study a perception-based network formation model. Here each individual is assumed to have his/her own perception of the actual network, and use it to decide whether to create a link to other individual. An individual with the least perception accuracy can benefit from updating his/her perception using that of the most accurate individual via a new link. This benefit is compared to the cost of linking in decision making. Once a new link is created, it affects the accuracies of other individuals' perceptions, leading to a further evolution of the actual network. The initial actual network and initial perceptions are modeled by Erd\\H{o}s-R\\'enyi random networks but with different linking probabilities. Then the stable link density of the actual network is found to show discontinuous transitions or jumps according to the cost of linking. The effect of initial conditions on the complexity o...
Numerical analysis of modeling based on improved Elman neural network.
Jie, Shao; Li, Wang; WeiSong, Zhao; YaQin, Zhong; Malekian, Reza
2014-01-01
A modeling based on the improved Elman neural network (IENN) is proposed to analyze the nonlinear circuits with the memory effect. The hidden layer neurons are activated by a group of Chebyshev orthogonal basis functions instead of sigmoid functions in this model. The error curves of the sum of squared error (SSE) varying with the number of hidden neurons and the iteration step are studied to determine the number of the hidden layer neurons. Simulation results of the half-bridge class-D power amplifier (CDPA) with two-tone signal and broadband signals as input have shown that the proposed behavioral modeling can reconstruct the system of CDPAs accurately and depict the memory effect of CDPAs well. Compared with Volterra-Laguerre (VL) model, Chebyshev neural network (CNN) model, and basic Elman neural network (BENN) model, the proposed model has better performance.
Numerical Analysis of Modeling Based on Improved Elman Neural Network
Directory of Open Access Journals (Sweden)
Shao Jie
2014-01-01
Full Text Available A modeling based on the improved Elman neural network (IENN is proposed to analyze the nonlinear circuits with the memory effect. The hidden layer neurons are activated by a group of Chebyshev orthogonal basis functions instead of sigmoid functions in this model. The error curves of the sum of squared error (SSE varying with the number of hidden neurons and the iteration step are studied to determine the number of the hidden layer neurons. Simulation results of the half-bridge class-D power amplifier (CDPA with two-tone signal and broadband signals as input have shown that the proposed behavioral modeling can reconstruct the system of CDPAs accurately and depict the memory effect of CDPAs well. Compared with Volterra-Laguerre (VL model, Chebyshev neural network (CNN model, and basic Elman neural network (BENN model, the proposed model has better performance.
An overview of the numerical and neural network accosts of ocean wave prediction
Digital Repository Service at National Institute of Oceanography (India)
Mandal, S.; Prabaharan, N.
This paper presents an overview of the development of the numerical wave prediction models and recently used neural networks for wave hindcasting and forecasting. The numerical wave models express the physical concepts of the phenomena...
Synthetic jet parameter identification and numerical results validation
Sabbatini, Danilo; Rimasauskiene, Ruta; Matejka, Milan; Kurowski, Marcin; Wandowski, Tomasz; Malinowski, Paweł; Doerffer, Piotr
2012-06-01
The design of a synthetic jet requires a careful identification of the components' parameters, in order to be able to perform accurate numerical simulations, this identification must be done by mean of a series of measurements that, due to the small dimensions of the components, are required to be non-contact techniques. The activities described in this paper have been performed in the frame of the STA-DY-WI-CO project, whose purpose is the design of a synthetic jet and demonstrate its effectiveness and efficiency for a real application. To measure the energy saving, due to the synthetic jet effects on the separation, the increased performances of the profile must be compared to the energy absorbed by the actuator and the weight of the system. In design phase a series of actuators has being considered as well as a series of cavity layout, in order to obtain the most effective, efficient and durable package. The modal characteristics of piezoelectric component was assessed by means of tests performed with a 3D scanning laser vibrometer, measuring the frequency response to voltage excitation. Analyzed the effects of the parameters, and chosen components and layout, the system can be dimensioned by means of numeric simulations. The outcome of the simulation is the effect of the synthetic jet, in an assumed flow, for the selected profile. The numerical results on the field of the separated flow with recirculating area were validated by means of tests performed in an Eiffel type wind tunnel. The last test performed on the synthetic jet aims to understand the acoustic impact, noise measurements were performed to have full analysis and synthesis.
Multi-Digit Handwritten Sindhi Numerals Recognition using SOM Neural Network
Directory of Open Access Journals (Sweden)
ASGHAR ALI CHANDIO
2017-10-01
Full Text Available In this research paper a multi-digit Sindhi handwritten numerals recognition system using SOM Neural Network is presented. Handwritten digits recognition is one of the challenging tasks and a lot of research is being carried out since many years. A remarkable work has been done for recognition of isolated handwritten characters as well as digits in many languages like English, Arabic, Devanagari, Chinese, Urdu and Pashto. However, the literature reviewed does not show any remarkable work done for Sindhi numerals recognition. The recognition of Sindhi digits is a difficult task due to the various writing styles and different font sizes. Therefore, SOM (Self-Organizing Map, a NN (Neural Network method is used which can recognize digits with various writing styles and different font sizes. Only one sample is required to train the network for each pair of multi-digit numerals. A database consisting of 4000 samples of multi-digits consisting only two digits from 10-50 and other matching numerals have been collected by 50 users and the experimental results of proposed method show that an accuracy of 86.89% is achieved.
A numerical modeling of nonlinear load behavior using artificial neural networks
Panoiu, Manuela; Ghiormez, Loredana; Panoiu, Caius; Iordan, Anca
2013-10-01
In this paper it is performed a numerical study of the voltage-current characteristic of an electric arc. To predict voltages and currents values, a multi-layer perceptron Artificial Neural Networks was used under the Matlab 2012 environment. The study is based on actual recorded data obtained from a 100 tones AC Electric Arc Furnace. Results obtained by simulation are compared with the measured one.
Numerical Simulation of Fluid Flow through Fractal-Based Discrete Fractured Network
Directory of Open Access Journals (Sweden)
Wendong Wang
2018-01-01
Full Text Available Abstract: In recent years, multi-stage hydraulic fracturing technologies have greatly facilitated the development of unconventional oil and gas resources. However, a quantitative description of the “complexity” of the fracture network created by the hydraulic fracturing is confronted with many unsolved challenges. Given the multiple scales and heterogeneity of the fracture system, this study proposes a “bifurcated fractal” model to quantitatively describe the distribution of induced hydraulic fracture networks. The construction theory is employed to generate hierarchical fracture patterns as a scaled numerical model. With the implementation of discrete fractal-fracture network modeling (DFFN, fluid flow characteristics in bifurcated fractal fracture networks are characterized. The effects of bifurcated fracture length, bifurcated tendency, and number of bifurcation stages are examined. A field example of the fractured horizontal well is introduced to calibrate the accuracy of the flow model. The proposed model can provide a more realistic representation of complex fracture networks around a fractured horizontal well, and offer the way to quantify the “complexity” of the fracture network in shale reservoirs. The simulation results indicate that the geometry of the bifurcated fractal fracture network model has a significant impact on production performance in the tight reservoir, and enhancing connectivity of each bifurcate fracture is the key to improve the stimulation performance. In practice, this work provides a novel and efficient workflow for complex fracture characterization and production prediction in naturally-fractured reservoirs of multi-stage fractured horizontal wells.
[Dementia Competence Network. Results and outlook].
Peters, Oliver; Heuser, Isabella; Frölich, Lutz; Rüther, Eckart; Rienhoff, Otto; Kornhuber, Johannes; Wiltfang, Jens; Maier, Wolfgang
2016-04-01
The Dementia Competence Network (DCN) is represented by academic memory clinics and has three major aims: (1) To facilitate the development of diagnostic tools including neuropsychology, biomarkers, imaging and genetics. (2) To implement clinical trials in mild cognitive impairment and dementia and (3) to improve standard care for dementia in Germany. This article summarizes the achievements of the DCN so far and highlights future perspectives. The DCN has built up two multicentre cohorts. Within the first cohort, patients with mild cognitive impairment or mild dementia were examined longitudinally using multiple neuropsychological assessments and numerous different biomarkers. In a subgroup of the first cohort, patients were treated with antidementive drugs in two placebo-controlled clinical trials. The second cohort included cognitively healthy older people and examined repetitively clinical, neuropsychological and psychosocial parameters for ten years. The DCN has generated a large data and biomaterial bank. Numerous publications have helped to develop further diagnostic procedures and treatment of cognitive disorders and dementia. The DCN has contributed to end stigmatisation of dementia.
Defect reaction network in Si-doped InAs. Numerical predictions.
Energy Technology Data Exchange (ETDEWEB)
Schultz, Peter A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-05-01
This Report characterizes the defects in the def ect reaction network in silicon - doped, n - type InAs predicted with first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si - doped InAs , until culminating in immobile reaction p roducts. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon - related defects in the reaction network. This Report serves to extend the results for the properties of intrinsic defects in bulk InAs as colla ted in SAND 2013 - 2477 : Simple intrinsic defects in InAs : Numerical predictions to include Si - containing simple defects likely to be present in a radiation - induced defect reaction sequence . This page intentionally left blank
Numerical Representations and User Behaviour in Social Networking Sites
DEFF Research Database (Denmark)
Sjöklint, Mimmi; Constantiou, Ioanna; Trier, Matthias
2013-01-01
is prominent in social networking sites, which are the empirical setting for the present study. This paper sets out to establish a multi-theoretical framework which enables the investigation of emerging phenomena of the role of numbers in social networking sites. The proposed framework rests on three...
Joint physical and numerical modeling of water distribution networks.
Energy Technology Data Exchange (ETDEWEB)
Zimmerman, Adam; O' Hern, Timothy John; Orear, Leslie Jr.; Kajder, Karen C.; Webb, Stephen Walter; Cappelle, Malynda A.; Khalsa, Siri Sahib; Wright, Jerome L.; Sun, Amy Cha-Tien; Chwirka, J. Benjamin; Hartenberger, Joel David; McKenna, Sean Andrew; van Bloemen Waanders, Bart Gustaaf; McGrath, Lucas K.; Ho, Clifford Kuofei
2009-01-01
This report summarizes the experimental and modeling effort undertaken to understand solute mixing in a water distribution network conducted during the last year of a 3-year project. The experimental effort involves measurement of extent of mixing within different configurations of pipe networks, measurement of dynamic mixing in a single mixing tank, and measurement of dynamic solute mixing in a combined network-tank configuration. High resolution analysis of turbulence mixing is carried out via high speed photography as well as 3D finite-volume based Large Eddy Simulation turbulence models. Macroscopic mixing rules based on flow momentum balance are also explored, and in some cases, implemented in EPANET. A new version EPANET code was developed to yield better mixing predictions. The impact of a storage tank on pipe mixing in a combined pipe-tank network during diurnal fill-and-drain cycles is assessed. Preliminary comparison between dynamic pilot data and EPANET-BAM is also reported.
A simple and accurate numerical network flow model for bionic micro heat exchangers
Energy Technology Data Exchange (ETDEWEB)
Pieper, M.; Klein, P. [Fraunhofer Institute (ITWM), Kaiserslautern (Germany)
2011-05-15
Heat exchangers are often associated with drawbacks like a large pressure drop or a non-uniform flow distribution. Recent research shows that bionic structures can provide possible improvements. We considered a set of such structures that were designed with M. Hermann's FracTherm {sup registered} algorithm. In order to optimize and compare them with conventional heat exchangers, we developed a numerical method to determine their performance. We simulated the flow in the heat exchanger applying a network model and coupled these results with a finite volume method to determine the heat distribution in the heat exchanger. (orig.)
The double queue method: a numerical method for integrate-and-fire neuron networks.
Lee, G; Farhat, N H
2001-01-01
Numerical methods for initial-value problems based on finite-differencing of differential equations (FDM) are not well suited for the simulation of an integrate-and-fire neuron network (IFNN) due to the discontinuities implied by the firing condition of the neurons. The Double Queue Method (DQM) is an event-queue based numerical method designed for the simulation of an IFNN that can deal with such discontinuities properly. In the DQM, the states of individual neurons at the next predicted discontinuous points are determined by an analytic solution, meaning an optimal performance in both accuracy and speed. A comparison study with the FDM demonstrates the superiority of the DQM, and provides some examples where the FDM gives inaccurate results that can possibly lead to a false conclusion about the dynamics of an IFNN.
Numerical calculations of high-altitude differential charging: Preliminary results
Laframboise, J. G.; Godard, R.; Prokopenko, S. M. L.
1979-01-01
A two dimensional simulation program was constructed in order to obtain theoretical predictions of floating potential distributions on geostationary spacecraft. The geometry was infinite-cylindrical with angle dependence. Effects of finite spacecraft length on sheath potential profiles can be included in an approximate way. The program can treat either steady-state conditions or slowly time-varying situations, involving external time scales much larger than particle transit times. Approximate, locally dependent expressions were used to provide space charge, density profiles, but numerical orbit-following is used to calculate surface currents. Ambient velocity distributions were assumed to be isotropic, beam-like, or some superposition of these.
Directory of Open Access Journals (Sweden)
Xiaobing Chen
2014-01-01
Full Text Available In this study, physical experiments and numerical simulations are combined to provide a detailed understanding of flow dynamics in fracture network. Hydraulic parameters such as pressure head, velocity field, Reynolds number on certain monitoring cross points, and total flux rate are examined under various clogging conditions. Applying the COMSOL Multiphysics code to solve the Navier-Stokes equation instead of Reynolds equation and using the measured data to validate the model, the fluid flow in the horizontal 2D cross-sections of the fracture network was simulated. Results show that local clogging leads to a significant reshaping of the flow velocity field and a reduction of the transport capacity of the entire system. The flow rate distribution is highly influenced by the fractures connected to the dominant flow channels, although local disturbances in velocity field are unlikely to spread over the whole network. Also, modeling results indicate that water flow in a fracture network, compared with that in a single fracture, is likely to transit into turbulence earlier under the same hydraulic gradient due to the influence of fracture intersections.
Ladd, A J C
1993-01-01
A new and very general technique for simulating solid-fluid suspensions has been described in a previous paper (Part I); the most important feature of the new method is that the computational cost scales with the number of particles. In this paper (Part II), extensive numerical tests of the method are described; for creeping flows, both with and without Brownian motion, and at finite Reynolds numbers. Hydrodynamic interactions, transport coefficients, and the short-time dynamics of random dispersions of up to 1024 colloidal particles have been simulated.
Numerical simulation with finite element and artificial neural network ...
Indian Academy of Sciences (India)
Further, this database after the neural network training; is used to analyse measured material properties of different test pieces. The ANN predictions are reconﬁrmed with contact type ﬁnite element analysis for an arbitrary selected test sample. The methodology evolved in this work can be extended to predict material ...
Directory of Open Access Journals (Sweden)
Xian Xu
2015-01-01
Full Text Available A three-dimensional tensegrity structure is used as a computational model for cross-linked actin networks. The postbuckling behavior of the members under compression is considered and the constitutive relation of the postbuckling members is modeled as a second-order polynomial. A numerical scheme incorporating the equivalent constitution of the postbuckling members is used to predict the structural response of the tensegrity model under compression loads. The numerical simulation shows that the stiffness of the tensegrity structure nonlinearly increases before member buckling and abruptly decreases to a lower level as soon as members buckle. This result qualitatively mimics the experimentally observed stiffness to compression stress response of cross-linked actin networks. In order to take member length variety into account, a large number of simulations with the length of buckling members varying in the given range are also carried out. It is found that the mean response of the simulations using different buckling member length exhibits more resemblance to the experimental observation.
Combining forming results via weld models to powerful numerical assemblies
Kose, K.; Rietman, Bert
2004-01-01
Forming simulations generally give satisfying results with respect to thinning, stresses, changed material properties and, with a proper springback calculation, the geometric form. The joining of parts by means of welding yields an extra change of the material properties and the residual stresses.
Numerical results for gauge theories near the conformal window
Lucini, Biagio
2015-01-01
A novel strong interaction beyond the standard model could provide a dynamical explanation of electroweak symmetry breaking. Experimental results strongly constrain properties of models that realise this mechanism. Whether these constraints are obeyed by any strongly interacting quantum field theory is a non-perturbative problem that needs to be addressed by first-principle calculations. Monte Carlo simulations of lattice regularised gauge theories is a powerful tool that enables us to address this question. Recently various lattice investigations have appeared that have studied candidate models of strongly interacting dynamics beyond the standard model. After a brief review of the main methods and of some recent results, we focus on the analysis of SU(2) gauge theory with one adjoint Dirac fermion flavour, which is shown to have a near-conformal behaviour with an anomalous dimension of order one. The implications of our findings are also discussed.
Simulation of two-phase flow in horizontal fracture networks with numerical manifold method
Ma, G. W.; Wang, H. D.; Fan, L. F.; Wang, B.
2017-10-01
The paper presents simulation of two-phase flow in discrete fracture networks with numerical manifold method (NMM). Each phase of fluids is considered to be confined within the assumed discrete interfaces in the present method. The homogeneous model is modified to approach the mixed fluids. A new mathematical cover formation for fracture intersection is proposed to satisfy the mass conservation. NMM simulations of two-phase flow in a single fracture, intersection, and fracture network are illustrated graphically and validated by the analytical method or the finite element method. Results show that the motion status of discrete interface significantly depends on the ratio of mobility of two fluids rather than the value of the mobility. The variation of fluid velocity in each fracture segment and the driven fluid content are also influenced by the ratio of mobility. The advantages of NMM in the simulation of two-phase flow in a fracture network are demonstrated in the present study, which can be further developed for practical engineering applications.
Correlations of seismic motions and energy distributions: numerical results
Carbajal-Romero, Manuel; Pineda-León, Ernesto; Ávila-Carrera, Rafael; Efraín Rodríguez-Sánchez, José; Rodríguez-Castellanos, Alejandro; José Sánchez-Sesma, Francisco
2017-12-01
It is well known that the response of a medium at a specified load is given by the Green’s function, which can be seen as an intrinsic property of the medium. However, in many situations, the Green’s function is not available. In seismology, the Green’s function is the fundamental characteristic of the medium where seismic waves propagate and this function can be recovered experimentally by correlations of seismic movements. Furthermore, in a two-dimensional infinite medium, waves (P- and SV-waves) propagate with fixed amounts of energy. These amounts of energy, associated with the P- and SV-waves, vary with the type of medium, which is characterized by the Poisson’s ratio. Additionally, the theoretical energy distribution has been reported in the literature as a function of the elastic properties of the medium, specifically its Poisson’s ratio. In this paper, an approach to calculate the energy distributions associated with P- and SV-waves is provided. This approach is based on the interpretation of theoretical seismograms and recovered seismograms by means of correlations. This approach has important implications because by the results obtained it is possible to validate if a correlation of seismic movements is close to fully validated theoretical values. This article shows some examples and cases varying types of materials, characterized by its Poisson’s ratio.
Black carbon network in Mexico. First Results
Barrera, Valter; Peralta, Oscar; Granado, Karen; Ortinez, Abraham; Alvarez-Ospina, Harry; Espinoza, Maria de la Luz; Castro, Telma
2017-04-01
heating. The annual BC concentration media for Mexico City and Monterrey site were near 2.5 μg/m3, Guadalajara near 2 μg/m3, and Juriquilla 1.2 μg/m3. Daily and weekly data showed the BC and CO strong relationships produced by the traffic source in the three main cities. BC can be used as a marker for mobile sources policies in cities to evaluate these results quickly. Guadalajara and Juriquilla had some monitoring issues. Data verification is still been verified. This work presents a first year BC experimental network extended measure campaign for year 2015 in some cities in Mexico, to obtain direct equivalent black carbon (eBC) concentrations (Also, named when eBC data is derived from optical absorption methods) (Petzold, 2013) using aethalometers and photoacoustic extinctiometers. After this effort (mainly from National University and local agencies) it is planned to extend this BC Network to other cities around Mexico and with the Mexican Government support. REFERENCES Bond, T. C., et al., (2013). Bounding the role of black carbon in the climate system: A scientific assessment, J. Geophys. Res.-Atmos., 118, 5380-5552. Ramanathan, V. and Carmichael, G. (2008). Global and regional climate changes due to black carbon, Nat. Geosci., 1, 221-227 Petzold A., et al. (2013). Recommendations for reporting "black carbon" measurements. Atmos. Chem. Phys., 13, 8365-8379.
The Stellar Observations Network Group - first results
DEFF Research Database (Denmark)
Antoci, Victoria; Grundahl, Frank; Christensen-Dalsgaard, Joergen
SONG - the Stellar Observations Network Group is a Danish-led project set to design and build a global network of 1-m telescopes to carry out detailed studies of solar-like stars using asteroseismology and to discover and characterise exo-planets and their star system. Here we present more than 100...... nights of high-precision radial velocity measurements from 2014 of the subgiant mu Herculis. Preliminary analyses of the largest ground-based data set ever obtained for such as star clearly show the detection of stochastically excited pressure modes. The high quality of our data allows unique extraction...
Direct Numerical Simulation of Cellular-Scale Blood Flow in 3D Microvascular Networks.
Balogh, Peter; Bagchi, Prosenjit
2017-12-19
We present, to our knowledge, the first direct numerical simulation of 3D cellular-scale blood flow in physiologically realistic microvascular networks. The vascular networks are designed following in vivo images and data, and are comprised of bifurcating, merging, and winding vessels. Our model resolves the large deformation and dynamics of each individual red blood cell flowing through the networks with high fidelity, while simultaneously retaining the highly complex geometric details of the vascular architecture. To our knowledge, our simulations predict several novel and unexpected phenomena. We show that heterogeneity in hemodynamic quantities, which is a hallmark of microvascular blood flow, appears both in space and time, and that the temporal heterogeneity is more severe than its spatial counterpart. The cells are observed to frequently jam at vascular bifurcations resulting in reductions in hematocrit and flow rate in the daughter and mother vessels. We find that red blood cell jamming at vascular bifurcations results in several orders-of-magnitude increase in hemodynamic resistance, and thus provides an additional mechanism of increased in vivo blood viscosity as compared to that determined in vitro. A striking result from our simulations is negative pressure-flow correlations observed in several vessels, implying a significant deviation from Poiseuille's law. Furthermore, negative correlations between vascular resistance and hematocrit are observed in various vessels, also defying a major principle of particulate suspension flow. To our knowledge, these novel findings are absent in blood flow in straight tubes, and they underscore the importance of considering realistic physiological geometry and resolved cellular interactions in modeling microvascular hemodynamics. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
M. Boumaza
2015-07-01
Full Text Available Transient convection heat transfer is of fundamental interest in many industrial and environmental situations, as well as in electronic devices and security of energy systems. Transient fluid flow problems are among the more difficult to analyze and yet are very often encountered in modern day technology. The main objective of this research project is to carry out a theoretical and numerical analysis of transient convective heat transfer in vertical flows, when the thermal field is due to different kinds of variation, in time and space of some boundary conditions, such as wall temperature or wall heat flux. This is achieved by the development of a mathematical model and its resolution by suitable numerical methods, as well as performing various sensitivity analyses. These objectives are achieved through a theoretical investigation of the effects of wall and fluid axial conduction, physical properties and heat capacity of the pipe wall on the transient downward mixed convection in a circular duct experiencing a sudden change in the applied heat flux on the outside surface of a central zone.
Borsche, Raul; Kall, Jochen
2016-12-01
In this paper we construct high order finite volume schemes on networks of hyperbolic conservation laws with coupling conditions involving ODEs. We consider two generalized Riemann solvers at the junction, one of Toro-Castro type and a solver of Harten, Enquist, Osher, Chakravarthy type. The ODE is treated with a Taylor method or an explicit Runge-Kutta scheme, respectively. Both resulting high order methods conserve quantities exactly if the conservation is part of the coupling conditions. Furthermore we present a technique to incorporate lumped parameter models, which arise from simplifying parts of a network. The high order convergence and the robust capturing of shocks are investigated numerically in several test cases.
Fatih Korkmaz; M.Faruk Çakır; İsmail Topaloğlu; Rıza Gürbüz
2012-01-01
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications.The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new col...
Stochastic modeling and numerical simulation of gene regulatory networks with protein bursting.
Pájaro, Manuel; Alonso, Antonio A; Otero-Muras, Irene; Vázquez, Carlos
2017-05-21
Gene expression is inherently stochastic. Advanced single-cell microscopy techniques together with mathematical models for single gene expression led to important insights in elucidating the sources of intrinsic noise in prokaryotic and eukaryotic cells. In addition to the finite size effects due to low copy numbers, translational bursting is a dominant source of stochasticity in cell scenarios involving few short lived mRNA transcripts with high translational efficiency (as is typically the case for prokaryotes), causing protein synthesis to occur in random bursts. In the context of gene regulation cascades, the Chemical Master Equation (CME) governing gene expression has in general no closed form solution, and the accurate stochastic simulation of the dynamics of complex gene regulatory networks is a major computational challenge. The CME associated to a single gene self regulatory motif has been previously approximated by a one dimensional time dependent partial integral differential equation (PIDE). However, to the best of our knowledge, multidimensional versions for such PIDE have not been developed yet. Here we propose a multidimensional PIDE model for regulatory networks involving multiple genes with self and cross regulations (in which genes can be regulated by different transcription factors) derived as the continuous counterpart of a CME with jump process. The model offers a reliable description of systems with translational bursting. In order to provide an efficient numerical solution, we develop a semilagrangian method to discretize the differential part of the PIDE, combined with a composed trapezoidal quadrature formula to approximate the integral term. We apply the model and numerical method to study sustained stochastic oscillations and the development of competence, a particular case of transient differentiation attained by certain bacterial cells under stress conditions. We found that the resulting probability distributions are distinguishable
Diffusion in random networks: Asymptotic properties, and numerical and engineering approximations
Padrino, Juan C.; Zhang, Duan Z.
2016-11-01
The ensemble phase averaging technique is applied to model mass transport by diffusion in random networks. The system consists of an ensemble of random networks, where each network is made of a set of pockets connected by tortuous channels. Inside a channel, we assume that fluid transport is governed by the one-dimensional diffusion equation. Mass balance leads to an integro-differential equation for the pores mass density. The so-called dual porosity model is found to be equivalent to the leading order approximation of the integration kernel when the diffusion time scale inside the channels is small compared to the macroscopic time scale. As a test problem, we consider the one-dimensional mass diffusion in a semi-infinite domain, whose solution is sought numerically. Because of the required time to establish the linear concentration profile inside a channel, for early times the similarity variable is xt- 1 / 4 rather than xt- 1 / 2 as in the traditional theory. This early time sub-diffusive similarity can be explained by random walk theory through the network. In addition, by applying concepts of fractional calculus, we show that, for small time, the governing equation reduces to a fractional diffusion equation with known solution. We recast this solution in terms of special functions easier to compute. Comparison of the numerical and exact solutions shows excellent agreement.
Numerical and experimental results on the spectral wave transfer in finite depth
Benassai, Guido
2016-04-01
Determination of the form of the one-dimensional surface gravity wave spectrum in water of finite depth is important for many scientific and engineering applications. Spectral parameters of deep water and intermediate depth waves serve as input data for the design of all coastal structures and for the description of many coastal processes. Moreover, the wave spectra are given as an input for the response and seakeeping calculations of high speed vessels in extreme sea conditions and for reliable calculations of the amount of energy to be extracted by wave energy converters (WEC). Available data on finite depth spectral form is generally extrapolated from parametric forms applicable in deep water (e.g., JONSWAP) [Hasselmann et al., 1973; Mitsuyasu et al., 1980; Kahma, 1981; Donelan et al., 1992; Zakharov, 2005). The present paper gives a contribution in this field through the validation of the offshore energy spectra transfer from given spectral forms through the measurement of inshore wave heights and spectra. The wave spectra on deep water were recorded offshore Ponza by the Wave Measurement Network (Piscopia et al.,2002). The field regressions between the spectral parameters, fp and the nondimensional energy with the fetch length were evaluated for fetch-limited sea conditions. These regressions gave the values of the spectral parameters for the site of interest. The offshore wave spectra were transfered from the measurement station offshore Ponza to a site located offshore the Gulf of Salerno. The offshore local wave spectra so obtained were transfered on the coastline with the TMA model (Bouws et al., 1985). Finally the numerical results, in terms of significant wave heights, were compared with the wave data recorded by a meteo-oceanographic station owned by Naples Hydrographic Office on the coastline of Salerno in 9m depth. Some considerations about the wave energy to be potentially extracted by Wave Energy Converters were done and the results were discussed.
Comparison of results of experimental research with numerical calculations of a model one-sided seal
Directory of Open Access Journals (Sweden)
Joachimiak Damian
2015-06-01
Full Text Available Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.
Directory of Open Access Journals (Sweden)
Deepa Devasenapathy
2015-01-01
Full Text Available The traffic in the road network is progressively increasing at a greater extent. Good knowledge of network traffic can minimize congestions using information pertaining to road network obtained with the aid of communal callers, pavement detectors, and so on. Using these methods, low featured information is generated with respect to the user in the road network. Although the existing schemes obtain urban traffic information, they fail to calculate the energy drain rate of nodes and to locate equilibrium between the overhead and quality of the routing protocol that renders a great challenge. Thus, an energy-efficient cluster-based vehicle detection in road network using the intention numeration method (CVDRN-IN is developed. Initially, sensor nodes that detect a vehicle are grouped into separate clusters. Further, we approximate the strength of the node drain rate for a cluster using polynomial regression function. In addition, the total node energy is estimated by taking the integral over the area. Finally, enhanced data aggregation is performed to reduce the amount of data transmission using digital signature tree. The experimental performance is evaluated with Dodgers loop sensor data set from UCI repository and the performance evaluation outperforms existing work on energy consumption, clustering efficiency, and node drain rate.
MEASURING RESULTS NUMERAL TREATMENT OF IMPULSIVE CURRENTS BY MEANS OF ROGOVSKY BELT APPLICATION
Directory of Open Access Journals (Sweden)
U. Batygin
2009-01-01
Full Text Available The technique of numerical processing of measurement results of pulse currents by means of Rogovsky belt application is offered in the given work. It is shown that at measurement of signals by digital oscillographs and further numerical transformation of target signals, the possibilities of Rogovsky belt without the application of additional devices that in turn allows to define parameters of pulse currents with any peak-time characteristics essentially expand.
Role of numerical scheme choice on the results of mathematical modeling of combustion and detonation
Yakovenko, I. S.; Kiverin, A. D.; Pinevich, S. G.; Ivanov, M. F.
2016-11-01
The present study discusses capabilities of dissipation-free CABARET numerical method application to unsteady reactive gasdynamic flows modeling. In framework of present research the method was adopted for reactive flows governed by real gas equation of state and applied for several typical problems of unsteady gas dynamics and combustion modeling such as ignition and detonation initiation by localized energy sources. Solutions were thoroughly analyzed and compared with that derived by using of the modified Euler-Lagrange method of “coarse” particles. Obtained results allowed us to distinguish range of phenomena where artificial effects of numerical approach may counterfeit their physical nature and to develop guidelines for numerical approach selection appropriate for unsteady reactive gasdynamic flows numerical modeling.
Assessment results of fluid-structure interaction numerical simulation using fuzzy logic
Directory of Open Access Journals (Sweden)
Marković Zoran J.
2016-01-01
Full Text Available A fuzzy approximation concept is applied in order to predict results of coupled computational structure mechanics and computational fluid dynamics while solving a problem of steady incompressible gas flow through thermally loaded rectangular thin-walled channel. Channel wall deforms into wave - type shapes depending on thermal load and fluid inlet velocity inducing the changes of fluid flow accordingly. A set of fluid - structure interaction (FSI numerical tests have been defined by varying the values of fluid inlet velocity, temperature of inner and outer surface of the channel wall and numerical grid density. The unsteady Navier-Stokes equations are numerically solved using an element-based finite volume method and second order backward Euler discretization scheme. The structural model is solved by finite element method including geometric and material nonlinearities. The implicit two-way iterative code coupling, partitioned solution approach, were used while solving these numerical tests. Results of numerical analysis indicate that gravity and pressure distribution inside the channel contributes to triggering the shape of deformation. In the inverse problem, the results of FSI numerical simulations formed a database of input variables for development fuzzy logic based models considering downstream pressure drop and maximum stresses as the objective functions. Developed fuzzy models predicted targeting results within a reasonable accuracy limit at lower computation cost compared to series of FSI numerical calculations. Smaller relative difference were obtained when calculating the values of pressure drop then maximal stresses indicating that transfer function influence on output values have to be additionally investigated. [Projekat Ministarstva nauke Republike Srbije, br. III42010, br.TR33050 i br. TR35035
Cao, Wenzhuo; Lei, Qinghua
2018-01-01
Natural fractures are ubiquitous in the Earth's crust and often deeply buried in the subsurface. Due to the difficulty in accessing to their three-dimensional structures, the study of fracture network geometry is usually achieved by sampling two-dimensional (2D) exposures at the Earth's surface through outcrop mapping or aerial photograph techniques. However, the measurement results can be considerably affected by the coverage of forests and other plant species over the exposed fracture patterns. We quantitatively study such effects using numerical simulation. We consider the scenario of nominally isotropic natural fracture systems and represent them using 2D discrete fracture network models governed by fractal and length scaling parameters. The groundcover is modelled as random patches superimposing onto the 2D fracture patterns. The effects of localisation and total coverage of landscape patches are further investigated. The fractal dimension and length exponent of the covered fracture networks are measured and compared with those of the original non-covered patterns. The results show that the measured length exponent increases with the reduced localisation and increased coverage of landscape patches, which is more evident for networks dominated by very large fractures (i.e. small underlying length exponent). However, the landscape coverage seems to have a minor impact on the fractal dimension measurement. The research findings of this paper have important implications for field survey and statistical analysis of geological systems.
Beerens, J.C.; Ooms, G.; Pourquie, M.J.B.M.; Westerweel, J.
2014-01-01
high-viscosity liquid core surrounded by a laminar low-viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is
Markov, Sergey; Martyanov, Victor; Preis, Elena; Abay, Asmelash
2017-11-01
Understanding of internal structure of the technogenic rock dumps (gob dumps) is required condition for estimation of using ones as filtration massifs for treatment of mine wastewater. Internal structure of gob piles greatly depends on dumping technology to applying restrictions for use them as filtration massifs. Numerical modelling of gob dumps allows adequately estimate them physical parameters, as a filtration coefficient, density, etc. The gob dumps numerical modelling results given in this article, in particular was examined grain size distribution of determined fractions depend on dump height. Shown, that filtration coefficient is in a nonlinear dependence on amount of several fractions of rock in gob dump. The numerical model adequacy both the gob structure and the dependence of filtration coefficient from gob height acknowledged equality of calculated and real filtration coefficient values. The results of this research can be apply to peripheral dumping technology.
Directory of Open Access Journals (Sweden)
Markov Sergey
2017-01-01
Full Text Available Understanding of internal structure of the technogenic rock dumps (gob dumps is required condition for estimation of using ones as filtration massifs for treatment of mine wastewater. Internal structure of gob piles greatly depends on dumping technology to applying restrictions for use them as filtration massifs. Numerical modelling of gob dumps allows adequately estimate them physical parameters, as a filtration coefficient, density, etc. The gob dumps numerical modelling results given in this article, in particular was examined grain size distribution of determined fractions depend on dump height. Shown, that filtration coefficient is in a nonlinear dependence on amount of several fractions of rock in gob dump. The numerical model adequacy both the gob structure and the dependence of filtration coefficient from gob height acknowledged equality of calculated and real filtration coefficient values. The results of this research can be apply to peripheral dumping technology.
Directory of Open Access Journals (Sweden)
M Soltani
Full Text Available Modeling of interstitial fluid flow involves processes such as fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. To date, majority of microvascular flow modeling has been done at different levels and scales mostly on simple tumor shapes with their capillaries. However, with our proposed numerical model, more complex and realistic tumor shapes and capillary networks can be studied. Both blood flow through a capillary network, which is induced by a solid tumor, and fluid flow in tumor's surrounding tissue are formulated. First, governing equations of angiogenesis are implemented to specify the different domains for the network and interstitium. Then, governing equations for flow modeling are introduced for different domains. The conservation laws for mass and momentum (including continuity equation, Darcy's law for tissue, and simplified Navier-Stokes equation for blood flow through capillaries are used for simulating interstitial and intravascular flows and Starling's law is used for closing this system of equations and coupling the intravascular and extravascular flows. This is the first study of flow modeling in solid tumors to naturalistically couple intravascular and extravascular flow through a network. This network is generated by sprouting angiogenesis and consisting of one parent vessel connected to the network while taking into account the non-continuous behavior of blood, adaptability of capillary diameter to hemodynamics and metabolic stimuli, non-Newtonian blood flow, and phase separation of blood flow in capillary bifurcation. The incorporation of the outlined components beyond the previous models provides a more realistic prediction of interstitial fluid flow pattern in solid tumors and surrounding tissues. Results predict higher interstitial pressure, almost two times, for realistic model compared to the simplified model.
Numerical modeling of on-orbit propellant motion resulting from an impulsive acceleration
Aydelott, John C.; Mjolsness, Raymond C.; Torrey, Martin D.; Hochstein, John I.
1987-01-01
In-space docking and separation maneuvers of spacecraft that have large fluid mass fractions may cause undesirable spacecraft motion in response to the impulsive-acceleration-induced fluid motion. An example of this potential low gravity fluid management problem arose during the development of the shuttle/Centaur vehicle. Experimentally verified numerical modeling techniques were developed to establish the propellant dynamics, and subsequent vehicle motion, associated with the separation of the Centaur vehicle from the shuttle orbiter cargo bay. Although the shuttle/Centaur development activity was suspended, the numerical modeling techniques are available to predict on-orbit liquid motion resulting from impulsive accelerations for other missions and spacecraft.
Sbarufatti, C.; Manson, G.; Worden, K.
2014-09-01
This paper describes a methodology for the design of a model-based diagnostic unit. The objective of the work is to define a suitable procedure for the design and verification of diagnostic performance in a simulated environment, trying to maximise the generalisation capability of pattern recognition algorithms when tested with real experimental signals. The system is designed and experimentally verified to solve the fatigue crack damage localisation and assessment problems in a realistic, though rather idealised, Structural Health Monitoring (SHM) framework. The study is applied to a piezoelectric Lamb wave sensor network and is validated experimentally on a simple aluminium skin. The analytically-derived dispersion curves for Lamb wave propagation in aluminium are used in order to determine the wave velocities and thus their arrival time at given sensors. The Local Interaction Simulation Approach (LISA) is used to simulate the entire waveform propagation. Once the agreement between analytical, numerical and experimental data is verified on a baseline undamaged condition, the parametric LISA model has been iteratively run, varying the position and the length of a crack on an aluminium skin panel, generating the virtual experience necessary to train a supervised learning regressor based on Artificial Neural Networks (ANNs). After the algorithm structure has been statistically optimised, the network sensitivity to input variations has been evaluated on simulated signals through a technique inspired by information gap theory. Real Lamb wave signals are then processed into the algorithm, providing feasible real-time indication of damage characteristics.
Numerical simulation of fibrous biomaterials with randomly distributed fiber network structure.
Jin, Tao; Stanciulescu, Ilinca
2016-08-01
This paper presents a computational framework to simulate the mechanical behavior of fibrous biomaterials with randomly distributed fiber networks. A random walk algorithm is implemented to generate the synthetic fiber network in 2D used in simulations. The embedded fiber approach is then adopted to model the fibers as embedded truss elements in the ground matrix, which is essentially equivalent to the affine fiber kinematics. The fiber-matrix interaction is partially considered in the sense that the two material components deform together, but no relative movement is considered. A variational approach is carried out to derive the element residual and stiffness matrices for finite element method (FEM), in which material and geometric nonlinearities are both included. Using a data structure proposed to record the network geometric information, the fiber network is directly incorporated into the FEM simulation without significantly increasing the computational cost. A mesh sensitivity analysis is conducted to show the influence of mesh size on various simulation results. The proposed method can be easily combined with Monte Carlo (MC) simulations to include the influence of the stochastic nature of the network and capture the material behavior in an average sense. The computational framework proposed in this work goes midway between homogenizing the fiber network into the surrounding matrix and accounting for the fully coupled fiber-matrix interaction at the segment length scale, and can be used to study the connection between the microscopic structure and the macro-mechanical behavior of fibrous biomaterials with a reasonable computational cost.
Vergara, Christian; Lange, Matthias; Palamara, Simone; Lassila, Toni; Frangi, Alejandro F.; Quarteroni, Alfio
2016-03-01
We present a model for the electrophysiology in the heart to handle the electrical propagation through the Purkinje system and in the myocardium, with two-way coupling at the Purkinje-muscle junctions. In both the subproblems the monodomain model is considered, whereas at the junctions a resistor element is included that induces an orthodromic propagation delay from the Purkinje network towards the heart muscle. We prove a sufficient condition for convergence of a fixed-point iterative algorithm to the numerical solution of the coupled problem. Numerical comparison of activation patterns is made with two different combinations of models for the coupled Purkinje network/myocardium system, the eikonal/eikonal and the monodomain/monodomain models. Test cases are investigated for both physiological and pathological activation of a model left ventricle. Finally, we prove the reliability of the monodomain/monodomain coupling on a realistic scenario. Our results underlie the importance of using physiologically realistic Purkinje-trees with propagation solved using the monodomain model for simulating cardiac activation.
First results from Japanese network for earthquake prediction
Energy Technology Data Exchange (ETDEWEB)
Okado, Y.
1984-12-06
A very extensive high-quality digital network for micro-earthquake and ground-tilt observation has recently been completed in the south Kanto-Tokai area surrounding Tokyo. The first scientific results are now appearing and allow, among other things, a remarkable three-dimensional picture of the earthquake hypocenter distribution to be produced. The distribution maps out the boundaries of the three plates that meet under this region of Japan. The network is described and results on the distribution of earthquakes and cross-sections of hypocenters from July, 1979 to June, 1984 are given. 5 references, 3 figures.
Beerens, J.C.; Ooms, G.; Pourquie, M.J.B.M.; Westerweel, J.
2014-01-01
high-viscosity liquid core surrounded by a laminar low-viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is that it is very well possible to simulate laminar core-annular flow in a pipe using the volume-of-fluid method.
Directory of Open Access Journals (Sweden)
Lazić Vukić N.
2014-01-01
Full Text Available The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code_Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results.
Improving the trust in results of numerical simulations and scientific data analytics
Energy Technology Data Exchange (ETDEWEB)
Cappello, Franck [Argonne National Lab. (ANL), Argonne, IL (United States); Constantinescu, Emil [Argonne National Lab. (ANL), Argonne, IL (United States); Hovland, Paul [Argonne National Lab. (ANL), Argonne, IL (United States); Peterka, Tom [Argonne National Lab. (ANL), Argonne, IL (United States); Phillips, Carolyn [Argonne National Lab. (ANL), Argonne, IL (United States); Snir, Marc [Argonne National Lab. (ANL), Argonne, IL (United States); Wild, Stefan [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-04-30
This white paper investigates several key aspects of the trust that a user can give to the results of numerical simulations and scientific data analytics. In this document, the notion of trust is related to the integrity of numerical simulations and data analytics applications. This white paper complements the DOE ASCR report on Cybersecurity for Scientific Computing Integrity by (1) exploring the sources of trust loss; (2) reviewing the definitions of trust in several areas; (3) providing numerous cases of result alteration, some of them leading to catastrophic failures; (4) examining the current notion of trust in numerical simulation and scientific data analytics; (5) providing a gap analysis; and (6) suggesting two important research directions and their respective research topics. To simplify the presentation without loss of generality, we consider that trust in results can be lost (or the results’ integrity impaired) because of any form of corruption happening during the execution of the numerical simulation or the data analytics application. In general, the sources of such corruption are threefold: errors, bugs, and attacks. Current applications are already using techniques to deal with different types of corruption. However, not all potential corruptions are covered by these techniques. We firmly believe that the current level of trust that a user has in the results is at least partially founded on ignorance of this issue or the hope that no undetected corruptions will occur during the execution. This white paper explores the notion of trust and suggests recommendations for developing a more scientifically grounded notion of trust in numerical simulation and scientific data analytics. We first formulate the problem and show that it goes beyond previous questions regarding the quality of results such as V&V, uncertainly quantification, and data assimilation. We then explore the complexity of this difficult problem, and we sketch complementary general
Henle, James M.
This pamphlet consists of 17 brief chapters, each containing a discussion of a numeration system and a set of problems on the use of that system. The numeration systems used include Egyptian fractions, ordinary continued fractions and variants of that method, and systems using positive and negative bases. The book is informal and addressed to…
Comparison of numerical and experimental results of water -pipe wall interaction
Ali Heidari; Poria Ghassemi
2015-01-01
Tube wall analysis on unsteady network flow of pipe shows that the column is separated when it reached to vapor pressure. In this study, we experiment dynamic behavior of fluid distribution pipe system. The model used in is a straight suspended pipe, which is striked by a solid steel bar. Then the results of pressure change in different parts of pipe has been studied and compared with valid results.
Directory of Open Access Journals (Sweden)
Yu Wang
2016-05-01
Full Text Available In this study, variable injection-rate technology was numerically investigated in a pre-existing discrete fracture network (DFN formation, the Tarim Basin in China. A flow-stress-damage (FSD coupling model has been used in an initial attempt towards how reservoir response to variable injection-rates at different hydraulic fracturing stages. The established numerical model simultaneously considered the macroscopic and microscopic heterogeneity characteristics. Eight numerical cases were studied. Four cases were used to study the variable injection-rate technology, and the other four cases were applied for a constant injection-rate in order to compare with the variable injection-rate technology. The simulation results show that the variable injection-rate technology is a potentially good method to a form complex fracturing networks. The hydraulic fracturing effectiveness when increasing the injection-rate at each stage is the best, also, the total injected fluid is at a minimum. At the initial stage, many under-fracturing points appear around the wellbore with a relatively low injection-rate; the sudden increase of injection rate drives the dynamic propagation of hydraulic fractures along many branching fracturing points. However, the case with decreasing injection rate is the worst. By comparing with constant injection-rate cases, the hydraulic fracturing effectiveness with variable flow rate technology is generally better than those with constant injection-rate technology. This work strongly links the production technology and hydraulic fracturing effectiveness evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.
Beijing Lightning Network (BLNET): Configuration, Function and Preliminary Results
Qie, X.; Wang, D.; Wang, Y.; Liu, M.; Tian, Y.; Lu, G.
2015-12-01
A regional multi-frequency-band lightning detection network in Beijing (BLNET) has been developed for both research and operational purposes. The network is employed in the experiment of Dynamic-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards (Storm973), supported by Ministry of Science and Technology as National Key Basic Research Program of China or 973 Program. The network consisted of 16 stations in 2015 covering most part of The "Jing-Jin-Ji" (Beijing-Tianjin-Hebei) metropolis zone, one of the most developed areas in China. Four different sensors, including slow antenna, fast antenna, magnetic antenna, and VHF antenna, are integrated in each station to detect lightning radiation signals in different frequency band. The Chan algorithm and Levenberg-Marquardt method are adopted jointly in the lightning location algorithm. In addition to locate the lightning radiation pulses in two-dimension or three-dimension in different band, the charge source neutralized by the lightning discharge can be retrieved either. The theoretical horizontal error over the network is less than 200 m and the vertical error is less than 500 m over the network. The comparison of total lightning location results with corresponding radar echoes for thunderstorm cases indicates the good performance of BLNET in the severe convection surveillance. The actual two-dimensional location error in VLF/LF band, compared with a ground truth that acquired with a GPS-synchronized high-speed video camera, is about 250 m.
Site, Luigi Delle
2014-01-01
In this paper I will discuss the overlap between the concept of Shannon Entropy and the concept of electronic correlation. Quantum Monte Carlo numerical results for the uniform electron gas are also presented; these latter on the one hand enhance the hypothesis of a direct link between the two concepts but on the other hand leave a series of open questions which may be employed to trace a roadmap for the future research in the field.
A method for data handling numerical results in parallel OpenFOAM simulations
Energy Technology Data Exchange (ETDEWEB)
Anton, Alin [Faculty of Automatic Control and Computing, Politehnica University of Timişoara, 2" n" d Vasile Pârvan Ave., 300223, TM Timişoara, Romania, alin.anton@cs.upt.ro (Romania); Muntean, Sebastian [Center for Advanced Research in Engineering Science, Romanian Academy – Timişoara Branch, 24" t" h Mihai Viteazu Ave., 300221, TM Timişoara (Romania)
2015-12-31
Parallel computational fluid dynamics simulations produce vast amount of numerical result data. This paper introduces a method for reducing the size of the data by replaying the interprocessor traffic. The results are recovered only in certain regions of interest configured by the user. A known test case is used for several mesh partitioning scenarios using the OpenFOAM toolkit{sup ®}[1]. The space savings obtained with classic algorithms remain constant for more than 60 Gb of floating point data. Our method is most efficient on large simulation meshes and is much better suited for compressing large scale simulation results than the regular algorithms.
Directory of Open Access Journals (Sweden)
B. Mahjoob
2014-08-01
Full Text Available Bridges are the most important structures in river engineering. One of the most causes in bridges destruction is local scouring around the bridge piers. Many bridges failed in the world because of the extreme scour around piers, which have caused to disappear a lot of investments. Then, it is essential to predict the scour depth around bridge piers. In this research, the Fluent three-dimensional numerical model was used to investigate the scouring around the group cylindrical pier in clear water and uniform sand bed conditions. In this model, sedimentary flow was considered as two-phase flow (water - sand and Eulerian two-phase model was used. To estimate the parameters of flow turbulence in the water phase, the RNG K-ε model was used. To evaluate and verify the numerical model, the computational results were compared with experimental data. The maximum scour depth in front of the first pier on a numerical model equal to 12.5 cm and in experimental model equal to 12 cm have been measured. Also scour depth at the second pier less than that at the first pier and scour depth at the third pier has been less than the values of the first and second pier .The results showed that the two phase model can simulate the scour phenomena around the pier.
Comparison of numerical and experimental results of the flow in the U9 Kaplan turbine model
Petit, O.; Mulu, B.; Nilsson, H.; Cervantes, M.
2010-08-01
The present work compares simulations made using the OpenFOAM CFD code with experimental measurements of the flow in the U9 Kaplan turbine model. Comparisons of the velocity profiles in the spiral casing and in the draft tube are presented. The U9 Kaplan turbine prototype located in Porjus and its model, located in Älvkarleby, Sweden, have curved inlet pipes that lead the flow to the spiral casing. Nowadays, this curved pipe and its effect on the flow in the turbine is not taken into account when numerical simulations are performed at design stage. To study the impact of the inlet pipe curvature on the flow in the turbine, and to get a better overview of the flow of the whole system, measurements were made on the 1:3.1 model of the U9 turbine. Previously published measurements were taken at the inlet of the spiral casing and just before the guide vanes, using the laser Doppler anemometry (LDA) technique. In the draft tube, a number of velocity profiles were measured using the LDA techniques. The present work extends the experimental investigation with a horizontal section at the inlet of the draft tube. The experimental results are used to specify the inlet boundary condition for the numerical simulations in the draft tube, and to validate the computational results in both the spiral casing and the draft tube. The numerical simulations were realized using the standard k-e model and a block-structured hexahedral wall function mesh.
Directory of Open Access Journals (Sweden)
A. YAZID MALIKI
2017-05-01
Full Text Available OBREC is the latest innovation of overtopping wave energy converter (WEC which is coalesced with the rubble mound breakwaters. The acquisition of wave overtopping in a front reservoir and consequently releasing process through turbine is the concept of energy production in OBREC. The physical scale model studies of overtopping discharge of the OBREC have recently been done by previous researcher in wave flume at Aalborg University. This paper demonstrates the overtopping behavior of OBREC device using a VOF method with capabilities to solve RANS equation in the numerical suite Flow3D. The purpose of this research is to validate the overtopping discharge performance of the numerical model against the experiments of the OBREC. Based on the observation, the results have shown a good agreement between the validation and physical experiment.
Liu, Richeng; Li, Bo; Jiang, Yujing; Yu, Liyuan
2018-01-01
Hydro-mechanical properties of rock fractures are core issues for many geoscience and geo-engineering practices. Previous experimental and numerical studies have revealed that shear processes could greatly enhance the permeability of single rock fractures, yet the shear effects on hydraulic properties of fractured rock masses have received little attention. In most previous fracture network models, single fractures are typically presumed to be formed by parallel plates and flow is presumed to obey the cubic law. However, related studies have suggested that the parallel plate model cannot realistically represent the surface characters of natural rock fractures, and the relationship between flow rate and pressure drop will no longer be linear at sufficiently large Reynolds numbers. In the present study, a numerical approach was established to assess the effects of shear on the hydraulic properties of 2-D discrete fracture networks (DFNs) in both linear and nonlinear regimes. DFNs considering fracture surface roughness and variation of aperture in space were generated using an originally developed code DFNGEN. Numerical simulations by solving Navier-Stokes equations were performed to simulate the fluid flow through these DFNs. A fracture that cuts through each model was sheared and by varying the shear and normal displacements, effects of shear on equivalent permeability and nonlinear flow characteristics of DFNs were estimated. The results show that the critical condition of quantifying the transition from a linear flow regime to a nonlinear flow regime is: 10-4 〈 J fluid flow is in a linear regime (i.e., J fluid flow in the nonlinear regime (J 〉 10-3), δ2 is nonlinearly correlated with J. A shear process would reduce the equivalent permeability significantly in the orientation perpendicular to the sheared fracture as much as 53.86% when J = 1, shear displacement Ds = 7 mm, and normal displacement Dn = 1 mm. By fitting the calculated results, the mathematical
Solving the Helmholtz equation for membranes of arbitrary shape: numerical results
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo [Facultad de Ciencias CUICBAS, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Physics Department, University of Texas at El Paso, El Paso, TX (United States)], E-mail: paolo.amore@gmail.google.com
2008-07-04
I calculate the modes of vibration of membranes of arbitrary shape using a collocation approach based on little sinc functions. The matrix representation of the PDE obtained using this method is explicit and does not require the calculation of integrals. To illustrate the virtues of this approach, I have considered a large number of examples, part of them are taken from the literature, and part of them new. When possible, I have tested the accuracy of these results by comparing them with the exact results (when available) or with results from the literature. In particular, in the case of the L-shaped membrane, the first example discussed in the paper, I show that it is possible to extrapolate the results obtained with different grid sizes to obtain highly precise results. Finally, I also show that the present collocation technique can be easily combined with conformal mapping to provide numerical approximations to the energies which quite rapidly converge to the exact results.
Numerical Results for SU(4) and SU(2) Kondo Effect in Carbon Nanotubes
Martins, George; Busser, Carlos
2006-03-01
New numerical results are presented for the Kondo effect in Carbon Nanotube (CNT) quantum dots (QDs). As recently reported by P. Jarillo-Herrero et al. (Nature 434, 484 (2005)), the Kondo effect in CNTs presents an SU(4) symmetry, which arises from the entanglement of orbital and spin degrees of freedom. As the number of co-tunneling processes increases, thanks to the extra (orbital) degree of freedom, the Kondo temperature reaches a high value of TK=7.7K. Interesting considerations can be drawn regarding the change from SU(4) to SU(2) symmetries depending on the hopping matrix elements between the leads and the CNT QD. Our results will analyze the transition between the SU(4) and the so-called two-level SU(2) (2LSU(2)) Kondo regimes induced by the variation of the coupling of the QD to the leads. The effect of an external magnetic field along the tube direction will also be analyzed. Our results will be compared with available Numerical Renormalization Group (NRG) results by M-S Choi et al. (Phys. Rev. Lett. 95, 067204 (2005)). A comparison with the experimental results will be made to gauge the adequacy of the model and approximations made.
2015-01-01
Background Due to the limited number of experimental studies that mechanically characterise human atherosclerotic plaque tissue from the femoral arteries, a recent trend has emerged in current literature whereby one set of material data based on aortic plaque tissue is employed to numerically represent diseased femoral artery tissue. This study aims to generate novel vessel-appropriate material models for femoral plaque tissue and assess the influence of using material models based on experimental data generated from aortic plaque testing to represent diseased femoral arterial tissue. Methods Novel material models based on experimental data generated from testing of atherosclerotic femoral artery tissue are developed and a computational analysis of the revascularisation of a quarter model idealised diseased femoral artery from a 90% diameter stenosis to a 10% diameter stenosis is performed using these novel material models. The simulation is also performed using material models based on experimental data obtained from aortic plaque testing in order to examine the effect of employing vessel appropriate material models versus those currently employed in literature to represent femoral plaque tissue. Results Simulations that employ material models based on atherosclerotic aortic tissue exhibit much higher maximum principal stresses within the plaque than simulations that employ material models based on atherosclerotic femoral tissue. Specifically, employing a material model based on calcified aortic tissue, instead of one based on heavily calcified femoral tissue, to represent diseased femoral arterial vessels results in a 487 fold increase in maximum principal stress within the plaque at a depth of 0.8 mm from the lumen. Conclusions Large differences are induced on numerical results as a consequence of employing material models based on aortic plaque, in place of material models based on femoral plaque, to represent a diseased femoral vessel. Due to these large
Rajchakit, G; Saravanakumar, R; Ahn, Choon Ki; Karimi, Hamid Reza
2017-02-01
This article examines the exponential stability analysis problem of generalized neural networks (GNNs) including interval time-varying delayed states. A new improved exponential stability criterion is presented by establishing a proper Lyapunov-Krasovskii functional (LKF) and employing new analysis theory. The improved reciprocally convex combination (RCC) and weighted integral inequality (WII) techniques are utilized to obtain new sufficient conditions to ascertain the exponential stability result of such delayed GNNs. The superiority of the obtained results is clearly demonstrated by numerical examples. Copyright © 2016 Elsevier Ltd. All rights reserved.
Numerical modelling of radon-222 entry into houses: An outline of techniques and results
DEFF Research Database (Denmark)
Andersen, C.E.
2001-01-01
diffusive and advective transport of radon. Models of different complexity have been used. The simpler ones are finite-difference models with one or two spatial dimensions. The more complex models allow for full three-dimensional and time dependency. Advanced features include: soil heterogeneity, anisotropy......, fractures, moisture, non-uniform soil temperature, non-Darcy flow of gas, and flow caused by changes in the atmospheric pressure. Numerical models can be used to estimate the importance of specific factors for radon entry. Models are also helpful when results obtained in special laboratory or test structure....... As an illustrative example, radon entry is calculated for a standard slab-on-grade house....
Analytical and numerical results on the stability of a planetary precessional model
Della Penna, G.
2000-10-01
A model for planetary precession is investigated using analytical and numerical techniques. A Hamiltonian function governing the model is derived in terms of action--angle Andoyer--Déprit variables under the assumption of equatorial symmetry. As a first approximation a simplified Hamiltonian with zero--eccentricity is considered and stability estimates are derived using KAM theory. A validation of the analytical results is performed computing Poincaré surfaces of section. We also investigate the role of the eccentricity and its connection with the appearance of resonances. Special attention is devoted to the particular case of the Earth-Moon system.
Numerical Modeling of Fluid Transient in Cryogenic Fluid Network of Rocket Propulsion System
Majumdar, Alok; Flachbart, Robin
2003-01-01
Fluid transients, also known as water hammer, can have a significant impact on the design and operation of both spacecraft and launch vehicles propulsion systems. These transients often occur at system activation and shut down. For ground safety reasons, many spacecrafts are launched with the propellant lines dry. These lines are often evacuated by the time the spacecraft reaches orbit. When the propellant isolation valve opens during propulsion system activation, propellant rushes into lines creating a pressure surge. During propellant system shutdown, a pressure surge is created due to sudden closure of a valve. During both activation and shutdown, pressure surges must be predicted accurately to ensure structural integrity of the propulsion system fluid network. The method of characteristics is the most widely used method of calculating fluid transients in pipeline [ 1,2]. The method of characteristics, however, has limited applications in calculating flow distribution in complex flow circuits with phase change, heat transfer and rotational effects. A robust cryogenic propulsion system analyzer must have the capability to handle phase change, heat transfer, chemical reaction, rotational effects and fluid transients in conjunction with subsystem flow model for pumps, valves and various pipe fittings. In recent years, such a task has been undertaken at Marshall Space Flight Center with the development of the Generalized Fluid System Simulation Program (GFSSP), which is based on finite volume method in fluid network [3]. GFSSP has been extensively verified and validated by comparing its predictions with test data and other numerical methods for various applications such as internal flow of turbo-pump [4], propellant tank pressurization [5,6], chilldown of cryogenic transfer line [7] and squeeze film damper rotordynamics [8]. The purpose of the present paper is to investigate the applicability of the finite volume method to predict fluid transient in cryogenic flow
Comparative analysis of results from experimental and numerical studies on concrete strength
Directory of Open Access Journals (Sweden)
Mkrtychev Oleg
2017-01-01
Full Text Available Some results of numerical experiments of testing concrete cubes and prisms on unconfined compression, and the comparison of results obtained with experimental and specified data, are presented in the article. When performing calculations of structures in a nonlinear setting, it is very important to choose adequate deformation diagrams or material models. Because of the fact that there are no instructions how to use the diagrams of concrete and armature deformation in collaboration of steel and concrete, the simulation of reinforced concrete structures by finite elements of the same type without any assumptions is impossible. Numerical experiments have been performed in the LS-DYNA software package. This software package allows simulating the collaboration of concrete and steeling with the help of three-dimensional (for concrete and rod (for the reinforcement finite elements. As samples, a cube and a prism with dimensions of 150×150×150 mm and 150×150×600 mm, respectively, have been taken. The samples are simulated by solid finite elements. For the simulation of concrete, the non-linear CSCM (Continuous Surface Cap Model material is used. The tests were carried out with samples of the following classes of concrete as for cylinder compressive strength: C12, C16, C20, C25, C30, C35. This corresponds to the following classes of cube compression strength: B15, B20, B25, B30, B37, B45. The tests have been carried out considering the friction coefficients between the plates of a testing machine, and a sample. The performed researches have shown that the destruction nature of the samples in a numerical experiment corresponds to the failure nature in real tests. The investigated model of CSCM concrete can be used in the calculation of concrete and reinforced concrete structures with acceptable accuracy for main classes of concrete.
Directory of Open Access Journals (Sweden)
Jianming He
2017-05-01
Full Text Available In this paper, configurations of pre-existing fractures in cubic rock blocks were investigated and reconstructed for the modeling of experimental hydraulic fracturing. The fluid-rock coupling process of hydraulic fracturing was simulated based on the displacement discontinuities method. The numerical model was validated against the related laboratory experiments. The stimulated fracture configurations under different conditions can be clearly shown using the validated numerical model. First, a dominated fracture along the maximum principle stress direction is always formed when the stress difference is large enough. Second, there are less reopened pre-existing fractures, more newly formed fractures and less shear fractures with the increase of the cohesion value of pre-existing fractures. Third, the length of the stimulated shear fracture decreases rapidly with the increase of the friction coefficient, while the length of the tensile fracture has no correlation to the fiction coefficient. Finally, the increase of the fluid injection rate is favorable to the formation of a fracture network. The unfavorable effects of the large stress difference and the large cohesion of pre-existing fractures can be partly suppressed by an increase of the injection rate in the hydraulic fracturing treatment. The results of this paper are useful for understanding fracture propagation behaviors during the hydraulic fracturing of shale reservoirs with pre-existing fractures.
Mathematics anxiety reduces default mode network deactivation in response to numerical tasks.
Pletzer, Belinda; Kronbichler, Martin; Nuerk, Hans-Christoph; Kerschbaum, Hubert H
2015-01-01
Mathematics anxiety is negatively related to mathematics performance, thereby threatening the professional success. Preoccupation with the emotional content of the stimuli may consume working memory resources, which may be reflected in decreased deactivation of areas associated with the default mode network (DMN) activated during self-referential and emotional processing. The common problem is that math anxiety is usually associated with poor math performance, so that any group differences are difficult to interpret. Here we compared the BOLD-response of 18 participants with high (HMAs) and 18 participants with low mathematics anxiety (LMAs) matched for their mathematical performance to two numerical tasks (number comparison, number bisection). During both tasks, we found stronger deactivation within the DMN in LMAs compared to HMAs, while BOLD-response in task-related activation areas did not differ between HMAs and LMAs. The difference in DMN deactivation between the HMA and LMA group was more pronounced in stimuli with additional requirement on inhibitory functions, but did not differ between number magnitude processing and arithmetic fact retrieval.
Mathematics anxiety reduces default mode network deactivation in response to numerical tasks
Directory of Open Access Journals (Sweden)
Belinda ePletzer
2015-04-01
Full Text Available Mathematics anxiety is negatively related to mathematics performance, thereby threatening the professional success. Preoccupation with the emotional content of the stimuli may consume working memory resources, which may be reflected in decreased deactivation of areas associated with the default mode network (DMN activated during self-referential and emotional processing. The common problem is that math anxiety is usually associated with poor math performance, so that any group differences are difficult to interpret.Here we compared the BOLD-response of 18 participants with high (HMAs and 18 participants with low mathematics anxiety (LMAs matched for their mathematical performance to two numerical tasks (number comparison, number bisection. During both tasks, we found stronger deactivation within the DMN in LMAs compared to HMAs, while BOLD-response in task-related activation areas did not differ between HMAs and LMAs. The difference in DMN deactivation between the HMA and LMA group was more pronounced in stimuli with additional requirement on inhibitory functions, but did not differ between number magnitude processing and arithmetic fact retrieval.
Mathematics anxiety reduces default mode network deactivation in response to numerical tasks
Pletzer, Belinda; Kronbichler, Martin; Nuerk, Hans-Christoph; Kerschbaum, Hubert H.
2015-01-01
Mathematics anxiety is negatively related to mathematics performance, thereby threatening the professional success. Preoccupation with the emotional content of the stimuli may consume working memory resources, which may be reflected in decreased deactivation of areas associated with the default mode network (DMN) activated during self-referential and emotional processing. The common problem is that math anxiety is usually associated with poor math performance, so that any group differences are difficult to interpret. Here we compared the BOLD-response of 18 participants with high (HMAs) and 18 participants with low mathematics anxiety (LMAs) matched for their mathematical performance to two numerical tasks (number comparison, number bisection). During both tasks, we found stronger deactivation within the DMN in LMAs compared to HMAs, while BOLD-response in task-related activation areas did not differ between HMAs and LMAs. The difference in DMN deactivation between the HMA and LMA group was more pronounced in stimuli with additional requirement on inhibitory functions, but did not differ between number magnitude processing and arithmetic fact retrieval. PMID:25954179
Directory of Open Access Journals (Sweden)
APG eCastro
2014-11-01
Full Text Available The Loaded Disc Culture System (LDCS is an Intervertebral Disc (IVD-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands, which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, 8 goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Detiger et al., 2013; Paul et al., 2013, 2012, 4 of these IVDs were kept in physiological condition (control and the other 4 were previously injected with chondroitinase ABC (CABC, in order to promote Degenerative Disc Disease (DDD. The loading profile intercalated 16h of activity loading with 8h of loading recovery to express the standard circadian variations.The displacement behavior of these 8 IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced Finite Element (FE model. The simulations were run on a custom FE solver (Castro et al., 2014.The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in 2 of the 4 IVDs. The 4 control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected. However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly describe the recovery
Re-Computation of Numerical Results Contained in NACA Report No. 496
Perry, Boyd, III
2015-01-01
An extensive examination of NACA Report No. 496 (NACA 496), "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen, is described. The examination included checking equations and solution methods and re-computing interim quantities and all numerical examples in NACA 496. The checks revealed that NACA 496 contains computational shortcuts (time- and effort-saving devices for engineers of the time) and clever artifices (employed in its solution methods), but, unfortunately, also contains numerous tripping points (aspects of NACA 496 that have the potential to cause confusion) and some errors. The re-computations were performed employing the methods and procedures described in NACA 496, but using modern computational tools. With some exceptions, the magnitudes and trends of the original results were in fair-to-very-good agreement with the re-computed results. The exceptions included what are speculated to be computational errors in the original in some instances and transcription errors in the original in others. Independent flutter calculations were performed and, in all cases, including those where the original and re-computed results differed significantly, were in excellent agreement with the re-computed results. Appendix A contains NACA 496; Appendix B contains a Matlab(Reistered) program that performs the re-computation of results; Appendix C presents three alternate solution methods, with examples, for the two-degree-of-freedom solution method of NACA 496; Appendix D contains the three-degree-of-freedom solution method (outlined in NACA 496 but never implemented), with examples.
Investigation of film boiling thermal hydraulics under FCI conditions. Results of a numerical study
Energy Technology Data Exchange (ETDEWEB)
Dinh, T.N.; Dinh, A.T.; Nourgaliev, R.R.; Sehgal, B.R. [Div. of Nuclear Power Safety Royal Inst. of Tech. (RIT), Brinellvaegen 60, 10044 Stockholm (Sweden)
1998-01-01
Film boiling on the surface of a high-temperature melt jet or of a melt particle is one of key phenomena governing the physics of fuel-coolant interactions (FCIs) which may occur during the course of a severe accident in a light water reactor (LWR). A number of experimental and analytical studies have been performed, in the past, to address film boiling heat transfer and the accompanying hydrodynamic aspects. Most of the experiments have, however, been performed for temperature and heat flux conditions, which are significantly lower than the prototypic conditions. For ex-vessel FCIs, high liquid subcooling can significantly affect the FCI thermal hydraulics. Presently, there are large uncertainties in predicting natural-convection film boiling of subcooled liquids on high-temperature surfaces. In this paper, research conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning film-boiling thermal hydraulics under FCI condition is presented. Notably, the focus is placed on the effects of (1) water subcooling, (2) high-temperature steam properties, (3) the radiation heat transfer and (4) mixing zone boiling dynamics, on the vapor film characteristics. Numerical investigations are performed using a novel CFD modeling concept named as the local-homogeneous-slip model (LHSM). Results of the analytical and numerical studies are discussed with respect to boiling dynamics under FCI conditions. (author)
Verification of Numerical Weather Prediction Model Results for Energy Applications in Latvia
Sīle, Tija; Cepite-Frisfelde, Daiga; Sennikovs, Juris; Bethers, Uldis
2014-05-01
A resolution to increase the production and consumption of renewable energy has been made by EU governments. Most of the renewable energy in Latvia is produced by Hydroelectric Power Plants (HPP), followed by bio-gas, wind power and bio-mass energy production. Wind and HPP power production is sensitive to meteorological conditions. Currently the basis of weather forecasting is Numerical Weather Prediction (NWP) models. There are numerous methodologies concerning the evaluation of quality of NWP results (Wilks 2011) and their application can be conditional on the forecast end user. The goal of this study is to evaluate the performance of Weather Research and Forecast model (Skamarock 2008) implementation over the territory of Latvia, focusing on forecasting of wind speed and quantitative precipitation forecasts. The target spatial resolution is 3 km. Observational data from Latvian Environment, Geology and Meteorology Centre are used. A number of standard verification metrics are calculated. The sensitivity to the model output interpretation (output spatial interpolation versus nearest gridpoint) is investigated. For the precipitation verification the dichotomous verification metrics are used. Sensitivity to different precipitation accumulation intervals is examined. Skamarock, William C. and Klemp, Joseph B. A time-split nonhydrostatic atmospheric model for weather research and forecasting applications. Journal of Computational Physics. 227, 2008, pp. 3465-3485. Wilks, Daniel S. Statistical Methods in the Atmospheric Sciences. Third Edition. Academic Press, 2011.
Blakeslee, R. J.; Bailey, J. C.; Pinto, O.; Athayde, A.; Renno, N.; Weidman, C. D.
2003-01-01
A four station Advanced Lightning Direction Finder (ALDF) network was established in the state of Rondonia in western Brazil in 1999 through a collaboration of U.S. and Brazilian participants from NASA, INPE, INMET, and various universities. The network utilizes ALDF IMPACT (Improved Accuracy from Combined Technology) sensors to provide cloud-to-ground lightning observations (i.e., stroke/flash locations, signal amplitude, and polarity) using both time-of- arrival and magnetic direction finding techniques. The observations are collected, processed and archived at a central site in Brasilia and at the NASA/Marshall Space Flight Center in Huntsville, Alabama. Initial, non-quality assured quick-look results are made available in near real-time over the Internet. The network, which is still operational, was deployed to provide ground truth data for the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite that was launched in November 1997. The measurements are also being used to investigate the relationship between the electrical, microphysical and kinematic properties of tropical convection. In addition, the long-time series observations produced by this network will help establish a regional lightning climatological database, supplementing other databases in Brazil that already exist or may soon be implemented. Analytic inversion algorithms developed at the NASA/Marshall Space Flight Center have been applied to the Rondonian ALDF lightning observations to obtain site error corrections and improved location retrievals. The data will also be corrected for the network detection efficiency. The processing methodology and the results from the analysis of four years of network operations will be presented.
Numerical results indicate a half-filling SU(4) Kondo state in carbon nanotubes
Büsser, C. A.; Martins, G. B.
2007-01-01
Numerical calculations simulate transport experiments in carbon nanotube quantum dots [P. Jarillo-Herrero , Nature 434, 484 (2005)], where a strongly enhanced Kondo temperature TK≈8.0K was associated with the SU(4) symmetry of the Hamiltonian at quarter-filling for an orbitally double-degenerate single-occupied electronic shell. Our results clearly suggest that the Kondo conductance measured for an adjacent shell with TK≈16.0K , interpreted as a singlet-triplet Kondo effect, can be associated instead to an SU(4) Kondo effect at half-filling. Besides presenting spin-charge Kondo screening similar to the quarter-filling SU(4), the half-filling SU(4) has been recently associated to very rich physical behavior, including a non-Fermi-liquid state [M. R. Galpin , Phys. Rev. Lett. 94, 186406 (2005)].
Convergence of infinite dimensional sampled LQR problems - Theory and numerical results
Rosen, I. G.; Wang, C.
1989-01-01
A theory is developed for the convergence of the closed-loop solution to infinite-dimensional discrete-time linear-quadratic regulator (LQR) problems on the infinite time interval to the solution of a corresponding continuous-time LQR problem as the length of the sampling interval tends toward zero. Convergence of solutions to the operator algebraic Riccati equation and corresponding optimal feedback control gains is guaranteed under appropriate uniform stabilizability and detectability conditions and consistent sampling. Also presented are numerical results involving the optimal LQ control of a heat or diffusion equation, a hereditary or delay differential equation, and a hybrid system of ordinary and partial differential equations describing the transverse vibration of a cantilevered Voigt-Kelvin viscoelastic beam with tip mass.
Numerical results in a vertical wind axis turbine with relative rotating blades
Energy Technology Data Exchange (ETDEWEB)
Bayeul-Laine, Annie-Claude; Dockter, Aurore; Simonet, Sophie; Bois, Gerard [Arts et Metiers PARISTECH (France)
2011-07-01
The use of wind energy to produce electricity through wind turbines has spread world-wide. The quantity of electricity produced is affected by numerous factors such as wind speed and direction and turbine design; the aim of this paper is to assess the influence of different blades on the performance of a turbine. This study was performed on a turbine in which the blades have a rotating movement, each around its own axis and around the turbine's axis. Unsteady simulations were carried out with several blade stagger angles and one wind speed and 2 different blade geometries were used for 4 rotational speeds. Results showed that the studied turbine gave better performance than vertical axis wind turbines and that blade sketch, blade speed ratios, and blade stagger angle were important influences on the performance. This study showed that this kind of turbine has the potential to achieve good performance but that further work needs to be done.
Delistoian, Dmitri; Chirchor, Mihael
2017-12-01
Fluid transportation from production areas to final customer is effectuated by pipelines. For oil and gas industry, pipeline safety and reliability represents a priority. From this reason, pipe quality guarantee directly influence pipeline designed life, but first of all protects environment. A significant number of longitudinally welded pipes, for onshore/offshore pipelines, are manufactured by UOE method. This method is based on cold forming. In present study, using finite element method is modeled UOE pipe manufacturing process and is obtained von Mises stresses for each step. Numerical simulation is performed for L415 MB (X60) steel plate with 7,9 mm thickness, length 30 mm and width 1250mm, as result it is obtained a DN 400 pipe.
Features of the accretion in the EX Hydrae system: Results of numerical simulation
Isakova, P. B.; Zhilkin, A. G.; Bisikalo, D. V.; Semena, A. N.; Revnivtsev, M. G.
2017-07-01
A two-dimensional numerical model in the axisymmetric approximation that describes the flow structure in the magnetosphere of the white dwarf in the EX Hya system has been developed. Results of simulations show that the accretion in EX Hya proceeds via accretion columns, which are not closed and have curtain-like shapes. The thickness of the accretion curtains depends only weakly on the thickness of the accretion disk. This thickness developed in the simulations does not agree with observations. It is concluded that the main reason for the formation of thick accretion curtains in the model is the assumption that the magnetic field penetrates fully into the plasma of the disk. An analysis based on simple estimates shows that a diamagnetic disk that fully or partially shields the magnetic field of the star may be a more attractive explanation for the observed features of the accretion in EX Hya.
Marom, Gil; Bluestein, Danny
2016-01-01
This paper evaluated the influence of various numerical implementation assumptions on predicting blood damage in cardiovascular devices using Lagrangian methods with Eulerian computational fluid dynamics. The implementation assumptions that were tested included various seeding patterns, stochastic walk model, and simplified trajectory calculations with pathlines. Post processing implementation options that were evaluated included single passage and repeated passages stress accumulation and time averaging. This study demonstrated that the implementation assumptions can significantly affect the resulting stress accumulation, i.e., the blood damage model predictions. Careful considerations should be taken in the use of Lagrangian models. Ultimately, the appropriate assumptions should be considered based the physics of the specific case and sensitivity analysis, similar to the ones presented here, should be employed.
Beniaiche, Ahmed; Ghenaiet, Adel; Carcasci, Carlo; Facchini, Bruno
2017-02-01
This paper presents a numerical validation of the aero-thermal study of a 30:1 scaled model reproducing an innovative trailing edge with one row of enlarged pedestals under stationary and rotating conditions. A CFD analysis was performed by means of commercial ANSYS-Fluent modeling the isothermal air flow and using k- ω SST turbulence model and an isothermal air flow for both static and rotating conditions (Ro up to 0.23). The used numerical model is validated first by comparing the numerical velocity profiles distribution results to those obtained experimentally by means of PIV technique for Re = 20,000 and Ro = 0-0.23. The second validation is based on the comparison of the numerical results of the 2D HTC maps over the heated plate to those of TLC experimental data, for a smooth surface for a Reynolds number = 20,000 and 40,000 and Ro = 0-0.23. Two-tip conditions were considered: open tip and closed tip conditions. Results of the average Nusselt number inside the pedestal ducts region are presented too. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.
Henker, Stephan; Partzsch, Johannes; Schüffny, René
2012-04-01
With the various simulators for spiking neural networks developed in recent years, a variety of numerical solution methods for the underlying differential equations are available. In this article, we introduce an approach to systematically assess the accuracy of these methods. In contrast to previous investigations, our approach focuses on a completely deterministic comparison and uses an analytically solved model as a reference. This enables the identification of typical sources of numerical inaccuracies in state-of-the-art simulation methods. In particular, with our approach we can separate the error of the numerical integration from the timing error of spike detection and propagation, the latter being prominent in simulations with fixed timestep. To verify the correctness of the testing procedure, we relate the numerical deviations to theoretical predictions for the employed numerical methods. Finally, we give an example of the influence of simulation artefacts on network behaviour and spike-timing-dependent plasticity (STDP), underlining the importance of spike-time accuracy for the simulation of STDP.
Directory of Open Access Journals (Sweden)
Hrubý J.
2013-04-01
Full Text Available The paper describes new results for an experimental heat exchanger equipped with a single corrugated capillary tube, basic information about the measurements and the experimental setup. Some of the results were compared with numerical simulations.
Kowalski, Julia; Francke, Gero; Feldmann, Marco; Espe, Clemens; Heinen, Dirk; Digel, Ilya; Clemens, Joachim; Schüller, Kai; Mikucki, Jill; Tulaczyk, Slawek M.; Pettit, Erin; Berry Lyons, W.; Dachwald, Bernd
2017-04-01
results of its deployment at Blood Falls. In contrast to conventional melting-probe applications, which can only melt vertically, the IceMole realized an oblique melting path to penetrate the englacial conduit. Experimental and numerical results on melting at oblique angles are rare. Besides reporting on the IceMole technology and the field deployment itself, we will compare and discuss the observed melting behavior with re-analysis results in the context of a recently developed numerical model. Finally, we will present our first steps in utilizing the model to infer on the ambient cryo-environment.
Directory of Open Access Journals (Sweden)
Popov V.V
2016-01-01
Full Text Available In this paper, a numerical study of the formation of nitrogen oxides in the combustion chamber based on the model created by Mitchellom and Terbellom. The distribution of furnace temperature and the concentration of nitrogen oxides, as well as a comparison of numerical results with the data of field experiment.
SSI on the Dynamic Behaviour of a Historical Masonry Building: Experimental versus Numerical Results
Directory of Open Access Journals (Sweden)
Francesca Ceroni
2014-11-01
Full Text Available A reliable procedure to identify the dynamic behaviour of existing masonry buildings is described in the paper, referring to a representative case study: a historical masonry palace located in Benevento (Italy. Since the building has been equipped with a permanent dynamic monitoring system by the Department of Civil Protection, some of the recorded data, acquired in various operating conditions, have been analysed with basic instruments of the Operational Modal Analysis in order to identify the main eigenfrequencies and vibration modes of the structure. The obtained experimental results have been compared to the numerical outcomes provided by three detailed Finite Element (FE models of the building. The influence of Soil-Structure Interaction (SSI has been also introduced in the FE model by a sub-structure approach where concentrated springs were placed at the base of the building to simulate the effect of soil and foundation on the global dynamic behaviour of the structure. The obtained results evidence that subsoil cannot a priori be disregarded in identifying the dynamic response of the building.
Numerical results on the contribution of an earthworm hole to infiltration
Pezzotti, Dario; Barontini, Stefano; Casali, Federico; Comincini, Mattia; Peli, Marco; Ranzi, Roberto; Rizzo, Gabriele; Tomirotti, Massimo; Vitale, Paolo
2017-04-01
On 9 March 2016 the WormEx I experiment was launched at the experimental site of Cividate Camuno (274ma.s.l., Oglio river basin, Central Italian Alps), aiming at contributing to understand how the soil-fauna digging activity affects soil-water flow. Particularly the experiment investigates the effects of earthworms holes on the soil-water constitutive laws, in the uppermost layers of a shallow anthropized soil. In this framework a set of simulations of the water flow in presence of an earthworm hole was preliminarily performed. The FV-FD numerical code AdHydra was used to solve the Richards equation in an axis-symmetric 2D domain around a vertical earthworm hole. The hole was represented both as a void cylinder and as a virtual porous domain with typical constitutive laws of a Δ-soil. The hypothesis of Poiseuille flow and the Jourin-Borelli law applied to determine its conductivity and soil-water retention relationship. Different scenarios of hole depth and infiltration rate were explored. As a result a meaningful change in the downflow condition was observed when burrows intersect a layered soil, both in saturated and partially unsaturated soils, in case a perched water table onsets at the interface between an upper and more conductive soil layer and a lower and less conductive one. These results may contribute to a better understanding of the streamflow generation processes and soil-water movement in shallow layered soils.
Spiking neural network simulation: numerical integration with the Parker-Sochacki method.
Stewart, Robert D; Bair, Wyeth
2009-08-01
Mathematical neuronal models are normally expressed using differential equations. The Parker-Sochacki method is a new technique for the numerical integration of differential equations applicable to many neuronal models. Using this method, the solution order can be adapted according to the local conditions at each time step, enabling adaptive error control without changing the integration timestep. The method has been limited to polynomial equations, but we present division and power operations that expand its scope. We apply the Parker-Sochacki method to the Izhikevich 'simple' model and a Hodgkin-Huxley type neuron, comparing the results with those obtained using the Runge-Kutta and Bulirsch-Stoer methods. Benchmark simulations demonstrate an improved speed/accuracy trade-off for the method relative to these established techniques.
The Italian VLBI Network: First Results and Future Perspectives
Stagni, Matteo; Negusini, Monia; Bianco, Giuseppe; Sarti, Pierguido
2016-12-01
A first 24-hour Italian VLBI geodetic experiment, involving the Medicina, Noto, and Matera antennas, shaped as an IVS standard EUROPE, was successfully performed. In 2014, starting from the correlator output, a geodetic database was created and a typical solution of a small network was achieved, here presented. From this promising result we have planned new observations in 2016, involving the three Italian geodetic antennas. This could be the beginning of a possible routine activity, creating a data set that can be combined with GNSS observations to contribute to the National Geodetic Reference Datum. Particular care should be taken in the scheduling of the new experiments in order to optimize the number of usable observations. These observations can be used to study and plan future experiments in which the time and frequency standards can be given by an optical fiber link, thus having a common clock at different VLBI stations.
System Identification Using Multilayer Differential Neural Networks: A New Result
Directory of Open Access Journals (Sweden)
J. Humberto Pérez-Cruz
2012-01-01
Full Text Available In previous works, a learning law with a dead zone function was developed for multilayer differential neural networks. This scheme requires strictly a priori knowledge of an upper bound for the unmodeled dynamics. In this paper, the learning law is modified in such a way that this condition is relaxed. By this modification, the tuning process is simpler and the dead-zone function is not required anymore. On the basis of this modification and by using a Lyapunov-like analysis, a stronger result is here demonstrated: the exponential convergence of the identification error to a bounded zone. Besides, a value for upper bound of such zone is provided. The workability of this approach is tested by a simulation example.
Saifutdinov, A.; Fadeev, S.; Fayrushin, I.
2017-11-01
A DC plasma torch “Thermoplasma 50-01” has been modeled and simulated by developing a 2D axisymmetric model of laminar flow and heat transfer coupled to electromagnetic fields. As a result of the numerical solution, the dynamics of the formation of the temperature field and the velocity field in the plasma torch channel and at its exit is presented. The numerical results of the gas temperature and axial velocity result to be quite satisfactory.
Half-filling SU(4) Kondo state in carbon nanotubes: Numerical results
Energy Technology Data Exchange (ETDEWEB)
Martins, G.B. [Department of Physics, Oakland University, Rochester, MI 48309 (United States)], E-mail: martins@oakland.edu; Buesser, C.A. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 2979 (United States)
2008-04-01
Charge transport measurements in carbon nanotube quantum dots by P. Jarillo-Herrero et al. [Nature 434 (2005) 484] have detected a strongly enhanced Kondo temperature T{sub K}{approx}8.0 K. This Kondo state was associated with the SU(4) symmetry of the Hamiltonian at quarter-filling for an orbitally double-degenerate single-occupied electronic shell, indicating the simultaneous Kondo screening of charge and spin. Pure SU(4) symmetry can only be achieved when the orbital quantum number is preserved upon tunneling. So-called channel mixing can destroy the SU(4) state, transforming it into an SU(2)-type Kondo state (the so-called two-level SU(2) state). In this work, numerical calculations of charge transport show in detail the transition between these two Kondo states. Our results indicate that the SU(4) state seems to be quite robust, surviving to considerable amount of channel mixing. Moreover, a curious behavior of the conductance is revealed close to the two level SU(2) state.
Half-filling SU(4) Kondo state in carbon nanotubes: Numerical results
Martins, G. B.; Büsser, C. A.
2008-04-01
Charge transport measurements in carbon nanotube quantum dots by P. Jarillo-Herrero et al. [Nature 434 (2005) 484] have detected a strongly enhanced Kondo temperature TK≈8.0 K. This Kondo state was associated with the SU(4) symmetry of the Hamiltonian at quarter-filling for an orbitally double-degenerate single-occupied electronic shell, indicating the simultaneous Kondo screening of charge and spin. Pure SU(4) symmetry can only be achieved when the orbital quantum number is preserved upon tunneling. So-called channel mixing can destroy the SU(4) state, transforming it into an SU(2)-type Kondo state (the so-called two-level SU(2) state). In this work, numerical calculations of charge transport show in detail the transition between these two Kondo states. Our results indicate that the SU(4) state seems to be quite robust, surviving to considerable amount of channel mixing. Moreover, a curious behavior of the conductance is revealed close to the two level SU(2) state.
Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.
2011-01-01
Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.
Directory of Open Access Journals (Sweden)
Milošević M.
2016-01-01
Full Text Available The role tachyon fields may play in evolution of early universe is discussed in this paper. We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index (n, and tensor-scalar ratio (r for the given potentials. We pay special attention to the inverse power potential, first of all to V (x ~ x−4, and compare the available results obtained by analytical and numerical methods with those obtained by observation. It is shown that the computed values of the observational parameters and the observed ones are in a good agreement for the high values of the constant X0. The possibility that influence of the radion field can extend a range of the acceptable values of the constant X0 to the string theory motivated sector of its values is briefly considered. [Projekat Ministarstva nauke Republike Srbije, br. 176021, br. 174020 i br. 43011
Klapp, J.; Cervantes-Cota, J.; Chauvet, P.
1990-11-01
RESUMEN. A nivel cosmol6gico pensamos que se ha estado prodticiendo radiaci6n gravitacional en cantidades considerables dentro de las galaxias. Si los eventos prodnctores de radiaci6n gravitatoria han venido ocurriendo desde Ia epoca de Ia formaci6n de las galaxias, cuando menos, sus efectos cosmol6gicos pueden ser tomados en cuenta con simplicidad y elegancia al representar la producci6n de radiaci6n y, por consiguiente, su interacci6n con materia ordinaria fenomenol6gicamente a trave's de una ecuaci6n de estado politr6pica, como lo hemos mostrado en otros trabajos. Presentamos en este articulo resultados nunericos de este modelo. ABSTRACT A common believe in cosmology is that gravitational radiation in considerable quantities is being produced within the galaxies. Ifgravitational radiation production has been running since the galaxy formation epoch, at least, its cosmological effects can be assesed with simplicity and elegance by representing the production of radiation and, therefore, its interaction with ordinary matter phenomenologically through a polytropic equation of state as shown already elsewhere. We present in this paper the numerical results of such a model. K words: COSMOLOGY - GRAVITATION
Energy Technology Data Exchange (ETDEWEB)
Sprenger, Lisa, E-mail: Lisa.Sprenger@tu-dresden.de; Lange, Adrian; Odenbach, Stefan [Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Measuring and Automation Technology, TU Dresden, 01062 Dresden (Germany)
2014-02-15
Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: S{sub T‖} = −0.152 K{sup −1} and S{sub T⊥} = −0.257 K{sup −1} at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ{sub ‖} and ξ{sub ⊥} used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field
Energy Technology Data Exchange (ETDEWEB)
Kam, Seung I.(PEMEX REFINACION); Gauglitz, Phillip A.(BATTELLE (PACIFIC NW LAB)); Rossen, William R.(UNKNOWN)
2000-12-01
The goal of this study is to fit model parameters to changes in waste level in response to barometric pressure changes in underground storage tanks at the Hanford Site. This waste compressibility is a measure of the quantity of gas, typically hydrogen and other flammable gases that can pose a safety hazard, retained in the waste. A one-dimensional biconical-pore-network model for compressibility of a bubbly slurry is presented in a companion paper. Fitting these results to actual waste level changes in the tanks implies that bubbles are long in the slurry layer and the ratio of pore-body radius to pore-throat radius is close to one; unfortunately, capillary effects can not be quantified unambiguously from the data without additional information on pore geometry. Therefore determining the quantity of gas in the tanks requires more than just slurry volume data. Similar ambiguity also exists with two other simple models: a capillary-tube model with contact angle hysteresis and spherical-p ore model.
A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers. 2; Numerical Results
Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)
2001-01-01
We present numerical results of the diffusion coefficients (DCs) in the coupled diffusion model derived in the preceding paper for a semiconductor quantum well. These include self and mutual DCs in the general two-component case, as well as density- and temperature-related DCs under the single-component approximation. The results are analyzed from the viewpoint of free Fermi gas theory with many-body effects incorporated. We discuss in detail the dependence of these DCs on densities and temperatures in order to identify different roles played by the free carrier contributions including carrier statistics and carrier-LO phonon scattering, and many-body corrections including bandgap renormalization and electron-hole (e-h) scattering. In the general two-component case, it is found that the self- and mutual- diffusion coefficients are determined mainly by the free carrier contributions, but with significant many-body corrections near the critical density. Carrier-LO phonon scattering is dominant at low density, but e-h scattering becomes important in determining their density dependence above the critical electron density. In the single-component case, it is found that many-body effects suppress the density coefficients but enhance the temperature coefficients. The modification is of the order of 10% and reaches a maximum of over 20% for the density coefficients. Overall, temperature elevation enhances the diffusive capability or DCs of carriers linearly, and such an enhancement grows with density. Finally, the complete dataset of various DCs as functions of carrier densities and temperatures provides necessary ingredients for future applications of the model to various spatially inhomogeneous optoelectronic devices.
Electron injection and acceleration at nonlinear shocks: Results of numerical simulations
Levinson, Amir
1994-01-01
We present results of numerical simulations of electron injection and acceleration at nonlinear high Mach number shocks. The electrons are assumed to be heated at the thermal subshock to an energy E(sub inj), which is treated as a free parameter, above which they are injected by self-generated whistlers to momentum m(sub p) x V(sub A). This injection mechanism requires Mach numbers greater than (43/(beta(sub -)))(((k T(sub e))/(E(sub inj)))(exp 1/2)), where T(sub e) and beta (sub -) are the upstream electron temperature and plasma beta parameter. Above m(sub p) x V(sub A) electrons are trapped in the shock by Alfven waves. In the proton precursor region the Alfven waves are assumed to be generated by protons accelerated at the shock, and have nonlinear intensities. Below GeV, however, electrons of a given rigidity propagate faster than protons with a similar rigidity and therefore diffuse to regions ahead of the proton precursor. In those regions the Alfven waves are generated by the electrons themselves. The diffusion coefficient appears to increase with decreasing acceleration efficiency. As a result, the number of electrons accelerated to energies GeV and above and, hence, the electron to proton ratio, depend only weakly on the extent of electron heating at the subshock. The negative feedback also renders the electron spectra insensitive to shock compression ratio and smoothing length scale. The estimated e/p ratio at GeV is between approximately 1%-10%.
DEFF Research Database (Denmark)
Victor, L.; Troch, P.; Kofoed, Jens Peter
2009-01-01
For overtopping wave energy converters (WECs) a more efficient energy conversion can be achieved when the volumes of water, wave by wave, that enter their reservoir are known and can be predicted. A numerical tool is being developed using a commercial CFD-solver to study and optimize...... nearshore 2Dstructure. First numerical model results are given for a specific test with regular waves, and are compared with the corresponding experimental results in this paper....
Didactic Strategy Discussion Based on Artificial Neural Networks Results.
Andina, D.; Bermúdez-Valbuena, R.
2009-04-01
Artificial Neural Networks (ANNs) are a mathematical model of the main known characteristics of biological brian dynamics. ANNs inspired in biological reality have been useful to design machines that show some human-like behaviours. Based on them, many experimentes have been succesfully developed emulating several biologial neurons characteristics, as learning how to solve a given problem. Sometimes, experimentes on ANNs feedback to biology and allow advances in understanding the biological brian behaviour, allowing the proposal of new therapies for medical problems involving neurons performing. Following this line, the author present results on artificial learning on ANN, and interpret them aiming to reinforce one of this two didactic estrategies to learn how to solve a given difficult task: a) To train with clear, simple, representative examples and feel confidence in brian generalization capabilities to achieve succes in more complicated cases. b) To teach with a set of difficult cases of the problem feeling confidence that the brian will efficiently solve the rest of cases if it is able to solve the difficult ones. Results may contribute in the discussion of how to orientate the design innovative succesful teaching strategies in the education field.
Bransgrove, Ashley; Levin, Yuri; Beloborodov, Andrei
2018-01-01
In this work we explore the evolution of magnetic fields inside strongly magnetized neutron stars in axisymmetry. We model numerically the coupled field evolution in the core and the crust. Our code models the Hall drift and Ohmic effects in the crust, the back-reaction on the field from magnetically induced elastic deformation of the crust, the magnetic twist exchange between the crust and the core, and the drift of superconducting flux tubes inside the core. The correct hydromagnetic equilibrium is enforced in the core. We find that (i) The Hall attractor found by Gourgouliatos and Cumming in the crust exists also for configurations when the B-field penetrates into the core. However, the evolution time-scale for the core-penetrating fields is dramatically different from that of the fields confined to the crust. (ii) The combination of Jones' flux tube drift and Ohmic dissipation in the crust can deplete the pulsar magnetic fields on the time-scale of 150 Myr if the crust is hot (T ∼ 2 × 108 K), but acts on much slower time-scales for cold neutron stars, such as recycled pulsars (∼1.8 Gyr, depending on impurity levels). (iii) The outward motion of superfluid vortices during the rapid spin-down of a young highly magnetized pulsar can result in a partial expulsion of flux from the core when B ≲ 1013 G. However for B ≳ 2 × 1013 G, the combination of a stronger magnetic field and a longer spin period implies that the core field cannot be expelled.
U-drawing of Fortiform 1050 third generation steels. Numerical and experimental results
Saenz de Argandoña, E.; Galdos, L.; Mendiguren, J.; Otero, I.; Mugarra, E.
2017-09-01
Elasto-plastic behavior of the third generation Fortiform 1050 steel has been analysed using cyclic tension-compression tests. At the same time, the pseudo elastic modulus evolution with plastic strain was analysed using cyclic loading and unloading tests. From the experiments, it was found that the cyclic behavior of the steel is strongly kinematic and elastic modulus decrease with plastic strain is relevant for numerical modelling. In order to numerically analyse a U-Drawing process, strip drawing tests have been carried out at different contact pressures and Filzek model has been used to fit the experimental data and implement a pressure dependent friction law in Autoform software. Finally, numerical predictions of springback have been compared with the experimentally ones obtained using a sensorized U-Drawing tooling. Different material and contact models have been examined and most influencing parameters have been identified to model the forming of these new steels.
Nonlinearities of waves propagating over a mild-slope beach: laboratory and numerical results
Rocha, Mariana V. L.; Michallet, Hervé; Silva, Paulo A.; Cienfuegos, Rodrigo
2014-05-01
As surface gravity waves propagate from deeper waters to the shore, their shape changes, primarily due to nonlinear wave interactions and further on due to breaking. The nonlinear effects amplify the higher harmonics and cause the oscillatory flow to transform from nearly sinusoidal in deep water, through velocity-skewed in the shoaling zone, to velocity asymmetric in the inner-surf and swash zones. In addition to short-wave nonlinearities, the presence of long waves and wave groups also results in a supplementary wave-induced velocity and influences the short-waves. Further, long waves can themselves contribute to velocity skewness and asymmetry at low frequencies, particularly for very dissipative mild-slope beach profiles, where long wave shoaling and breaking can also occur. The Hydralab-IV GLOBEX experiments were performed in a 110-m-long flume, with a 1/80 rigid-bottom slope and allowed the acquisition of high-resolution free-surface elevation and velocity data, obtained during 90-min long simulations of random and bichromatic wave conditions, and also of a monochromatic long wave (Ruessink et al., Proc. Coastal Dynamics, 2013). The measurements are compared to numerical results obtained with the SERR-1D Boussinesq-type model, which is designed to reproduce the complex dynamics of high-frequency wave propagation, including the energy transfer mechanisms that enhance infragravity-wave generation. The evolution of skewness and asymmetry along the beach profile until the swash zone is analyzed, relatively to that of the wave groupiness and long wave propagation. Some particularities of bichromatic wave groups are further investigated, such as partially-standing long-wave patterns and short-wave reformation after the first breakpoint, which is seen to influence particularly the skewness trends. Decreased spectral width (for random waves) and increased modulation (for bichromatic wave groups) are shown to enhance energy transfers between super- and sub
Dameron, O; Gibaud, B; Morandi, X
2004-06-01
The human cerebral cortex anatomy describes the brain organization at the scale of gyri and sulci. It is used as landmarks for neurosurgery as well as localization support for functional data analysis or inter-subject data comparison. Existing models of the cortex anatomy either rely on image labeling but fail to represent variability and structural properties or rely on a conceptual model but miss the inner 3D nature and relations of anatomical structures. This study was therefore conducted to propose a model of sulco-gyral anatomy for the healthy human brain. We hypothesized that both numeric knowledge (i.e., image-based) and symbolic knowledge (i.e., concept-based) have to be represented and coordinated. In addition, the representation of this knowledge should be application-independent in order to be usable in various contexts. Therefore, we devised a symbolic model describing specialization, composition and spatial organization of cortical anatomical structures. We also collected numeric knowledge such as 3D models of shape and shape variation about cortical anatomical structures. For each numeric piece of knowledge, a companion file describes the concept it refers to and the nature of the relationship. Demonstration software performs a mapping between the numeric and the symbolic aspects for browsing the knowledge base.
Bruel, D.; Baujard, C.
2005-05-01
. The examples also confirm that the migration rate of the seismic front is not affected by the irreversible changes in hydraulic parameters experienced by the fractures in between the injection zone and the failure front. The DFN numerical procedure is shown appropriate to discuss the occurence of delayed seismic events, triggered in the far field after the injection phase has terminated. This direct approach seems well suited to predict the change in permeability resulting from a stimulation treatment and gives pressure estimates to properly stimulate a network made of several fracture sets, accounting from a given anisotropic stress tensor. [1] Bruel, D., (2002) Impact of induced thermal stress during circulation tests in an engineered fractured geothermal reservoir. Oil & Gas Science and Technology - Rev. IFP, 57, no. 5, 459-470 [2] Shapiro, S.A., Royer, J. and Audigane, P., (1999), Large scale in situ permeability tensor of rocks from induced microseismicity. Geophysical Journal International, 137, 207-213.
Digital Repository Service at National Institute of Oceanography (India)
Unnikrishnan, A.S.; Manoj, N.T.
Various numerical models used to study the dynamics and horizontal distribution of salinity in Mandovi-Zuari estuaries, Goa, India is discussed in this chapter. Earlier, a one-dimensional network model was developed for representing the complex...
Electric analogue for the dynamics of decompression sickness bubbles: Numerical results
Zueco, Joaquín; Hernández-González, A.
2010-01-01
Since the development of the first decompression tables in 1908 by Boycott, Damant and Haldane, considerable research and effort have been expended in the development of safer and more rapid decompression procedures and tables. The models for gas exchange have been principally empirical and provide "safe" decompression only over a limited range of depth and bottom times. In this work a numerical method based on an electrical analogy is used to solve the system of equations simulating the growth and decay dynamics of decompression bubbles. The numerical procedure employed, which satisfies the conservation law for the flux variable and the uniqueness law for voltages, also permits the direct visualisation of the evolution of the local and/or integrated transport variables at any point or section of the medium.
Radioluminescence in Al2O3: C - analytical and numerical simulation results
DEFF Research Database (Denmark)
Pagonis, V.; Lawless, J.; Chen, R.
2009-01-01
used to provide a quantitative description of the thermoluminescence and optically stimulated luminescence processes in Al2O3 : C. Using appropriate sets of trapping parameters for the kinetic model, the RL signal along with the occupancies of the relevant traps and centres are simulated numerically....... The set of differential equations is also solved analytically by assuming dynamic balance during sample irradiation. Analytical expressions are obtained for the concentrations of traps and centres in the material during irradiation with short irradiation pulses, by assuming that quasi-steady conditions...... hold during irradiation. Several experimentally observed characteristics of the RL signals are explained by using the model. Good quantitative agreement is found between the analytical expressions and the numerical solutions of the model for short irradiation pulses....
Petrova, N.; Zagidullin, A.; Nefedyev, Y.; Kosulin, V.; Andreev, A.
2017-11-01
Observing physical librations of celestial bodies and the Moon represents one of the astronomical methods of remotely assessing the internal structure of a celestial body without conducting expensive space experiments. The paper contains a review of recent advances in studying the Moon's structure using various methods of obtaining and applying the lunar physical librations (LPhL) data. In this article LPhL simulation methods of assessing viscoelastic and dissipative properties of the lunar body and lunar core parameters, whose existence has been recently confirmed during the seismic data reprocessing of ;Apollo; space mission, are described. Much attention is paid to physical interpretation of the free librations phenomenon and the methods for its determination. In the paper the practical application of the most accurate analytical LPhL tables (Rambaux and Williams, 2011) is discussed. The tables were built on the basis of complex analytical processing of the residual differences obtained when comparing long-term series of laser observations with the numerical ephemeris DE421. In the paper an efficiency analysis of two approaches to LPhL theory is conducted: the numerical and the analytical ones. It has been shown that in lunar investigation both approaches complement each other in various aspects: the numerical approach provides high accuracy of the theory, which is required for the proper processing of modern observations, the analytical approach allows to comprehend the essence of the phenomena in the lunar rotation, predict and interpret new effects in the observations of lunar body and lunar core parameters.
Ponderomotive stabilization of flute modes in mirrors Feedback control and numerical results
Similon, P. L.
1987-01-01
Ponderomotive stabilization of rigid plasma flute modes is numerically investigated by use of a variational principle, for a simple geometry, without eikonal approximation. While the near field of the studied antenna can be stabilizing, the far field has a small contribution only, because of large cancellation by quasi mode-coupling terms. The field energy for stabilization is evaluated and is a nonnegligible fraction of the plasma thermal energy. A new antenna design is proposed, and feedback stabilization is investigated. Their use drastically reduces power requirements.
Molenaar, P.C.M.; Raijmakers, M.E.J.; van der Maas, H.L.J.
1996-01-01
On-center off-surround shunting neural networks are often applied as models for content-addressable memory (CAM), the equilibria being the stored memories. One important demand of biological plausible CAMs is that they function under a broad range of parameters, since several parameters vary due to
Hun Yeon, Ju; Chan, Karen Y T; Wong, Ting-Chia; Chan, Kelvin; Sutherland, Michael R; Ismagilov, Rustem F; Pryzdial, Edward L G; Kastrup, Christian J
2015-05-15
Developing bio-compatible smart materials that assemble in response to environmental cues requires strategies that can discriminate multiple specific stimuli in a complex milieu. Synthetic materials have yet to achieve this level of sensitivity, which would emulate the highly evolved and tailored reaction networks of complex biological systems. Here we show that the output of a naturally occurring network can be replaced with a synthetic material. Exploiting the blood coagulation system as an exquisite biological sensor, the fibrin clot end-product was replaced with a synthetic material under the biological control of a precisely regulated cross-linking enzyme. The functions of the coagulation network remained intact when the material was incorporated. Clot-like polymerization was induced in indirect response to distinct small molecules, phospholipids, enzymes, cells, viruses, an inorganic solid, a polyphenol, a polysaccharide, and a membrane protein. This strategy demonstrates for the first time that an existing stimulus-responsive biological network can be used to control the formation of a synthetic material by diverse classes of physiological triggers.
Cosoli, G; Scalise, L; Tricarico, G; Russo, P; Cerri, G
2017-06-01
Bioimpedance measurements represent an advantageous method to evaluate the physio-pathological conditions of biological tissues and their use is spreading in different application fields, from the evaluation of body composition to the vital signs monitoring, passing through the individuation of cancer tissues and the detection of different substances (e.g. glucose measurements in people affected by diabetes). In fact, tissues electric properties vary with their conditions; for example, electrical conductivity increases when there is an inflammatory process, because of the presence of oedema, hyperaemia and infiltration. Inflammatory phenomena are frequent in dentistry, in diseases like periodontitis and peri-implantitis; however, at present the diagnosis is mainly done with the naked eye, by observing the gingiva redness and swelling. The aim of this work is to prove the feasibility of the inflammation detection by means of bioimpedance measurements. Both numerical simulations and preliminary experimental measurements provide significant outcomes in differentiating between healthy and inflamed tissues. Percentage differences in the impedance modulus equal to 4-20% (numerical simulations) and 35-56% (experimental measurements), respectively, depending on the considered conditions (e.g. electrodes characteristics and inflammation severity), were found. Such a measure could be integrated in electromedical devices designed, for example, for the therapy of peri-implantitis, in order to personalise the therapeutic dose in terms of intensity and duration and focusing it on the impaired area, minimising the effects on the surrounding tissues.
Estimation of geopotential from satellite-to-satellite range rate data: Numerical results
Thobe, Glenn E.; Bose, Sam C.
1987-01-01
A technique for high-resolution geopotential field estimation by recovering the harmonic coefficients from satellite-to-satellite range rate data is presented and tested against both a controlled analytical simulation of a one-day satellite mission (maximum degree and order 8) and then against a Cowell method simulation of a 32-day mission (maximum degree and order 180). Innovations include: (1) a new frequency-domain observation equation based on kinetic energy perturbations which avoids much of the complication of the usual Keplerian element perturbation approaches; (2) a new method for computing the normalized inclination functions which unlike previous methods is both efficient and numerically stable even for large harmonic degrees and orders; (3) the application of a mass storage FFT to the entire mission range rate history; (4) the exploitation of newly discovered symmetries in the block diagonal observation matrix which reduce each block to the product of (a) a real diagonal matrix factor, (b) a real trapezoidal factor with half the number of rows as before, and (c) a complex diagonal factor; (5) a block-by-block least-squares solution of the observation equation by means of a custom-designed Givens orthogonal rotation method which is both numerically stable and tailored to the trapezoidal matrix structure for fast execution.
Characteristics of Social Network Gamers: Results of an Online Survey.
Geisel, Olga; Panneck, Patricia; Stickel, Anna; Schneider, Michael; Müller, Christian A
2015-01-01
Current research on Internet addiction (IA) reported moderate to high prevalence rates of IA and comorbid psychiatric symptoms in users of social networking sites (SNS) and online role-playing games. The aim of this study was to characterize adult users of an Internet multiplayer strategy game within a SNS. Therefore, we conducted an exploratory study using an online survey to assess sociodemographic variables, psychopathology, and the rate of IA in a sample of adult social network gamers by Young's Internet Addiction Test (IAT), the Toronto Alexithymia Scale (TAS-26), the Beck Depression Inventory-II (BDI-II), the Symptom Checklist-90-R (SCL-90-R), and the WHO Quality of Life-BREF (WHOQOL-BREF). All participants were listed gamers of "Combat Zone" in the SNS "Facebook." In this sample, 16.2% of the participants were categorized as subjects with IA and 19.5% fulfilled the criteria for alexithymia. Comparing study participants with and without IA, the IA group had significantly more subjects with alexithymia, reported more depressive symptoms, and showed poorer quality of life. These findings suggest that social network gaming might also be associated with maladaptive patterns of Internet use. Furthermore, a relationship between IA, alexithymia, and depressive symptoms was found that needs to be elucidated by future studies.
Xu, Zexuan; Hu, Bill X.; Davis, Hal; Kish, Stephen
2015-11-01
In this study, a groundwater flow cycling in a karst springshed and an interaction between two springs, Spring Creek Springs and Wakulla Springs, through a subground conduit network are numerically simulated using CFPv2, the latest research version of MODFLOW-CFP (Conduit Flow Process). The Spring Creek Springs and Wakulla Springs, located in a marine estuary and 11 miles inland, respectively, are two major groundwater discharge spots in the Woodville Karst Plain (WKP), North Florida, USA. A three-phase conceptual model of groundwater flow cycling between the two springs and surface water recharge from a major surface creek (Lost Creek) was proposed in various rainfall conditions. A high permeable subground karst conduit network connecting the two springs was found by tracer tests and cave diving. Flow rate of discharge, salinity, sea level and tide height at Spring Creek Springs could significantly affect groundwater discharge and water stage at Wakulla Springs simultaneously. Based on the conceptual model, a numerical hybrid discrete-continuum groundwater flow model is developed using CFPv2 and calibrated by field measurements. Non-laminar flows in conduits and flow exchange between conduits and porous medium are implemented in the hybrid coupling numerical model. Time-variable salinity and equivalent freshwater head boundary conditions at the submarine spring as well as changing recharges have significant impacts on seawater/freshwater interaction and springs' discharges. The developed numerical model is used to simulate the dynamic hydrological process and quantitatively represent the three-phase conceptual model from June 2007 to June 2010. Simulated results of two springs' discharges match reasonably well to measurements with correlation coefficients 0.891 and 0.866 at Spring Creeks Springs and Wakulla Springs, respectively. The impacts of sea level rise on regional groundwater flow field and relationship between the inland springs and submarine springs are
Potential flows in a core-dipole-shell system: numerical results
Energy Technology Data Exchange (ETDEWEB)
Ujevic, Maximiliano; Letelier, Patricio S [Departamento de Matematica Aplicada, Instituto de Matematica, Estatistica e Computacao Cientifica, Universidade Estadual de Campinas, 13081-970, Campinas, SP (Brazil)
2002-08-07
Numerical solutions for the integral curves of the velocity field (streamlines), the density contours and the accretion rate of a steady-state flow of an ideal fluid with p=Kn{sup {gamma}} equation of state orbiting in a core-dipole-shell system are presented. For {gamma} {ne} 2, we found that the nonlinear contribution appearing in the partial differential equation for the velocity potential has little effect in the form of the streamlines and density contour lines, but can be noticed in the density values. The study of several cases indicates that this appears to be the general situation. The accretion rate was found to increase when the constant {gamma} decreases.
CSIR Research Space (South Africa)
Jansen van Rensburg, Gerhardus J
2011-10-01
Full Text Available In the present study, numerical results obtained on different but related shapes are compared by using a non-rigid mapping. Non-rigid registration is employed to obtain mesh representations of different human skull geometries with the same mesh...
Uygur, Fatih; Sever, Celalettin; Yüksel, Fuat
2009-01-01
The carpal tunnel syndrome is the most common nerve entrapment syndrome. Many different methods have been described for treatment. We performed a novel method to release the carpal tunnel. Subsequently, we compared the surgery results of this novel limited incision technique and the standard longitudinal incision technique by using a 'Numerical Grading System'. There is no reported study about the use of 'Numerical Grading System' for assessment of carpal tunnel syndrome in the literature. The novel technique is simple and effective, employs inexpensive instruments, and has a low complication rate. The aim of this paper is to record a novel limited incision technique and a new assessment method for the carpal tunnel syndrome.
Ding, Lei; Van Renterghem, Timothy; Botteldooren, Dick; Horoshenkov, Kirill; Khan, Amir
2013-12-01
The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound). Typically, there is an unaffected change in the low frequency absorption coefficient (below 250 Hz), an increase in the middle frequency absorption coefficient (500-2000 Hz) and a decrease in the absorption at higher frequencies. The influence of leaves becomes most pronounced when the substrate has a low mass density. A combination of the Biot's elastic frame porous model, viscous damping in the leaf boundary layers and plate vibration theory is implemented via a finite-difference time-domain model, which is able to predict accurately the absorption spectrum of a leaf above a porous substrate system. The change in the absorption spectrum caused by the leaf vibration can be modeled reasonably well assuming the leaf and porous substrate properties are uniform.
Numerical Algorithms for Personalized Search in Self-organizing Information Networks
Kamvar, Sep
2010-01-01
This book lays out the theoretical groundwork for personalized search and reputation management, both on the Web and in peer-to-peer and social networks. Representing much of the foundational research in this field, the book develops scalable algorithms that exploit the graphlike properties underlying personalized search and reputation management, and delves into realistic scenarios regarding Web-scale data. Sep Kamvar focuses on eigenvector-based techniques in Web search, introducing a personalized variant of Google's PageRank algorithm, and he outlines algorithms--such as the now-famous quad
Hagrey, S. A. Al; Strahser, M. H. P.; Rabbel, W.
2009-04-01
The research project "CO2 MoPa" (modelling and parameterisation of CO2 storage in deep saline formations for dimensions and risk analysis) has been initiated in 2008 by partners from different disciplines (e.g. geology, hydrogeology, geochemistry, geophysics, geomechanics, hydraulic engineering and law). It deals with the parameterisation of virtual subsurface storage sites to characterise rock properties, with high pressure-temperature experiments to determine in situ hydro-petrophysical and mechanical parameters, and with modelling of processes related to CCS in deep saline reservoirs. One objective is the estimation of the sensitivity and the resolution of reflection seismic and geoelectrical time-lapse measurements in order to determine the underground distribution of CO2. Compared with seismic, electric resistivity tomography (ERT) has lower resolution, but its permanent installation and continuous monitoring can make it an economical alternative or complement. Seismic and ERT (in boreholes) applications to quantify changes of intrinsic aquifers properties with time are justified by the velocity and resistivity decrease related to CO2 injection. Our numerical 2D/3D modelling reveals the capability of the techniques to map CO2 plumes and changes as a function of thickness, concentration, receiver/electrode configuration, aspect ratio and modelling and inversion constraint parameters. Depending on these factors, some configurations are favoured due to their better spatial resolution and lower artefacts. Acknowledgements This work has been carried out in the framework of "CO2 MoPa" research project funded by the Federal German Ministry of Education and Research (BMBF) and a consortium of energy companies (E.ON Energy, EnBW AG, RWE Dea AG, Stadtwerke Kiel AG, Vattenfall Europe Technology Research GmbH and Wintershall Holding AG).
DEFF Research Database (Denmark)
Sørensen, Jens Nørkær; Gelfgat, A. Yu; Naumov, I. V.
2009-01-01
The three-dimensional axisymmetry-breaking instability of axisymmetric flow between a rotating lid and a stationary cylinder is analyzed both numerically and experimentally for the case of tall cylinders with the height/radius aspect ratio between 3.3 and 5.5. A complete stability diagram for the...... is in a good agreement with the numerical results. Disagreements observed in supercritical regimes can be explained by secondary bifurcations that are not accounted for by linear stability analysis of the primary base flow. ©2009 American Institute of Physics......The three-dimensional axisymmetry-breaking instability of axisymmetric flow between a rotating lid and a stationary cylinder is analyzed both numerically and experimentally for the case of tall cylinders with the height/radius aspect ratio between 3.3 and 5.5. A complete stability diagram...... for each mode. The onset of three-dimensional flow behavior is measured by combining the high spatial resolution of particle image velocimetry and the temporal accuracy of laser Doppler anemometry. The results are compared to the numerical stability analysis. The measured onset of three dimensionality...
National Research Council Canada - National Science Library
Stefano Busanelli; Filippo Rebecchi; Marco Picone; Nicola Iotti; Gianluigi Ferrari
2013-01-01
.... The proposed communication architecture has been implemented on Android smartphones. The obtained experimental results show that an effective cross-network information dissemination service can entirely rely on smartphone-based communications...
Directory of Open Access Journals (Sweden)
Gianluigi Ferrari
2013-08-01
Full Text Available In this work, we present an innovative approach for effective cross-network information dissemination, with applications to vehicular ad hoc networks (VANETs. The proposed approach, denoted as "Cross-Network Effective Traffic Alert Dissemination" (X-NETAD, leverages on the spontaneous formation of local WiFi (IEEE 802.11b VANETs, with direct connections between neighboring vehicles, in order to disseminate, very quickly and inexpensively, traffic alerts received from the cellular network. The proposed communication architecture has been implemented on Android smartphones. The obtained experimental results show that an effective cross-network information dissemination service can entirely rely on smartphone-based communications. This paves the way to future Internet architectures, where vehicles will play a key role as information destinations and sources.
Protein networks identify novel symbiogenetic genes resulting from plastid endosymbiosis.
Méheust, Raphaël; Zelzion, Ehud; Bhattacharya, Debashish; Lopez, Philippe; Bapteste, Eric
2016-03-29
The integration of foreign genetic information is central to the evolution of eukaryotes, as has been demonstrated for the origin of the Calvin cycle and of the heme and carotenoid biosynthesis pathways in algae and plants. For photosynthetic lineages, this coordination involved three genomes of divergent phylogenetic origins (the nucleus, plastid, and mitochondrion). Major hurdles overcome by the ancestor of these lineages were harnessing the oxygen-evolving organelle, optimizing the use of light, and stabilizing the partnership between the plastid endosymbiont and host through retargeting of proteins to the nascent organelle. Here we used protein similarity networks that can disentangle reticulate gene histories to explore how these significant challenges were met. We discovered a previously hidden component of algal and plant nuclear genomes that originated from the plastid endosymbiont: symbiogenetic genes (S genes). These composite proteins, exclusive to photosynthetic eukaryotes, encode a cyanobacterium-derived domain fused to one of cyanobacterial or another prokaryotic origin and have emerged multiple, independent times during evolution. Transcriptome data demonstrate the existence and expression of S genes across a wide swath of algae and plants, and functional data indicate their involvement in tolerance to oxidative stress, phototropism, and adaptation to nitrogen limitation. Our research demonstrates the "recycling" of genetic information by photosynthetic eukaryotes to generate novel composite genes, many of which function in plastid maintenance.
Energy Technology Data Exchange (ETDEWEB)
Tanaka, H.; Wada, A. (Central Research Inst. of Electric Power Industry, Tokyo (Japan))
1981-06-01
When warm water is discharged into the surf zone of gently sloping coast facing open sea, the discharged warm water may be affected by breaking waves, and the complicated shape of the thermal diffusion range is shown. In order to predict the diffusion of discharged warm water with a numerical model in such case, it is necessary to reproduce a velocity vector field due to near-shore current, and to estimate correctly the advection term in a thermal diffusion equation. It is also important to estimate adequately the diffusion coefficient under the effect of near-shore current. In this report, the propriety of the numerical model used for this study is discussed. The characteristics of coastal current and waves in the sea region off Fukushima No. 1 Nuclear Power Station, Tokyo Electric Power Co., Inc., the numerical models for wave field and near-shore current, the prediction of the horizontal distribution of water temperature, and the comparison of the results of numerical simulation and experiment on the reproducibility of breaker line, the velocity vector field due to near-shore current, the range of water temperature rise and the diffusion range under the action of irregular waves are reported.
Comparison of results between numerical simulation and experiment for radiative ablation of CH foil
Sheng Jia Tian; Feng Ting Gui; Zhang Li; Li Meng; Yang Jia Min; Ding Yao Nan; Jiang Shao En
2002-01-01
The radiation ablation experiments of CH foils are simulated using the experiment radiation flow in the hohlraum by 1-D radiation transfer code RDMG. The results of simulation show that influence of Non-LTE radiation source on the ablation of CH foil is very obvious. The results of simulation and experiment including radiation flow total intensity and the variation of radiation temperature with time at the rear of CH foil, as well as the time delay of 400 eV photon arriving at the rear of CH foil are consistent basically
Multi-Country Experience in Delivering a Joint Course on Software Engineering--Numerical Results
Budimac, Zoran; Putnik, Zoran; Ivanovic, Mirjana; Bothe, Klaus; Zdravkova, Katerina; Jakimovski, Boro
2014-01-01
A joint course, created as a result of a project under the auspices of the "Stability Pact of South-Eastern Europe" and DAAD, has been conducted in several Balkan countries: in Novi Sad, Serbia, for the last six years in several different forms, in Skopje, FYR of Macedonia, for two years, for several types of students, and in Tirana,…
Directory of Open Access Journals (Sweden)
Mikulović Jovan Č.
2014-01-01
Full Text Available A methodology for calculation of overvoltages in transformer windings, based on a numerical method of inverse Laplace transform, is presented. Mathematical model of transformer windings is described by partial differential equations corresponding to distributed parameters electrical circuits. The procedure of calculating overvoltages is applied to windings having either isolated neutral point, or grounded neutral point, or neutral point grounded through impedance. A comparative analysis of the calculation results obtained by the proposed numerical method and by analytical method of calculation of overvoltages in transformer windings is presented. The results computed by the proposed method and measured voltage distributions, when a voltage surge is applied to a three-phase 30 kVA power transformer, are compared. [Projekat Ministartsva nauke Republike Srbije, br. TR-33037 i br. TR-33020
Li, Xuanying; Li, Xiaotong; Hu, Cheng
2017-12-01
In this paper, without transforming the second order inertial neural networks into the first order differential systems by some variable substitutions, asymptotic stability and synchronization for a class of delayed inertial neural networks are investigated. Firstly, a new Lyapunov functional is constructed to directly propose the asymptotic stability of the inertial neural networks, and some new stability criteria are derived by means of Barbalat Lemma. Additionally, by designing a new feedback control strategy, the asymptotic synchronization of the addressed inertial networks is studied and some effective conditions are obtained. To reduce the control cost, an adaptive control scheme is designed to realize the asymptotic synchronization. It is noted that the dynamical behaviors of inertial neural networks are directly analyzed in this paper by constructing some new Lyapunov functionals, this is totally different from the traditional reduced-order variable substitution method. Finally, some numerical simulations are given to demonstrate the effectiveness of the derived theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.
Hu, Cong; Li, Zhi; Zhou, Tian; Zhu, Aijun; Xu, Chuanpei
2016-01-01
We propose a new meta-heuristic algorithm named Levy flights multi-verse optimizer (LFMVO), which incorporates Levy flights into multi-verse optimizer (MVO) algorithm to solve numerical and engineering optimization problems. The Original MVO easily falls into stagnation when wormholes stochastically re-span a number of universes (solutions) around the best universe achieved over the course of iterations. Since Levy flights are superior in exploring unknown, large-scale search space, they are integrated into the previous best universe to force MVO out of stagnation. We test this method on three sets of 23 well-known benchmark test functions and an NP complete problem of test scheduling for Network-on-Chip (NoC). Experimental results prove that the proposed LFMVO is more competitive than its peers in both the quality of the resulting solutions and convergence speed.
DEFF Research Database (Denmark)
Paramanathan, Achuthan; Rasmussen, Ulrik Wilken; Hundebøll, Martin
2012-01-01
This paper presents an energy model and energy measurements for network coding enabled wireless meshed networks based on IEEE 802.11 technology. The energy model and the energy measurement testbed is limited to a simple Alice and Bob scenario. For this toy scenario we compare the energy usages...... a flexible, low cost tool to be able to measure at any given node in a meshed network. We verify the precision of our tool by comparing it to a sophisticated device. Our main results in this paper are the derivation of an analytical energy model, the implementation of a distributed energy measurement testbed...
Deluca, E. E.; Werne, J.; Rosner, R.; Cattaneo, F.
1990-01-01
Results on the transition from soft to hard turbulence in simulations of two-dimensional Boussinesq convection are reported. The computed probability densities for temperature fluctuations are exponential in form in both soft and hard turbulence, unlike what is observed in experiments. In contrast, a change is obtained in the Nusselt number scaling on Rayleigh number in good agreement with the three-dimensional experiments.
A parallel program for numerical simulation of discrete fracture network and groundwater flow
Huang, Ting-Wei; Liou, Tai-Sheng; Kalatehjari, Roohollah
2017-04-01
The ability of modeling fluid flow in Discrete Fracture Network (DFN) is critical to various applications such as exploration of reserves in geothermal and petroleum reservoirs, geological sequestration of carbon dioxide and final disposal of spent nuclear fuels. Although several commerical or acdametic DFN flow simulators are already available (e.g., FracMan and DFNWORKS), challenges in terms of computational efficiency and three-dimensional visualization still remain, which therefore motivates this study for developing a new DFN and flow simulator. A new DFN and flow simulator, DFNbox, was written in C++ under a cross-platform software development framework provided by Qt. DFNBox integrates the following capabilities into a user-friendly drop-down menu interface: DFN simulation and clipping, 3D mesh generation, fracture data analysis, connectivity analysis, flow path analysis and steady-state grounwater flow simulation. All three-dimensional visualization graphics were developed using the free OpenGL API. Similar to other DFN simulators, fractures are conceptualized as random point process in space, with stochastic characteristics represented by orientation, size, transmissivity and aperture. Fracture meshing was implemented by Delaunay triangulation for visualization but not flow simulation purposes. Boundary element method was used for flow simulations such that only unknown head or flux along exterior and interection bounaries are needed for solving the flow field in the DFN. Parallel compuation concept was taken into account in developing DFNbox for calculations that such concept is possible. For example, the time-consuming seqential code for fracture clipping calculations has been completely replaced by a highly efficient parallel one. This can greatly enhance compuational efficiency especially on multi-thread platforms. Furthermore, DFNbox have been successfully tested in Windows and Linux systems with equally-well performance.
Preliminary results from a numerical study on the appendix gap losses in a Stirling engine
DEFF Research Database (Denmark)
Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove
2005-01-01
been included directly into a one dimensional Stirling engine model. Practical aspects of the method, such as handling the moving wall in the gap while achieving an energy conserving model formulation and handling discontinuous derivatives in the equations, are discussed. A study on the convergence...... with different algorithms for computing the heat transfer in the gap. The results showed higher losses for small gap sizes but smaller losses for large gap sizes when compared to analytical expressions for the appendix gap losses. The appendix gap losses were found to influence both the heat intake and work...
CRSP, numerical results for an electrical resistivity array to detect underground cavities
Amini, Amin; Ramazi, Hamidreza
2017-03-01
This paper is devoted to the application of the Combined Resistivity Sounding and Profiling electrode configuration (CRSP) to detect underground cavities. Electrical resistivity surveying is among the most favorite geophysical methods due to its nondestructive and economical properties in a wide range of geosciences. Several types of the electrode arrays are applied to detect different certain objectives. In one hand, the electrode array plays an important role in determination of output resolution and depth of investigations in all resistivity surveys. On the other hand, they have their own merits and demerits in terms of depth of investigations, signal strength, and sensitivity to resistivity variations. In this article several synthetic models, simulating different conditions of cavity occurrence, were used to examine the responses of some conventional electrode arrays and also CRSP array. The results showed that CRSP electrode configuration can detect the desired objectives with a higher resolution rather than some other types of arrays. Also a field case study was discussed in which electrical resistivity approach was conducted in Abshenasan expressway (Tehran, Iran) U-turn bridge site for detecting potential cavities and/or filling loose materials. The results led to detect an aqueduct tunnel passing beneath the study area.
Wang, Hui; Liu, Mian; Ye, Jiyang; Cao, Jianling; Jing, Yan
2017-11-01
Stepovers and bends along strike-slip faults are where push-up ranges and pull-apart basins are formed. They are also commonly where fault ruptures terminate. Field study and analogue models suggest that the configuration of faults plays a key role in crustal deformation around bends and stepovers, but the related mechanics of stress perturbation, strain partitioning, and fault evolution remains poorly understood. Here we present results of systematical mechanical models of stress changes and strain partitioning around simple stepovers and bends, using three-dimensional viscoelasto-plastic finite element code. Our model predicts elevated deviatoric stress around all stepovers and bends, with higher stresses around the restraining ones. Narrow stepovers localize strain between the fault gaps to form connecting faults, whereas wide stepovers localize strain on the tips of fault segments so the stepovers may evolve into subparallel faults. We explored how various configurations of stepovers and bends change the stress field and strain distribution, and show that these results can help explain some key differences between the pull-apart basins in the Dead Sea Trough and Death Valley, and the push-up ranges along the San Andreas Fault.
Refined analysis results for multimedia network costs and profits
DEFF Research Database (Denmark)
Tahkokorpi, M.; Falch, Morten; Skouby, Knud Erik
This deliverable describes the techno-economic business model developed in EURORIM WP3 and presents the refined results of the multimedia service delivery cost-profit calculations......This deliverable describes the techno-economic business model developed in EURORIM WP3 and presents the refined results of the multimedia service delivery cost-profit calculations...
Numerical Predictions and Experimental Results of Air Flow in a Smooth Quarter-Scale Nacelle
Energy Technology Data Exchange (ETDEWEB)
BLACK, AMALIA R.; SUO-ANTTILA, JILL M.; GRITZO, LOUIS A.; DISIMILE, PETER J.; TUCKER, JAMES R.
2002-06-01
Fires in aircraft engine nacelles must be rapidly suppressed to avoid loss of life and property. The design of new and retrofit suppression systems has become significantly more challenging due to the ban on production of Halon 1301 for environmental concerns. Since fire dynamics and the transport of suppressants within the nacelle are both largely determined by the available air flow, efforts to define systems using less effective suppressants greatly benefit from characterization of nacelle air flow fields. A combined experimental and computational study of nacelle air flow therefore has been initiated. Calculations have been performed using both CFD-ACE (a Computational Fluid Dynamics (CFD) model with a body-fitted coordinate grid) and WLCAN (a CFD-based fire field model with a Cartesian ''brick'' shaped grid). The flow conditions examined in this study correspond to the same Reynolds number as test data from the full-scale nacelle simulator at the 46 Test Wing. Pre-test simulations of a quarter-scale test fixture were performed using CFD-ACE and WLCAN prior to fabrication. Based on these pre-test simulations, a quarter-scale test fixture was designed and fabricated for the purpose of obtaining spatially-resolved measurements of velocity and turbulence intensity in a smooth nacelle. Post-test calculations have been performed for the conditions of the experiment and compared with experimental results obtained from the quarter-scale test fixture. In addition, several different simulations were performed to assess the sensitivity of the predictions to the grid size, to the turbulence models, and to the use of wall functions. In general, the velocity predictions show very good agreement with the data in the center of the channel but deviate near the walls. The turbulence intensity results tend to amplify the differences in velocity, although most of the trends are in agreement. In addition, there were some differences between WLCAN and CFD
Multi-Country Experience in Delivering a Joint Course on Software Engineering – Numerical Results
Directory of Open Access Journals (Sweden)
Zoran Budimac1, 1, 1, 2, 3, and 3
2014-02-01
Full Text Available A joint course, created as a result of a project under the auspices of the ‘Stability Pact of South-Eastern Europe’ and DAAD, has been conducted in several Balkan countries: in Novi Sad, Serbia, for the last six years in several different forms, in Skopje, FYR of Macedonia, for two years, for several types of students, and in Tirana, Albania, in the form of a crash, seven-day course, for the last two years. In this paper, we will put an emphasis on the assessment methods used within these courses, and compare them with the ‘original’ course that has been conducted at the Humboldt University in Berlin for almost a decade. Having a good environment for comparisons we draw some conclusions about teaching software engineering in different environments.
The Formation of Asteroid Satellites in Catastrophic Impacts: Results from Numerical Simulations
Durda, D. D.; Bottke, W. F., Jr.; Enke, B. L.; Asphaug, E.; Richardson, D. C.; Leinhardt, Z. M.
2003-01-01
We have performed new simulations of the formation of asteroid satellites by collisions, using a combination of hydrodynamical and gravitational dynamical codes. This initial work shows that both small satellites and ejected, co-orbiting pairs are produced most favorably by moderate-energy collisions at more direct, rather than oblique, impact angles. Simulations so far seem to be able to produce systems qualitatively similar to known binaries. Asteroid satellites provide vital clues that can help us understand the physics of hypervelocity impacts, the dominant geologic process affecting large main belt asteroids. Moreover, models of satellite formation may provide constraints on the internal structures of asteroids beyond those possible from observations of satellite orbital properties alone. It is probable that most observed main-belt asteroid satellites are by-products of cratering and/or catastrophic disruption events. Several possible formation mechanisms related to collisions have been identified: (i) mutual capture following catastrophic disruption, (ii) rotational fission due to glancing impact and spin-up, and (iii) re-accretion in orbit of ejecta from large, non-catastrophic impacts. Here we present results from a systematic investigation directed toward mapping out the parameter space of the first and third of these three collisional mechanisms.
Directory of Open Access Journals (Sweden)
Enzo Martinelli
2014-03-01
Full Text Available The use of mechanically-fastened fiber-reinforced polymer (MF-FRP systems has recently emerged as a competitive solution for the flexural strengthening of reinforced concrete (RC beams and slabs. An overview of the experimental research has proven the effectiveness and the potentiality of the MF-FRP technique which is particularly suitable for emergency repairs or when the speed of installation and immediacy of use are imperative. A finite-element (FE model has been recently developed by the authors with the aim to simulate the behavior of RC beams strengthened in bending by MF-FRP laminates; such a model has also been validated by using a wide experimental database collected from the literature. By following the previous study, the FE model and the assembled database are considered herein with the aim of better exploring the influence of some specific aspects on the structural response of MF-FRP strengthened members, such as the bearing stress-slip relationship assumed for the FRP-concrete interface, the stress-strain law considered for reinforcing steel rebars and the cracking process in RC members resulting in the well-known tension stiffening effect. The considerations drawn from this study will be useful to researchers for the calibration of criteria and design rules for strengthening RC beams through MF-FRP laminates.
Directory of Open Access Journals (Sweden)
Timothée Masquelier
Full Text Available In the brain, synchronization among cells of an assembly is a common phenomenon, and thought to be functionally relevant. Here we used an in vitro experimental model of cell assemblies, cortical cultures, combined with numerical simulations of a spiking neural network (SNN to investigate how and why spontaneous synchronization occurs. In order to deal with excitation only, we pharmacologically blocked GABAAergic transmission using bicuculline. Synchronous events in cortical cultures tend to involve almost every cell and to display relatively constant durations. We have thus named these "network spikes" (NS. The inter-NS-intervals (INSIs proved to be a more interesting phenomenon. In most cortical cultures NSs typically come in series or bursts ("bursts of NSs", BNS, with short (~1 s INSIs and separated by long silent intervals (tens of s, which leads to bimodal INSI distributions. This suggests that a facilitating mechanism is at work, presumably short-term synaptic facilitation, as well as two fatigue mechanisms: one with a short timescale, presumably short-term synaptic depression, and another one with a longer timescale, presumably cellular adaptation. We thus incorporated these three mechanisms into the SNN, which, indeed, produced realistic BNSs. Next, we systematically varied the recurrent excitation for various adaptation timescales. Strong excitability led to frequent, quasi-periodic BNSs (CV~0, and weak excitability led to rare BNSs, approaching a Poisson process (CV~1. Experimental cultures appear to operate within an intermediate weakly-synchronized regime (CV~0.5, with an adaptation timescale in the 2-8 s range, and well described by a Poisson-with-refractory-period model. Taken together, our results demonstrate that the INSI statistics are indeed informative: they allowed us to infer the mechanisms at work, and many parameters that we cannot access experimentally.
Pearson, A.; Pizzuto, J. E.
2015-12-01
Previous work at run-of-river (ROR) dams in northern Delaware has shown that bedload supplied to ROR impoundments can be transported over the dam when impoundments remain unfilled. Transport is facilitated by high levels of sand in the impoundment that lowers the critical shear stresses for particle entrainment, and an inversely sloping sediment ramp connecting the impoundment bed (where the water depth is typically equal to the dam height) with the top of the dam (Pearson and Pizzuto, in press). We demonstrate with one-dimensional bed material transport modeling that bed material can move through impoundments and that equilibrium transport (i.e., a balance between supply to and export from the impoundment, with a constant bed elevation) is possible even when the bed elevation is below the top of the dam. Based on our field work and previous HEC-RAS modeling, we assess bed material transport capacity at the base of the sediment ramp (and ignore detailed processes carrying sediment up and ramp and over the dam). The hydraulics at the base of the ramp are computed using a weir equation, providing estimates of water depth, velocity, and friction, based on the discharge and sediment grain size distribution of the impoundment. Bedload transport rates are computed using the Wilcock-Crowe equation, and changes in the impoundment's bed elevation are determined by sediment continuity. Our results indicate that impoundments pass the gravel supplied from upstream with deep pools when gravel supply rate is low, gravel grain sizes are relatively small, sand supply is high, and discharge is high. Conversely, impoundments will tend to fill their pools when gravel supply rate is high, gravel grain sizes are relatively large, sand supply is low, and discharge is low. The rate of bedload supplied to an impoundment is the primary control on how fast equilibrium transport is reached, with discharge having almost no influence on the timing of equilibrium.
Radhakrishnan, Sreeram
Harbor observation and prediction system (NYHOPS) which provides 48-hour forecasts of salinity and temperature profiles. Initial results indicate that the NYHOPS forecast of sound speed profiles used in conjunction with the acoustic propagation model is able to make realistic forecasts of TL in the Hudson River Estuary.
Report #11-P-0429, August 3, 2011. Vulnerability testing of EPA’s NHEERL Western Ecology Division network conducted in March 2011 identified Internet Protocol addresses with numerous high-risk and medium-risk vulnerabilities.
2014-05-01
distortion and drag, droplet interactions in terms of collision and coalescence , turbulent dispersion, and evaporation. The two phases are coupled...its surroundings promotes liquid atomization into fine droplets as a result of aerodynamic instabilities and surface tension forces. The continuation...of the process leads to further breakup, droplet - droplet interactions, droplet -wall interactions, and evaporation. If critical conditions are
The development of computer networks: First results from a microeconomic model
Maier, Gunther; Kaufmann, Alexander
Computer networks like the Internet are gaining importance in social and economic life. The accelerating pace of the adoption of network technologies for business purposes is a rather recent phenomenon. Many applications are still in the early, sometimes even experimental, phase. Nevertheless, it seems to be certain that networks will change the socioeconomic structures we know today. This is the background for our special interest in the development of networks, in the role of spatial factors influencing the formation of networks, and consequences of networks on spatial structures, and in the role of externalities. This paper discusses a simple economic model - based on a microeconomic calculus - that incorporates the main factors that generate the growth of computer networks. The paper provides analytic results about the generation of computer networks. The paper discusses (1) under what conditions economic factors will initiate the process of network formation, (2) the relationship between individual and social evaluation, and (3) the efficiency of a network that is generated based on economic mechanisms.
DEFF Research Database (Denmark)
Zhao, Fang; Médard, Muriel; Hundebøll, Martin
2012-01-01
CATWOMAN that can run on standard WiFi hardware. We present an analytical model to evaluate the performance of COPE in simple networks, and our results show the excellent predictive quality of this model. By closely examining the performance in two simple topologies, we observe that the coding gain results...
Evaluation of stress resultant of offshore jacket platform using neural network
Digital Repository Service at National Institute of Oceanography (India)
Mandal, S.; Hegde, G.; Gupta, K.G.
. This paper deals with the prediction of stress resultant deflections of fixed offshore platform to the varying environmental loading conditions using neural networks. The manual estimation of stress resultant to the varying loading conditions involves tedious...
A query result merging scheme for providing energy efficiency in underwater sensor networks.
Kim, Yunsung; Park, Soo-Hyun
2011-01-01
Underwater sensor networks are emerging as a promising distributed data management system for various applications in underwater environments, despite their limited accessibility and restricted energy capacity. With the aid of recent developments in ubiquitous data computing, an increasing number of users are expected to overcome low accessibility by applying queries to underwater sensor networks. However, when multiple users send queries to an underwater sensor network in a disorganized manner, it may incur lethal energy waste and problematic network traffic. The current query management mechanisms cannot effectively deal with this matter due to their limited applicability and unrealistic assumptions. In this paper, a novel query management scheme involving query result merging is proposed for underwater sensor networks. The mechanism is based on a relational database model and is adjusted to the practical restrictions affecting underwater communication environments. Network simulations will prove that the scheme becomes more efficient with a greater number of queries and a smaller period range.
Mapping the networks of cancer research in Portugal: first results
Energy Technology Data Exchange (ETDEWEB)
Bras, O.R.; Cointet, J.P.; Nunes, J.A.; David, L.; Cambrosio, A.
2016-07-01
Social studies of cancer research at the international level have contributed to a better understanding of the developmental dynamics – both organizational and epistemic – of this field (Keating & Cambrosio, 2012). In contrast, despite its robust development, oncology research in Portugal has been the subject of only few studies. Most of them have a strong focus on the first half of the 20th century (Raposo, 2004; Costa, 2010, 2012a; 2012b), while a few focus on more contemporary events (Nunes, 2001). Consequently, we do not have a clear picture of recent trends in oncology research in Portugal, and how it integrates into the international landscape. This hinders public accountability of oncology research while also limiting the analysis of how this research relates to health care delivery, health outcomes, and health policy formulations. This paper presents the first results of an ongoing research project on the organizational and epistemic development of oncology research in Portugal, covering the period from the end of the 20th century to 2015. Among other issues, we intend to explore the extent to which oncology research in Portugal mirrors the international dynamics at a smaller scale, and the extent to which it presents features of its own. The study draws upon computer-based analysis of publications using the platform CorText (http://www.cortext.net/) of IFRIS (Institut Francilien Recherche, Innovation, Société), along with interviews with Portuguese oncologists and related practitioners. (Author)
Expatriates ill after travel: Results from the Geosentinel Surveillance Network
Directory of Open Access Journals (Sweden)
Lim Poh-Lian
2012-12-01
Full Text Available Abstract Background Expatriates are a distinct population at unique risk for health problems related to their travel exposure. Methods We analyzed GeoSentinel data comparing ill returned expatriates with other travelers for demographics, travel characteristics, and proportionate morbidity (PM for travel-related illness. Results Our study included 2,883 expatriates and 11,910 non-expatriates who visited GeoSentinel clinics ill after travel. Expatriates were more likely to be male, do volunteer work, be long-stay travelers (>6 months, and have sought pre-travel advice. Compared to non-expatriates, expatriates returning from Africa had higher proportionate morbidity (PM for malaria, filariasis, schistosomiasis, and hepatitis E; expatriates from the Asia-Pacific region had higher PM for strongyloidiasis, depression, and anxiety; expatriates returning from Latin America had higher PM for mononucleosis and ingestion-related infections (giardiasis, brucellosis. Expatriates returning from all three regions had higher PM for latent TB, amebiasis, and gastrointestinal infections (other than acute diarrhea compared to non-expatriates. When the data were stratified by travel reason, business expatriates had higher PM for febrile systemic illness (malaria and dengue and vaccine-preventable infections (hepatitis A, and volunteer expatriates had higher PM for parasitic infections. Expatriates overall had higher adjusted odds ratios for latent TB and lower odds ratios for acute diarrhea and dermatologic illness. Conclusions Ill returned expatriates differ from other travelers in travel characteristics and proportionate morbidity for specific diseases, based on the region of exposure and travel reason. They are more likely to present with more serious illness.
Directory of Open Access Journals (Sweden)
Marco Panero
2006-11-01
Full Text Available We review some recent progress in quantum field theory in non-commutative space, focusing onto the fuzzy sphere as a non-perturbative regularisation scheme. We first introduce the basic formalism, and discuss the limits corresponding to different commutative or non-commutative spaces. We present some of the theories which have been investigated in this framework, with a particular attention to the scalar model. Then we comment on the results recently obtained from Monte Carlo simulations, and show a preview of new numerical data, which are consistent with the expected transition between two phases characterised by the topology of the support of a matrix eigenvalue distribution.
Bank, R.A.; Koppele, J.M. te
1999-01-01
Swelling of cartilage, one of the early signs of osteoarthritis (OA), is considered to be the result of a collagen network that has lost its integrity. So far, no quantitative data directly support this assertion: combined measurements of the state of the collagen network per se and the degree of
Schuetze, Oliver; Trujillo, Leonardo; Legrand, Pierrick; Maldonado, Yazmin
2016-01-01
International audience; This volume comprises a selection of works presented at the Numerical and Evolutionary Optimization (NEO) workshop held in September 2015 in Tijuana, Mexico. The development of powerful search and optimization techniques is of great importance in today’s world that requires researchers and practitioners to tackle a growing number of challenging real-world problems. In particular, there are two well-established and widely known fields that are commonly applied in this a...
Becus, Georges A.; Chan, Alistair K.
1993-01-01
Three neural network processing approaches in a direct numerical optimization model reduction scheme are proposed and investigated. Large structural systems, such as large space structures, offer new challenges to both structural dynamicists and control engineers. One such challenge is that of dimensionality. Indeed these distributed parameter systems can be modeled either by infinite dimensional mathematical models (typically partial differential equations) or by high dimensional discrete models (typically finite element models) often exhibiting thousands of vibrational modes usually closely spaced and with little, if any, damping. Clearly, some form of model reduction is in order, especially for the control engineer who can actively control but a few of the modes using system identification based on a limited number of sensors. Inasmuch as the amount of 'control spillover' (in which the control inputs excite the neglected dynamics) and/or 'observation spillover' (where neglected dynamics affect system identification) is to a large extent determined by the choice of particular reduced model (RM), the way in which this model reduction is carried out is often critical.
Shibata, Masaru
2016-01-01
This book is composed of two parts: First part describes basics in numerical relativity, that is, the formulations and methods for a solution of Einstein's equation and general relativistic matter field equations. This part will be helpful for beginners of numerical relativity who would like to understand the content of numerical relativity and its background. The second part focuses on the application of numerical relativity. A wide variety of scientific numerical results are introduced focusing in particular on the merger of binary neutron stars and black holes.
Bottari, C.; Albano, M.; Capizzi, P.; D'Alessandro, A.; Doumaz, F.; Martorana, R.; Moro, M.; Saroli, M.
2018-01-01
Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to the acquisition of deep geological data for the reconstruction of slope process and the thickness of mobilized materials. The applied geophysical techniques included seismic refraction tomography and electrical resistivity tomography. The surveys were performed to delineate the sliding surface and to assess approximately the thickness of mobilized materials. The geophysical and geomorphologic data confirmed the presence of different overlapped landslides in the studied area. Moreover, a numerical simulation of the slope under seismic loads supports the hypothesis of a mobilization of the landslide mass in case of strong earthquakes (PGA > 0.3 g). However, numerical results highlight that the main cause of destruction for the Abakainon necropolis is the amplification of the seismic waves, occasionally accompanied by surficial sliding.
Bottari, C.; Albano, M.; Capizzi, P.; D'Alessandro, A.; Doumaz, F.; Martorana, R.; Moro, M.; Saroli, M.
2017-08-01
Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to the acquisition of deep geological data for the reconstruction of slope process and the thickness of mobilized materials. The applied geophysical techniques included seismic refraction tomography and electrical resistivity tomography. The surveys were performed to delineate the sliding surface and to assess approximately the thickness of mobilized materials. The geophysical and geomorphologic data confirmed the presence of different overlapped landslides in the studied area. Moreover, a numerical simulation of the slope under seismic loads supports the hypothesis of a mobilization of the landslide mass in case of strong earthquakes (PGA > 0.3 g). However, numerical results highlight that the main cause of destruction for the Abakainon necropolis is the amplification of the seismic waves, occasionally accompanied by surficial sliding.
Liu, Wenjia; Schmittmann, Beate; Zia, R. K. P.
2012-02-01
Network studies have played a central role for understanding many systems in nature - e.g., physical, biological, and social. So far, much of the focus has been the statistics of networks in isolation. Yet, many networks in the world are coupled to each other. Recently, we considered this issue, in the context of two interacting social networks. In particular, We studied networks with two different preferred degrees, modeling, say, introverts vs. extroverts, with a variety of ``rules for engagement.'' As a first step towards an analytically accessible theory, we restrict our attention to an ``extreme scenario'': The introverts prefer zero contacts while the extroverts like to befriend everyone in the society. In this ``maximally frustrated'' system, the degree distributions, as well as the statistics of cross-links (between the two groups), can depend sensitively on how a node (individual) creates/breaks its connections. The simulation results can be reasonably well understood in terms of an approximate theory.
Gumley, L.
2013-12-01
The Space Science and Engineering Center at the University of Wisconsin-Madison is creating a network of direct broadcast satellite data reception stations to acquire and process infrared and microwave sounder data in real-time from polar orbiting meteorological satellites and deliver the resulting products to NOAA with low latency for assimilation in NCEP numerical weather prediction models. The network will include 4 antenna sites that will be operated directly by SSEC, including Madison WI, Honolulu HI, Miami FL, and Mayaguez PR. The network will also include partner antenna sites not directly controlled by SSEC, including Corvallis OR, Monterey CA, Suitland MD, Fairbanks AK, and Guam. All of the antenna sites will have a combined X/L-band reception system capable of receiving data via direct broadcast from polar orbiting satellites including Suomi NPP and JPSS-1, Metop-A/B, POES,Terra, and Aqua. Each site will collect raw data from these satellites locally, process it to Level 1 (SDR) and Level 2 (EDR) products, and transmit the products back to SSEC for delivery to NOAA/NCEP. The primary purpose of the antenna systems is to provide real-time infrared and microwave sounder data from Metop and Suomi-NPP to NOAA to support data assimilation for NOAA/NCEP operational numerical weather prediction models. At present, NOAA/NCEP use of advanced infrared (CrIS, IASI, AIRS) and microwave (ATMS, AMSU) sounder data over North America in NWP data assimilation is limited because of the latency of the products in relation to the cutoff times for assimilation runs. This network will deliver infrared and microwave sounder data to NCEP with the lowest latency possible, via the reception and processing of data received via direct broadcast. CIMSS/SSEC is managing the procurement and installation of the antenna systems at the two new sites, and will operate the stations remotely. NOAA will establish the reception priorities (Metop and SNPP will be at the highest priority) and
Energy Technology Data Exchange (ETDEWEB)
Ammoser, H. [Technische Univ. Dresden (Germany). Inst. fuer Wirtschaft und Verkehr; Kuehnert, C. [Technische Univ. Dresden (Germany). Inst. fuer Wirtschaft und Verkehr; Imperial College, London (United Kingdom); Buzna, L. [Zilina Univ. (Slovakia). Dept. of Transportation Networks
2006-07-01
In the context of a DFG research project, scientists of Prof. Helbing's chair at the Institute of Transport and Economics deal with the dynamics of disasters, being experienced in the modelling of complex systems and in the simulation of emergency scenarios. The analyses of systems and their behaviour in extraordinary events are based on the latest results of network sciences and on numerous empirical investigations. The results shall be used for precaution measures and innovations in disaster recovery. (orig.)
Head teacher professional networks in Italy: preliminary results of a national survey
Directory of Open Access Journals (Sweden)
Maurissens Isabel de
2016-06-01
Full Text Available In this article, we present the preliminary results of a national survey conducted by INDIRE on head teachers communities and professional networks. About one-fourth of the total population of Italian public school leaders participated in the survey. One of the main intents of this research is to contribute to understanding of the phenomenon of professional networks frequented by school leaders and to pave the way for a further reflection on how to use such networks for head teachers’ training so as to support their daily professional practice conducted too often in isolation.
Narayanareddy, V. V.; Chandrasekhar, N.; Vasudevan, M.; Muthukumaran, S.; Vasantharaja, P.
2016-02-01
In the present study, artificial neural network modeling has been employed for predicting welding-induced angular distortions in autogenous butt-welded 304L stainless steel plates. The input data for the neural network have been obtained from a series of three-dimensional finite element simulations of TIG welding for a wide range of plate dimensions. Thermo-elasto-plastic analysis was carried out for 304L stainless steel plates during autogenous TIG welding employing double ellipsoidal heat source. The simulated thermal cycles were validated by measuring thermal cycles using thermocouples at predetermined positions, and the simulated distortion values were validated by measuring distortion using vertical height gauge for three cases. There was a good agreement between the model predictions and the measured values. Then, a multilayer feed-forward back propagation neural network has been developed using the numerically simulated data. Artificial neural network model developed in the present study predicted the angular distortion accurately.
Directory of Open Access Journals (Sweden)
Hamid Teimouri
2015-09-01
Full Text Available Artificial Neural Networks (ANNs are used as a new approach in determination of Nusselt number of copper water nanofluid in an inclined channel with three heat sources. For training the ANNs, the simulation results are obtained by Finite Volume Method (FVM. The effects of independent parameters, including the Reynolds number, Rayleigh number, inclination angle, and the solid volume fraction of nanoparticles, on the streamlines, isotherm lines, and the average Nusselt number have been studied. Artificial neural networks (ANN used to find a relation involve independent parameters for estimating the Nusselt number. The back propagation-learning algorithm with the tangent sigmoid transfer function is used to sequence the ANN. Finally, analytical relations for the nanofluid mixed convection in a channel are derived from the available ANN. It is shown that the coefficient of multiple determination (R 2 between the FVM and ANN predicted values is equal to 0.99866, maximum relative error is less than 5.9128% and mean square error is 1.13×10 -3 . Results show that the obtained formulation is obviously within acceptable limits.
Blakeslee, Rich; Bailey, Jeff; Koshak, Bill
1999-01-01
A four station Advanced Lightning Direction Finder (ALDF) network was recently established in the state of Rondonia in western Brazil through a collaboration of U.S. and Brazilian participants from NASA, INPE, INMET, and various universities. The network utilizes ALDF IMPACT (Improved Accuracy from Combined Technology) sensors to provide cloud-to-ground lightning observations (i.e., stroke/flash locations, signal amplitude, and polarity) using both time-of-arrival and magnetic direction finding techniques. The observations are collected, processed and archived at a central site in Brasilia and at the NASA/ Marshall Space Flight Center (MSFC) in Huntsville, Alabama. Initial, non-quality assured quick-look results are made available in near real-time over the internet. The network will remain deployed for several years to provide ground truth data for the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite which was launched in November 1997. The measurements will also be used to investigate the relationship between the electrical, microphysical and kinematic properties of tropical convection. In addition, the long-term observations from this network will contribute in establishing a regional lightning climatological data base, supplementing other data bases in Brazil that already exist or may soon be implemented. Analytic inversion algorithms developed at NASA/Marshall Space Flight Center (MSFC) are now being applied to the Rondonian ALDF lightning observations to obtain site error corrections and improved location retrievals. The processing methodology and the initial results from an analysis of the first 6 months of network operations will be presented.
Directory of Open Access Journals (Sweden)
2015-12-01
Full Text Available Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.
Energy Technology Data Exchange (ETDEWEB)
Hand, J W; Li, Y; Hajnal, J V [Imaging Sciences Department, Imperial College London (Hammersmith Campus), London W12 0NN (United Kingdom)], E-mail: j.hand@imperial.ac.uk
2010-02-21
Numerical simulations of specific absorption rate (SAR) and temperature changes in a 26-week pregnant woman model within typical birdcage body coils as used in 1.5 T and 3 T MRI scanners are described. Spatial distributions of SAR and the resulting spatial and temporal changes in temperature are determined using a finite difference time domain method and a finite difference bio-heat transfer solver that accounts for discrete vessels. Heat transfer from foetus to placenta via the umbilical vein and arteries as well as that across the foetal skin/amniotic fluid/uterine wall boundaries is modelled. Results suggest that for procedures compliant with IEC normal mode conditions (maternal whole-body averaged SAR{sub MWB} {<=} 2 W kg{sup -1} (continuous or time-averaged over 6 min)), whole foetal SAR, local foetal SAR{sub 10g} and average foetal temperature are within international safety limits. For continuous RF exposure at SAR{sub MWB} = 2 W kg{sup -1} over periods of 7.5 min or longer, a maximum local foetal temperature >38 deg. C may occur. However, assessment of the risk posed by such maximum temperatures predicted in a static model is difficult because of frequent foetal movement. Results also confirm that when SAR{sub MWB} = 2 W kg{sup -1}, some local SAR{sub 10g} values in the mother's trunk and extremities exceed recommended limits.
Moreno-Tapia, Sandra Veronica; Vera-Salas, Luis Alberto; Osornio-Rios, Roque Alfredo; Dominguez-Gonzalez, Aurelio; Stiharu, Ion; Romero-Troncoso, Rene de Jesus
2010-01-01
Computer numerically controlled (CNC) machines have evolved to adapt to increasing technological and industrial requirements. To cover these needs, new generation machines have to perform monitoring strategies by incorporating multiple sensors. Since in most of applications the online Processing of the variables is essential, the use of smart sensors is necessary. The contribution of this work is the development of a wireless network platform of reconfigurable smart sensors for CNC machine applications complying with the measurement requirements of new generation CNC machines. Four different smart sensors are put under test in the network and their corresponding signal processing techniques are implemented in a Field Programmable Gate Array (FPGA)-based sensor node.
A network-based approach to prioritize results from genome-wide association studies.
Directory of Open Access Journals (Sweden)
Nirmala Akula
Full Text Available Genome-wide association studies (GWAS are a valuable approach to understanding the genetic basis of complex traits. One of the challenges of GWAS is the translation of genetic association results into biological hypotheses suitable for further investigation in the laboratory. To address this challenge, we introduce Network Interface Miner for Multigenic Interactions (NIMMI, a network-based method that combines GWAS data with human protein-protein interaction data (PPI. NIMMI builds biological networks weighted by connectivity, which is estimated by use of a modification of the Google PageRank algorithm. These weights are then combined with genetic association p-values derived from GWAS, producing what we call 'trait prioritized sub-networks.' As a proof of principle, NIMMI was tested on three GWAS datasets previously analyzed for height, a classical polygenic trait. Despite differences in sample size and ancestry, NIMMI captured 95% of the known height associated genes within the top 20% of ranked sub-networks, far better than what could be achieved by a single-locus approach. The top 2% of NIMMI height-prioritized sub-networks were significantly enriched for genes involved in transcription, signal transduction, transport, and gene expression, as well as nucleic acid, phosphate, protein, and zinc metabolism. All of these sub-networks were ranked near the top across all three height GWAS datasets we tested. We also tested NIMMI on a categorical phenotype, Crohn's disease. NIMMI prioritized sub-networks involved in B- and T-cell receptor, chemokine, interleukin, and other pathways consistent with the known autoimmune nature of Crohn's disease. NIMMI is a simple, user-friendly, open-source software tool that efficiently combines genetic association data with biological networks, translating GWAS findings into biological hypotheses.
A Network-Based Approach to Prioritize Results from Genome-Wide Association Studies
Akula, Nirmala; Baranova, Ancha; Seto, Donald; Solka, Jeffrey; Nalls, Michael A.; Singleton, Andrew; Ferrucci, Luigi; Tanaka, Toshiko; Bandinelli, Stefania; Cho, Yoon Shin; Kim, Young Jin; Lee, Jong-Young; Han, Bok-Ghee; McMahon, Francis J.
2011-01-01
Genome-wide association studies (GWAS) are a valuable approach to understanding the genetic basis of complex traits. One of the challenges of GWAS is the translation of genetic association results into biological hypotheses suitable for further investigation in the laboratory. To address this challenge, we introduce Network Interface Miner for Multigenic Interactions (NIMMI), a network-based method that combines GWAS data with human protein-protein interaction data (PPI). NIMMI builds biological networks weighted by connectivity, which is estimated by use of a modification of the Google PageRank algorithm. These weights are then combined with genetic association p-values derived from GWAS, producing what we call ‘trait prioritized sub-networks.’ As a proof of principle, NIMMI was tested on three GWAS datasets previously analyzed for height, a classical polygenic trait. Despite differences in sample size and ancestry, NIMMI captured 95% of the known height associated genes within the top 20% of ranked sub-networks, far better than what could be achieved by a single-locus approach. The top 2% of NIMMI height-prioritized sub-networks were significantly enriched for genes involved in transcription, signal transduction, transport, and gene expression, as well as nucleic acid, phosphate, protein, and zinc metabolism. All of these sub-networks were ranked near the top across all three height GWAS datasets we tested. We also tested NIMMI on a categorical phenotype, Crohn’s disease. NIMMI prioritized sub-networks involved in B- and T-cell receptor, chemokine, interleukin, and other pathways consistent with the known autoimmune nature of Crohn’s disease. NIMMI is a simple, user-friendly, open-source software tool that efficiently combines genetic association data with biological networks, translating GWAS findings into biological hypotheses. PMID:21915301
Energy Technology Data Exchange (ETDEWEB)
Hartwell, William T.; Daniels, Jeffrey; Nikolich, George; Shadel, Craig; Giles, Ken; Karr, Lynn; Kluesner, Tammy
2012-01-01
During the period April to June 2008, at the behest of the Department of Energy (DOE), National Nuclear Security Administration, Nevada Site Office (NNSA/NSO); the Desert Research Institute (DRI) constructed and deployed two portable environmental monitoring stations at the Tonopah Test Range (TTR) as part of the Environmental Restoration Project Soils Activity. DRI has operated these stations since that time. A third station was deployed in the period May to September 2011. The TTR is located within the northwest corner of the Nevada Test and Training Range (NTTR), and covers an area of approximately 725.20 km2 (280 mi2). The primary objective of the monitoring stations is to evaluate whether and under what conditions there is wind transport of radiological contaminants from Soils Corrective Action Units (CAUs) associated with Operation Roller Coaster on TTR. Operation Roller Coaster was a series of tests, conducted in 1963, designed to examine the stability and dispersal of plutonium in storage and transportation accidents. These tests did not result in any nuclear explosive yield. However, the tests did result in the dispersal of plutonium and contamination of surface soils in the surrounding area.
Faciobrachial dystonic seizures result from fronto-temporo-basalganglial network involvement.
Iyer, Rajesh Shankar; Ramakrishnan, T C R; Karunakaran; Shinto, Ajit; Kamaleshwaran, Koramadai Karuppuswamy
2017-01-01
•Faciobrachial dystonic seizures (FBDS) are caused by autoantibodies to leucine-rich glioma-inactivated1 proteins, a component of the voltage-gated potassium channel complex (VGKC-complex) and precede the clinical presentation of limbic encephalitis.•The exact pathophysiology of FBDS is not known and whether they are seizures or movement disorder is still debated.•We suggest the fronto-temporo-basal ganglia network involving the medial frontal and temporal regions along with the corpus striatum and substantia nigra being responsible for the clinical phenomenon of FBDS.•The varied clinical, electrical and imaging features of FBDS in our cases and in the literature are best explained by involvement of this network.•Entrainment from any part of this network will result in similar clinical expression of FBDS, whereas other electro-clinical associations and duration depends on the extent of involvement of the network.
Directory of Open Access Journals (Sweden)
S. Trzaska
1996-10-01
Full Text Available This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder than the long-term mean in the southern hemisphere (northern hemisphere]. Atlantic SSTAs may also play a significant role.
Randolph, J. B.; Saar, M. O.
2009-12-01
Carbon dioxide (CO2) sequestration in deep saline aquifers and exhausted oil fields has been widely considered as a means for reducing CO2 emissions to the atmosphere as a counter-measure to global warming. However, rather than treating CO2 as a waste fluid in need of permanent disposal, it could additionally be used as a working fluid in geothermal energy capture as its thermodynamic properties suggest it transfers heat more efficiently than water. Therefore, utilizing CO2 may permit more widespread implementation of geothermal power systems. Here, we present numerical modeling results of coupled CO2 injection into a brine and heat transfer in geothermal reservoirs under conditions relevant for both CO2 sequestration and geothermal electricity generation. In particular, we examine subsurface flow and heating of the sequestered CO2, cooling of the geothermal reservoir, and changes in pore-fluid pressures under a variety of generalized CO2 injection and production scenarios and reservoir characteristics. While additional research is required, modeling results at present suggest that geologic reservoirs with CO2 as the heat mining fluid would be viable geothermal energy sources for electric power production for decades, potentially even in regions with relatively low geothermal temperatures and heat flow rates.
Directory of Open Access Journals (Sweden)
Junya Lv
2017-01-01
Full Text Available The application of accurate constitutive relationship in finite element simulation would significantly contribute to accurate simulation results, which play critical roles in process design and optimization. In this investigation, the true stress-strain data of an Inconel 718 superalloy were obtained from a series of isothermal compression tests conducted in a wide temperature range of 1153–1353 K and strain rate range of 0.01–10 s−1 on a Gleeble 3500 testing machine (DSI, St. Paul, DE, USA. Then the constitutive relationship was modeled by an optimally-constructed and well-trained back-propagation artificial neural network (ANN. The evaluation of the ANN model revealed that it has admirable performance in characterizing and predicting the flow behaviors of Inconel 718 superalloy. Consequently, the developed ANN model was used to predict abundant stress-strain data beyond the limited experimental conditions and construct the continuous mapping relationship for temperature, strain rate, strain and stress. Finally, the constructed ANN was implanted in a finite element solver though the interface of “URPFLO” subroutine to simulate the isothermal compression tests. The results show that the integration of finite element method with ANN model can significantly promote the accuracy improvement of numerical simulations for hot forming processes.
Directory of Open Access Journals (Sweden)
Z. Xu
2018-01-01
Full Text Available Long-distance seawater intrusion has been widely observed through the subsurface conduit system in coastal karst aquifers as a source of groundwater contaminant. In this study, seawater intrusion in a dual-permeability karst aquifer with conduit networks is studied by the two-dimensional density-dependent flow and transport SEAWAT model. Local and global sensitivity analyses are used to evaluate the impacts of boundary conditions and hydrological characteristics on modeling seawater intrusion in a karst aquifer, including hydraulic conductivity, effective porosity, specific storage, and dispersivity of the conduit network and of the porous medium. The local sensitivity analysis evaluates the parameters' sensitivities for modeling seawater intrusion, specifically in the Woodville Karst Plain (WKP. A more comprehensive interpretation of parameter sensitivities, including the nonlinear relationship between simulations and parameters, and/or parameter interactions, is addressed in the global sensitivity analysis. The conduit parameters and boundary conditions are important to the simulations in the porous medium because of the dynamical exchanges between the two systems. The sensitivity study indicates that salinity and head simulations in the karst features, such as the conduit system and submarine springs, are critical for understanding seawater intrusion in a coastal karst aquifer. The evaluation of hydraulic conductivity sensitivity in the continuum SEAWAT model may be biased since the conduit flow velocity is not accurately calculated by Darcy's equation as a function of head difference and hydraulic conductivity. In addition, dispersivity is no longer an important parameter in an advection-dominated karst aquifer with a conduit system, compared to the sensitivity results in a porous medium aquifer. In the end, the extents of seawater intrusion are quantitatively evaluated and measured under different scenarios with the variabilities of
Xu, Zexuan; Hu, Bill X.; Ye, Ming
2018-01-01
Long-distance seawater intrusion has been widely observed through the subsurface conduit system in coastal karst aquifers as a source of groundwater contaminant. In this study, seawater intrusion in a dual-permeability karst aquifer with conduit networks is studied by the two-dimensional density-dependent flow and transport SEAWAT model. Local and global sensitivity analyses are used to evaluate the impacts of boundary conditions and hydrological characteristics on modeling seawater intrusion in a karst aquifer, including hydraulic conductivity, effective porosity, specific storage, and dispersivity of the conduit network and of the porous medium. The local sensitivity analysis evaluates the parameters' sensitivities for modeling seawater intrusion, specifically in the Woodville Karst Plain (WKP). A more comprehensive interpretation of parameter sensitivities, including the nonlinear relationship between simulations and parameters, and/or parameter interactions, is addressed in the global sensitivity analysis. The conduit parameters and boundary conditions are important to the simulations in the porous medium because of the dynamical exchanges between the two systems. The sensitivity study indicates that salinity and head simulations in the karst features, such as the conduit system and submarine springs, are critical for understanding seawater intrusion in a coastal karst aquifer. The evaluation of hydraulic conductivity sensitivity in the continuum SEAWAT model may be biased since the conduit flow velocity is not accurately calculated by Darcy's equation as a function of head difference and hydraulic conductivity. In addition, dispersivity is no longer an important parameter in an advection-dominated karst aquifer with a conduit system, compared to the sensitivity results in a porous medium aquifer. In the end, the extents of seawater intrusion are quantitatively evaluated and measured under different scenarios with the variabilities of important parameters
Search Result Caching in Peer-to-Peer Information Retrieval Networks
Tigelaar, A.S.; Hiemstra, Djoerd; Trieschnigg, Rudolf Berend
2011-01-01
For peer-to-peer web search engines it is important to quickly process queries and return search results. How to keep the perceived latency low is an open challenge. In this paper we explore the solution potential of search result caching in large-scale peer-to-peer information retrieval networks by
Directory of Open Access Journals (Sweden)
Viswanathan Arunachalam
2013-01-01
Full Text Available The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008 in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.
Zeebe, Richard E.
2017-11-01
I report results from accurate numerical integrations of solar system orbits over the past 100 Myr with the integrator package HNBody. The simulations used different integrator algorithms, step sizes, and initial conditions, and included effects from general relativity, different models of the Moon, the Sun’s quadrupole moment, and up to 16 asteroids. I also probed the potential effect of a hypothetical Planet 9, using one set of possible orbital elements. The most expensive integration (Bulirsch-Stoer) required 4 months of wall-clock time with a maximum relative energy error ≲ 3× {10}-13. The difference in Earth’s eccentricity ({{Δ }}{e}{ E }) was used to track the difference between two solutions, considered to diverge at time τ when max | {{Δ }}{e}{ E }| irreversibly crossed ˜10% of mean {e}{ E } ({{˜ }}0.028× 0.1). The results indicate that finding a unique orbital solution is limited by initial conditions from current ephemerides and asteroid perturbations to ˜54 Myr. Bizarrely, the 4-month Bulirsch-Stoer integration and a symplectic integration that required only 5 hr of wall-clock time (12-day time step, with the Moon as a simple quadrupole perturbation), agree to ˜63 Myr. Internally, such symplectic integrations are remarkably consistent even for large time steps, suggesting that the relationship between time step and τ is not a robust indicator of the absolute accuracy of symplectic integrations. The effect of a hypothetical Planet 9 on {{Δ }}{e}{ E } becomes discernible at ˜65 Myr. Using τ as a criterion, the current state-of-the-art solutions all differ from previously published results beyond ˜50 Myr. I also conducted an eigenmode analysis, which provides some insight into the chaotic nature of the inner solar system. The current study provides new orbital solutions for applications in geological studies. .
Blast-cooling of beef-in-sauce catering meals: numerical results based on a dynamic zero-order model
Directory of Open Access Journals (Sweden)
Jose A. Rabi
2014-10-01
Full Text Available Beef-in-sauce catering meals under blast-cooling have been investigated in a research project which aims at quantitative HACCP (hazard analysis critical control point. In view of its prospective coupling to a predictive microbiology model proposed in the project, zero-order spatial dependence has proved to suitably predict meal temperatures in response to temperature variations in the cooling air. This approach has modelled heat transfer rates via the a priori unknown convective coefficient hc which is allowed to vary due to uncertainty and variability in the actual modus operandi of the chosen case study hospital kitchen. Implemented in MS Excel®, the numerical procedure has successfully combined the 4th order Runge-Kutta method, to solve the governing equation, with non-linear optimization, via the built-in Solver, to determine the coefficient hc. In this work, the coefficient hc was assessed for 119 distinct recently-cooked meal samples whose temperature-time profiles were recorded in situ after 17 technical visits to the hospital kitchen over a year. The average value and standard deviation results were hc = 12.0 ± 4.1 W m-2 K-1, whilst the lowest values (associated with the worst cooling scenarios were about hc » 6.0 W m-2 K-1.
Lepage, J; Jayyosi, C; Lecomte-Grosbras, P; Brieu, M; Duriez, C; Cosson, M; Rubod, C
2015-04-01
We created a pregnant woman pelvic model to perform a simulation of delivery to understand the pathophysiology of urogenital prolapse by studying the constraints on the pelvic components (muscles, ligaments, pelvic organs) during childbirth. These simulations will also provide valuable tools to understand and teach obstetrical mechanics. We built a numerical model of the pelvic system from a term pregnant woman, using the finite element method on a mesh built from magnetic resonance images of a nulliparous pregnant woman. Mechanical properties of pelvic tissues already determined by the team were adapted to account for pregnancy. The system allows delivery to be simulated. When a fetal head at the 50th percentile for the term goes through the pelvic system, uterosacral ligaments undergo a deformation of around 30 %. Uterosacral ligaments are the major pelvic sustaining structures, their lesion may be a potential cause of urogenital prolapse. We built a model of childbirth as a function of pregnancy term by varying volumes of fetal head and uterus. The impact on uterosacral ligaments is higher when the fetal head is larger. Our modelling is rather complete considering that it involves many organs including ligaments. It allows us to analyse the effect of childbirth on uterosacral ligaments and to understand how they impact on pelvic statics. First results are promising, but optimisation and future simulations will be needed. We also plan to simulate various delivery scenarios (cephalic, breech presentation, instrumental extraction), which will be useful to study perineal lesions and also to teach obstetrical mechanics.
Bersuker, Isaac B.; Balabanov, Nikolai B.; Pekker, David; Boggs, James E.
2002-12-01
The pseudo Jahn-Teller (PJT) effect as the only source of instability of molecular high-symmetry configurations in nondegenerate states is given a deeper insight by means of a novel method of ab initio evaluation of the vibronic Kv and nonvibronic K0 contributions to the curvature K=K0+Kv of the adiabatic potential energy surface in the direction of distortion. The method overcomes two essential difficulties: (1) the low accuracy in calculation of K0 because of the singularities at the nuclei where existing basis sets yield inadequate results, and (2) the lack of sufficiently accurate data on excited states (including the continuum spectrum) for calculation of Kv. This is achieved by summing up the contributions of the excited states to result in expressions with only the ground state wave function and its derivatives, and excluding the singularities by canceling mutually compensating diagonal matrix elements in K0 and Kv. After these essential changes K=K0+Kv is no longer a small difference between two large numbers, and it can be calculated with reasonable accuracy, while the separation of Kv allows one to reveal the PJT origin of the instability: the direction of distortion for which the negative Kv value overcomes the positive K0 one. A further insight into the origin of the instability is reached by estimating the relative contribution of the most active excited states for different distortions (and for the same distortions in similar compounds), since the contribution of the continuum states (the largest part of Kv) does not affect the bonding and hence the differences in Kv. Illustrative numerical calculations were carried out on several series of molecular systems: planar AH4, A=B-, C, N+, O2+, Si, planar BH3, CH3-, NH3, octahedral MH6, M=Sc3-, Ti2-, V-, Cr, Mn+, and octahedral TeF62-, IF6-, and XeF6.
Trzaska, S.; Moron, V.; Fontaine, B.
1996-10-01
This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST) patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP) climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder) than the long-term mean in the southern hemisphere (northern hemisphere)]. Atlantic SSTAs may also play a significant role. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->
Directory of Open Access Journals (Sweden)
Vladimir M. Krasnopolsky
2013-01-01
Full Text Available A novel approach based on the neural network (NN ensemble technique is formulated and used for development of a NN stochastic convection parameterization for climate and numerical weather prediction (NWP models. This fast parameterization is built based on learning from data simulated by a cloud-resolving model (CRM initialized with and forced by the observed meteorological data available for 4-month boreal winter from November 1992 to February 1993. CRM-simulated data were averaged and processed to implicitly define a stochastic convection parameterization. This parameterization is learned from the data using an ensemble of NNs. The NN ensemble members are trained and tested. The inherent uncertainty of the stochastic convection parameterization derived following this approach is estimated. The newly developed NN convection parameterization has been tested in National Center of Atmospheric Research (NCAR Community Atmospheric Model (CAM. It produced reasonable and promising decadal climate simulations for a large tropical Pacific region. The extent of the adaptive ability of the developed NN parameterization to the changes in the model environment is briefly discussed. This paper is devoted to a proof of concept and discusses methodology, initial results, and the major challenges of using the NN technique for developing convection parameterizations for climate and NWP models.
SPIEGEL, B.; BOLUS, R.; HARRIS, L. A.; LUCAK, S.; NALIBOFF, B.; ESRAILIAN, E.; CHEY, W. D.; LEMBO, A.; KARSAN, H.; TILLISCH, K.; TALLEY, J.; MAYER, E.; CHANG, L.
2009-01-01
Background Controversy exists about how to effectively measure patient reported outcomes in IBS clinical trials. Pain numeric rating scales (NRS) are widely used in the non-IBS pain literature. The FDA has proposed using the NRS in IBS. Aim To test the psychometrics of an abdominal pain NRS in IBS. Methods We analyzed data from a longitudinal cohort of Rome III IBS subjects. At entry, subjects completed a 10-point NRS, bowel symptoms, IBS severity measurements (IBSSS, FBDSI), health related quality of life indices (IBS-QOL, EQ5D), and the worker productivity activity index (WPAI). We repeated assessments at 3 months along with a response scale to calculate the minimal clinically important difference (MCID). Results There were 277 subjects (82% women; age=42±15) at baseline and 90 at 3 months. The NRS correlated cross-sectionally with IBSSS (r=0.60; p<0.0011), FBDSI (r=0.49; p<0.0001), IBS-QOL (r=0.43; p<0.0001), EQ5D (r=0.48; p<0.0001), presenteeism (r=0.39; p<0.0001), absenteeism (r=0.17; p=0.04), and distension (r=0.46; p<0.0001), but not stool frequency or form. The MCID was 2.2 points, correlating with a 29.5% reduction over time. Conclusions An abdominal pain NRS exhibits excellent validity and can be readily interpreted with an MCID in patients with IBS. These data support the use of the NRS in IBS clinical trials. PMID:19751360
Yin, Xiaohong; Huang, Zhijiong; Zheng, Junyu; Yuan, Zibing; Zhu, Wenbo; Huang, Xiaobo; Chen, Duohong
2017-04-01
As one of the most populous and developed provinces in China, Guangdong province (GD) has been experiencing regional haze problems. Identification of source contributions to ambient PM2.5 level is essential for developing effective control strategies. In this study, using the most up-to-date emission inventory and validated numerical model, source contributions to ambient PM2.5 from eight emission source sectors (agriculture, biogenic, dust, industry, power plant, residential, mobile and others) in GD in 2012 were quantified. Results showed that mobile sources are the dominant contributors to the ambient PM2.5 (24.0%) in the Pearl River Delta (PRD) region, the central and most developed area of GD, while industry sources are the major contributors (21.5% 23.6%) to those in the Northeastern GD (NE-GD) region and the Southwestern GD (SW-GD) region. Although many industries have been encouraged to move from the central GD to peripheral areas such as NE-GD and SW-GD, their emissions still have an important impact on the PM2.5 level in the PRD. In addition, agriculture sources are responsible for 17.5% to ambient PM2.5 in GD, indicating the importance of regulations on agricultural activities, which has been largely ignored in the current air quality management. Super-regional contributions were also quantified and their contributions to the ambient PM2.5 in GD are significant with notable seasonal differences. But they might be overestimated and further studies are needed to better quantify the transport impacts.
Results from the industrial network 2003[Norway]; Resultater fra industrinettverket 2003
Energy Technology Data Exchange (ETDEWEB)
NONE
2004-07-01
The report presents a survey of various activities within the industrial network with emphasis on energy consumption and conservation and alternative energy systems. There are sections on the various programs, results and measures in the energy activities illustrated by industrial examples. (tk)
New Results of a Class of Two-Neuron Networks with Time-Varying Delays
Directory of Open Access Journals (Sweden)
He Yigang
2008-01-01
Full Text Available With the help of the continuation theorem of the coincidence degree, a priori estimates, and differential inequalities, we make a further investigation of a class of planar systems, which is generalization of some existing neural networks under a time-varying environment. Without assuming the smoothness, monotonicity, and boundedness of the activation functions, a set of sufficient conditions is given for checking the existence of periodic solution and global exponential stability for such neural networks. The obtained results extend and improve some earlier publications.
Selected Flight Test Results for Online Learning Neural Network-Based Flight Control System
Williams-Hayes, Peggy S.
2004-01-01
The NASA F-15 Intelligent Flight Control System project team developed a series of flight control concepts designed to demonstrate neural network-based adaptive controller benefits, with the objective to develop and flight-test control systems using neural network technology to optimize aircraft performance under nominal conditions and stabilize the aircraft under failure conditions. This report presents flight-test results for an adaptive controller using stability and control derivative values from an online learning neural network. A dynamic cell structure neural network is used in conjunction with a real-time parameter identification algorithm to estimate aerodynamic stability and control derivative increments to baseline aerodynamic derivatives in flight. This open-loop flight test set was performed in preparation for a future phase in which the learning neural network and parameter identification algorithm output would provide the flight controller with aerodynamic stability and control derivative updates in near real time. Two flight maneuvers are analyzed - pitch frequency sweep and automated flight-test maneuver designed to optimally excite the parameter identification algorithm in all axes. Frequency responses generated from flight data are compared to those obtained from nonlinear simulation runs. Flight data examination shows that addition of flight-identified aerodynamic derivative increments into the simulation improved aircraft pitch handling qualities.
Directory of Open Access Journals (Sweden)
Tomoki Murakami
2017-01-01
Full Text Available This paper introduces a network-assisted interference suppression scheme using beam-tilt switching per frame for wireless local area network systems and its effectiveness in an actual indoor environment. In the proposed scheme, two access points simultaneously transmit to their own desired station by adjusting angle of beam-tilt including transmit power assisted from network server for the improvement of system throughput. In the conventional researches, it is widely known that beam-tilt is effective for ICI suppression in the outdoor scenario. However, the indoor effectiveness of beam-tilt for ICI suppression has not yet been indicated from the experimental evaluation. Thus, this paper indicates the effectiveness of the proposed scheme by analyzing multiple-input multiple-output channel matrices from experimental measurements in an office environment. The experimental results clearly show that the proposed scheme offers higher system throughput than the conventional scheme using just transmit power control.
Directory of Open Access Journals (Sweden)
Jacob W Malcom
Full Text Available One of the goals of biology is to bridge levels of organization. Recent technological advances are enabling us to span from genetic sequence to traits, and then from traits to ecological dynamics. The quantitative genetics parameter heritability describes how quickly a trait can evolve, and in turn describes how quickly a population can recover from an environmental change. Here I propose that we can link the details of the genetic architecture of a quantitative trait--i.e., the number of underlying genes and their relationships in a network--to population recovery rates by way of heritability. I test this hypothesis using a set of agent-based models in which individuals possess one of two network topologies or a linear genotype-phenotype map, 16-256 genes underlying the trait, and a variety of mutation and recombination rates and degrees of environmental change. I find that the network architectures introduce extensive directional epistasis that systematically hides and reveals additive genetic variance and affects heritability: network size, topology, and recombination explain 81% of the variance in average heritability in a stable environment. Network size and topology, the width of the fitness function, pre-change additive variance, and certain interactions account for ∼75% of the variance in population recovery times after a sudden environmental change. These results suggest that not only the amount of additive variance, but importantly the number of loci across which it is distributed, is important in regulating the rate at which a trait can evolve and populations can recover. Taken in conjunction with previous research focused on differences in degree of network connectivity, these results provide a set of theoretical expectations and testable hypotheses for biologists working to span levels of organization from the genotype to the phenotype, and from the phenotype to the environment.
Directory of Open Access Journals (Sweden)
P. Bala Anki Reddy
2016-09-01
Full Text Available In this paper, the prediction of the magnetohydrodynamic boundary layer slip flow over a permeable stretched cylinder with chemical reaction is investigated by using some mathematical techniques, namely Runge–Kutta fourth order method along with shooting technique and artificial neural network (ANN. A numerical method is implemented to approximate the flow of heat and mass transfer characteristics as a function of some input parameters, explicitly the curvature parameter, magnetic parameter, permeability parameter, velocity slip, Grashof number, solutal Grashof number, Prandtl number, temperature exponent, Schmidt number, concentration exponent and chemical reaction parameter. The non-linear partial differential equations of the governing flow are converted into a system of highly non-linear ordinary differential equations by using the suitable similarity transformations, which are then solved numerically by a Runge–Kutta fourth order along with shooting technique and then ANN is applied to them. The Back Propagation Neural Network is applied for forecasting the desired outputs. The reported numerical values and the ANN values are in good agreement than those published works on various special cases. According to the findings of this study, the ANN approach is reliable, effective and easily applicable for simulating heat and mass transfer flow over a stretched cylinder.
van Aalsburg, Jordan; Rundle, John B.; Grant, Lisa B.; Rundle, Paul B.; Yakovlev, Gleb; Turcotte, Donald L.; Donnellan, Andrea; Tiampo, Kristy F.; Fernandez, Jose
2010-08-01
In weather forecasting, current and past observational data are routinely assimilated into numerical simulations to produce ensemble forecasts of future events in a process termed "model steering". Here we describe a similar approach that is motivated by analyses of previous forecasts of the Working Group on California Earthquake Probabilities (WGCEP). Our approach is adapted to the problem of earthquake forecasting using topologically realistic numerical simulations for the strike-slip fault system in California. By systematically comparing simulation data to observed paleoseismic data, a series of spatial probability density functions (PDFs) can be computed that describe the probable locations of future large earthquakes. We develop this approach and show examples of PDFs associated with magnitude M > 6.5 and M > 7.0 earthquakes in California.
2014-07-01
R.H., and Meyers, M.B., 1991. On the seasonal phytoplankton concentration and sea surface temperature cycles of the Gulf of Mexico as determined by...autochthonous sources, such as phytoplankton and its subsequent heterotrophic processing (Blough and Del Vecchio, 2002; Nelson et al., 2007, and references...98) Prescribed by ANSI Std Z39-18 pass. In contrast, numerical circulation model outputs such as temperature and salinity that can be directly or
DEFF Research Database (Denmark)
Spangenberg, J.; Roussel, N.; Hattel, J.H.
2012-01-01
In this paper, we describe and compare the various physical phenomena which potentially lead to flow induced particle migration in concrete. We show that, in the case of industrial casting of concrete, gravity induced particle migration dominates all other potential sources of heterogeneities ind...... the apparent viscosity nor from the plastic viscosity of the suspending phase but from its tangential viscosity. Finally, the transfer of this type of numerical prediction tool to real concrete is discussed....
Integrated RF/Optical Interplanetary Networking Preliminary Explorations and Empirical Results
Raible, Daniel E.; Hylton, Alan G.
2012-01-01
Over the last decade interplanetary telecommunication capabilities have been significantly expanded--specifically in support of the Mars exploration rover and lander missions. NASA is continuing to drive advances in new, high payoff optical communications technologies to enhance the network to Gbps performance from Mars, and the transition from technology demonstration to operational system is examined through a hybrid RF/optical approach. Such a system combines the best features of RF and optical communications considering availability and performance to realize a dual band trunk line operating within characteristic constraints. Disconnection due to planetary obscuration and solar conjunction, link delays, timing, ground terminal mission congestion and scheduling policy along with space and atmospheric weather disruptions all imply the need for network protocol solutions to ultimately manage the physical layer in a transparent manner to the end user. Delay Tolerant Networking (DTN) is an approach under evaluation which addresses these challenges. A multi-hop multi-path hybrid RF and optical test bed has been constructed to emulate the integrated deep space network and to support protocol and hardware refinement. Initial experimental results characterize several of these challenges and evaluate the effectiveness of DTN as a solution to mitigate them.
Moreno-Tapia, Sandra Veronica; Vera-Salas, Luis Alberto; Osornio-Rios, Roque Alfredo; Dominguez-Gonzalez, Aurelio; Stiharu, Ion; de Jesus Romero-Troncoso, Rene
2010-01-01
Computer numerically controlled (CNC) machines have evolved to adapt to increasing technological and industrial requirements. To cover these needs, new generation machines have to perform monitoring strategies by incorporating multiple sensors. Since in most of applications the online Processing of the variables is essential, the use of smart sensors is necessary. The contribution of this work is the development of a wireless network platform of reconfigurable smart sensors for CNC machine applications complying with the measurement requirements of new generation CNC machines. Four different smart sensors are put under test in the network and their corresponding signal processing techniques are implemented in a Field Programmable Gate Array (FPGA)-based sensor node. PMID:22163602
Directory of Open Access Journals (Sweden)
Ion Stiharu
2010-08-01
Full Text Available Computer numerically controlled (CNC machines have evolved to adapt to increasing technological and industrial requirements. To cover these needs, new generation machines have to perform monitoring strategies by incorporating multiple sensors. Since in most of applications the online Processing of the variables is essential, the use of smart sensors is necessary. The contribution of this work is the development of a wireless network platform of reconfigurable smart sensors for CNC machine applications complying with the measurement requirements of new generation CNC machines. Four different smart sensors are put under test in the network and their corresponding signal processing techniques are implemented in a Field Programmable Gate Array (FPGA-based sensor node.
Energy Technology Data Exchange (ETDEWEB)
Sprenger, Lisa, E-mail: Lisa.Sprenger@tu-dresden.de; Lange, Adrian; Odenbach, Stefan [Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Measuring and Automation Technology, TU Dresden, 01062 Dresden (Germany)
2013-12-15
Ferrofluids are colloidal suspensions consisting of magnetic nanoparticles dispersed in a carrier liquid. Their thermodiffusive behaviour is rather strong compared to molecular binary mixtures, leading to a Soret coefficient (S{sub T}) of 0.16 K{sup −1}. Former experiments with dilute magnetic fluids have been done with thermogravitational columns or horizontal thermodiffusion cells by different research groups. Considering the horizontal thermodiffusion cell, a former analytical approach has been used to solve the phenomenological diffusion equation in one dimension assuming a constant concentration gradient over the cell's height. The current experimental work is based on the horizontal separation cell and emphasises the comparison of the concentration development in different concentrated magnetic fluids and at different temperature gradients. The ferrofluid investigated is the kerosene-based EMG905 (Ferrotec) to be compared with the APG513A (Ferrotec), both containing magnetite nanoparticles. The experiments prove that the separation process linearly depends on the temperature gradient and that a constant concentration gradient develops in the setup due to the separation. Analytical one dimensional and numerical three dimensional approaches to solve the diffusion equation are derived to be compared with the solution used so far for dilute fluids to see if formerly made assumptions also hold for higher concentrated fluids. Both, the analytical and numerical solutions, either in a phenomenological or a thermodynamic description, are able to reproduce the separation signal gained from the experiments. The Soret coefficient can then be determined to 0.184 K{sup −1} in the analytical case and 0.29 K{sup −1} in the numerical case. Former theoretical approaches for dilute magnetic fluids underestimate the strength of the separation in the case of a concentrated ferrofluid.
Energy Technology Data Exchange (ETDEWEB)
Koch, S; Harlander, U; Egbers, C [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Hollerbach, R, E-mail: uwe.harlander@tu-cottbus.de [Institute of Geophysics, ETH Zuerich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)
2013-06-15
We begin with an experimental investigation of the flow induced in a rotating spherical shell. The shell globally rotates with angular velocity {Omega}. A further periodic oscillation with angular velocity 0 Less-Than-Or-Slanted-Equal-To {omega} Less-Than-Or-Slanted-Equal-To 2{Omega}, a so-called longitudinal libration, is added on the inner sphere's rotation. The primary response is inertial waves spawned at the critical latitudes on the inner sphere, and propagating throughout the shell along inclined characteristics. For sufficiently large libration amplitudes, the higher harmonics also become important. Those harmonics whose frequencies are still less than 2{Omega} behave as inertial waves themselves, propagating along their own characteristics. The steady component of the flow consists of a prograde zonal jet on the cylinder tangent to the inner sphere and parallel to the axis of rotation, and increases with decreasing Ekman number. The jet becomes unstable for larger forcing amplitudes as can be deduced from the preliminary particle image velocimetry observations. Finally, a wave attractor is experimentally detected in the spherical shell as the pattern of largest variance. These findings are reproduced in a two-dimensional numerical investigation of the flow, and certain aspects can be studied numerically in greater detail. One aspect is the scaling of the width of the inertial shear layers and the width of the steady jet. Another is the partitioning of the kinetic energy between the forced wave, its harmonics and the mean flow. Finally, the numerical simulations allow for an investigation of instabilities, too local to be found experimentally. For strong libration amplitudes, the boundary layer on the inner sphere becomes unstable, triggering localized Goertler vortices during the prograde phase of the forcing. This instability is important for the transition to turbulence of the spherical shell flow. (paper)
Directory of Open Access Journals (Sweden)
Sri Subekti Bendryman Soedjoko
2012-09-01
Full Text Available Using enzyme characters by starch gel electrophoresis, we have applied the method of Numerical Taxonomy to the Schistosomes isolate/stocks. Seven isoenzymes (Phosphoglucomutase = PGM; Phospho glucose isomerase = PGI; Hexokinase = HK; Mannose phosphate isomerase = MPI; Alcaline phosphatase = ALP; Malic enzyme = ME and Malate deshydrogenase = MDH of 15 isolats/stocks are examined. Twenty six electromorphs, corresponding to equivalent number of isoenzymes, are identified by this method, and then grouped into 8 zymodemes. These zymodemes were used as Operational Taxonomy Unit (OTU and compared pairwise, using these indice and it forms the basis for the taxonomic scheme elaborated. The final relationships are exhibited in the agglomerative dendrogram, constructed using complete linkage. The separation into phenons is confirmed by correspondence analysis. It is concluded that the original lines fall into four groups correspondings to the complexes Schistosoma mansoni, S. bovis, S. curasonni and S. haematobium. The phenons are recognised by Numerical Taxonomy, can be equated with the taxa of traditional systematics.
A new algorithm to detect earthquakes outside the seismic network: preliminary results
Giudicepietro, Flora; Esposito, Antonietta Maria; Ricciolino, Patrizia
2017-04-01
In this text we are going to present a new technique for detecting earthquakes outside the seismic network, which are often the cause of fault of automatic analysis system. Our goal is to develop a robust method that provides the discrimination result as quickly as possible. We discriminate local earthquakes from regional earthquakes, both recorded at SGG station, equipped with short period sensors, operated by Osservatorio Vesuviano (INGV) in the Southern Apennines (Italy). The technique uses a Multi Layer Perceptron (MLP) neural network with an architecture composed by an input layer, a hidden layer and a single node output layer. We pre-processed the data using the Linear Predictive Coding (LPC) technique to extract the spectral features of the signals in a compact form. We performed several experiments by shortening the signal window length. In particular, we used windows of 4, 2 and 1 seconds containing the onset of the local and the regional earthquakes. We used a dataset of 103 local earthquakes and 79 regional earthquakes, most of which occurred in Greece, Albania and Crete. We split the dataset into a training set, for the network training, and a testing set to evaluate the network's capacity of discrimination. In order to assess the network stability, we repeated this procedure six times, randomly changing the data composition of the training and testing set and the initial weights of the net. We estimated the performance of this method by calculating the average of correct detection percentages obtained for each of the six permutations. The average performances are 99.02%, 98.04% and 98.53%, which concern respectively the experiments carried out on 4, 2 and 1 seconds signal windows. The results show that our method is able to recognize the earthquakes outside the seismic network using only the first second of the seismic records, with a suitable percentage of correct detection. Therefore, this algorithm can be profitably used to make earthquake automatic
Directory of Open Access Journals (Sweden)
John V. Ringwood
2013-08-01
Full Text Available Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model.
Maximizing influence in a social network: Improved results using a genetic algorithm
Zhang, Kaiqi; Du, Haifeng; Feldman, Marcus W.
2017-07-01
The influence maximization problem focuses on finding a small subset of nodes in a social network that maximizes the spread of influence. While the greedy algorithm and some improvements to it have been applied to solve this problem, the long solution time remains a problem. Stochastic optimization algorithms, such as simulated annealing, are other choices for solving this problem, but they often become trapped in local optima. We propose a genetic algorithm to solve the influence maximization problem. Through multi-population competition, using this algorithm we achieve an optimal result while maintaining diversity of the solution. We tested our method with actual networks, and our genetic algorithm performed slightly worse than the greedy algorithm but better than other algorithms.
Energy Technology Data Exchange (ETDEWEB)
Zokimila, P
2005-10-15
Deep geological disposal is one of the privileged options for the storage of High Level radioactive waste. A good knowledge of the behavior and properties of the potential geological formations as well as theirs evolution in time under the effect of the stress change induced by a possible installation of storage is required. The geological formation host will be subjected to mechanical and thermal solicitations due respectively to the excavation of the disposal tunnels and the release of heat of the canisters of radioactive waste. These thermomechanical solicitations will generate a stress relief in the host layer and disposal tunnels deformations as well as the extension of the damaged zones (EDZ) could cause local and global instabilities. This work aims to develop calculation methods to optimize numerical modeling of the thermoelastic behavior of the disposal at a large scale and to evaluate thermomechanical disturbance induced by storage on the geological formation host. Accordingly, after a presentation of the state of knowledge on the thermomechanical aspects of the rocks related to deep storage, of numerical modeling 2D and 3D of the thermoelastic behavior of individual disposal tunnel and a network of tunnels were carried out by a discrete approach. However, this classical approach is penalizing to study the global behavior of disposal storage. To mitigate that, an approach of numerical modeling, based on homogenization of periodic structures, was proposed. Formulations as numerical procedures were worked out to calculate the effective thermoelastic behavior of an equivalent heterogeneous structure. The model, obtained by this method, was validated with existing methods of homogenization such as the self-consistent model, as well as the Hashin-Shtrikman bounds. The comparison between the effective thermoelastic behavior and current thermoelastic behavior of reference showed a good coherence of the results. For an application to deep geological storage, the
Financialisation as a result of the network economy’s development
Directory of Open Access Journals (Sweden)
Joanna Cichorska
2016-10-01
Full Text Available In the last thirty years, the world’s economies have changed significantly. New technology developments have enabled the transition from the industrial economy to the network economy. The network economy is based on information technology, connectivity and human knowledge. Its development has caused changes in the way of life, consumer behaviour on the markets and companies’ business models, especially the process of goods and services creation and distribution. Electronic commerce and services have become one of the fastest developing fields of the economy. As a result, the role of government has diminished while the role of markets has increased economic transactions between countries and their citizens have substantially risen, and financial transactions have grown remarkably. This changing landscape has been characterised by globalization and financialisation. The increasing role of financial motives, financial markets, and financial institutions have influenced domestic and international transactions. A new category of finance called e-finance has been created and implemented. Despite the advantages of electronic finance networks, concurrently there are some disadvantages of their diffusion. The purpose of the paper is to present both aspects of financialisation and its influence on the financial and banking system. This purpose determines the structure of the paper. As financialisation is a relatively new term the first section of the paper focuses on defining its phenomenon. This part presents different authors’ perspectives and definitions. Next, the influence of financialisation on the Polish financial system’s quantitative and qualitative structure is discussed. The last section focuses on the current role and functions of banks in the finance system network structure as a result of a rapidly changing technological environment.
Scalapino, D. J.; Sugar, R. L.; White, S. R.; Bickers, N. E.; Scalettar, R. T.
1989-01-01
Numerical simulations on the half-filled three-dimensional Hubbard model clearly show the onset of Neel order. Simulations of the two-dimensional electron-phonon Holstein model show the competition between the formation of a Peierls-CDW state and a superconducting state. However, the behavior of the partly filled two-dimensional Hubbard model is more difficult to determine. At half-filling, the antiferromagnetic correlations grow as T is reduced. Doping away from half-filling suppresses these correlations, and it is found that there is a weak attractive pairing interaction in the d-wave channel. However, the strength of the pair field susceptibility is weak at the temperatures and lattice sizes that have been simulated, and the nature of the low-temperature state of the nearly half-filled Hubbard model remains open.
Sergeev, E. N.; Grach, S. M.
2017-07-01
The data on measured dynamic characteristics of diagnostic stimulated electromagnetic emission (SEE) of the ionosphere are presented. Numerical simulations of the SEE evolution within the framework of a theoretical model of the broad-continuum SEE feature with the use of improved (3D) empirical model of the spatial spectrum of artificial irregularities of the HF pumped ionospheric plasma are performed and compared with the measurement data. Possible applications of such a comparison for determining the spectrum parameters and studying the evolution of the geomagnetic field-aligned artificial irregularities (striations) are discussed. It is concluded that changes in the intensity and spectrum shape of the striations, mainly for transverse scales l ⊥ 2-18 m, play the decisive role in the observed variations of the magnitude and temporal characteristics of the overshoot effect (formation of the intensity maximum followed by the suppression of the ionospheric SEE intensity).
Vallianatos, F.; Hloupis, G.; Papadopoulos, I.
2012-04-01
The Hellenic arc and the adjacent areas of the Greek mainland are the most active in western Eurasia and some of the most seismically active zones of the world. The seismicity of South Aegean is extremely high and is characterised by the frequent occurrence of large shallow and intermediate depth earthquakes. Until 2004, the installed seismological stations from several providers (NOA, GEOFON, MEDNET) provide average interstation distance around 130km resulting to catalogues with minimum magnitude of completeness (Mc) equals to 3.7. Towards to the direction of providing dense and state of the art instrumental coverage of seismicity in the South Aegean, HSNC begun its operation in 2004. Today it consists of (12) permanent seismological stations equipped with short period and broadband seismographs coupled with 3rd generation 24bit data loggers as well as from (2) accelerographs . The addition of HSNC along with combined use of all the active networks in South Aegean area (NOA, GEOFON, AUTH) decrease the average interstation distance to 60km and provide catalogues with Mc≥3.2. Data transmission and telemetry is implemented by a hybrid network consisting of dedicated wired ADSL links as well as VSAT links by using a unique private satellite hub. Real time data spread over collaborating networks (AUTH) and laboratories (Department of Earth Science - UCL) while at the same time, events are appended automatically and manually to EMSC database. Additional value to the network is provided by means of prototype systems which deployed in-situ for the purposes of: a) Acquiring aftershock data in the minimum time after main event. This is a mobile seismological network called RaDeSeis (Rapid Deployment Seismological network) which consists of a central station acting also as the central communication hub and wifi coupled mobile stations. b) The development of dedicated hardware and software solutions for rapid installation times (around 1 hour for each station) leading to
Directory of Open Access Journals (Sweden)
Adrian TOADER
2010-09-01
Full Text Available The paper was conceived in two parts. Part I, previously published in this journal, highlighted the main steps of adaptive output feedback control for non-affine uncertain systems, having a known relative degree. The main paradigm of this approach was the feedback linearization (dynamic inversion with neural network augmentation. Meanwhile, based on new contributions of the authors, a new paradigm, that of robust servomechanism problem solution, has been added to the controller architecture. The current Part II of the paper presents the validation of the controller hereby obtained by using the longitudinal channel of a hovering VTOL-type aircraft as mathematical model.
Directory of Open Access Journals (Sweden)
Guzmán Juan
2015-07-01
Full Text Available There are a lot of applications of the Thomson ring: levitation of superconductor materials, power interrupters (used as actuator and elimination of electric arcs. Therefore, it is important the numerical modeling of Thomson ring. The aim of this work is to model the stationary levitation of the Thomson ring. This Thomson ring consists of a copper coil with ferromagnetic core and an aluminum ring threaded in the core. The coil is fed by a cosine voltage to ensure that the aluminum ring is in a stationary levitated position. In this situation, the state of the electromagnetic field is stable and can be used the phasor equations of the electromagnetic field. These equations are discretized using the Galerkin method in the Lagrange base space (finite element method, FEM. These equations are solved using the COMSOL software. A methodology is also described (which uses the Newton-Raphson method that obtains the separation between coil and aluminum ring. The numerical solutions of this separation are compared with experimental data. The conclusion is that the magnetic coupling of the aluminum ring on the coil can be neglected if the source voltage is high.
Shul'ga, T. Ya
2017-09-01
The paper discusses methods of sharing information obtained by remote sensing of the sea surface from space and model solutions. The estimation of the quality of the model prediction is made depending on the intervals between the assimilation of satellite data. Numerical hydrodynamic modelling of the Azov Sea water area is performed on the basis of the POM model for real atmospheric forcing SKIRON in the period from 2013 to 2014. The peculiarities of spatial and temporal dynamics of the pollution in the Sea of Azov have been studied on the basis of a joint analysis of numerical simulation data and space monitoring data from the Terra/Aqua satellites. Based on the developed new model algorithms, the results of numerical simulation and data of satellite observations on the state of water in the Sea of Azov water area are summarized.
Diaz-Espinosa, O
2006-01-01
We study the effect of noise on one--dimensional critical dynamical systems (that is, maps with a renormalization theory). We consider in detail two examples of such dynamical systems: unimodal maps of the interval at the accumulation of period--doubling and smooth homeomorphisms of the circle with a critical point and with golden mean rotation number. We show that, if we scale the space and the time, several properties of the noise (the cumulants or Wick--ordered moments) satisfy some scaling relations. A consequence of the scaling relations is that a version of the central limit theorem holds. Irrespective of the shape of the initial noise, if the bare noise is weak enough, the effective noise becomes close to Gaussian in several senses that we can make precise. We notice that the conclusions are false for maps with positive Lyapunov exponents. The method of analysis is close in spirit to the study of scaling limits in renormalization theory. We also perform several numerical experiments that confirm the ri...
Ramdhan, Mohamad; Widiyantoro, Sri; Nugraha, Andri Dian; Métaxian, Jean-Philippe; Saepuloh, Asep; Kristyawan, Said; Sembiring, Andry Syaly; Santoso, Agus Budi; Laurin, Antoine; Fahmi, Ahmad Ali
2017-04-01
Merapi volcano located in central Java, Indonesia, is one of the most active stratovolcanoes in the world. Many Earth scientists have conducted studies on this volcano using various methods. The geological features around Merapi are very attractive to be investigated because they have been formed by a complex tectonic process and volcanic activities since tens of millions of years ago. The southern mountain range, Kendeng basin and Opak active fault located around the study area resulted from these processes. DOMERAPI project was conducted to understand deep magma sources of the Merapi volcano comprehensively. The DOMERAPI network was running from October 2013 to mid-April 2015 by deploying 46 broad-band seismometers around the volcano. Several steps, i.e., earthquake event identification, arrival time picking of P and S waves, hypocenter determination and hypocenter relocation, were carried out in this study. We used Geiger's method (Geiger 1912) for hypocenter determination and double-difference method for hypocenter relocation. The relocation result will be used to carry out seismic tomographic imaging of structures beneath the Merapi volcano and its surroundings. For the hypocenter determination, the DOMERAPI data were processed simultaneously with those from the Agency for Meteorology, Climatology and Geophysics (BMKG) seismic network in order to minimize the azimuthal gap. We found that the majority of earthquakes occurred outside the DOMERAPI network. There are 464 and 399 earthquakes obtained before and after hypocenter relocation, respectively. The hypocenter relocation result successfully detects some tectonic features, such as a nearly vertical cluster of events indicating a subduction-related backthrust to the south of central Java and a cluster of events to the east of Opak fault suggesting that the fault has an eastward dip.
Baker, John G.
2009-01-01
Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.
The eel pollutant monitoring network in Flanders, Belgium. Results of 10 years monitoring
Energy Technology Data Exchange (ETDEWEB)
Goemans, G.; Belpaire, C. [Inst. for Forestry and Game Management, Hoeilaart (Belgium)
2004-09-15
Since 1994 the Institute for Forestry and Game Management (IBW) has build out a pollutant monitoring network for public water bodies in Flanders (Belgium) using eel (Anguilla anguilla) as a biomonitor. The results presented here come from 2000 individually analysed eels originating from 260 different localities in Flanders, including rivers, canals, polder waters and closed water bodies. The sampling took place from 1994 to 2002. Eel is used for biomonitoring because it is a very fatty (strong lipophylic character of a.o. pesticides and PCB's), benthic, sedentary (during the yellow eel phase), long-living and widespread fish (in non-polluted as well as in polluted waters) and because of the absence of a seasonal effect through reproduction and its place on the trophic ladder. Some results represented are: (1) on 80 % of all sampled localities the Belgian PCB-standard for fish (75ng/g BW) is exceeded; (2) in the north-western part of Flanders is a severe lindanecontamination; (3) many long time prohibited pesticides are still found in considerable amounts in our food-chain; (4) several locations contain high to very high concentrations of brominated flame retardants. For several contaminants a comparison is made between the Flemish values and other values found in literature. The results of the Flemish eel pollutant monitoring network have initiated a catch-and-release obligation for eel in Flanders and for all fish on the 5 most polluted waters in Flanders.
Kozłowski, S. K.; Sybilski, P. W.; Konacki, M.; Pawłaszek, R. K.; Ratajczak, M.; Hełminiak, K. G.; Litwicki, M.
2017-10-01
We present the design and commissioning of Project Solaris, a global network of autonomous observatories. Solaris is a Polish scientific undertaking aimed at the detection and characterization of circumbinary exoplanets and eclipsing binary stars. To accomplish this, a network of four fully autonomous observatories has been deployed in the Southern Hemisphere: Solaris-1 and Solaris-2 in the South African Astronomical Observatory in South Africa; Solaris-3 in Siding Spring Observatory in Australia; and Solaris-4 in Complejo Astronomico El Leoncito in Argentina. The four stations are nearly identical and are equipped with 0.5-m Ritchey-Crétien (f/15) or Cassegrain (f/9, Solaris-3) optics and high-grade 2 K × 2 K CCD cameras with Johnson and Sloan filter sets. We present the design and implementation of low-level security; data logging and notification systems; weather monitoring components; all-sky vision system, surveillance system; and distributed temperature and humidity sensors. We describe dedicated grounding and lighting protection system design and robust fiber data transfer interfaces in electrically demanding conditions. We discuss the outcomes of our design, as well as the resulting software engineering requirements. We describe our system’s engineering approach to achieve the required level of autonomy, the architecture of the custom high-level industry-grade software that has been designed and implemented specifically for the use of the network. We present the actual status of the project and first photometric results; these include data and models of already studied systems for benchmarking purposes (Wasp-4b, Wasp-64b, and Wasp-98b transits, PG 1663-018, an eclipsing binary with a pulsator) as well J024946-3825.6, an interesting low-mass binary system for which a complete model is provided for the first time.
Ozonometer M-124 calibration for the Ukrainian network: method and results
Grytsai, A.; Milinevsky, G.; Evtushevsky, O.; Sosonkin, M.; Kravchenko, V.; Danylevsky, V.
2016-12-01
M-124 filter ozonometers are used for total ozone measuring in Ukraine since 1970s. Recently the need to calibrate several M-124 instruments of the Ukrainian filter ozonometer network is raised to continue ozone observations. The calibration became possible owing to the accurate ozone measurements by Dobson spectrophotometer started in 2010 at the Kyiv-Goloseyev WMO station located at the Main Astronomical Observatory of National Academy of Sciences of Ukraine. For calibration purposes the simultaneous M-124 and Dobson Direct Sun measurements were carried out during the 2013-2016 period by researchers from Taras Shevchenko National University of Kyiv and Main Astronomical Observatory. The M-124 instrument has two spectral channels: first is 305 nm and second is 325 nm. Outgoing signal from M-124 is determined by transparency of the terrestrial atmosphere and filter characteristics. Theoretical description of the solar radiation propagation through the atmosphere is determined by the Bouguer-Lambert-Beer law taking into account ozone absorption, Rayleigh and aerosol scattering. Parameters of the aerosol scattering have been determined from observations with the CIMEL sunphotometer of Aerosol Robotic Network which is also located at the Kyiv-Goloseyev station. The ozonometers optical characteristics were studied after M-124 refurbishment and modernization at the Central Geophysical Observatory of Ukraine that includes a significant part of the whole calibration work. Knowing the spectral dependence of each filter is necessary to calculate signal ratios in two channels. This information allowed solving the inverse problem of determining total ozone content in the terrestrial atmosphere. Comparison of these results with Dobson spectrophotometer data shows their good quality even without an additional correction. These results open a possibility to calibrate M-124 filter ozonometers for future ozone measurements at the observation sites of the Ukraine ozonometer network.
Multistatic Wireless Fidelity Network Based Radar – Results of the Chrcynno Experiment
Directory of Open Access Journals (Sweden)
S. Rzewuski
2014-04-01
Full Text Available This paper presents the theory and experimental result of passive radar using WIFI transmitters as illuminators of opportunity. As a result of experiments conducted on 17th August 2013 at airfield Chrcynno a Cessna C208 airplane was detected and tracked using multistatic passive radar system based on low power signal from WIFI network nodes, which were acting as non cooperative illuminators of opportunity. In the experiment 3 wireless access points were communicating with each other and illuminating the radar scene (airfield. The direct reference and reflected (surveillance signals have been acquired and processed using specially developed algorithm presented in the paper. After signal processing using Passive Coherent Location methods target has been detected. This paper describes in details the algorithms and the results of the experiment for the multistatic passive radar based on the WIFI signal.
Lane, J.W.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.
2000-01-01
The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons
Illuminating the nomological network of digital aggression: Results from two studies.
Burt, S Alexandra; Alhabash, Saleem
2018-03-01
We examined the nomological network surrounding digital aggression (DA), in regards to other forms of aggression/antisocial behavior and individual difference variables commonly associated with other forms of aggression/antisocial behavior. Two large samples of university students (N = 713 and 633, respectively) completed a series of questionnaires and in some cases, an additional experience sampling study. Results revealed that, in emerging adulthood, DA appears to have a unique demographic profile relative to the other forms of aggression and antisocial behavior. Results further suggested that, when examined simultaneously, only social aggression and non-aggressive rule-breaking evidenced independent associations with DA. These associations persisted even in the absence of social media use. Unique associations with most individual difference variables dissipated once we controlled for social aggression and rule-breaking, although DA was independently associated with extraversion and alcohol use problems. Such findings begin to embed DA in its broader nomological network and suggest clear functional links with both social aggression and non-aggressive rule-breaking. © 2017 Wiley Periodicals, Inc.
Sciare, Jean; Petit, Jean-Eudes; Sarda-Esteve, Roland; Bonnaire, Nicolas; Gros, Valérie; Pernot, Pierre; Ghersi, Véronique; Ampe, Christophe; Songeur, Charlotte; Brugge, Benjamin; Debert, Christophe; Favez, Olivier; Le Priol, Tiphaine; Mocnik, Grisa
2013-04-01
://www.airparif.asso.fr/). Contribution of imported versus local EBC is calculated using the "Lenschow" methodology (Lenschow et al., 2001), whereas the influence of domestic wood burning EBC (vs traffic) over the region of Paris is evaluated using the Aethalometer model developed by Sandradewi et al. (2008). Results and discussion. First results of this BC network are presented here including the temporal variations of EBC from wood burning (domestic heating) and fossil fuel (traffic) for the various sites (1-year observation for rural background and traffic sites; 4-year observations for urban background). The local versus imported contributions of EBC are also presented and discussed for these 2 sources. References. Lenschow, P., et al., Some ideas about the sources of PM10, Atmospheric Environment 35 Supplement No. 1 (2001) S23-S33 Sandradewi, J., et al., Using aerosol light absorption measurements for the quantitative determination of wood burning and traffic emission contributions to particulate matter, Environ. Sci. Technol., 42, 3316-3323, 2008
Balancing Relations and Results in Regional Networks of Public-Policy Implementation
Klaster, E.; Wilderom, Celeste P.M.; Muntslag, Dennis R.
2017-01-01
Regional networks have become popular routes for central governments to translate national ambitions into regional policies and actions; but these networks face challenges, having to balance between the dual objectives of obtaining short-term goals and establishing enduring network relations. This
2017-01-01
Although Arabic numerals (like ‘2016’ and ‘3.14’) are ubiquitous, we show that in interactive computer applications they are often misleading and surprisingly unreliable. We introduce interactive numerals as a new concept and show, like Roman numerals and Arabic numerals, interactive numerals introduce another way of using and thinking about numbers. Properly understanding interactive numerals is essential for all computer applications that involve numerical data entered by users, including finance, medicine, aviation and science. PMID:28484609
A review of results of the international ionospheric Doppler sounder network
Laštovička, Jan; Chum, Jaroslav
2017-10-01
This paper summarizes main recent results reached by the Czech-lead international network of ionospheric Doppler shift sounders. The network consists of Doppler sounders in the western half of Czechia (5 measuring paths, 3 frequencies with central receivers in Prague), northern Taiwan (3 transmitters, two separated receivers, 1 frequency), and two similar systems (3 measuring paths with 1 receiver and 1 frequency) in Tucuman (north-western Argentina) and Hermanus (the southernmost South Africa). Main areas of research have been: (1) propagation of gravity waves; (2) ionospheric effects of earthquakes; (3) low latitude/equatorial phenomena; (4) ionospheric response to strong meteorological phenomena; (5) effects of solar flares, geomagnetic activity and geomagnetic micropulsations. Main results: (1) Theoretically expected dominance of gravity wave propagation against wind has been confirmed. (2) Impact of a train of seismic waves (P, S, SS, Rayleigh) generated by the Tohoku 2011 M9.0 earthquake was registered in the ionosphere over the Czech Republic as long-period infrasound at the distance of about 9000 km from epicenter. (3) Analysis of ionospheric infrasound excited by the Nepal 2015 M7.8 earthquake observed by the Czech and Taiwan Doppler sounders showed that the intensity of ionospheric signal is significantly height and latitude dependent. Air/plasma compression has to be considered to compute air particle velocities from the observed Doppler shift. (4) Nonlinear effects result in formation of N-shaped pulse disturbance in the upper atmosphere/ionosphere above strong earthquakes as was documented by the example of the M8.3 Illapel 2016 earthquake. (5) Spread F structures observed by Doppler sounders in Tucuman and Taiwan (both under the crest of equatorial ionization anomaly) provide results consistent with S4 scintillation data and with previous optical, GPS and satellite measurements. (6) Short period gravity waves and rarely infrasound are observed in the
Regueiro, Ander; Fernández-Rodríguez, Diego; Freixa, Xavier; Bosch, Xavier; Martín-Yuste, Victoria; Brugaletta, Salvatore; Roqué, Mercè; Sabaté, Manel; Masotti, Mónica
2017-07-12
ST-segment elevation myocardial infarction (STEMI) network activation by a noncardiologist reduces delay times but may increase the rate of false-positive STEMI diagnoses. We aimed to determine the prevalence, predictors, and clinical impact of false-positive activations within the Catalonian STEMI network (Codi Infart). From January 2010 through December 2011, all consecutive patients treated within the Codi Infart network were included. Code activations were classified as appropriate if they satisfied both electrocardiogram and clinical STEMI criteria. Appropriate activations were classified as false positives using 2 nonexclusive definitions: a) "angiographic" if a culprit coronary artery was not identified, and b) "clinical" if the discharge diagnosis was other than STEMI. In total, 5701 activations were included. Appropriate activation was performed in 87.8% of the episodes. The rate of angiographic false positives was 14.6%, while the rate of clinical false positives was 11.6%. Irrespective of the definition, female sex, left bundle branch block, and previous myocardial infarction were independent predictors of false-positive STEMI diagnoses. Using the clinical definition, hospitals without percutaneous coronary intervention and patients with complications during the first medical contact also had a false-positive STEMI diagnoses rate higher than the mean. In-hospital and 30-day mortality rates were similar for false-positive and true-positive STEMI patients after adjustment for possible confounders. False-positive STEMI diagnoses were frequent. Outcomes were similar for patients with a true-positive or false-positive STEMI diagnosis treated within a STEMI network. The presence of any modifiable predictors of a false-positive STEMI diagnosis warrants careful assessment to optimize the use of STEMI networks. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.
van Wonderen, A.J.; Suttorp, L.G.
1991-01-01
Instabilities in the nearest side-modes are predicted for dispersive optical bistability in a nonideal Fabry-Perot cavity. The results are based on a linear stability analysis of the Maxwell-Bloch equations. This analysis leads to a boundary value problem for a four-dimensional set of linear
Directory of Open Access Journals (Sweden)
Ginés A. Abanto
2017-06-01
Different adobes have been studied. Effective thermal conductivity and heat capacity were measured by means of a hot parallel-plate method. Density was estimated using a pycnometer and measuring physical dimensions and mass of each sample, which allowed the calculation of thermal effusivity and diffusivity. Some numerical simulation results displayed good agreement with experimental outcomes. The work presented here has implications for future studies of this traditional building material and might potentially help solving the problem of sustainable housing.
Directory of Open Access Journals (Sweden)
Titarenko Vera
2017-01-01
Full Text Available For the safe operation of the pipeline, ensuring its smooth operation was conducted analysis of the results of numerical simulation of melting of paraffin jams with using a mobile source of electromagnetic radiation. Carried out varying different parameters of the radiation source, the peculiarities of its movement, the nature of the change of geometry of the boundary of melting of paraffin plugs under different external conditions
Cao, Xinhua; Xu, Xiaoyin; Voss, Stephan
2017-03-01
In this paper, we describe an enhanced DICOM Secondary Capture (SC) that integrates Image Quantification (IQ) results, Regions of Interest (ROIs), and Time Activity Curves (TACs) with screen shots by embedding extra medical imaging information into a standard DICOM header. A software toolkit of DICOM IQSC has been developed to implement the SC-centered information integration of quantitative analysis for routine practice of nuclear medicine. Primary experiments show that the DICOM IQSC method is simple and easy to implement seamlessly integrating post-processing workstations with PACS for archiving and retrieving IQ information. Additional DICOM IQSC applications in routine nuclear medicine and clinic research are also discussed.
Agelet de Saracibar Bosch, Carlos; Boman, Romain; Bussetta, Philippe; Cajas García, Juan Carlos; Cervera Ruiz, Miguel; Chiumenti, Michèle; Coll Sans, Abel; Dadvand, Pooyan; Hernández Ortega, Joaquín Alberto; Houzeaux, Guillaume; Pasenau de Riera, Miguel; Ponthot, Jean Philippe
2016-01-01
As one of the results of an ambitious project, this handbook provides a well-structured directory of globally available software tools in the area of Integrated Computational Materials Engineering (ICME). The compilation covers models, software tools, and numerical methods allowing describing electronic, atomistic, and mesoscopic phenomena, which in their combination determine the microstructure and the properties of materials. It reaches out to simulations of component manufacture compris...
Directory of Open Access Journals (Sweden)
D. A. Lovtsov
2016-01-01
Full Text Available The purpose of this article is perfection of using metodology of technological and organization and legal protect of intellectual activity results and related intellectual rights in information sphere of Global Telematics Networks (such as of «Internet», «Relkom», «Sitek», «Sedab», «Remart», and others. On the conduct analysis base of the peculiarities and possibilities of using of different technological, organization and legal methods and ways protection of information objects the offers of perfection of corresponding organization and legal safeguarding are formulated. The effectiveness of the protection is provided on the basis of rational aggregation technological, organization and legal methods and ways possible in a particular situation.
Higher education and curriculum innovation: results of an institutional network research
Directory of Open Access Journals (Sweden)
Martha Maria Prata-Linhares
2013-06-01
Full Text Available In this article we share the paths of an investigation carried out by a group of researchers from different Brazilian universities (FORPEC, which, based on the results of the investigation, built a network of information and research involving various education institutions. While describing this group’s pathway, the text presents innovating experiences of curriculums in higher education which provided important and significant pedagogic changes in their projects. During the period of investigation, 6 (six projects of university courses with innovation proposals were brought up and analyzed. This analysis allowed for the elaboration of innovation concepts for Higher Education, identify active innovating methodologies, create and implant innovative projects in Higher Education, as well as give the start off to investigation concerning the development of the docents integrating the innovating curricular projects. The groups’ pathway in itself may be considered an innovative research project.
Gkanis, Vasileios; Housiadas, Christos
2010-06-01
There is a great need to fabricate heart valves that have similar haemodynamic properties with the natural ones. Towards this goal, we examine the dynamics of fluid flow in a mechanical heart valve with one leaflet. The fluid is incompressible and Newtonian and the leaflet is a neo-Hookean material. The Arbitrary Lagrangian Eulerian method is used to model the fluid-leaflet interaction, and the system of equations is solved using the Finite Element method. The pseudo solid approach along with a set of algebraic equations are used to deform the mesh, while care is taken to avoid remeshing of the domain, at the moment of valve closure. The computational results are compared against the experimental results, and we find an excellent agreement for the time period of valve closure, the time the valve is fully opened, and the value of the maximum valve opening angle. This study indicates that the present model is capable of describing the valve dynamics in physiological geometries.
Directory of Open Access Journals (Sweden)
K. A. Trukhanov
2014-01-01
Full Text Available State-of-the-art machinery development enables people with lost lower limb to continue their previous life despite a loss. International companies dealing with this area pursue a minimization of human behaviour problems because of amputation. Researches to create an optimal design of the artificial knee joint are under way.The work task was to define analytical relationships of changing kinematic parameters of the human walking on the flat surface such as an angle of the knee joint, knee point (moment, definition of reduced knee actuator (A load, as well as to compare obtained results with experimental data.As an A in created design, the article proposes to use a controlled shock absorber based on the hydraulic cylinder.A knee unit is a kinematic two-tier mechanism. One of the mechanism links performs rotational motion, and the other is rotation-translational to provide a rotation of the first one.When studying the hydraulic actuator device dynamics, as a generalized coordinate a coordinate of the piston x (or ρ position is chosen while in the study of link movements an angle β is preferable.Experimental data are obtained for a human with the body weight of 57.6 kg walking on the flat surface to estimate a value of the knee joint angle, speed, acceleration, torque, and capacity in the knee joint and are taken from the published works of foreign authors.A trigonometric approximation was used for fitting the experimental data. The resulting dependence of the reduced load on the stock of A is necessary to perform the synthesis of A. The criterion for linear mechanisms mentioned in the D.N. Popov’s work is advisable to use as a possible criterion for optimization of A.The results obtained are as follows:1. Kinematics linkage mechanism is described using relationships for dependencies of its geometrical parameters, namely a cylinder piston stroke x (or ρ and a links angle β.2. Obtained polynomials of kinematic relationships allow a synthesis of
Mamo, Laura A; Browe, Dennis K; Logan, Holly C; Kim, Katherine K
2013-01-01
Understanding how to govern emerging distributed research networks is essential to their success. Distributed research networks aggregate patient medical data from many institutions leaving data within the local provider security system. While much is known about patients' views on secondary medical research, little is known about their views on governance of research networks. We conducted six focus groups with patients from three medical centers across the U.S. to understand their perspectives on privacy, consent, and ethical concerns of sharing their data as part of research networks. Participants positively endorsed sharing their health data with these networks believing that doing so could advance healthcare knowledge. However, patients expressed several concerns regarding security and broader ethical issues such as commercialism, public benefit, and social responsibility. We suggest that network governance guidelines move beyond strict technical requirements and address wider socio-ethical concerns by fully including patients in governance processes.
Energy Technology Data Exchange (ETDEWEB)
Ribando, R.J.
1979-01-01
A comparison is made between computed results and experimental data for a single-phase natural convection test in an experimental sodium loop. The test was conducted in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility, an engineering-scale high temperature sodium loop at the Oak Ridge National Laboratory (ORNL) used for thermal-hydraulic testing of simulated Liquid Metal Fast Breeder Reactor (LMFBR) subassemblies at normal and off-normal operating conditions. Heat generation in the 19 pin assembly during the test was typical of decay heat levels. The test chosen for analysis in this paper was one of seven natural convection runs conducted in the facility using a variety of initial conditions and testing parameters. Specifically, in this test the bypass line was open to simulate a parallel heated assembly and the test was begun with a pump coastdown from a small initial forced flow. The computer program used to analyze the test, LONAC (LOw flow and NAtural Convection) is an ORNL-developed, fast-running, one-dimensional, single-phase, finite-difference model used for simulating forced and free convection transients in the THORS loop.
Randol, Brent M.; Christian, Eric R.
2016-01-01
A parametric study is performed using the electrostatic simulations of Randol and Christian (2014) in which the number density, n, and initial thermal speed, theta, are varied. The range of parameters covers an extremely broad plasma regime, all the way from the very weak coupling of space plasmas to the very strong coupling of solid plasmas. The first result is that simulations at the same Lambda(sub D), where Lambda(sub D) is the plasma coupling parameter, but at different combinations of n and theta, behave exactly the same. As a function of Lambda(sub D), the form of p(v), the velocity distribution function of v, the magnitude of v, the velocity vector, is studied. For intermediate to high D, heating is observed in p(v) that obeys conservation of energy, and a suprathermal tail is formed, with a spectral index that depends on Lambda(sub D). For strong coupling (Lambda(sub D) much > 1), the form of the tail is v5, consistent with the findings of Randol and Christian (2014). For weak coupling (Lambda(sub D much <1), no acceleration or heating occurs, as there is no free energy. The dependence on N, the number of particles in the simulation, is also explored. There is a subtle dependence in the index of the tail, such that v5 appears to be the N approaches infinity limit.
Predicting Football Matches Results using Bayesian Networks for English Premier League (EPL)
Razali, Nazim; Mustapha, Aida; Yatim, Faiz Ahmad; Aziz, Ruhaya Ab
2017-08-01
The issues of modeling asscoiation football prediction model has become increasingly popular in the last few years and many different approaches of prediction models have been proposed with the point of evaluating the attributes that lead a football team to lose, draw or win the match. There are three types of approaches has been considered for predicting football matches results which include statistical approaches, machine learning approaches and Bayesian approaches. Lately, many studies regarding football prediction models has been produced using Bayesian approaches. This paper proposes a Bayesian Networks (BNs) to predict the results of football matches in term of home win (H), away win (A) and draw (D). The English Premier League (EPL) for three seasons of 2010-2011, 2011-2012 and 2012-2013 has been selected and reviewed. K-fold cross validation has been used for testing the accuracy of prediction model. The required information about the football data is sourced from a legitimate site at http://www.football-data.co.uk. BNs achieved predictive accuracy of 75.09% in average across three seasons. It is hoped that the results could be used as the benchmark output for future research in predicting football matches results.
[psychenet - Hamburg Network for Mental Health: Results of the Process Evaluation].
Makowski, Anna C; Mnich, Eva E; Kofahl, Christopher; von dem Knesebeck, Olaf
2015-07-01
Aspects of implementation, functionality, acceptability and sustainability of the network psychenet - Hamburg network for mental health were examined.In March 2012 and September 2013, 19 expert interviews were carried out with leaders of subprojects and representatives of insurances, public authorities and patients.The complexity of the network was hindering. Positive aspects were communication, clear hierarchies and qualified staff.The implementation of a complex network requires shared goals. The establishment of a steering committee has proved as crucial. © Georg Thieme Verlag KG Stuttgart · New York.
Foliar nutrients in Italian forests: results from the 1995-2009 monitoring network sites CONECOFOR
Directory of Open Access Journals (Sweden)
De Cinti B
2013-11-01
Full Text Available Foliar nutrients in Italian forests: results from the 1995-2009 monitoring network sites CONECOFOR. In 1995, the Italian Forest Service (CFS established the National Network for Forest Ecosystem Monitoring (CONECOFOR with the aim to study the ecological interactions among structural and functional components of forest stands. In the 31 permanent plots of the CONECOFOR Network, surveys are carried out including vegetation, trees crown condition, chemistry of leaves and soils, tree growth, atmospheric deposition, climate, microclimate, ozone and biodiversity. These surveys are carried out by CFS in collaboration with several scientific institutions. In such context, IBAF/CNR is specifically involved in the investigation of foliage chemical content. The foliar nutritional status was analyzed in 25 sites, taking as a reference the values published by the ICP-Forests and those published in the literature. The study involved 7 forest species (Quercus cerris, Q. petraea, Q. robur, Q. ilex, Fagus sylvatica, Carpinus betulus and Picea abies investigating the concentrations of the major macronutrients as nitrogen (N, phosphorus (P, potassium (K, magnesium (Mg, sulfur (S and calcium (Ca and the N/P ratio. In beech, N, S and K were found in quite high concentrations, though without showing imbalances due to concentration excesses. Ca and Mg are present in very high concentrations, highlighting the possibility of imbalances, especially in relation to the other nutrients. For these two nutrients, spruce shows substantially balanced conditions as also for N/P ratio. For deciduous Oaks nutrients arewithin the parameters of normality, with the exception of Ca. This has been observed in 4 out of the 6 studied sites, with potential indication of nutritional imbalances related to Calcium. Nutrient concentrations in Holm oak are within the average of published data, except for Ca and Mg of site TOS-1, the former being slightly low, the latter being unusually high
Monitoring snow avalanches in the medium range by a network of infrasonic arrays: first results
ulivieri, giacomo; marchetti, emanuele; ripepe, maurizio; durand, nathalie; frigo, barbara; chiambretti, igor; segor, valerio
2013-04-01
Monitoring of small-to-medium sized avalanches activity represents a crucial parameter to compare predictions and real effects. However, at present natural avalanche activity is mainly based on field observations, which have a limited range and are possible only during the daylight. Since 2009, the Department of Earth Sciences of University of Florence in collaboration with the Regione Valle d'Aosta is using the infrasonic array technology for near real-time monitoring of natural and artificial avalanche activity in the Alpine area. The results obtained during the last 3 years indicate that small-to-medium sized snow avalanches can be detected in the short-to-medium range distance (2-6 km). However, despite single array analysis allows to recognise many natural (microbarom, earthquakes, avalanches) and artificial (airplane, explosions) infrasound sources by using apparent velocity criterion, any unique identification and precise location of infrasonic sources is not possible without any additional information. In order to solve this problem, the monitoring system is upgraded by installing two additional arrays. In fact, a network of 3 arrays is operating since December 2012 around the MonteRosa and Cervino international ski resorts on the related massifs. Each infrasonic array consists of 4 infrasonic sensors deployed in triangular geometry and ~150 m of aperture. Data are sampled at 100 Hz and transmitted in real-time to Department of Earth Sciences in Florence for near real-time (<2 minutes) processing. The network has improved the capability in locating avalanches sources in a medium range distance (from 6 km to more than 10 km). In fact, the 3 arrays are covering an area of ~ 250 km2. Efficiency of source location and sensitivity of this infrasonic array network are tested by using artificial triggered avalanches: avalanches can now be located with a precision of ~ 1 km. Information on geographical position, origin time and infrasonic energy will be supplied to
Optimizing CO2 observing networks in the presence of model error: results from TransCom 3
Directory of Open Access Journals (Sweden)
R. J Rayner
2004-01-01
Full Text Available We use a genetic algorithm to construct optimal observing networks of atmospheric concentration for inverse determination of net sources. Optimal networks are those that produce a minimum in average posterior uncertainty plus a term representing the divergence among source estimates for different transport models. The addition of this last term modifies the choice of observing sites, leading to larger networks than would be chosen under the traditional estimated variance metric. Model-model differences behave like sub-grid heterogeneity and optimal networks try to average over some of this. The optimization does not, however, necessarily reject apparently difficult sites to model. Although the results are so conditioned on the experimental set-up that the specific networks chosen are unlikely to be the best choices in the real world, the counter-intuitive behaviour of the optimization suggests the model error contribution should be taken into account when designing observing networks. Finally we compare the flux and total uncertainty estimates from the optimal network with those from the 3 control case. The 3 control case performs well under the chosen uncertainty metric and the flux estimates are close to those from the optimal case. Thus the 3 findings would have been similar if minimizing the total uncertainty guided their network choice.
Westphalen, H.; Spjeldvik, W. N.
1982-01-01
A theoretical method by which the energy dependence of the radial diffusion coefficient may be deduced from spectral observations of the particle population at the inner edge of the earth's radiation belts is presented. This region has previously been analyzed with numerical techniques; in this report an analytical treatment that illustrates characteristic limiting cases in the L shell range where the time scale of Coulomb losses is substantially shorter than that of radial diffusion (L approximately 1-2) is given. It is demonstrated both analytically and numerically that the particle spectra there are shaped by the energy dependence of the radial diffusion coefficient regardless of the spectral shapes of the particle populations diffusing inward from the outer radiation zone, so that from observed spectra the energy dependence of the diffusion coefficient can be determined. To insure realistic simulations, inner zone data obtained from experiments on the DIAL, AZUR, and ESRO 2 spacecraft have been used as boundary conditions. Excellent agreement between analytic and numerical results is reported.
Altered Micro-RNA Degradation Promotes Tumor Heterogeneity: A Result from Boolean Network Modeling.
Wu, Yunyi; Krueger, Gerhard R F; Wang, Guanyu
2016-02-01
Cancer heterogeneity may reflect differential dynamical outcomes of the regulatory network encompassing biomolecules at both transcriptional and post-transcriptional levels. In other words, differential gene-expression profiles may correspond to different stable steady states of a mathematical model for simulation of biomolecular networks. To test this hypothesis, we simplified a regulatory network that is important for soft-tissue sarcoma metastasis and heterogeneity, comprising of transcription factors, micro-RNAs, and signaling components of the NOTCH pathway. We then used a Boolean network model to simulate the dynamics of this network, and particularly investigated the consequences of differential miRNA degradation modes. We found that efficient miRNA degradation is crucial for sustaining a homogenous and healthy phenotype, while defective miRNA degradation may lead to multiple stable steady states and ultimately to carcinogenesis and heterogeneity. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
Network Traffic Analysis With Query Driven VisualizationSC 2005HPC Analytics Results
Energy Technology Data Exchange (ETDEWEB)
Stockinger, Kurt; Wu, Kesheng; Campbell, Scott; Lau, Stephen; Fisk, Mike; Gavrilov, Eugene; Kent, Alex; Davis, Christopher E.; Olinger,Rick; Young, Rob; Prewett, Jim; Weber, Paul; Caudell, Thomas P.; Bethel,E. Wes; Smith, Steve
2005-09-01
Our analytics challenge is to identify, characterize, and visualize anomalous subsets of large collections of network connection data. We use a combination of HPC resources, advanced algorithms, and visualization techniques. To effectively and efficiently identify the salient portions of the data, we rely on a multi-stage workflow that includes data acquisition, summarization (feature extraction), novelty detection, and classification. Once these subsets of interest have been identified and automatically characterized, we use a state-of-the-art-high-dimensional query system to extract data subsets for interactive visualization. Our approach is equally useful for other large-data analysis problems where it is more practical to identify interesting subsets of the data for visualization than to render all data elements. By reducing the size of the rendering workload, we enable highly interactive and useful visualizations. As a result of this work we were able to analyze six months worth of data interactively with response times two orders of magnitude shorter than with conventional methods.
The South America VLF Network - SAVNET: Achievements, Latest Results and Future Directions
Raulin, J.
2013-05-01
In this paper we present recent results obtained by the South America VLF Network (SAVNET). The use of the VLF technique by tracking subionospheric propagation anomalies appears as a very promising tool to study various aspects of Space Weather disturbances. On long timescales it is possible to indirectly monitor the solar Lyman-alpha radiation along the solar cycles. Short time phenomena like solar explosive events can be observed with 100% probability, even for the small intensity events. The effect of high-energy precipitating solar particles can be tracked in the low ionosphere. The same technique is also relevant to study the ionospheric perturbations caused by geomagnetic storms on typical timescales of a day to few days. Extra solar and terrestrial high-energy phenomena are naturally detected in the very sensitive low ionospheric plasma, as Gamma-ray bursts and Soft Gamma-ray repeaters. Finally, the remote sensing of the low ionosphere is also used to search for seismic-electromagnetic effects prior to Earthquakes. At the present time, SAVNET is composed of nine (9) tracking receiver stations in Brazil, Peru, Argentina and Mexico. In this presentation we will describe our future plans for expanding the array. Eastern Europe, Ecuador and Asia are good host candidates to participate in these forthcoming activities. The array expansion is necessary to improve the probability detection of very high-energy remote phenomena, and to demonstrate that these processes of great astrophysical importance can be easily detected using a cheap and simple technique.
Methods and Results for a Global Precipitation Measurement (GPM) Validation Network Prototype
Morris, Kenneth R.; Schwaller, Mathew R.
2010-01-01
As one component of a ground validation system to meet requirements for the upcoming Global Precipitation Measurement (GPM) mission, a quasi-operational prototype a system to compare satellite- and ground-based radar measurements has been developed. This prototype, the GPM Validation Network (VN), acquires data from the Precipitation Radar (PR) on the Tropical Rainfall Measuring Mission (TRMM) satellite and from ground radar (GR) networks in the continental U.S. and participating international sites. PR data serve as a surrogate for similar observations from the Dual-frequency Precipitation Radar (DPR) to be present on GPM. Primary goals of the VN prototype are to understand and characterize the variability and bias of precipitation retrievals between the PR and GR in various precipitation regimes at large scales, and to improve precipitation retrieval algorithms for the GPM instruments. The current VN capabilities concentrate on comparisons of the base reflectivity observations between the PR and GR, and include support for rain rate comparisons. The VN algorithm resamples PR and GR reflectivity and other 2-D and 3-D data fields to irregular common volumes defined by the geometric intersection of the instrument observations, and performs statistical comparisons of PR and GR reflectivity and estimated rain rates. Algorithmic biases and uncertainties introduced by traditional data analysis techniques are minimized by not performing interpolation or extrapolation of data to a fixed grid. The core VN dataset consists of WSR-88D GR data and matching PR orbit subset data covering 21 sites in the southeastern U. S., from August, 2006 to the present. On average, about 3.5 overpass events per month for these WSR-88D sites meet VN criteria for significant precipitation, and have matching PR and GR data available. This large statistical sample has allowed the relative calibration accuracy and stability of the individual ground radars, and the quality of the PR reflectivity
Report #09-P-0227, August 31, 2009. Vulnerability testing conducted in April 2009 of EPA’s Research Triangle Park Finance Center network identified Internet Protocol addresses with several highrisk vulnerabilities.
Wireless M-Bus Sensor Networks for Smart Water Grids: Analysis and Results
National Research Council Canada - National Science Library
Spinsante, S; Squartini, S; Gabrielli, L; Pizzichini, M; Gambi, E; Piazza, F
2014-01-01
Wireless sensor network technologies are experiencing an impressive development, as they represent one of the building blocks upon which new paradigms, such as Internet of Things and Smart Cities, may be implemented...
National Research Council Canada - National Science Library
Andorf, Sandra; Meyer, Rhonda C; Selbig, Joachim; Altmann, Thomas; Repsilber, Dirk
2012-01-01
To contribute to a further insight into heterosis we applied an integrative analysis to a systems biological network approach and a quantitative genetics analysis towards biomass heterosis in early...
European Central Bank ; Center for Financial Studies (CFS)
2008-01-01
In April 2002 the European Central Bank (ECB) and the Center for Financial Studies (CFS) launched the ECB-CFS Research Network to promote research on “Capital Markets and Financial Integration in Europe”. The ECB-CFS research network aims at stimulating top-level and policy-relevant research, significantly contributing to the understanding of the current and future structure and integration of the financial system in Europe and its international linkages with the United States and Japan. This...
DEFF Research Database (Denmark)
Wiechowski, Wojciech Tomasz; Lykkegaard, Jan; Bak, Claus Leth
2007-01-01
In this paper two methods of validation of transmission network harmonic models are introduced. The methods were developed as a result of the work presented in [1]. The first method allows calculating the transfer harmonic impedance between two nodes of a network. Switching a linear, series network...... are used for calculation of the transfer harmonic impedance between the nodes. The determined transfer harmonic impedance can be used to validate a computer model of the network. The second method is an extension of the fist one. It allows switching a series element that contains a shunt branch...... component that links the nodes causes a variation of the background harmonic voltage distortion at the nodes. Harmonic current in the series element is measured together with the harmonic voltages at both nodes, before and after the switching. Obtained incremental values of harmonic voltages and the current...
Does an interdisciplinary network improve dementia care? Results from the IDemUck-study.
Köhler, Leonore; Meinke-Franze, Claudia; Hein, Jürgen; Fendrich, Konstanze; Heymann, Romy; Thyrian, Jochen René; Hoffmann, Wolfgang
2014-01-01
Most persons with dementia live at home and are treated in the primary care. However, the ambulatory health care system in Germany contains a lot of "interface problems" and is not optimized for the future challenges. Innovative concepts like regional networks in dementia care exist on a project level and need to be tested for efficacy to encourage implementation. The goal of the study is the scientific evaluation of an already existing regional dementia network. Prospective randomized controlled trial of 235 community-living elderly with dementia and their family caregivers of network treatment (n=117) compared to usual care (n=118) in a predominantly rural region. The allocation to intervention or control group was based on network membership of their General Practitioner. Intervention patients received diagnostic evaluation and subsequent treatment according to network guidelines. Main outcome measures were the early contact with a neurologic or psychiatric specialist and dementia-specific medication as well as quality of life of the patients, and as secondary outcomes caregiver burden and caregiver health-related quality of life. Network patients were more likely to receive antidementive drugs (50.5 % vs. 35.8 %; p=0.035) and had more often contact to a neurologist (18.6 % vs. 2.8 %; pinterdisciplinary regional network solelyprovides measurable advantages with respect to the provision of dementia-specific medication and utilization of medical treatment i.e. referral rates to specialists. Further evaluation research is needed to identify relevant mechanismsof collaborative processes with respect to their impact on patient and caregiver related outcomes.
Local Seismological Networks in Northern Baja California: Some Interpretation of Results.
Frez, J.; Acosta, J.; Nava, F.; Gonzalez, J.; Alvarez, M.
2002-12-01
Since 1997, we have installed local seismological networks in northern Baja California (Reftek stations, three digital components, one to four months operation, covering areas of about 50 km x 50 km) for detailed microseismicity surveys of several fault systems in the region: Cerro Prieto, San Miguel, Agua Blanca, Sierra Juarez, and areas in between. Immediate results are location of about 1500 hypocenters, determination of about 400 focal mechanisms, and some structural information on the crust. In this presentation, we focus on: a) a summary of the spatial distribution of the hypocenters, focal mechanisms, and P and T axes; b) the role of the Ojos Negros Valley in the regional seismotectonics, and c) the existence of orthogonal alignments of epicenters not necessarily associated with mapped fault traces. Most of the activity is not clearly associated with fault traces: the exception is the SE segment of the San Miguel fault, the same one where destructive earthquakes occurred in 1954 and 1956. Most of the activity appears to be correlated with valleys (Ojos Negros, Trinidad-San Matias), or to simply occur between fault traces, or to belong to epicenter alignments of ~15 km or more in length which are part of longer segments that are apparent in regional seismicity maps (SCSN and RESNOM catalogs). This regional and local alignments show an orthogonal pattern. In a simple interpretation, they could represent a very new fracture proccess in a still mostly homogeneous material, not yet expressed as fault ruptures. All P and T axes azimuthal distributions from the various areas of study show a well defined global maximum consistent with the direction of regional stresses (about NS and EW, for P and T axes, respectively). However, the P axes are distributed on the focal sphere as an almost NS strip, particularly for the Ojos Negros Valley, indicating an extensional regime.
Ionov, D. V.; Poberovskii, A. V.
2017-03-01
The results of spectroscopic measurements of tropospheric NO2 content performed on a closed route along the circular road around the city of St. Petersburg in 2012, 2014, and 2015 are presented. A procedure for determining the integral emission of NO x based on the data of measurements on the route enveloping the sources under study is described. An analysis of the experimental data together with the results of a numerical simulation of air pollutant dispersion (the HYSPLIT model) provided an estimate of the total volume of NO x emitted by all sources located inside the circular road. The average emission rate of NO x according to the sources of the megacity of St. Petersburg is 57000 t/yr, which correlates satisfactorily with the official data of a municipal inventory of the sources of air pollution (62000-63 000 t/yr).
Agus, M.; Mascia, M. L.; Fastame, M. C.; Melis, V.; Pilloni, M. C.; Penna, M. P.
2015-02-01
A body of literature shows the significant role of visual-spatial skills played in the improvement of mathematical skills in the primary school. The main goal of the current study was to investigate the impact of a combined visuo-spatial and mathematical training on the improvement of mathematical skills in 146 second graders of several schools located in Italy. Participants were presented single pencil-and-paper visuo-spatial or mathematical trainings, computerised version of the above mentioned treatments, as well as a combined version of computer-assisted and pencil-and-paper visuo-spatial and mathematical trainings, respectively. Experimental groups were presented with training for 3 months, once a week. All children were treated collectively both in computer-assisted or pencil-and-paper modalities. At pre and post-test all our participants were presented with a battery of objective tests assessing numerical and visuo-spatial abilities. Our results suggest the positive effect of different types of training for the empowerment of visuo-spatial and numerical abilities. Specifically, the combination of computerised and pencil-and-paper versions of visuo-spatial and mathematical trainings are more effective than the single execution of the software or of the pencil-and-paper treatment.
Directory of Open Access Journals (Sweden)
J. M. Schmidt
1995-05-01
Full Text Available This work follows the paper titled "Spatial transport and spectral transfer of solar wind turbulence composed of Alfvén waves and convective structures I: The theoretical model", and deals with the detailed physics and numerical solution of a two-component solar wind model, consisting of small-scale Alfvén waves and convected structures. In particular, we present numerical results which qualitatively reflect many of the observed features of the radial and spectral evolution of the turbulent energies, the residual energy, the cross-helicity and Alfvén-ratio in high-speed solar wind streams. These features are the following: the formation of a characteristic "inclined eye", which evolves between the energy spectra displayed over the frequency axis and tends to close in the radial development of the spectra, a steepening of all spectra towards Kolmogorov-like f-5/3 spectra, the development of the normalized cross-helicity towards a constant not much less than one and the formation of a "trough" form of the Alfvén ratio with a z-shaped left boundary, By weighting special terms in the equations differently, we can also cast light on the physical role of parametric conversion model terms, wave-structure scattering model terms, nonlinear terms, spherical expansion terms and their effects on the radial evolution of turbulent energies in high-speed solar wind streams.
Dietrich, Tim; Hinderer, Tanja
2017-06-01
We present a detailed comparison between tidal effective-one-body (EOB) models and new state-of-the-art numerical relativity simulations for nonspinning binary neutron star systems. This comparison is the most extensive one to date, covering a wide range in the parameter space and encompassing the energetics of the binary, the periastron advance, the time and frequency evolution of the gravitational wave phase for the dominant mode, and several subdominant modes. We consider different EOB models with tidal effects that have been proposed, including the model with dynamical tides of Hinderer et al. [Phys. Rev. Lett. 116, 181101 (2016), 10.1103/PhysRevLett.116.181101] and the gravitational self-force (GSF) inspired tidal EOB model of Bernuzzi et al. [Phys. Rev. Lett. 114, 161103 (2015), 10.1103/PhysRevLett.114.161103]. The EOB model with dynamical tides leads to the best representation of the systems considered here; however, the differences to the GSF-inspired model are small. A common feature is that for systems where matter effects are large, i.e., stiff equations of state or small total masses, all EOB models underestimate the tidal effects and differences to the results from numerical relativity simulations become noticeable near the merger. We analyze this regime to diagnose the shortcomings of the models in the late inspiral, where the two neutron stars are no longer isolated bodies moving in vacuum. Our work will serve to guide further advances in modeling these systems.
Directory of Open Access Journals (Sweden)
Paweł WRONA
2016-07-01
Full Text Available The paper presents the results of numerical simulations into the distribution of methane concentration at the intersec-tion of two excavations with a fan (turned on giving the air stream to the area of the crossing. Assumed case represents emergency situation related to the unexpected flow of methane from an excavation and its mixing with fresh air. It is possible when sudden gas outburst takes place, methane leaks from methane drainage system or gas leaks out the pipelines of underground coal gasification devices. Three options were considered – corresponding to three different speeds of the jet fan. They represent three stages of fan work. First – low air speed is forced by a pneumatic fan, when electricity is cut off after high methane concentration detection. Medium speed can be forced by pneumatic-electric device when methane concentration allows to turn on the electricity. Third, the highest speed is for electric fans. Simula-tions were carried out in the Fire Dynamics Simulator (FDS belongs to the group of programs Computational Fluid Dy-namics (CFD. The governing equations are being solved in a numerical way. It was shown that proposed solution allows partial dilution of methane in every variant of speed what should allow escape of the miners from hazardous area.
[Results of the evaluation of German benchmarking networks funded by the Ministry of Health].
de Cruppé, Werner; Blumenstock, Gunnar; Fischer, Imma; Selbmann, Hans-Konrad; Geraedts, Max
2011-01-01
Nine out of ten demonstration projects on clinical benchmarking funded by the German Ministry of Health were evaluated. Project reports and interviews were uniformly analysed using a list of criteria and a scheme to categorize the realized benchmarking approach. At the end of the funding period four benchmarking networks had implemented all benchmarking steps, and six were continued after funding had expired. The improvement of outcome quality cannot yet be assessed. Factors promoting the introduction of benchmarking networks with regard to organisational and process aspects of benchmarking implementation were derived. Copyright © 2011. Published by Elsevier GmbH.
Ziegler, Gerhard
2011-01-01
Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. This book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a reference guide for s
Khabaza, I M
1960-01-01
Numerical Analysis is an elementary introduction to numerical analysis, its applications, limitations, and pitfalls. Methods suitable for digital computers are emphasized, but some desk computations are also described. Topics covered range from the use of digital computers in numerical work to errors in computations using desk machines, finite difference methods, and numerical solution of ordinary differential equations. This book is comprised of eight chapters and begins with an overview of the importance of digital computers in numerical analysis, followed by a discussion on errors in comput
Directory of Open Access Journals (Sweden)
Sun Shaoan
2011-11-01
Full Text Available A statistical correlation method is used to study the effect of instability of the calculation datum (used in traditional method of indirect adjustment on calculated gravity results, using data recorded by Long-men Mountain regional gravity network during 1996 – 2007. The result shows that when this effect is corrected, anomalous gravity changes before the 2008 Wenchuan Ms8.0 earthquake become obvious and characteristically distinctive. Thus the datum-stability problem must be considered when processing and analyzing data recorded by a regional gravity network.
Moon, Jiwon; Yeo, In Wook
2013-04-01
Underground unlined caverns have been constructed in fractured rocks to stockpile oil and petroleum products, where they are hydraulically contained by natural groundwater pressure. However, for the case that natural groundwater pressure is not maintained at the required level, water curtain boreholes, through which water is injected, are often constructed above the cavern as engineering barrier to secure water pressure enough to overwhelm the operational pressure of the cavern. For secure containment of oil and petroleum products inside the cavern, it is essential to keep water pressure around the cavern higher than operational pressure of the cavern using either natural groundwater pressure or engineering barrier. In the Republic of Korea, a number of underground stockpile bases are being operated by Korea National Oil Corporation (KNOC) and private companies, most of which have water curtain system. The criterion that KNOC adopts for water curtain system design and operation such as the vertical distance from the cavern and operational injection rate is based on the Åberg hypothesis that the vertical hydraulic gradient should be larger than one. The criterion has been used for maintaining oil storage cavern without its thorough review. In this study, systematic numerical works have been done for reviewing the Åberg criterion. As groundwater predominantly takes places through fractures in underground caverns, discrete fracture modeling approach is essential for this study. Fracture data, obtained from boreholes drilled at the stage of site investigation at the Yeosu stockpile base in Korea, were statistically analyzed in terms of orientation and intensity, which were used to generate the site descriptive three dimensional fracture networks. Then, groundwater flow modeling has been carried out for the fracture networks. Constant head boundaries were applied along the circumference of the cavern and water curtain boreholes. Main flow channel and hydraulic
Self-organizing cooperative sensor network for remote surveillance: current results
Burne, Richard A.; Buczak, Anna L.; Jin, Yaochu; Jamalabad, Vikram R.; Kadar, Ivan; Eadan, Eitan R.
1999-07-01
The capabilities of unattended ground sensors (UGSs) have steadily improved and have been shown to be of value in various military missions. Today's UGS are multi-functional, integrated sensor platforms that can detect and locate a wide variety of ground-based and airborne targets. The rather large size (> 1 cubic foot) and relatively expensive cost of these integrated platforms are two main drawbacks for remote surveillance applications that support rapidly deployable, small unit operations. As an alternative, remote surveillance may be possible with smaller, less costly sensors that work cooperatively together as a network. The objective of this study was to develop algorithms that can optimally organized and adaptively control a network of UGSs in order to achieve a surveillance mission. In the present study, the sensor network, a random distribution of acoustic sensors over a surveillance area, is tasked to detect and track any targets entering into the surveillance area. In addition, the sensor network is required to maximize its tracking accuracy and minimize its power utilization.
Edmonds, Lisa A.
2016-01-01
This article examines Verb Network Strengthening Treatment (VNeST), a relatively new treatment approach for anomia in people with aphasia. The VNeST protocol aims to promote generalization to increased lexical retrieval of untrained words across a hierarchy of linguistic tasks, including single-word naming of nouns and verbs, sentence production,…
Results from the industrial network 2002[Norway]; Resultater fra industrinettverket 2002
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-07-01
The report presents a survey of various activities within the industrial network with emphasis on energy consumption and conservation and alternative energy systems. There are sections on the Enova counselling service and auxiliary measures in the energy activities illustrated by industrial examples. (tk)
The E-Business Research Network: summary of the results of the Dutch pilot survey
A. van der Wiele (Ton); A.R.T. Williams (Roger); J.D. van Iwaarden (Jos); M. Wilson (Melanie); B.G. Dale (Barry)
2001-01-01
textabstractA project has been started with the intention to develop an E-Business Research Network on E-business related research in business and management. The initiative has been taken in co-operation between Erasmus University and UMIST to develop a project in which the first stage concerns the
Goals, Motivation for, and Outcomes of Personal Learning through Networks: Results of a Tweetstorm
Sie, Rory L. L.; Pataraia, Nino; Boursinou, Eleni; Rajagopal, Kamakshi; Margaryan, Anoush; Falconer, Isobel; Bitter-Rijpkema, Marlies; Littlejohn, Allison; Sloep, Peter B.
2013-01-01
Recent developments in the use of social media for learning have posed serious challenges for learners. The information overload that these online social tools create has changed the way learners learn and from whom they learn. An investigation of learners' goals, motivations and expected outcomes when using a personal learning network is…
Ashrafian, Hutan; Toma, Tania; Harling, Leanne; Kerr, Karen; Athanasiou, Thanos; Darzi, Ara
2014-09-01
The global epidemic of obesity continues to escalate. Obesity accounts for an increasing proportion of the international socioeconomic burden of noncommunicable disease. Online social networking services provide an effective medium through which information may be exchanged between obese and overweight patients and their health care providers, potentially contributing to superior weight-loss outcomes. We performed a systematic review and meta-analysis to assess the role of these services in modifying body mass index (BMI). Our analysis of twelve studies found that interventions using social networking services produced a modest but significant 0.64 percent reduction in BMI from baseline for the 941 people who participated in the studies' interventions. We recommend that social networking services that target obesity should be the subject of further clinical trials. Additionally, we recommend that policy makers adopt reforms that promote the use of anti-obesity social networking services, facilitate multistakeholder partnerships in such services, and create a supportive environment to confront obesity and its associated noncommunicable diseases. Project HOPE—The People-to-People Health Foundation, Inc.
A long-term environmental sensor network in a glacial environment: challenges and results
Martinez, K.; Hart, J. K.; Basford, P. J.; Gong, X.; Edwards, L.; Pethica, C.; Glacsweb Team
2011-12-01
We report the findings from wireless environmental sensor network installed at Skalafellsjökull, Iceland, which has now been deployed for three years. The scientific aim of the project was to use a sensor network to better understand subglacial processes in order to investigate the response of glaciers to climate change. The engineering aim was to produce a working environmental sensor network which could operate in a very challenging environment. The sensor network comprised: 1. Wireless subglacial probes which monitored the subglacial environment for 2 years. They were able to show the nature of the subglacial environment, in particular the occurrence of stick-slip motion. 2. Base Station on the glacier surface, collecting probe data, as well as GPS and weather data for 3 years. 3. Reference Station close to the glacier, collecting GPS and weather data for 2 years 4. Automatic web-data harvesting of weather, GPS recordings and web cams. A combination of this data allowed us to interpret glacier dynamics over the period, while evaluating the performance of the sensor network under extreme conditions. This paper will report on the most recent deployments which include; long range WiFi alongside GPRS backup for communications off-site, Python scripting of base station power-sensitive behaviour, adaptive sampling based on energy availability and trials of the Contiki operating system in the new custom wireless sensor nodes. Additional data streams have also been established by equipping the base station with geophones and putting a full weather station at the reference station. Further enhancements that have been made include moving further into the glacier in order to experience faster flows.
Grecu, Bogdan; Zahria, Bogdan; Manea, Elena; Neagoe, Cristian; Borleanu, Felix; Diaconescu, Mihai; Constantinescu, Eduard; Bala, Andrei
2017-04-01
The seismic activity in Romania is dominated by the intermediate-depth earthquakes occurring in Vrancea region, although weak to moderate crustal earthquakes are produced regularly in different areas of the country. The National Institute for Earth Physics (NIEP) built in the last years an impressive infrastructure for monitoring this activity, known as the Romanian Seismic Network (RSN). At present, RSN consists of 122 seismic stations, of which 70 have broadband velocity sensors and 42 short period sensors. One hundred and eleven stations out of 122 have accelerometer sensors collocated with velocity sensors and only 10 stations have only accelerometers. All the stations record continuously the ground motion and the data are transmitted in real-time to the Romanian National Data Center (RoNDC), in Magurele. Last year, NIEP has started a national project that addresses the characterization of all real-time seismic stations that constitute the RSN. We present here the steps that were undertaken and the preliminary results obtained since the beginning the project. The first two activities consisted of collecting all the existent technical and geological data, with emphasize on the latter. Then, we performed station noise investigations and analyses in order to characterize the noise level and estimate the resonances of the sites. The computed H/V ratios showed clear resonant peaks at different frequencies which correlate relatively well with the thickness of the sedimentary package beneath the stations. The polarization analysis of the H/V ratios indicates for some stations a strong directivity of the resonance peak which suggests possible topographic effects at the stations. At the same time, special attention was given to the estimation of the site amplification from earthquake data. The spectral ratios obtained from the analysis of more than 50 earthquakes with magnitudes (Mw) larger than 4.1 are characterized by similar resonance peaks as those obtained from
Energy Technology Data Exchange (ETDEWEB)
Webster, Jennifer B.; Erikson, Luke E.; Gastelum, Zoe N.; Lewis, Valerie A.; Best, Daniel M.; Hogan, Emilie A.; Chikkagoudar, Satish
2014-05-12
The illicit trafficking of strategic nuclear commodities (defined here as the goods needed for a covert nuclear program excluding special nuclear materials) poses a significant challenge to the international nuclear nonproliferation community. Export control regulations, both domestically and internationally, seek to inhibit the spread of strategic nuclear commodities by restricting their sale to parties that may use them for nefarious purposes. However, export controls alone are not sufficient for preventing the illicit transfer of strategic nuclear goods. There are two major pitfalls to relying solely on export control regulations for the deterrence of proliferation of strategic goods. First, export control enforcement today relies heavily on the honesty and willingness of participants to adhere to the legal framework already in place. Secondly, current practices focus on the evaluation of single records which allow for the necessary goods to be purchased separately and hidden within the thousands of legitimate commerce transactions that occur each day, disregarding strategic information regarding several purchases. Our research presents two preliminary data-centric approaches for investigating procurement networks of strategic nuclear commodities. Pacific Northwest National Laboratory (PNNL) has been putting significant effort into nonproliferation activities as an institution, both in terms of the classical nuclear material focused approach and in the examination of other strategic goods necessary to implement a nuclear program. In particular, the PNNL Signature Discovery Initiative (SDI) has codified several scientific methodologies for the detection, characterization, and prediction of signatures that are indicative of a phenomenon of interest. The methodologies and tools developed under SDI have already been applied successfully to problems in bio-forensics, cyber security and power grid balancing efforts and they have now made the nonproliferation of
Schmitz, R; Dünweg, B
2012-11-21
A new lattice method is presented in order to efficiently solve the electrokinetic equations, which describe the structure and dynamics of the charge cloud and the flow field surrounding a single charged colloidal sphere, or a fixed array of such objects. We focus on calculating the electrophoretic mobility in the limit of small driving field, and systematically linearize the equations with respect to the latter. This gives rise to several subproblems, each of which is solved by a specialized numerical algorithm. For the total problem we combine these solvers in an iterative procedure. Applying this method, we study the effect of the screening mechanism (salt screening versus counterion screening) on the electrophoretic mobility, and find a weak non-trivial dependence, as expected from scaling theory. Furthermore, we find that the orientation of the charge cloud (i.e. its dipole moment) depends on the value of the colloid charge, as a result of a competition between electrostatic and hydrodynamic effects.
Jacques, Ian
1987-01-01
This book is primarily intended for undergraduates in mathematics, the physical sciences and engineering. It introduces students to most of the techniques forming the core component of courses in numerical analysis. The text is divided into eight chapters which are largely self-contained. However, with a subject as intricately woven as mathematics, there is inevitably some interdependence between them. The level of difficulty varies and, although emphasis is firmly placed on the methods themselves rather than their analysis, we have not hesitated to include theoretical material when we consider it to be sufficiently interesting. However, it should be possible to omit those parts that do seem daunting while still being able to follow the worked examples and to tackle the exercises accompanying each section. Familiarity with the basic results of analysis and linear algebra is assumed since these are normally taught in first courses on mathematical methods. For reference purposes a list of theorems used in the t...
Zanardo, S.; Zaliapin, I.; Foufoula-Georgiou, E.
2013-03-01
The topology of river networks has been a subject of intense research in hydro-geomorphology, with special attention to self-similar (SS) structures that allow one to develop concise representations and scaling frameworks for hydrological fluxes. Tokunaga self-similar (TSS) networks represent a particularly popular two-parameter class of self-similar models, commonly accepted in hydrology but rarely tested rigorously. In this paper we (a) present a statistical framework for testing the TSS assumption and estimating the Tokunaga parameters; (b) present an improved method for estimating the Horton ratios using the Tokunaga parameters; (c) evaluate the proposed testing and estimation frameworks using synthetic TSS networks with a broad range of parameters; (d) perform self-similar analysis of 408 river networks of maximum order Ω ≥ 6 from 50 catchments across the US; and (e) use the Tokunaga parameters as discriminatory metrics to explore climate effects on network topology. We find that the TSS assumption cannot be rejected in the majority of the examined river networks. The theoretical expression for the Horton ratios based on the estimated Tokunaga parameters in the TSS networks provides a significantly better approximation to the true ratios than the conventional linear regression approach. A correlation analysis shows that the Tokunaga parameter c, which determines the degree of side-branching, exhibits significant dependence on the hydroclimatic variables of the basin: storm frequency, storm duration, and mean annual rainfall, offering the possibility of relating climate to landscape dissection. While other possible physical controls have been neglected in this study, this result is intriguing and warrants further analysis.
Directory of Open Access Journals (Sweden)
David Sadowsky
2016-11-01
Full Text Available Background: Ex vivo machine perfusion (MP can better preserve organs for transplantation. We have recently reported on the first application of a MP protocol in which liver allografts were fully oxygenated, under dual pressures and subnormothermic conditions, with a new hemoglobin-based oxygen carrier solution specifically developed for ex vivo utilization. In those studies, MP improved organ function post-operatively and reduced inflammation in porcine livers. Herein, we sought to refine our knowledge regarding the impact of MP by defining dynamic networks of inflammation in both tissue and perfusate. Methods: Porcine liver allografts were preserved either with MP (n = 6 or with cold static preservation (CSP; n = 6, then transplanted orthotopically after 9 h of preservation. Fourteen inflammatory mediators were measured in both tissue and perfusate during liver preservation at multiple time points, and analyzed using Dynamic Bayesian Network (DyBN inference to define feedback interactions, as well as Dynamic Network Analysis (DyNA to define the time-dependent development of inflammation networks.Results: Network analyses of tissue and perfusate suggested an NLRP3 inflammasome-regulated response in both treatment groups, driven by the pro-inflammatory cytokine interleukin (IL-18 and the anti-inflammatory mediator IL-1 receptor antagonist (IL-1RA. Both DyBN and DyNA suggested a reduced role of IL-18 and increased role of IL-1RA with MP, along with increased liver damage with CSP. DyNA also suggested divergent progression of responses over the 9 h preservation time, with CSP leading to a stable pattern of IL-18-induced liver damage and MP leading to a resolution of the pro-inflammatory response. These results were consistent with prior clinical, biochemical, and histological findings after liver transplantation. Conclusion: Our results suggest that analysis of dynamic inflammation networks in the setting of liver preservation may identify novel
Buda, Andrzej
2016-01-01
Information spread plays crucial role in risk management in case of environmental danger. The structure of local society may be well described by social network analysis. We have investigated the role of hubs within that concept. In case of danger, there are two different strategies of information management: 1) information spread that leads to awareness of the whole society 2) keeping the whole information in secret under control that leads to a partial social awareness, available to a small number of people only. In our model, the probability of information spread between two nodes is inverse proportional to connectivity of the next node because people who have a lot of connections are more immune. We have applied agent-based modelling on Barabasi Albert networks to explore various scenarios of information spread. We have considered recent arsenic environmental danger in G{\\l}og\\'ow and Legnica (Copper Basin) according to the official available data (2015 - 2016) from social network analysis point of view. ...
Michael, A.; Opher, M.; Toth, G.; Borovikov, D.; Tenishev, V.; Provornikova, E.
2016-12-01
Several studies suggest that there is a need to move beyond ideal MHD in order to explain the Voyager 1 and 2 observations (Richardson et al. 2013; Michael et al. 2015). In the numerical simulations there is inherent and unavoidable numerical dissipation in the heliospheric current sheet that greatly exceeds the realistic dissipation rates. The magnetic dissipation inherent in modeling the heliospheric current sheet offers us a chance to explore non-ideal MHD effects in the heliosphere and heliosheath. In this work we investigate the role magnetic dissipation has on the overall structure of the heliosheath by comparing models describing the solar magnetic field both as a unipole and a dipole. We show that magnetic dissipation reduces the solar wind magnetic field strength over a significant fraction of the heliosheath. The region affected by the dissipation is increased when 11-year solar cycle variations in the solar wind are included and we discuss how this alters our prediction for Voyager 1 and 2 observations. We also present a new kinetic-MHD model of the outer heliosphere, which couples the Outer Heliosphere (OH) and Particle Tracker (PT) components within the Space Weather Modeling Framework (SWMF). The OH component uses the BATS-R-US MHD solver, a highly parallel, 3D, and block-adaptive code. The PT component is based on the Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct simulation Monte Carlo model that solves the Boltzmann equation for the motion and interaction of a multi-species gas within a plasma. The neutrals and plasma in the outer heliosphere are coupled through charge-exchange; the OH-PT model combines the MHD solution for the plasma with the kinetic solution for the neutrals to form a self-consistent model of the heliosphere. We present preliminary results of this model and discuss the implications on the structure of the heliosphere.
Nastos, P. T.; Matsangouras, I. T.; Chronis, T. G.
2014-07-01
Lightning is a natural phenomenon in the atmosphere, being a major cause of storm related deaths, main trigger of forest fires and affects many electrochemical systems of the body. Significant scientific interest has come up in the last decades, as numerous lightning detection networks have been established in operational basis, providing lightning data to assess and mitigate lightning impact to the local society by spatio-temporal analysis. In this study, a preliminary analysis of spatial and temporal variabilities of recorded lightnings over Greece during the period from January 2008 to December 2009 is presented. The data for retrieving the location and time-of-occurrence (TOA) of lightning were acquired from the Hellenic National Meteorological Service (HNMS). An operational precision lightning network (PLN) has been established since 2007 by HNMS, consisting of eight time-of-arrival (TOA) sensors, spatially distributed across Greek territory. The spatial variability of lightnings revealed their incidence within specific geographical sub-regions while the temporal variability concerns the seasonal and monthly distributions. All the analyses were carried out with respect to cloud to cloud (CC), cloud to ground (CG) and ground to cloud (GC) lightnings, within the examined time period. During the autumn season, lightning activity was the highest, followed by summer and spring. Higher frequencies of stokes appear over Ionian Sea and Aegean Sea than over land during winter period against continental mountainous regions during summer period.
Directory of Open Access Journals (Sweden)
Milewski Robert
2016-12-01
Full Text Available There are high hopes for using the artificial neural networks (ANN technique to predict results of infertility treatment using the in vitro fertilization (IVF method. Some reports show superiority of the ANN approach over conventional methods. However, fully satisfactory results have not yet been achieved. Hence, there is a need to continue searching for new data describing the treatment process, as well as for new methods of extracting information from these data. There are also some reports that the use of principal component analysis (PCA before the process of training the neural network can further improve the efficiency of generated models. The aim of the study herein presented was to verify the thesis that the use of PCA increases the effectiveness of the prediction by ANN for the analysis of results of IVF treatment. Results for the PCA-ANN approach proved to be slightly better than the ANN approach, however the obtained differences were not statistically significant.
Scalable Virtual Network Mapping Algorithm for Internet-Scale Networks
Yang, Qiang; Wu, Chunming; Zhang, Min
The proper allocation of network resources from a common physical substrate to a set of virtual networks (VNs) is one of the key technical challenges of network virtualization. While a variety of state-of-the-art algorithms have been proposed in an attempt to address this issue from different facets, the challenge still remains in the context of large-scale networks as the existing solutions mainly perform in a centralized manner which requires maintaining the overall and up-to-date information of the underlying substrate network. This implies the restricted scalability and computational efficiency when the network scale becomes large. This paper tackles the virtual network mapping problem and proposes a novel hierarchical algorithm in conjunction with a substrate network decomposition approach. By appropriately transforming the underlying substrate network into a collection of sub-networks, the hierarchical virtual network mapping algorithm can be carried out through a global virtual network mapping algorithm (GVNMA) and a local virtual network mapping algorithm (LVNMA) operated in the network central server and within individual sub-networks respectively with their cooperation and coordination as necessary. The proposed algorithm is assessed against the centralized approaches through a set of numerical simulation experiments for a range of network scenarios. The results show that the proposed hierarchical approach can be about 5-20 times faster for VN mapping tasks than conventional centralized approaches with acceptable communication overhead between GVNCA and LVNCA for all examined networks, whilst performs almost as well as the centralized solutions.
Second-Year Results from the Circumarctic Lakes Observation Network (CALON) Project
Hinkel, K. M.; Arp, C. D.; Beck, R. A.; Eisner, W. R.; Frey, K. E.; Gaglioti, B.; Grosse, G.; Jones, B. M.; Kim, C.; Lenters, J. D.; Liu, H.; Townsend-Small, A.
2013-12-01
Beginning in April 2012, over 55 lakes in northern Alaska were instrumented as the initial phase of CALON, a project designed to document landscape-scale variability in physical and biogeochemical processes of Arctic lakes developed atop permafrost. The current network has nine observation nodes along two latitudinal transects that extend from the Arctic Ocean south 200 km to the foothills of the Brooks Range. At each node, six representative lakes of differing area and depth were instrumented at different intensity levels, and a suite of instruments were deployed to collect field measurements on lake physiochemistry, lake-surface and terrestrial climatology, and lake bed and permafrost temperature. Each April, sensors measuring water temperature and water depth are deployed through the ice and water samples are collected. Sensors are downloaded from lakes and meteorological stations in August, recording a timeline of lake regimes and events from ice decay to the summertime energy and water balance. In general, lake ice thickness increased with latitude. In 2012, ice on deeper (>2 m) lakes was about 1.4 m thick in the Arctic Foothills and 1.7 m thick near the Arctic Ocean coast. Lake ice thickness was about 20 cm thicker in winter 2013 although winter temperatures were several degrees warmer than the previous year; this is likely due to a thinner snow cover in 2013. Lake ice elevations agree with this general trend, showing higher absolute elevation in April 2013 compared to 2012 for most of the surveyed lakes. Regionally, ice-off occurs 2-4 weeks later on lakes near the coast, although there is significant inter-lake variability related to lake depth. Following ice-off, rapid lake warming occurs and water temperature varies synchronously in response to synoptic weather variations and associated changes in net radiation and turbulent heat fluxes. Average mid-summer (July) lake temperatures spanned a relatively wide range in 2012 from 7°C to 18°C, with higher
First Year Results from the Circumarctic Lakes Observation Network (CALON) Project
Hinkel, K. M.; Arp, C. D.; Frey, K. E.; Lenters, J. D.; Beck, R. A.; Eisner, W. R.; Gaglioti, B.; Grosse, G.; Jones, B. M.; Kim, C.; Liu, H.; Townsend-Small, A.
2012-12-01
In April 2012, instruments were deployed in over 50 lakes in northern Alaska as the initial phase of CALON, a project designed to observe short- and long-term variability in physical, limnological and biogeochemical processes in Arctic lakes. The network currently consists of nine observation nodes on two parallel transects extending from the Arctic Ocean south to the Brooks Range Foothills. At each node, at least six representative lakes that vary by surface area and depth were instrumented at different intensity levels: basic, enhanced and comprehensive. At each node we deployed a suite of instrumentation and collected a variety of field measurements. This approach allows for the study of lakes and their diversity across strong physical and biological gradients. To date we have established sites at a wide variety of Arctic lake types; 25 are thermokarst lakes set in ice-rich, fine-grained marine surficial sediments (Outer Coastal Plain), 6 lakes are in alluvial/aeolian sediments (Inner Coastal Plain) and 6 are in ice-rich silt (Arctic Foothills Yedoma), 5 are depressional lakes formed in a late Pleistocene sand sheet (Ikpikpuk Sand Sea), 6 represent glacial thermokarst or kettle lakes near the Brooks Range (Toolik region), 7 lakes are of fluvial or deltaic origin (Fish Creek basin, Ikpikpuk Delta), and Teshekpuk Lake, the largest lake in Arctic Alaska, is of a complex origin. In April, sensors measuring water temperature and water depth were deployed through the ice cover, water samples were collected, and real-time time lapse cameras were installed to capture snow melt and ice-off. Sensors were recovered from lakes and meteorological stations in August, recording lake regimes and events from ice decay and snowmelt influx to open-water warming and water balance. In general, lake ice thickness increased with latitude; in lakes deeper than 2 m, ice was about 1.4 m thick in the Arctic Foothills and 1.7 m thick near the coast of the Arctic Ocean with inter
Gregoire, C.; Joesten, P.K.; Lane, J.W.
2006-01-01
Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature
Bright, William
In most languages encountered by linguists, the numerals, considered as a paradigmatic set, constitute a morpho-syntactic problem of only moderate complexity. The Indo-Aryan language family of North India, however, presents a curious contrast. The relatively regular numeral system of Sanskrit, as it has developed historically into the modern…
Rao, G Shanker
2006-01-01
About the Book: This book provides an introduction to Numerical Analysis for the students of Mathematics and Engineering. The book is designed in accordance with the common core syllabus of Numerical Analysis of Universities of Andhra Pradesh and also the syllabus prescribed in most of the Indian Universities. Salient features: Approximate and Numerical Solutions of Algebraic and Transcendental Equation Interpolation of Functions Numerical Differentiation and Integration and Numerical Solution of Ordinary Differential Equations The last three chapters deal with Curve Fitting, Eigen Values and Eigen Vectors of a Matrix and Regression Analysis. Each chapter is supplemented with a number of worked-out examples as well as number of problems to be solved by the students. This would help in the better understanding of the subject. Contents: Errors Solution of Algebraic and Transcendental Equations Finite Differences Interpolation with Equal Intervals Interpolation with Unequal Int...
Chatzopoulos, Georgios; Papadopoulos, Ilias; Vallianatos, Filippos
2015-04-01
The number and quality of seismological networks in Europe has increased in the past decades. Nevertheless, the need for localized networks monitoring areas of great seismic and scientific interest is constant. Hellenic Seismological Network of Crete (HSNC) covers this need for the vicinity of the South Aegean Sea and Crete Island. In the present work with the use of Z-map software (www.seismo.ethz.ch) the spatial variability of Magnitude of Completeness (Mc) is calculated from HSNC's manual analysis catalogue of events for the period 2011 until today, proving the good coverage of HSNC in the areas. Furthermore the 2013, South Aegean seismicity where two large shallow earthquakes occurred in the vicinity of Crete Island, is discussed. The first event takes place on 15th June 2013 in the front of the Hellenic Arc, south from central Crete, while the second one on 12th October, 2013 on the western part of Crete. The two main shocks and their aftershock sequences have been relocated with the use of hypoinverse earthquake location software and an appropriate crust model. The HSNC identified more than 500 and 300 aftershocks respectively followed after the main events. The detailed construction of aftershocks catalogue permits the applicability of modern theories based on complexity sciences as described recently in the frame of non extensive statistical physics. In addition site effects in the stations locations are presented using event and noise recordings. This work was implemented through the project IMPACT-ARC in the framework of action "ARCHIMEDES III-Support of Research Teams at TEI of Crete" (MIS380353) of the Operational Program "Education and Lifelong Learning" and is co-financed by the European Union (European Social Fund) and Greek national funds References A. Tzanis and F. Vallianatos, "Distributed power-law seismicity changes and crustal deformation in the EW Hellenic Arc", Natural Hazards and Earth Systems Sciences, 3, 179-195, 2003 F. Vallianatos, G
Benyo, Theresa L.
2011-01-01
Flow matching has been successfully achieved for an MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment helped perform a thermodynamic cycle analysis to properly match the flows from an inlet employing a MHD energy bypass system (consisting of an MHD generator and MHD accelerator) on a supersonic turbojet engine. Working with various operating conditions (such as the applied magnetic field, MHD generator length and flow conductivity), interfacing studies were conducted between the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis. This paper further describes the analysis of a supersonic turbojet engine with an MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to a range of 0 to 7.0 Mach with specific net thrust range of 740 N-s/kg (at ambient Mach = 3.25) to 70 N-s/kg (at ambient Mach = 7). These results were achieved with an applied magnetic field of 2.5 Tesla and conductivity levels in a range from 2 mhos/m (ambient Mach = 7) to 5.5 mhos/m (ambient Mach = 3.5) for an MHD generator length of 3 m.
Qin, Mingpu; Shi, Hao; Zhang, Shiwei
2017-08-01
Optical lattice experiments with ultracold fermion atoms and quantum gas microscopy have recently realized direct measurements of magnetic correlations at the site-resolved level. We calculate the short-range spin-correlation functions in the ground state of the two-dimensional repulsive Hubbard model with the auxiliary-field quantum Monte Carlo (AFQMC) method. The results are numerically exact at half filling where the fermion sign problem is absent. Away from half filling, we employ the constrained path AFQMC approach to eliminate the exponential computational scaling from the sign problem. The constraint employs unrestricted Hartree-Fock trial wave functions with an effective interaction strength U , which is optimized self-consistently within AFQMC. Large supercells are studied, with twist averaged boundary conditions as needed, to reach the thermodynamic limit. We find that the nearest-neighbor spin correlation always increases with the interaction strength U , contrary to the finite-temperature behavior where a maximum is reached at a finite U value. We also observe a change of sign in the next-nearest-neighbor spin correlation with increasing density, which is a consequence of the buildup of the long-range antiferromagnetic correlation. We expect the results presented in this paper to serve as a benchmark as lower temperatures are reached in ultracold atom experiments.
Hermanstyne, Keith A; Green, Harold D; Cook, Ryan; Tieu, Hong-Van; Dyer, Typhanye V; Hucks-Ortiz, Christopher; Wilton, Leo; Latkin, Carl; Shoptaw, Steven
2018-02-07
and SettingBlack men who have sex with men (MSM) in the United States (U.S.) have disproportionately high HIV infection rates. Social networks have been shown to influence HIV risk behavior; however, little is known about whether they affect the risk of HIV seroconversion. This study uses data from the BROTHERS (HPTN 061) study to test whether contextual factors related to social networks are associated with HIV seroconversion among black MSM.MethodsWe analyzed data from the BROTHERS study (2009-2011), which examined a multi-component intervention for black MSM in 6 U.S. cities. We ran a series of Cox regression analyses to examine associations between time-dependent measures of network support (personal/emotional, financial, medical, and social participation) and time to HIV seroconversion. We ran unadjusted models followed by models adjusted for participant age at enrollment and study location.ResultsA total of 1000 black MSM tested HIV negative at baseline and were followed at 6- and 12-month study visits. Twenty-eight men tested HIV positive. In adjusted hazard ratio models, study participants who remained HIV negative had higher proportions of social network members who provided personal/emotional (0.92 [95% CI = (0.85, 0.99)]), medical (0.92 [95% CI = (0.85, 0.99)]), or social participation (0.91 [95% CI = (0.86, 0.97)]) support.ConclusionFindings suggest that the increased presence of social network support can be protective against HIV acquisition. Future research should explore the processes that link social network support with sexual and other transmission risk behaviors as a basis to inform HIV prevention efforts.
Towner, Allison P.; Hardegree-Ullman, K.; Walker-LaFollette, A.; McGraw, A. M.; Robertson, A.; Smith, C.; Biddle, L. I.; Turner, J.
2013-06-01
Membership in formal or informal groups of students with similar interests provides many benefits to undergraduate astronomy majors at the University of Arizona. First and foremost, members benefit from peer social and academic support within the major. These benefits are both tangible and intangible: students form friendships with like-minded peers, which can sustain them through difficult periods of study, but these social networks are the basis of later professional networks as well. Students in the U of A Astronomy Club have received both informal and formal research positions at other institutions as a direct result of the support, peer mentoring, and connections of club members, and at least six also hold paid, non-research positions within the department as a result of their connection to the club. Finally, most Astronomy Club members take their first steps into professional astronomy, such as attendance at a AAS Meeting, as a result of Club membership and the encouragement of older club members.
Geissler, W. H.; Matias, L. M.; Monna, S.; Stich, D.; Iben Brahim, A.; Mancilla, F.; Zitellini, N.; Nearest Working Group
2009-04-01
The geophysical and geological investigations conducted so far in the Gulf of Cadiz allow us today to have an idea of the largest active faults that can generate destructive earthquakes and tsunamis comparable to the Nov 1st, 1755 Lisbon event. However, their kinematics and seismic activity are poorly known because the seismic networks based on land do not allow a precise hypocenter location and estimation of focal mechanisms for the smaller events. Therefore the EC project NEAREST (Integrated observation from NEAR shore sourcES of Tsunamis: towards an early warning system) was initiated (GOCE, contract n. 037110). One of the main objectives of the project is the characterisation of the tsunamigenic sources in the Gulf of Cadiz through seismological monitoring of natural seismicity by means of 24 BB seismometers deployed for 11 months in addition to the GEOSTAR multi-parameter deep-sea observatory. Together with the dense onshore seismic networks the temporary OBS network will allow the location and characterization of small seismic events more precisely than it can be done with onshore stations only. Spectrograms are used to identify previously unknown earthquakes. One of the major questions is the maximum depth of seismic activity beneath the Gulf of Cadiz. In the recording period from September 2007 to August 2008 about 300 events were located within the OBS network using the Portuguese onshore seismic stations. Magnitudes range from 1 to 4.7 (ML from Institute of Meteorology Lisbon, Portugal). Using the OBS network many events could be detected which are not located by the onshore stations. First results show that the events occur to approximately 50 km depth, often deeper than the locations by land stations, and confirming the results available from regional and teleseismic waveform modelling. Focal mechanisms show strike-slip and thrust-slip events.
Schlesinger, Rosert E.
1990-06-01
This paper presents preliminary results from an investigation into the feedback between convective storms and their new surroundings, using output from a three-dimensional anelastic cloud-scale model. Convective feedback budgets for heat, moisture and horizontal momentum are diagnosed from horizontally Reynolds-averaged governing equations, analogous to the theory of Anthes. There is limited horizontal scale separation between the active convection area and the averaging area, which at 30 km on a side is comparable to one grid cell of a typical mesoscale numerical weather prediction model.The simulation is run with an idealized midlatitude severe thunderstorm sounding. The resulting storm displays several supercell features. These include a vigorous erect large-diameter updraft that splits at lower levels, a vaulted weak echo region in the lower part of the main (right flank) updraft core, and a midlevel mesovortex couplet with cyclonic vorticity in the main updraft.The vertical profiles of the various budget terms show several findings of potential relevance to cumulus parameterization. The vertical eddy transport (flux divergence) is highly important to each budget; it significantly raises the height of the maximum apparent heat source and lowers the height of the maximum apparent moisture sink, and acts to reduce the net tropospheric vertical wind shear. At the same time, the horizontal eddy momentum transport and the mean horizontal pressure gradient force both act strongly to sharpen the tropopause-level jet, so that the net shear is little changed. The horizontal eddy transport is much less important to the heat budget, and remains negligible for moisture. Mean storage contributes significantly to the apparent source for each budget under consideration. Other terms derived by Anthes but ignored in existing cumulus parameterizations (the resultant of eddy storage, transport of mean fields by the eddy wind, and transport of eddy fields by the mean wind) become
Benyo, Theresa L.
2010-01-01
Preliminary flow matching has been demonstrated for a MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment was used to perform a thermodynamic cycle analysis to properly match the flows from an inlet to a MHD generator and from the exit of a supersonic turbojet to a MHD accelerator. Working with various operating conditions such as the enthalpy extraction ratio and isentropic efficiency of the MHD generator and MHD accelerator, interfacing studies were conducted between the pre-ionizers, the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis and describes the NPSS analysis of a supersonic turbojet engine with a MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to an explored and desired range of 0 to 7.0 Mach.
Tarao, Hiroo; Korpinen, Leena H; Kuisti, Harri A; Hayashi, Noriyuki; Elovaara, Jarmo A; Isaka, Katsuo
2013-01-01
An ungrounded human, such as a substation worker, receives contact currents when touching a grounded object in electric fields. In this article, contact currents and internal electric fields induced in the human when exposed to non-uniform electric fields at 50 Hz are numerically calculated. This is done using a realistic human model standing at a distance of 0.1-0.5 m from the grounded conductive object. We found that the relationship between the external electric field strength and the contact current obtained by calculation is in good agreement with previous measurements. Calculated results show that the contact currents largely depend on the distance, and that the induced electric fields in the tissues are proportional to the contact current regardless of the non-uniformity of the external electric field. Therefore, it is concluded that the contact current, rather than the spatial average of the external electric field, is more suitable for evaluating electric field dosimetry of tissues. The maximum induced electric field appears in the spinal cord in the central nervous system tissues, with the induced electric field in the spinal cord approaching the basic restriction (100 mV/m) of the new 2010 International Commission on Non-Ionizing Radiation Protection guidelines for occupational exposure, if the contact current is 0.5 mA. Copyright © 2012 Wiley Periodicals, Inc.
Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S
2016-05-01
The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures. Copyright © 2016 Elsevier B.V. All rights reserved.
Buldakov, M. A.; Vershkov, V. A.; Isaev, M. Yu; Shelukhin, D. A.
2017-10-01
The antenna system of reflectometry diagnostics at the T-10 tokamak allows to study long-range toroidal correlations of plasma density fluctuations along the magnetic field lines. The antenna systems are installed in two poloidal cross-sections of the vacuum chamber separated by a 90° angle in the toroidal direction. The experiments, which were conducted at the low field side, showed that the high level of toroidal correlations is observed only for quasi-coherent fluctuations. However, broadband and stochastic low frequency fluctuations are not correlated. Numerical modeling of the plasma turbulence structure in the T-10 tokamak was conducted to interpret the experimental results and take into account non-locality of reflectometry measurements. In the model used, it was assumed that the magnitudes of density fluctuations are constant along the magnetic field lines. The 2D full-wave Tamic-RTH code was used to model the reflectometry signals. High level of correlations for quasi-coherent fluctuations was obtained during the modeling, which agrees with the experimental observations. However, the performed modeling also predicts high level of correlations for broadband fluctuations, which contradicts the experimental data. The modeling showed that the effective reflection radius, from which the information on quasi-coherent plasma turbulence is obtained, is shifted outwards from the reflection radius by approximately 7 mm.
Preliminary Results of Ocular Artefacts Identification in EEC Series by Neural Network
Directory of Open Access Journals (Sweden)
M. Kofronova
1996-06-01
Full Text Available The human electroencephalogram (EEG, is record of the electrical activity of the brain and contains useful diagnostic information on a variety of neurological disorders. Normal EEG signal are usually registered from electrodes placed on the scalp, and are often very small in amplitude, of 20 Ã‚ÂµV. The EEG, like all biomedical signals, is very susceptible to a variety of large signal contamination or artefacts (signals of other than brain activity which reduce its clinical usefulness. For example, blinking or moving eyes produces large electrical potentials around the eyes called the electrooculogram (EOG. The EOG spreads across the scalp to contaminate the EEG, when it is referred to as an ocular artefact (OA. This paper includes method of identification portion of the EEG record where ocular artefact appears and classification its type by neural network.
The Status of Honey Bee Health in Italy: Results from the Nationwide Bee Monitoring Network.
Porrini, Claudio; Mutinelli, Franco; Bortolotti, Laura; Granato, Anna; Laurenson, Lynn; Roberts, Katherine; Gallina, Albino; Silvester, Nicholas; Medrzycki, Piotr; Renzi, Teresa; Sgolastra, Fabio; Lodesani, Marco
2016-01-01
In Italy a nation-wide monitoring network was established in 2009 in response to significant honey bee colony mortality reported during 2008. The network comprised of approximately 100 apiaries located across Italy. Colonies were sampled four times per year, in order to assess the health status and to collect samples for pathogen, chemical and pollen analyses. The prevalence of Nosema ceranae ranged, on average, from 47-69% in 2009 and from 30-60% in 2010, with strong seasonal variation. Virus prevalence was higher in 2010 than in 2009. The most widespread viruses were BQCV, DWV and SBV. The most frequent pesticides in all hive contents were organophosphates and pyrethroids such as coumaphos and tau-fluvalinate. Beeswax was the most frequently contaminated hive product, with 40% of samples positive and 13% having multiple residues, while 27% of bee-bread and 12% of honey bee samples were contaminated. Colony losses in 2009/10 were on average 19%, with no major differences between regions of Italy. In 2009, the presence of DWV in autumn was positively correlated with colony losses. Similarly, hive mortality was higher in BQCV infected colonies in the first and second visits of the year. In 2010, colony losses were significantly related to the presence of pesticides in honey bees during the second sampling period. Honey bee exposure to poisons in spring could have a negative impact at the colony level, contributing to increase colony mortality during the beekeeping season. In both 2009 and 2010, colony mortality rates were positively related to the percentage of agricultural land surrounding apiaries, supporting the importance of land use for honey bee health.
Edwards, E.; Washburn, B.; Harter, T.; Fogg, G. E.; Nelson, C.; Lock, B.; Li, X.
2016-12-01
Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas with low permeability soils or cover. Stormwater runoff that would otherwise be routed to streams or drains in urban areas can be used as a source of aquifer recharge, potentially mitigating the effects of drought and harm to natural water bodies. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil and near surface sediment attenuation processes has prevented more widespread use of drywells as a recharge mechanism. A field study was conducted in Elk Grove, CA, to determine the effects of drywell-induced stormwater infiltration on the local hydrogeologic system. Two drywells 13.5 meters in depth were constructed for the project: one in a preexisting drainage basin fed by residential lots, and one at an industrial site. Both sites were outfitted with vegetated pretreatments, and upgradient and downgradient groundwater monitoring wells. Site stormwater and groundwater were sampled between November, 2014, and May, 2016, and analyzed for contaminants. Results of water quality sampling have been statistically analyzed for trends and used to determine the contaminants of interest and the concentrations of these contaminants in influent stormwater. The fate and transport of these contaminants have been simulated using a 1D variably saturated flow and transport model and site specific parameters to predict long-term effects of stormwater infiltration on the surrounding hydrogeologic system. The potential for remobilization of geogenic heavy metals from changes in subsurface hydrochemistry caused by drywell infiltration have also been assessed. The results of the field study and numerical modeling assessment indicate that the study's drywells do not pose a long-term threat to groundwater quality and may be an effective source of aquifer recharge and tool for urban stormwater management.
Guy, R.; Stubailo, I.; Skinner, S.; Phillips, K.; Foote, E.; Lukac, M.; Aguilar, V.; Tavera, H.; Audin, L.; Husker, A.; Clayton, R.; Davis, P. M.
2008-12-01
This work describes preliminary results from a 50 station broadband seismic network recently installed from the coast to the high Andes in Peru. UCLA's Center for Embedded Network Sensing (CENS) and Caltech's Tectonic Observatory are collaborating with the IRD (French L'Institut de Recherche pour le Developpement) and the Institute of Geophysics, in Lima Peru in a broadband seismic experiment that will study the transition from steep to shallow slab subduction. The currently installed line has stations located above the steep subduction zone at a spacing of about 6 km. In 2009 we plan to install a line of 50 stations north from this line along the crest of the Andes, crossing the transition from steep to shallow subduction. A further line from the end of that line back to the coast, completing a U shaped array, is in the planning phase. The network is wirelessly linked using multi-hop network software designed by computer scientists in CENS in which data is transmitted from station to station, and collected at Internet drops, from where it is transmitted over the Internet to CENS each night. The instrument installation in Peru is almost finished and we have been receiving data daily from 10 stations (out of total 50) since June 2008. The rest are recording on-site while the RF network is being completed. The software system provides dynamic link quality based routing, reliable data delivery, and a disruption tolerant shell interface for managing the system from UCLA without the need to travel to Peru. The near real-time data delivery also allows immediate detection of any problems at the sites. We are building a seismic data and GPS quality control toolset that would greatly minimize the station's downtime by alerting the users of any possible problems.
First results of functioning of the Ukraine-China Telescope Network on Space Debris Observations
Shulga, A. V.; Kozyrev, E. S.; Sibiryakova, E. S.; Koshkin, N. I.; Blagodyr, Ya. T.; Epishev, V. P.; Blagodyr, Ya. T.; Epishev, V. P.; Mao, Yi; Li, Y.; Chen, Zh.; Tang, Zh.
2010-05-01
Substantial growth of space debris (SD) on the near-Earth orbits is caused by increasing launch number of the Earth artificial satellites (EAS). Leading space countries assign considerable efforts and contributions for creation, maintenance and development of space control systems (SCS). Effective work of SCS is achieved by usage of radio and optical means based both on the ground and space. Control system of space environment (CSSE) developed by National Space Agency is working in Ukraine. CSSE provides space tracking of up to 300 objects and supplies information about them to customers. Usage of optical telescopes belonging to Ukrainian research institutes and universities of Ministry of Education and Science (MES) is a prospective way to enlarge number of information sources about the SD at low orbits (less than 2500 km) for CSSE. The network of the MES telescopes has a perspective in international cooperation in particular with People's Republic of China. Ukraine and China are members of the Interagency Coordinating Committee on Space Debris; and in accordance with the resolution of the United Nations General Assembly #61/11, they are responsible for collection and distribution of data on SD. This project is directed towards creation of the first Ukrainian-Chinese network of optical telescopes for observations of the SD on the low orbits. The telescopes are equipped with the short focus objectives and sensitive TV CCD Watec cameras. A list of telescope features, such as an institution name, telescope abbreviation, focal length, f-number, field of view are given below: 1) RI NAO, FRT, 85 mm, 1.8, 4.2° x 3.2°; 2) RI AOONU, KT-50, 250 mm, 2.5, 1.5° x 1.1°; 3) AOLNU, TPL1M, 250 mm, 2.5, 1.5° x 1.1°; 4) LSRUNU, TPL1M, 85 mm, 1.5, 4.2° x3.2°; 5) ShAO, TV,85 mm, 1.8, 4.2° x 3.2°. An original method of TV observations of the low orbit objects with a static telescope was tested at all the telescopes. This method was developed and successfully used in RI NAO in
Pérez-Molina, Jose A; Martinez-Perez, Angela; Serre, Nuria; Treviño, Begoña; Ruiz-Giardín, José Manuel; Torrús, Diego; Goikoetxea, Josune; Echevarría, Esteban Martín; Malmierca, Eduardo; Rojo, Gerardo; Calabuig, Eva; Gutierrez, Belén; Norman, Francesca; Lopez-Velez, Rogelio
2016-02-01
The improvement in the prognosis of HIV infection, coupled with the increase in international travel and migration, has led to a rising number of HIV infected travelers. The objective of this study was to describe the epidemiological and clinical features of returning travelers, according to their HIV status. An observational prospective study was conducted including travelers and immigrants who traveled to visit friends and relatives (VFRs) registered in the +REDIVI collaborative network (January-2009; October-2014). +REDIVI is a national network that registers information regarding infections imported by travelers and immigrants at 21 different centers using a standardized protocol. A total of 3464 travellers were identified: 72 were HIV+ (2.1%) and 3.392 HIV- (98%). HIV+ vs. HIV- travelers were often older (40.5y vs. 34.2y P=.001), VFRs (79.1% vs. 44.4%; P<.001), and consulted less for pre-travel advice (27% vs. 37%; P=.078). The main destinations for both groups were sub-Saharan Africa and Latin America. The most frequent reasons for consultation after travel were fever, request for a health examination, gastrointestinal complaints, and abnormal laboratory tests (mainly eosinophilia and anemia), which differed between groups. The most frequent diagnoses in HIV+ travelers were malaria (38.8%), newly diagnosed HIV infection (25%), and intestinal parasites (19.4%), while for HIV- travelers the main diagnoses were "healthy" (17.9%), malaria (14%), and intestinal parasites (17.3%). The typical profile of an HIV+ traveler in +REDIVI was that of a VFR traveler who did not seek pre-travel advice and made high-risk trips. This may increase the chance of acquiring travel-related infections which may pose a special risk for HIV-infected travelers. The post-travel visit was a good opportunity for HIV infection screening. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.
Scherwath, M.; Riedel, M.; Roemer, M.; Heesemann, M.; Chun, J. H.; Moran, K.; Spence, G.; Thomsen, L.
2016-12-01
The key for a scientific understanding of natural environments and the determination of baselines is the long-term monitoring of environmental factors. For seafloor environments including gas hydrate systems, cabled ocean observatories are important platforms for the remote acquisition of a comprehensive suite of datasets. This is particularly critical for those datasets that are difficult to acquire with autonomous, battery-powered systems, such as cameras or high-bandwidth sonar because cable connections provide continuous power and communication from shore to the seafloor. Ocean Networks Canada is operating the NEPTUNE cabled undersea observatory in the Northeast Pacific with two nodes at gas hydrate sites, Barkley Canyon and Clayoquot Slope. With up to seven years of continuous data from these locations we are now beginning to understand the dynamics of the natural systems and are able to classify the variations within the gas hydrate system. For example, the long-term monitoring of gas vent activity has allowed us to classify phases of low, intermittent and high activity that seem to reoccur periodically. Or, by recording the speeds of bacterial mat growth or detecting periods of increased productivity of flora and fauna at hydrates sites we can start to classify benthic activity and relate that to outside environmental parameters. This will eventually allow us to do enhanced environmental monitoring, establish baselines, and potentially detect anthropogenic variations or events for example during gas hydrate production.
Deployment and early results from the CanSIM (Canadian Solar Spectral Irradiance Meter) network
Tatsiankou, Viktar; Hinzer, Karin; Schriemer, Henry; McVey-White, Patrick; Beal, Richard
2017-09-01
Three of seven stations have been deployed as part of the Canadian Solar Spectral Irradiance (CanSIM) network situated in Ottawa, Varennes and Egbert to measure long term spectral variation of the direct normal (DNI) and global horizontal irradiances (GHI) across the country. Every station is equipped with a solar tracker, SolarSIM-D2+, SolarSIM-G+, and SR20 pyranometer, reporting the spectral DNI, GHI, diffuse horizontal irradiance (DHI) and aerosol optical depth in the 280-4000 nm range, broadband DNI, GHI, and DHI, atmospheric total column ozone and water vapour amounts. The spectral GHI as measured by the SolarSIM-G+ was within 5% as compared to EKO MS-700 spectroradiometer in 350-1050 nm range on 17 March 2017. The difference in the GHI as reported by SolarSIM-G+ and SR20 pyranometer from all stations was within 2% on 14 April 2017. Furthermore, on this day, the daily GHI sum for the Ottawa, Varennes, and Egbert stations was 7.01, 6.95, and 7.11 kWh/m2, respectively, while the daily DNI sum was 10.65, 10.86, 10.04 kWh/m2, respectively.
Doumounia, Ali; Gosset, Marielle; Cazenave, Frederic; Kacou, Modeste; Zougmore, François
2014-08-01
Rainfall monitoring based on commercial terrestrial microwave links is tested for the first time in Burkina Faso, in Sahelian West Africa. In collaboration with one national cellular phone operator, Telecel Faso, the attenuation on a 29 km long microwave link operating at 7 GHz was monitored at 1 s time rate for the monsoon season 2012. The time series of attenuation is transformed into rain rates and compared with rain gauge data. The method is successful in quantifying rainfall: 95% of the rainy days are detected. The correlation with the daily rain gauge series is 0.8, and the season bias is 6%. The correlation at the 5 min time step within each event is also high. These results demonstrate the potential interest of exploiting national and regional wireless telecommunication networks for monitoring rainfall in Africa, where operational rain gauge networks are degrading and the hydrometeorological risk increasing.
Brezinski, C
2012-01-01
Numerical analysis has witnessed many significant developments in the 20th century. This book brings together 16 papers dealing with historical developments, survey papers and papers on recent trends in selected areas of numerical analysis, such as: approximation and interpolation, solution of linear systems and eigenvalue problems, iterative methods, quadrature rules, solution of ordinary-, partial- and integral equations. The papers are reprinted from the 7-volume project of the Journal of Computational and Applied Mathematics on '/homepage/sac/cam/na2000/index.html<
Query Load Balancing by Caching Search Results in Peer-to-Peer Information Retrieval Networks
Tigelaar, A.S.; Hiemstra, Djoerd
2011-01-01
For peer-to-peer web search engines it is important to keep the delay between receiving a query and providing search results within an acceptable range for the end user. How to achieve this remains an open challenge. One way to reduce delays is by caching search results for queries and allowing
Kogan, M.; Laursen, S. L.
2011-12-01
While the number of women receiving advanced degrees in the geosciences has been rising, the faces of scientific leaders in academia remain dominantly male. Women are currently underrepresented in tenure-track positions in Earth science departments at research universities. Additionally, women are less likely to have more senior positions within their academic institutions. ESWN is a peer-mentoring network of early career women in the Earth sciences. We conducted a survey of ESWN members as part of an evaluation-with-research study that aims to determine the career needs of young female geoscientists. We also conducted a survey of the co-ed Earth Science Jobs list also run by ESWN and used its male and female members as comparison samples. The survey data provide insight into critical career junctures for women in geosciences and identify salient issues that institutions will need to address to successfully recruit, retain and promote women scientists. Prior research has shown that women are subjected to unintended and unrecognized biases that can have an ultimate impact on their productivity, advancement, and success. Our data corroborate these findings: women consistently rated the professional atmosphere in their departments and their interactions with colleagues less favorably than men. Moreover, women indicated lower rates of collaboration with colleagues in their unit compared to their male peers. Possibly due to this discrepancy in collaboration, women also reported lower research productivity than men in our study. Attaining work/life balance is a particular concern to early-career scientists, especially since tenure clock and the biological clock can coincide and reduce the opportunity for women to achieve tenure and have children. Family issues may impact the success of women in academic careers, such as travel to meetings and field work. Our research shows that women's partners more often worked in STEM fields, potentially complicating women's careers by
Lombard, John
2017-01-01
We introduce the construction of a new framework for probing discrete emergent geometry and boundary-boundary observables based on a fundamentally a-dimensional underlying network structure. Using a gravitationally motivated action with Forman weighted combinatorial curvatures and simplicial volumes relying on a decomposition of an abstract simplicial complex into realized embeddings of proper skeletons, we demonstrate properties such as a minimal volume-scale cutoff, the necessity of a term playing the role of a positive definite cosmological constant as a regulator for nondegenerate geometries, and naturally emergent simplicial structures from Metropolis network evolution simulations with no restrictions on attachment rules or regular building blocks. We see emergent properties which echo results from both the spinfoam formalism and causal dynamical triangulations in quantum gravity, and provide analytical and numerical results to support the analogy. We conclude with a summary of open questions and intent for future work in developing the program.
McDermid, I. S.; Bergwerff, J. B.; Bodeker, G.; Boyd, I. S.; Brinksma, E. J.; Connor, B. J.; Farmer, R.; Gross, M. R.; Kimvilakani, P.; Matthews, W. A.; McGee, T. J.; Ormel, F. T.; Parrish, A.; Singh, U.; Swart, D. P. J.; Tsou, J. J.
1998-11-01
Following a blind intercomparison of ozone profiling instruments in the Network for the Detection of Stratospheric Change at Lauder, New Zealand, revisions to the analyses were made resulting in a new data set. This paper compares the revised results from two differential absorption lidars (RIVM and GSFC), a microwave radiometer (Millitech/LaRC), and electrochemical concentration cell (ECC) balloon sondes (NIWA). In general, the results are substantially improved compared to the earlier blind intercomparison. The level of agreement was similar both for single profiles and for the campaign average profile and was approximately 5% for the lidars and the sondes over the altitude range from 15 to 42 km (32 km for sondes). The revised microwave data show a bias of 5-10% high in the region from 22 to 42 km. Starting at 42 km, the lidar errors increase significantly, and comparisons of the microwave results were not possible above this altitude.
Nakamura, T
1993-01-01
In GR13 we heard many reports on recent. progress as well as future plans of detection of gravitational waves. According to these reports (see the report of the workshop on the detection of gravitational waves by Paik in this volume), it is highly probable that the sensitivity of detectors such as laser interferometers and ultra low temperature resonant bars will reach the level of h ~ 10—21 by 1998. in this level we may expect the detection of the gravitational waves from astrophysical sources such as coalescing binary neutron stars once a year or so. Therefore the progress in numerical relativity is urgently required to predict the wave pattern and amplitude of the gravitational waves from realistic astrophysical sources. The time left for numerical relativists is only six years or so although there are so many difﬁculties in principle as well as in practice.
Directory of Open Access Journals (Sweden)
William J Love
2016-11-01
Full Text Available Surveillance of antimicrobial resistance (AMR is an important component of public health. Antimicrobial drug use generates selective pressure that may lead to resistance against to the administered drug, and may also select for collateral resistances to other drugs. Analysis of AMR surveillance data has focused on resistance to individual drugs but joint distributions of resistance in bacterial populations are infrequently analyzed and reported. New methods are needed to characterize and communicate joint resistance distributions. Markov networks are a class of graphical models that define connections, or edges, between pairs of variables with non-zero partial correlations and are used here to describe AMR resistance relationships. The graphical least absolute shrinkage and selection operator is used to estimate sparse Markov networks from AMR surveillance data. The method is demonstrated using a subset of Escherichia coli isolates collected by the National Antimicrobial Resistance Monitoring System between 2004 and 2012 which included AMR results for 16 drugs from 14418 isolates. Of the 119 possible unique edges, 33 unique edges were identified at least once during the study period and graphical density ranged from 16.2% to 24.8%. Two frequent dense subgraphs were noted, one containing the five β-lactam drugs and the other containing both sulfonamides, three aminoglycosides, and tetracycline. Density did not appear to change over time (p = 0.71. Unweighted modularity did not appear to change over time (p = 0.18, but a significant decreasing trend was noted in the modularity of the weighted networks (p < 0.005 indicating relationships between drugs of different classes tended to increase in strength and frequency over time compared to relationships between drugs of the same class. The current method provides a novel method to study the joint resistance distribution, but additional work is required to unite the underlying biological and genetic
Orton, Glenn; Momary, Thomas; Bolton, Scott; Levin, Steven; Hansen, Candice; Janssen, Michael; Adriani, Alberto; Gladstone, G. Randall; Bagenal, Fran; Ingersoll, Andrew
2017-04-01
The Juno mission has promoted and coordinated a network of Earth-based observations, including both Earth-proximal and ground-based facilities, to extend and enhance observations made by the Juno mission. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Among the earliest of these were observation of Jovian auroral phenomena at X-ray, ultraviolet and infrared wavelengths and measurements of Jovian synchrotron radiation from the Earth simultaneously with the measurement of properties of the upstream solar wind. Other observations of significance to the magnetosphere measured the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter's neutral atmosphere included observations of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 μm through the radio region. The point of these measurements is to relate properties of the deep atmosphere that are the focus of Juno's mission to the state of the "weather layer" at much higher atmospheric levels. These observations cover spectral regions not included in Juno's instrumentation, provide spatial context for Juno's often spatially limited coverage of Jupiter, and they describe the evolution of atmospheric features in time that are measured only once by Juno. We will summarize the results of measurements during the approach phase of the mission that characterized the state of the atmosphere, as well as observations made by Juno and the supporting campaign during Juno's perijoves 1 (2016 August 27), 3 (2016 December 11), 4 (2017 February 2) and possibly "early" results from 5 (2017 March 27). Besides a global network of professional astronomers, the Juno mission also benefited from the enlistment of a network of dedicated amateur astronomers who provided a quasi-continuous picture of the evolution of features observed by
Pathway Processor: A Tool for Integrating Whole-Genome Expression Results into Metabolic Networks
Grosu, Paul; Townsend, Jeffrey P.; Hartl, Daniel L.; Cavalieri, Duccio
2002-01-01
We have developed a new tool to visualize expression data on metabolic pathways and to evaluate which metabolic pathways are most affected by transcriptional changes in whole-genome expression experiments. Using the Fisher Exact Test, the method scores biochemical pathways according to the probability that as many or more genes in a pathway would be significantly altered in a given experiment by chance alone. This method has been validated on diauxic shift experiments and reproduces well known effects of carbon source on yeast metabolism. The analysis is implemented with Pathway Analyzer, one of the tools of Pathway Processor, a new statistical package for the analysis of whole-genome expression data. Results from multiple experiments can be compared, reducing the analysis from the full set of individual genes to a limited number of pathways of interest. The pathways are visualized with OpenDX, an open-source visualization software package, and the relationship between genes in the pathways can be examined in detail using Expression Mapper, the second program of the package. This program features a graphical output displaying differences in expression on metabolic charts of the biochemical pathways to which the open reading frames are assigned. [Supplementary materials are available at http://www.cgr.harvard.edu/cavalieri/pp.html and http://www.genome.org.] PMID:12097350
DEFF Research Database (Denmark)
Thorup, Anne; Petersen, Lone; Jeppesen, Pia
2006-01-01
Social network has considerable impact on physical and mental health. Patients experiencing first-episode psychosis early in adult life may experience severe problems concerning development and maintenance of their social network.......Social network has considerable impact on physical and mental health. Patients experiencing first-episode psychosis early in adult life may experience severe problems concerning development and maintenance of their social network....
Prexl, A.; Golle, M.; Hoffmann, H.; Kudraß, S.; Wahl, M.
2011-01-01
Springback prediction and compensation is nowadays a widely recommended discipline in finite element modeling. Many researches have shown an improvement of the accuracy in prediction of springback using advanced modeling techniques, e.g. by including the Bauschinger effect. In this work different models were investigated in the commercial simulation program AutoForm for a large series production part, manufactured from the dual phase steel HC340XD. The work shows the differences between numerical drawbead models and geometrically modeled drawbeads. Furthermore, a sensitivity analysis was made for a reduced kinematic hardening model, implemented in the finite element program AutoForm.
Preliminary results from EMERSITO, a rapid response network for site-effect studies
Directory of Open Access Journals (Sweden)
Paola Bordoni
2012-10-01
Full Text Available On May 20, 2012, at 02:03 UTC, a Ml 5.9 reverse-fault earthquake occurred in the Emilia-Romagna region, northern Italy, at a hypocentral depth of 6.3 km (http://iside.rm.ingv.it/, close to the cities of Modena and Ferrara in the plain of the Po River. The epicenter was near the village of Finale Emilia where macroseismic intensity was assessed at 7 EMS98 [Tertulliani et al. 2012, this issue], while the closest accelerometric station, MRN, located less than 20 km west-ward at Mirandola (Figure 1 recorded peaks of ground accelerations of about 300 cm/s2 (www.protezionecivile.gov.it/resources/cms/documents/Report_DPC_1_Emilia_EQSd.pdf. The mainshock triggered liquefaction phenomena a few kilometers eastwards of the epicenter, around the village of San Carlo. On the same day, two other shocks of Ml 5.1 followed (02:07, 13:18 GMT; http://iside.rm.ingv.it/. On May 29, 2012, at 07:00 UTC another Ml 5.8 earthquake hit the region (http://iside.rm.ingv.it/, with the epicenter close to the village of Mirandola (Figure 1. Three other strong aftershocks occurred afterwards, of Ml 5.3 (May 29, at 10:55, Ml 5.2 (May 29, at 11:00 and Ml 5.1 (June 3, at 19:20. For a detailed description of the seismic sequence, see Moretti et al. [2012], Scognamiglio et al. [2012], and Massa et al. [2012], in this issue. The Emilia seismic sequence resulted in 25 casualties, several of whom were among the workers in the many factories that collapsed during working hours, and there was extensive damage to monuments, public buildings, industrial sites, and private homes. […
A Numerical Model for the Microcirculation in Skeletal Muscle Fascia
Jacobitz, Frank G.; Schmid-Schönbein, Geert W.
2002-11-01
A numerical model for blood flow in a microvascular network has been developed. The model uses the complete network topology of rat spinotrapezius muscle fascia that was reconstructed from microscopic images. The fascia's network is composed of a feeding arterial network, a collecting venous network, and bundles of capillaries. The flow in the network's vessels is characterized by low Reynolds and Womersley numbers. The model consideres that the microvessels are distensible by pressure and that the arterioles are actively contractile. The blood has non-Newtonian apparent viscosity and blood cells are distributed at bifurcations according to the flow rates into the side branches. These properties have previously been determined experimentally. The method of indefinite admittances is used to compute the flow in the network. The apparent viscosity is computed from local values of hematocrit, shear, and vessel diameter. The model provides detailed information about the flow in all of the network's vessels. Statistical properties of the network, such as the overall flowrate through the network or distributions of pressure, shear stress, and hematocrit in the network are determined. Results for the flow in arterial, venous, and capillary vessels are compared.
Recent results and performance of the multi-gap resistive plate chambers network for the EEE Project
Abbrescia, M.; Avanzini, C.; Baldini, L.; Baldini Ferroli, R.; Batignani, G.; Bencivenni, G.; Bossini, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; Corvaglia, A.; De Gruttola, D.; De Pasquale, S.; Di Giovanni, A.; D`Incecco, M.; Dreucci, M.; Fabbri, F. L.; Fattibene, E.; Ferraro, A.; Frolov, V.; Galeotti, P.; Garbini, M.; Gemme, G.; Gnesi, I.; Grazzi, S.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Licciulli, F.; Maggiora, A.; Maragoto Rodriguez, O.; Maron, G.; Martelli, B.; Mazziotta, M. N.; Miozzi, S.; Nania, R.; Noferini, F.; Nozzoli, F.; Panareo, M.; Panetta, M. P.; Paoletti, R.; Park, W.; Perasso, L.; Pilo, F.; Piragino, G.; Riggi, F.; Righini, G. C.; Sartorelli, G.; Scapparone, E.; Schioppa, M.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Squarcia, S.; Stori, L.; Taiuti, M.; Terreni, G.; Visnyei, O. B.; Vistoli, M. C.; Votano, L.; Williams, M. C. S.; Zani, S.; Zichichi, A.; Zuyeusky, R.
2016-11-01
The Extreme Energy Events (EEE) Project is devoted to the study of Extensive Atmospheric Showers through a network of muon telescopes, installed in High Schools, with the further aim of introducing young students to particle and astroparticle physics. Each telescope is a tracking detector composed of three Multi-gap Resistive Plate Chambers (MRPC) with an active area of 1.60 × 0.80 m2. Their characteristics are similar to the ones built for the Time Of Flight array of the ALICE Experimentat LHC . The EEE Project started with a few pilot towns, where the telescopes have been taking data since 2008, and it has been constantly extended, reaching at present more than 50 MRPCs telescopes. They are spread across Italy with two additional stations at CERN, covering an area of around 3 × 105 km2, with a total surface area for all the MRPCs of 190 m2. A comprehensive description of the MRPCs network is reported here: efficiency, time and spatial resolution measured using cosmic rays hitting the telescopes. The most recent results on the detector and physics performance from a series of coordinated data acquisition periods are also presented.
Burton, M. R.; Caltabiano, T.; Murè, F.; Salerno, G.; Randazzo, D.
2009-05-01
SO 2 fluxes emitted by Stromboli during the 27th February-2nd April 2007 effusive eruption were regularly measured both by an automatic network of scanning ultraviolet spectrometers and by traverse measurements conducted by boat and helicopter. The results from both methodologies agree reasonably well, providing a validation for the automatic flux calculations produced by the network. Approximately 22,000 t of SO 2 were degassed during the course of the 35 day eruption at an average rate of 620 t per day. Such a degassing rate is much higher than that normally observed (150-200 t/d), because the cross-sectional area occupied by ascending degassed magma is much greater than normal during the effusion, as descending, degassed magma that would normally occupy a large volume of the conduit is absent. We propose that the hydrostatically controlled magma level within Stromboli's conduit is the main control on eruptive activity, and that a high effusion rate led to the depressurisation of an intermediate magma reservoir, creating a decrease in the magma level until it dropped beneath the eruptive fissure, causing the rapid end of the eruption. A significant decrease in SO 2 flux was observed prior to a paroxysm on 15th March 2007, suggesting that choking of the gas flowing in the conduit may have induced a coalescence event, and consequent rapid ascent of gas and magma that produced the explosion.
Onisko, Agnieszka; Druzdzel, Marek J; Austin, R Marshall
2016-01-01
Classical statistics is a well-established approach in the analysis of medical data. While the medical community seems to be familiar with the concept of a statistical analysis and its interpretation, the Bayesian approach, argued by many of its proponents to be superior to the classical frequentist approach, is still not well-recognized in the analysis of medical data. The goal of this study is to encourage data analysts to use the Bayesian approach, such as modeling with graphical probabilistic networks, as an insightful alternative to classical statistical analysis of medical data. This paper offers a comparison of two approaches to analysis of medical time series data: (1) classical statistical approach, such as the Kaplan-Meier estimator and the Cox proportional hazards regression model, and (2) dynamic Bayesian network modeling. Our comparison is based on time series cervical cancer screening data collected at Magee-Womens Hospital, University of Pittsburgh Medical Center over 10 years. The main outcomes of our comparison are cervical cancer risk assessments produced by the three approaches. However, our analysis discusses also several aspects of the comparison, such as modeling assumptions, model building, dealing with incomplete data, individualized risk assessment, results interpretation, and model validation. Our study shows that the Bayesian approach is (1) much more flexible in terms of modeling effort, and (2) it offers an individualized risk assessment, which is more cumbersome for classical statistical approaches.
Sentiment contagion in complex networks
Zhao, Laijun; Wang, Jiajia; Huang, Rongbing; Cui, Hongxin; Qiu, Xiaoyan; Wang, Xiaoli
2014-01-01
Sentiment contagion such as the spread of panic in emergencies is a common phenomenon in human society. Considering the difference between sentiment contagion and epidemic contagion, we define the transition probabilities of the binary emotional state (optimism, pessimism) and establish a sentiment contagion model. Transition equations are given in a homogeneous network and the stability of the zero solution is discussed. Also the Monte Carlo method is used for numerical simulation in the inhomogeneous networks. Simulation results show that the overall tendency of sentiment variation in the BA scale-free network is similar in the homogeneous network. Furthermore, the assimilation and weight combination exert influences on sentiment contagion.
Angiola, Nunzio; Bianchi, Piervito
2017-10-01
Until now very little research has been carried out on the performance of health and human services networks in evolution. In particular, previous studies mainly referred to "centrally governed services networks" in the US context. According to Provan and Kenis (2008), these networks are "lead organization-governed", and are different from the "participant-governed" model or the "network administrative organization (NAO)" solution. We focused our attention on the Apulia region care services networks (Italy). In the last few years, the governance of these networks has passed from the "participant-governed" model to the NAO approach. We examined how the integration mechanisms work in this type of networks, and if there were challenges to tackle in order to improve their overall performance. These networks were examined at their initial stage, exactly when their governance model moved to a more integrated solution. We collected survey data from 17 health and human services networks out of 45 (38%). The research is carried out by means of statistical methods (OLS). The analysis is cross sectional. The implementation of "rational/technocratic" factors is important but not sufficient to enhance collaboration. The integration at the "professional level" should be kept in mind. In particular, the role of network (case) managers is paramount. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Directory of Open Access Journals (Sweden)
Rebeca Silveira Rocha
2012-09-01
Full Text Available Objective: To evaluate the prenatal care assistance in the primary health care network in Fortaleza-CE, considering the structure, process and results. Methods: A cross sectional descriptive study, of quantitative approach, performed between October 2009 and February 2011, in 30 Health Units randomly selected, keeping the ratio for each Regional Executive Secretary. For analysis of the structure, the information obtained was scored and classified as: excellent, satisfactory, precarious or insufficient. The form used was submitted to four experts for validation. In evaluating the process and results, data was available by the Municipal Health Secretary of Fortaleza for obtainance of the indicators recommended by the Ministry of Health. Results: There was, in general, a satisfactory structure. As for the process and result, we obtained: pregnant women who had, at least, six prenatal visits (7.6%; pregnant women who received tetanus immunization (22.8%; newborns with congenital syphilis (1.4%; newborns with neonatal tetanus (0%; maternal mortality rate (78.5% in 2008 and 51% in 2009 and total neonatal mortality rate (10.1% in 2008 and 11.2% in 2009. Conclusions: Despite good results with regard to the structure, the reflections on the process and outcome indicators were not positive, with low rates compared to those expected by the World Health Organization or the Ministry of Health, or in comparison with other regions.
Directory of Open Access Journals (Sweden)
A. Smirnov
2011-03-01
Full Text Available The Maritime Aerosol Network (MAN has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops hand-held sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations.
Directory of Open Access Journals (Sweden)
J. B. Habarulema
2009-05-01
Full Text Available This paper attempts to describe the search for the parameter(s to represent solar wind effects in Global Positioning System total electron content (GPS TEC modelling using the technique of neural networks (NNs. A study is carried out by including solar wind velocity (V_{sw}, proton number density (N_{p} and the B_{z} component of the interplanetary magnetic field (IMF B_{z} obtained from the Advanced Composition Explorer (ACE satellite as separate inputs to the NN each along with day number of the year (DN, hour (HR, a 4-month running mean of the daily sunspot number (R4 and the running mean of the previous eight 3-hourly magnetic A index values (A8. Hourly GPS TEC values derived from a dual frequency receiver located at Sutherland (32.38° S, 20.81° E, South Africa for 8 years (2000–2007 have been used to train the Elman neural network (ENN and the result has been used to predict TEC variations for a GPS station located at Cape Town (33.95° S, 18.47° E. Quantitative results indicate that each of the parameters considered may have some degree of influence on GPS TEC at certain periods although a decrease in prediction accuracy is also observed for some parameters for different days and seasons. It is also evident that there is still a difficulty in predicting TEC values during disturbed conditions. The improvements and degradation in prediction accuracies are both close to the benchmark values which lends weight to the belief that diurnal, seasonal, solar and magnetic variabilities may be the major determinants of TEC variability.
Control and Optimization of Network in Networked Control System
Directory of Open Access Journals (Sweden)
Wang Zhiwen
2014-01-01
Full Text Available In order to avoid quality of performance (QoP degradation resulting from quality of service (QoS, the solution to network congestion from the point of control theory, which marks departure of our results from the existing methods, is proposed in this paper. The congestion and bandwidth are regarded as state and control variables, respectively; then, the linear time-invariant (LTI model between congestion state and bandwidth of network is established. Consequently, linear quadratic method is used to eliminate the network congestion by allocating bandwidth dynamically. At last, numerical simulation results are given to illustrate the effectiveness of this modeling approach.
Shahesmaeili, Armita; Haghdoost, Ali Akbar; Soori, Hamid
2015-01-01
Despite the implementation of harm reduction program, some injecting drug users (IDU) continue to engage in high-risk behaviors. It seems that there are some social factors that contribute to risk of human immunodeficiency virus (HIV) transmission in IDUs. The aim of this study was to analysis the social network of IDUs and examines the effect of network location on HIV transmission risk using the multiple membership multilevel models. From October 2013 to March 2014 we conducted face-to-face interviews on 147 IDUs. We asked participants to nominate up to 20 people whom they had more than causal contact with them during the last month and specify if each nominee is drug injector or not. We defined four Network locations as Core and Peripheries of main components. The risk of HIV transmission for each individual was measured based on 7 items scale. We applied Multiple Membership Multilevel Linear Regression analysis to examine the relationship between network location and HIV transmission risk. We used Stata and UCINET software's for the analysis of data. The mean age of participants was 37 ± 9.32. Most of the individuals were male, single and educated up to guidance school. Being a core member of the main component as like as being a member of other small components in comparison with Isolates/unlinked significantly increased the HIV Transmission risk. Engagement in methadone maintenance therapies (MMT) was associated with a decrease in HIV transmission score. Network analysis is a useful guide to find the most influential members of IDUs network and may have a complementary role for harm reduction program. The efficacy of interventions programs can be reinforced by addressing them to core individuals within the network. Furthermore, it provides the harm reduction staff to find the broader number of IDUs who are usually hard to reach by routine outreach case-finding tasks.
Expected Transmission Energy Route Metric for Wireless Mesh Senor Networks
Directory of Open Access Journals (Sweden)
YanLiang Jin
2011-01-01
Full Text Available Mesh is a network topology that achieves high throughput and stable intercommunication. With great potential, it is expected to be the key architecture of future networks. Wireless sensor networks are an active research area with numerous workshops and conferences arranged each year. The overall performance of a WSN highly depends on the energy consumption of the network. This paper designs a new routing metric for wireless mesh sensor networks. Results from simulation experiments reveal that the new metric algorithm improves the energy balance of the whole network and extends the lifetime of wireless mesh sensor networks (WMSNs.
2014-01-01
Background The Global Influenza Hospital Surveillance Network (GIHSN) was developed to improve understanding of severe influenza infection, as represented by hospitalized cases. The GIHSN is composed of coordinating sites, mainly affiliated with health authorities, each of which supervises and compiles data from one to seven hospitals. This report describes the distribution of influenza viruses A(H1N1), A(H3N2), B/Victoria, and B/Yamagata resulting in hospitalization during 2012–2013, the network’s first year. Methods In 2012–2013, the GIHSN included 21 hospitals (five in Spain, five in France, four in the Russian Federation, and seven in Turkey). All hospitals used a reference protocol and core questionnaire to collect data, and data were consolidated at five coordinating sites. Influenza infection was confirmed by reverse-transcription polymerase chain reaction. Hospitalized patients admitted within 7 days of onset of influenza-like illness were included in the analysis. Results Of 5034 patients included with polymerase chain reaction results, 1545 (30.7%) were positive for influenza. Influenza A(H1N1), A(H3N2), and both B lineages co-circulated, although distributions varied greatly between coordinating sites and over time. All age groups were affected. A(H1N1) was the most common influenza strain isolated among hospitalized adults 18–64 years of age at four of five coordinating sites, whereas A(H3N2) and B viruses were isolated more often than A(H1N1) in adults ≥65 years of age at all five coordinating sites. A total of 16 deaths and 20 intensive care unit admissions were recorded among patients with influenza. Conclusions Influenza strains resulting in hospitalization varied greatly between coordinating sites and over time. These first-year results of the GIHSN are relevant, useful, and timely. Due to its broad regional representativeness and sustainable framework, this growing network should contribute substantially to understanding the
Shantakumar, Sumitra; Nordstrom, Beth L; Hall, Susan A; Djousse, Luc; van Herk-Sukel, Myrthe P P; Fraeman, Kathy H; Gagnon, David R; Chagin, Karen; Nelson, Jeanenne J
2017-04-20
Pazopanib received US Food and Drug Administration approval in 2009 for advanced renal cell carcinoma. During clinical development, liver chemistry abnormalities and adverse hepatic events were observed, leading to a boxed warning for hepatotoxicity and detailed label prescriber guidelines for liver monitoring. As part of postapproval regulatory commitments, a cohort study was conducted to assess prescriber compliance with liver monitoring guidelines. Over a 4-year period, a distributed network approach was used across 3 databases: US Veterans Affairs Healthcare System, a US outpatient oncology community practice database, and the Dutch PHARMO Database Network. Measures of prescriber compliance were designed using the original pazopanib label guidelines for liver monitoring. Results from the VA (n = 288) and oncology databases (n = 283) indicate that prescriber liver chemistry monitoring was less than 100%: 73% to 74% compliance with baseline testing and 37% to 39% compliance with testing every 4 weeks. Compliance was highest near drug initiation and decreased over time. Among patients who should have had weekly testing, the compliance was 56% in both databases. The more serious elevations examined, including combinations of liver enzyme elevations meeting the laboratory definition of Hy's law were infrequent but always led to appropriate discontinuation of pazopanib. Only 4 patients were identified for analysis in the Dutch database; none had recorded baseline testing. In this population-based study, prescriber compliance was reasonable near pazopanib initiation but low during subsequent weeks of treatment. This study provides information from real-world community practice settings and offers feedback to regulators on the effectiveness of label monitoring guidelines.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the
Büscher, C; Thorenz, A; Grochocka, A; Koch, U; Watzke, B
2011-12-01
Breast cancer patients are as a rule in need of a multiple sequential in-patient, day-patient and out-patient permanent treatment. The required care demands a trans-sectoral networking of all multi-professional persons involved in diagnostics, therapies, rehabilitation and aftercare. A method to develop the integration of treatment processes, as well as thereby resulting in increased effectiveness and efficiency, can constitute the concept of case management. A prerequisite for an effective implementation of case management and thus the starting point of the present survey is a well-functioning network encompassing optimal cooperation. Within the framework of the evaluation of the case management-based integrated care model "mammaNetz" for women with mamma carcinoma as a whole and against the background of the potential for innovation and improvement of case management on the one hand as well as the existence of only few empirical data otherwise, the present survey of members of a trans-sectoral network of the service centre was accomplished. Medical and non-medical networking partners of the service centre (N=168) were questioned by regular mail about different aspects of the cooperation. Identical items in both surveys were compared. The return rate for the medical networking partners is about 59% (n=35), whereby only medical network partners in private practice participated in the survey. For the non-medical networking partners about 60% (n=66) participated. Medical networking partners assess the cooperation with the service centre in reference to the exchange of information slightly more positively (66%) than the non-medical networking partners (59%). Medical networking partners are in significantly more frequent contact with the service centre and see in the cooperation significantly more advantages for their own office/facility (each with p=0.001) than non-medical networking partners. Overall the results suggest that medical as well as non-medical networking
Zelenev, Alexei; Long, Elisa; Bazazi, Alexander R; Kamarulzaman, Adeeba; Altice, Frederick L
2016-11-01
HIV is primarily concentrated among people who inject drugs (PWID) in Malaysia, where currently HIV prevention and treatment coverage is inadequate. To improve the targeting of interventions, we examined HIV clustering and the role that social networks and geographical distance play in influencing HIV transmission among PWID. Data were derived from a respondent-driven survey sample (RDS) collected during 2010 of 460 PWID in greater Kuala Lumpur. Analysis focused on socio-demographic, clinical, behavioural, and network information. Spatial probit models were developed based on a distinction between the influence of peers (individuals nominated through a recruitment network) and neighbours (residing a close distance to the individual). The models were expanded to account for the potential influence of the network formation. Recruitment patterns of HIV-infected PWID clustered both spatially and across the recruitment networks. In addition, HIV-infected PWID were more likely to have peers and neighbours who inject with clean needles were HIV-infected and lived nearby (network formation and sero-sorting. The relationship between HIV status across networks and space in Kuala Lumpur underscores the importance of these factors for surveillance and prevention strategies, and this needs to be more closely integrated. RDS can be applied to identify injection network structures, and this provides an important mechanism for improving public health surveillance, accessing high-risk populations, and implementing risk-reduction interventions to slow HIV transmission. Copyright © 2016 Elsevier B.V. All rights reserved.
A heterogeneous approach to achieve QoS in fixed access networks -- results from FP6 project MUSE
Nooren, P.; Deventer, M.O. van; Gamelas, A.; Elizondo, A.J.; Vimel, R.; Eriksson, A.E.
2005-01-01
Next-generation networks are composed of different types of access, aggregation and core networks and they are expected to offer a wide range of services. Based on an analysis of the requirements that this heterogeneity introduces for QoS control, this paper concludes that a single QoS solution can
Raith, Stefan; Vogel, Eric Per; Anees, Naeema; Keul, Christine; Güth, Jan-Frederik; Edelhoff, Daniel; Fischer, Horst
2017-01-01
Chairside manufacturing based on digital image acquisition is gainingincreasing importance in dentistry. For the standardized application of these methods, it is paramount to have highly automated digital workflows that can process acquired 3D image data of dental surfaces. Artificial Neural Networks (ANNs) arenumerical methods primarily used to mimic the complex networks of neural connections in the natural brain. Our hypothesis is that an ANNcan be developed that is capable of classifying dental cusps with sufficient accuracy. This bears enormous potential for an application in chairside manufacturing workflows in the dental field, as it closes the gap between digital acquisition of dental geometries and modern computer-aided manufacturing techniques.Three-dimensional surface scans of dental casts representing natural full dental arches were transformed to range image data. These data were processed using an automated algorithm to detect candidates for tooth cusps according to salient geometrical features. These candidates were classified following common dental terminology and used as training data for a tailored ANN.For the actual cusp feature description, two different approaches were developed and applied to the available data: The first uses the relative location of the detected cusps as input data and the second method directly takes the image information given in the range images. In addition, a combination of both was implemented and investigated.Both approaches showed high performance with correct classifications of 93.3% and 93.5%, respectively, with improvements by the combination shown to be minor.This article presents for the first time a fully automated method for the classification of teeththat could be confirmed to work with sufficient precision to exhibit the potential for its use in clinical practice,which is a prerequisite for automated computer-aided planning of prosthetic treatments with subsequent automated chairside manufacturing. Copyright
Organization of complex networks
Kitsak, Maksim
Many large complex systems can be successfully analyzed using the language of graphs and networks. Interactions between the objects in a network are treated as links connecting nodes. This approach to understanding the structure of networks is an important step toward understanding the way corresponding complex systems function. Using the tools of statistical physics, we analyze the structure of networks as they are found in complex systems such as the Internet, the World Wide Web, and numerous industrial and social networks. In the first chapter we apply the concept of self-similarity to the study of transport properties in complex networks. Self-similar or fractal networks, unlike non-fractal networks, exhibit similarity on a range of scales. We find that these fractal networks have transport properties that differ from those of non-fractal networks. In non-fractal networks, transport flows primarily through the hubs. In fractal networks, the self-similar structure requires any transport to also flow through nodes that have only a few connections. We also study, in models and in real networks, the crossover from fractal to non-fractal networks that occurs when a small number of random interactions are added by means of scaling techniques. In the second chapter we use k-core techniques to study dynamic processes in networks. The k-core of a network is the network's largest component that, within itself, exhibits all nodes with at least k connections. We use this k-core analysis to estimate the relative leadership positions of firms in the Life Science (LS) and Information and Communication Technology (ICT) sectors of industry. We study the differences in the k-core structure between the LS and the ICT sectors. We find that the lead segment (highest k-core) of the LS sector, unlike that of the ICT sector, is remarkably stable over time: once a particular firm enters the lead segment, it is likely to remain there for many years. In the third chapter we study how
Directory of Open Access Journals (Sweden)
M. Granet
1997-06-01
Full Text Available Local earthquake data collected by seven national and regional seismic networks have been compiled into a travel time catalog of 32341 earthquakes for the period 1980 to 1995 in South-Central Europe. As a prerequisite, a complete and corrected station list (master station list has been prepared according to updated information provided by every network. By simultaneous inversion of some 600 well-locatable events we obtained one-dimensional (1D velocity propagation models for each network. Consequently, these velocity models with appropriate station corrections have been used to obtain high-quality hypocenter locations for events inside and among the station networks. For better control, merging of phase data from several networks was performed as an iterative process where at each iteration two data sets of neighbouring networks or groups of networks were merged. Particular care was taken to detect and correctly identify phase data from events common to data sets from two different networks. In case of reports of the same phase data from more than one network, the phase data from the network owning and servicing the station were used according to the master station list. The merging yielded a data set of 278007 P and 191074 S-wave travel time observations from 32341 events in the greater Alpine region. Restrictive selection (number of P-wave observations >7; gap <160 degrees yielded a data set of about 10000 events with a total of more than 128000 P and 87000 S-wave observations well suited for local earthquake seismic tomography study. Preliminary tomographic results for South-Central Europe clearly show the topography of the crust-mantle boundary in the greater Alpine region and outline the 3D structure of the seismic Ivrea body.
Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.
2017-05-01
In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and deformation of the shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron aortic prosthesis is modelled as an orthotropic circular cylindrical shell described by means of the Novozhilov nonlinear shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. For the first time in literature, coupled fluid-structure Lagrange equations of motion for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron aortic graft conveying blood flow. A pulsatile time-dependent blood flow model is considered by applying the first harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure, considering the propagation of pressure and velocity changes inside the shell, is here presented via frequency-response curves, time histories, bifurcation
Dynamical detection of network communities
Quiles, Marcos G.; Macau, Elbert E. N.; Rubido, Nicolás
2016-05-01
A prominent feature of complex networks is the appearance of communities, also known as modular structures. Specifically, communities are groups of nodes that are densely connected among each other but connect sparsely with others. However, detecting communities in networks is so far a major challenge, in particular, when networks evolve in time. Here, we propose a change in the community detection approach. It underlies in defining an intrinsic dynamic for the nodes of the network as interacting particles (based on diffusive equations of motion and on the topological properties of the network) that results in a fast convergence of the particle system into clustered patterns. The resulting patterns correspond to the communities of the network. Since our detection of communities is constructed from a dynamical process, it is able to analyse time-varying networks straightforwardly. Moreover, for static networks, our numerical experiments show that our approach achieves similar results as the methodologies currently recognized as the most efficient ones. Also, since our approach defines an N-body problem, it allows for efficient numerical implementations using parallel computations that increase its speed performance.
Choquette, Anne F.; Freiwald, R. Scott; Kraft, Carol L.
2012-01-01
7 percent, respectively, of the 2009–2010 samples. A comparison of agrichemical land-use effects on groundwater quality, determined on the basis of samples from LWRM Network wells in citrus and in non-citrus land-use areas, indicated significantly higher (p<0.05) concentrations of inorganic constituents in samples from citrus land-use areas compared to samples from non-citrus areas. These inorganic constituents include calcium, magnesium, chloride, sulfate, potassium, nitrate, aluminum, manganese, strontium, and total nitrogen, and also specific conductance, an indicator of total dissolved solutes in water. In addition to land use, including irrigation, site differences such as soils and groundwater reduction/oxidation conditions might have contributed to the differences in some of these constituents. Pesticide detections were primarily restricted to the citrus land-use wells, where 22 of 23 wells yielded pesticide detections, with a median of four detected pesticide compounds per well. For the non-citrus land-use wells, typically surrounded by mixed land use including developed and undeveloped land, one of the eight sampled wells yielded pesticide detections consisting of norflurazon and its degradate, and the source(s) of these detections might have been active or recently active citrus orchards in the vicinity of this well. Results from the LWRM Network during the 1989 through May 2010 period have provided early warning of chemicals prone to leaching, guidance for developing or modifying chemical usage practices to minimize impacts to groundwater, and a mechanism for prioritizing State sampling of domestic wells to assure safe drinking-water supplies. Given the typically long time period (years to tens of years or longer) required to remove chemical contamination once it enters the groundwater system, groundwater monitoring is important to protect drinking-water sources as well as the numerous lakes in this region, which are closely connected with the surficial
Directory of Open Access Journals (Sweden)
F Nadi
2017-05-01
Full Text Available Introduction The significant of solar energy as a renewable energy source, clean and without damage to the environment, for the production of electricity and heat is of great importance. Furthermore, due to the oil crisis as well as reducing the cost of home heating by 70%, solar energy in the past two decades has been a favorite of many researchers. Solar collectors are devices for collecting solar radiant energy through which this energy is converted into heat and then heat is transferred to a fluid (usually air or water. Therefore, a key component in performance improvement of solar heating system is a solar collector optimization under different testing conditions. However, estimation of output parameters under different testing conditions is costly, time consuming and mostly impossible. As a result, smart use of neural networks as well as CFD (computational fluid dynamics to predict the properties with which desired output would have been acquired is valuable. To the best of our knowledge, there are no any studies that compare experimental results with CFD and ANN. Materials and Methods A corrugated galvanized iron sheet of 2 m length, 1 m wide and 0.5 mm in thickness was used as an absorber plate for absorbing the incident solar radiation (Fig. 1 and 2. Corrugations in absorber were caused turbulent air and improved heat transfer coefficient. Computational fluid dynamics K-ε turbulence model was used for simulation. The following assumptions are made in the analysis. (1 Air is a continuous medium and incompressible. (2 The flow is steady and possesses have turbulent flow characteristics, due to the high velocity of flow. (3 The thermal-physical properties of the absorber sheet and the absorber tube are constant with respect to the operating temperature. (4 The bottom side of the absorber tube and the absorber plate are assumed to be adiabatic. Artificial neural network In this research a one-hidden-layer feed-forward network based on the
Molin, Sonja; Bauer, Andrea; Schnuch, Axel; Geier, Johannes
2015-03-01
Healthcare workers are occupationally exposed to various allergens in protective gloves, surface or instrument disinfectants, drugs, and skin care products. An increased prevalence of sensitization to thiurams, glutaraldehyde, formaldehyde and glyoxal in nurses with occupational contact dermatitis (OCD) has been known since the 1990s. To update the range of occupational allergens in healthcare professionals. We retrospectively analysed patch test data from the Information Network of Departments of Dermatology (IVDK), 2003-2012. Patch test results from 2248 nurses with OCD were compared with those of 2138 nurses without OCD. Significantly increased sensitization rates were found for thiuram mix (6.7%), potassium dichromate (5.7%), methylchloroisothiazolinone/methylisothiazolinone (4.4%), colophonium (3.4%), 2-bromo-2-nitropropane-1,3-diol (1.7%), and zinc diethyldithiocarbamate (1.7%). Patch testing with products from the patients' workplaces gave additional clues to further allergens, for example tetrazepam. The known range of contact sensitization in nurses with OCD has been confirmed. Formaldehyde allergy seems to be less important today. Drugs such as tetrazepam are occupational sensitizers in nurses. The increase in chromium sensitization remains unexplained. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
LENUS (Irish Health Repository)
Whitfield, Kate
2010-11-12
Abstract Background \\'Compassionate use\\' programmes allow medicinal products that are not authorised, but are in the development process, to be made available to patients with a severe disease who have no other satisfactory treatment available to them. We sought to understand how such programmes are regulated in ten European Union countries. Methods The European Clinical Research Infrastructures Network (ECRIN) conducted a comprehensive survey on clinical research regulatory requirements, including questions on regulations of \\'compassionate use\\' programmes. Ten European countries, covering approximately 70% of the EU population, were included in the survey (Austria, Denmark, France, Germany, Hungary, Ireland, Italy, Spain, Sweden, and the UK). Results European Regulation 726\\/2004\\/EC is clear on the intentions of \\'compassionate use\\' programmes and aimed to harmonise them in the European Union. The survey reveals that different countries have adopted different requirements and that \\'compassionate use\\' is not interpreted in the same way across Europe. Four of the ten countries surveyed have no formal regulatory system for the programmes. We discuss the need for \\'compassionate use\\' programmes and their regulation where protection of patients is paramount. Conclusions \\'Compassionate use\\' is a misleading term and should be replaced with \\'expanded access\\'. There is a need for expanded access programmes in order to serve the interests of seriously ill patients who have no other treatment options. To protect these patients, European legislation needs to be more explicit and informative with regard to the regulatory requirements, restrictions, and responsibilities in expanded access programmes.
Lee, Eek-Sung; Yoo, Kwangsun; Lee, Young-Beom; Chung, Jinyong; Lim, Ji-Eun; Yoon, Bora; Jeong, Yong
2016-01-01
Default mode network (DMN) functional connectivity is one of the neuroimaging candidate biomarkers of Alzheimer disease. However, no studies have investigated DMN connectivity at different stages of mild cognitive impairment (MCI). The aim of this study was to investigate patterns of DMN connectivity and its breakdown among cognitively normal (CN), early MCI (EMCI), and late MCI (LMCI) subjects. Magnetic resonance imaging data and neuropsychological test scores from 130 subjects (CN=43, EMCI=47, LMCI=40) were obtained from the Alzheimer's Disease Neuroimaging Initiative. DMN functional connectivity was extracted using independent components analysis and compared between groups. Functional connectivity in the precuneus, bilateral medial frontal, parahippocampal, middle temporal, right superior temporal, and left angular gyri was decreased in EMCI subjects compared with CN subjects. When the 2 MCI groups were directly compared, LMCI subjects exhibited decreased functional connectivity in the precuneus, bilateral medial frontal gyri, and left angular gyrus. There was no significant difference in gray matter volume among the 3 groups. Amyloid-positive EMCI subjects revealed more widespread breakdown of DMN connectivity than amyloid-negative EMCI subjects. A quantitative index of DMN connectivity correlated well with measures of cognitive performance. Our results suggest that the breakdown of DMN connectivity may occur in the early stage of MCI.
Riley, Joseph L; Gordan, Valeria V; Rindal, D Brad; Fellows, Jeffrey L; Qvist, Vibeke; Patel, Sagar; Foy, Pat; Williams, O Dale; Gilbert, Gregg H
2012-09-01
The authors conducted a study to identify components of patient satisfaction with restorative dental care and to test the hypothesis that certain dentist, patient and procedure factors are associated with patient satisfaction. Practitioner-investigators (P-Is) from 197 practices in The Dental Practice-Based Research Network (DPBRN) recruited consecutively seen patients who had defective permanent-tooth restorations that were replaced or repaired. At the end of the treatment visit, P-Is asked each participant to complete a satisfaction survey and mail it directly to a DPBRN regional coordinator. Analysis of the results of 5,879 satisfaction surveys revealed three satisfaction components: interpersonal relationship-comfort factors, material choice-value factors and sensory-evaluative factors. Satisfaction was highest among patients who received care in a private practice model, whose restorations were repaired rather than replaced and whose restored teeth were not molars. These data suggest that a patient's judgments of a dentist's skills and quality of care are based on personal interactions with the dentist, the level of comfort the patient perceives while receiving care and any experience of posttreatment sensitivity in the treated tooth. These conclusions have direct implications for management of patient care before, during and after the procedure. By taking a patient-centered approach, dentists should seek to understand how patients evaluate and rate the service provided, thereby enabling themselves to focus on what each patient values most.
Yang, Mingfeng; Li, Xuefeng; Bu, Chunya; Wang, Hui; Shi, Guanglu; Yang, Xiushan; Hu, Yong; Wang, Xiaoqin
2014-11-01
Pyruvate decarboxylase and alcohol dehydrogenase are efficient enzymes for ethanol production in Zymomonas mobilis. These two enzymes were over-expressed in Escherichia coli, a promising candidate for industrial ethanol production, resulting in high ethanol production in the engineered E. coli. To investigate the intracellular changes to the enzyme overexpression for homoethanol production, 2-DE and LC-MS/MS were performed. More than 1,000 protein spots were reproducibly detected in the gel by image analysis. Compared to the wild-type, 99 protein spots showed significant changes in abundance in the recombinant E. coli, in which 46 were down-regulated and 53 were up-regulated. Most proteins related to tricarboxylic acid cycle, glycerol metabolism and other energy metabolism were up-regulated, whereas proteins involved in glycolysis and glyoxylate pathway were down-regulated, indicating the rewired metabolism in the engineered E. coli. As glycolysis is the main pathway for ethanol production, and it was inhibited significantly in engineered E. coli, further efforts should be directed at minimizing the repression of glycolysis to optimize metabolism network for higher yields of ethanol production.
Directory of Open Access Journals (Sweden)
Ihsanul Arief
2016-11-01
Full Text Available Study on cytotoxicity of diarylaniline derivatives by using quantitative structure-activity relationship (QSAR has been done. The structures and cytotoxicities of diarylaniline derivatives were obtained from the literature. Calculation of molecular and electronic parameters was conducted using Austin Model 1 (AM1, Parameterized Model 3 (PM3, Hartree-Fock (HF, and density functional theory (DFT methods. Artificial neural networks (ANN analysis used to produce the best equation with configuration of input data-hidden node-output data = 5-8-1, value of r2 = 0.913; PRESS = 0.069. The best equation used to design and predict new diarylaniline derivatives. The result shows that compound N1-(4′-Cyanophenyl-5-(4″-cyanovinyl-2″,6″-dimethyl-phenoxy-4-dimethylether benzene-1,2-diamine is the best-proposed compound with cytotoxicity value (CC50 of 93.037 μM.
Prospect for VLBI network extension: the first results of an Ad-hoc S2 array experiments
Molotov, I.; Likhachev, S.; Chuprikov, A.; Lipatov, B.; Dementiev, A.
2001-01-01
There are many large radio telescopes not integrated into current VLBI networks because of the shortage of modern compatible VLBI recorders. Above all, this situation is negative for Russia. The wide use of Canadian S2 systems that there are now in 13 countries gives its a chance to be involved in the VLBI Community. It is proposed to arrange an ad-hoc S2 VLBI array from the telescopes around the world, equipped with S2 system, and Penticton S2 correlator. The six successful international VLBI experiments that were carried out since 1993 confirms the feasibility of this S2 initiative. Three Russian antennas (Bear Lakes, Puschino, Svetloe) were joined with three foreign radio telescopes during observations INTAS98.5 (Arecibo, Green Bank, HartRAO) and INTAS99.4 (HartRAO, Noto, Shanghai) to investigate AGNs, OH-masers, interplanetary medium and stars. The pioneer VLBI radar experiment VLBR99.1 was organized in June 1999 for Mars and Venus planets to develop the new method of investigations of Solar system bodies. A review of the S2 experiments results is presented.
Energy Technology Data Exchange (ETDEWEB)
Tarek Haddadin; Stephen Andrew Laraway; Arslan Majid; Taylor Sibbett; Daryl Leon Wasden; Brandon F Lo; Lloyd Landon; David Couch; Hussein Moradi; Behrouz Farhang-Boroujeny
2016-04-01
This paper proposes and presents the design and implementation of an underlay communication channel (UCC) for 5G cognitive mesh networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MCSS) signaling. The use of this novel spread spectrum signaling allows the device-to-device (D2D) user equipments (UEs) to communicate at a level well below noise temperature and hence, minimize taxation on macro-cell/small-cell base stations and their UEs in 5G wireless systems. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by macro-cell and small-cell users. Hence, both D2D-to-cellular and cellular-to-D2D interference will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present the detail of an implementation of the proposed transceiver on a software radio platform and compare our experimental results with those from a theoretical analysis of our packet detection algorithm.
Orton, G. S.; Bolton, S. J.; Levin, S.; Hansen, C. J.; Janssen, M. A.; Adriani, A.; Gladstone, R.; Bagenal, F.; Ingersoll, A. P.; Momary, T.; Payne, A.
2016-12-01
The Juno mission has promoted and coordinated a network of Earth-based observations, including both space- and ground-based facilities, to extend and enhance observations made by the Juno mission. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Among the earliest of these were observation of Jovian auroral phenomena at X-ray, ultraviolet and infrared wavelengths and measurements of Jovian synchrotron radiation from the Earth simultaneously with the measurement of properties of the upstream solar wind described elsewhere in this meeting. Other observations of significance to the magnetosphere measured the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter's neutral atmosphere included observations of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 microns through the radio region. The point of these measurements is to relate properties of the deep atmosphere that are the focus of Juno's mission to the state of the "weather layer" at much higher atmospheric levels. These observations cover spectral regions not included in Juno's instrumentation, provide spatial context for Juno's often spatially limited coverage of Jupiter, and they describe the evolution of atmospheric features in time that are measured only once by Juno. We will summarize the results of measurements during the approach phase of the mission that characterized the state of the atmosphere, as well as observations made by Juno and the supporting campaign during Juno's perijoves 1 (August 27), 2 (October 19), 3 (November 2), 4 (November 15), and 5 (November 30). The Juno mission also benefited from the enlistment of a network of dedicated amateur astronomers who, besides providing input needed for public operation of the JunoCam visible camera, tracked the evolution of features in Jupiter
Barabasi, Albert-Laszlo
2016-01-01
Networks are everywhere, from the Internet, to social networks, and the genetic networks that determine our biological existence. Illustrated throughout in full colour, this pioneering textbook, spanning a wide range of topics from physics to computer science, engineering, economics and the social sciences, introduces network science to an interdisciplinary audience. From the origins of the six degrees of separation to explaining why networks are robust to random failures, the author explores how viruses like Ebola and H1N1 spread, and why it is that our friends have more friends than we do. Using numerous real-world examples, this innovatively designed text includes clear delineation between undergraduate and graduate level material. The mathematical formulas and derivations are included within Advanced Topics sections, enabling use at a range of levels. Extensive online resources, including films and software for network analysis, make this a multifaceted companion for anyone with an interest in network sci...
Energy-aware virtual network embedding in flexi-grid networks.
Lin, Rongping; Luo, Shan; Wang, Haoran; Wang, Sheng
2017-11-27
Network virtualization technology has been proposed to allow multiple heterogeneous virtual networks (VNs) to coexist on a shared substrate network, which increases the utilization of the substrate network. Efficiently mapping VNs on the substrate network is a major challenge on account of the VN embedding (VNE) problem. Meanwhile, energy efficiency has been widely considered in the network design in terms of operation expenses and the ecological awareness. In this paper, we aim to solve the energy-aware VNE problem in flexi-grid optical networks. We provide an integer linear programming (ILP) formulation to minimize the electricity cost of each arriving VN request. We also propose a polynomial-time heuristic algorithm where virtual links are embedded sequentially to keep a reasonable acceptance ratio and maintain a low electricity cost. Numerical results show that the heuristic algorithm performs closely to the ILP for a small size network, and we also demonstrate its applicability to larger networks.
Wetherbee, Gregory A.; Latysh, Natalie E.; Gordon, John D.
2004-01-01
Five external quality-assurance programs were operated by the U.S. Geological Survey for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) from 2000 through 2001 (study period): the intersite-comparison program, the blind-audit program, the field-audit program, the interlaboratory-comparison program, and the collocated-sampler program. Each program is designed to measure specific components of the total error inherent in NADP/NTN wet-deposition measurements. The intersite-comparison program assesses the variability and bias of pH and specific-conductance determinations made by NADP/NTN site operators with respect to accuracy goals. The accuracy goals are statistically based using the median of all of the measurements obtained for each of four intersite-comparison studies. The percentage of site operators responding on time that met the pH accuracy goals ranged from 84.2 to 90.5 percent. In these same four intersite-comparison studies, 88.9 to 99.0 percent of the site operators met the accuracy goals for specific conductance. The blind-audit program evaluates the effects of routine sample handling, processing, and shipping on the chemistry of weekly precipitation samples. The blind-audit data for the study period indicate that sample handling introduced a small amount of sulfate contamination and slight changes to hydrogen-ion content of the precipitation samples. The magnitudes of the paired differences are not environmentally significant to NADP/NTN data users. The field-audit program (also known as the 'field-blank program') was designed to measure the effects of field exposure, handling, and processing on the chemistry of NADP/NTN precipitation samples. The results indicate potential low-level contamination of NADP/NTN samples with calcium, ammonium, chloride, and nitrate. Less sodium contamination was detected by the field-audit data than in previous years. Statistical analysis of the paired differences shows that contaminant ions
Rijkhorst, Erik-Jan
2005-01-01
The late stages of evolution of stars like our Sun are dominated by several episodes of violent mass loss. Space based observations of the resulting objects, known as Planetary Nebulae, show a bewildering array of highly symmetric shapes. The interplay between gasdynamics and radiative processes
Brzezicka, Aneta
2013-01-01
Depression is a disorder characterized not only by persistent negative mood, lack of motivation and a "ruminative" style of thinking, but also by specific deficits in cognitive functioning. These deficits are especially pronounced when integration of information is required. Previous research on linear syllogisms points to a clear pattern of cognitive disturbances present in people suffering from depressive disorders, as well as in people with elevated negative mood. Such disturbances are characterized by deficits in the integration of piecemeal information into coherent mental representations. In this review, I present evidence which suggests that the dysfunction of specific brain areas plays a crucial role in creating reasoning and information integration problems among people with depression and with heightened negative mood. As the increasingly prevalent systems neuroscience approach is spreading into the study of mental disorders, it is important to understand how and which brain networks are involved in creating certain symptoms of depression. Two large brain networks are of particular interest when considering depression: the default mode network (DMN) and the fronto-parietal (executive) network (FNP). The DMN network shows abnormally high activity in the depressed population, whereas FNP circuit activity is diminished. Disturbances within the FNP network seem to be strongly associated with cognitive problems in depression, especially those concerning executive functions. The dysfunctions within the fronto-parietal network are most probably connected to ineffective transmission of information between prefrontal and parietal regions, and also to an imbalance between FNP and DMN circuits. Inefficiency of this crucial circuits functioning may be a more general mechanism leading to problems with flexible cognition and executive functions, and could be the cause of more typical symptoms of depression like persistent rumination.
Li, Yi-Wei; Elishakoff, Isaac; Starnes, James H., Jr.; Bushnell, David
1998-01-01
This study is an extension of a previous investigation of the combined effect of axisymmetric thickness variation and axisymmetric initial geometric imperfection on buckling of isotropic shells under uniform axial compression. Here the anisotropic cylindrical shells are investigated by means of Koiter's energy criterion. An asymptotic formula is derived which can be used to determine the critical buckling load for composite shells with combined initial geometric imperfection and thickness variation. Results are compared with those obtained by the software packages BOSOR4 and PANDA2.
Beniaiche, Ahmed; Ghenaiet, Adel; Facchini, Bruno
2017-02-01
The aero-thermal behavior of the flow field inside 30:1 scaled model reproducing an innovative smooth trailing edge of shaped wedge discharge duct with one row of enlarged pedestals have been investigated in order to determine the effect of rotation, inlet velocity and blowing conditions effects, for Re = 20,000 and 40,000 and Ro = 0-0.23. Two configurations are presented: with and without open tip configurations. Thermo-chromic liquid crystals technique is used to ensure a local measurement of the heat transfer coefficient on the blade suction side under stationary and rotation conditions. Results are reported in terms of detailed 2D HTC maps on the suction side surface as well as the averaged Nusselt number inside the pedestal ducts. Two correlations are proposed, for both closed and open tip configurations, based on the Re, Pr, Ro and a new non-dimensional parameter based on the position along the radial distance, to assess a reliable estimation of the averaged Nusselt number at the inter-pedestal region. A good agreement is found between prediction and experimental data with about ±10 to ±12 % of uncertainty, for the simple form correlation, and about ±16 % using a complex form. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.
Frontiers in Numerical Relativity
Evans, Charles R.; Finn, Lee S.; Hobill, David W.
2011-06-01
Preface; Participants; Introduction; 1. Supercomputing and numerical relativity: a look at the past, present and future David W. Hobill and Larry L. Smarr; 2. Computational relativity in two and three dimensions Stuart L. Shapiro and Saul A. Teukolsky; 3. Slowly moving maximally charged black holes Robert C. Ferrell and Douglas M. Eardley; 4. Kepler's third law in general relativity Steven Detweiler; 5. Black hole spacetimes: testing numerical relativity David H. Bernstein, David W. Hobill and Larry L. Smarr; 6. Three dimensional initial data of numerical relativity Ken-ichi Oohara and Takashi Nakamura; 7. Initial data for collisions of black holes and other gravitational miscellany James W. York, Jr.; 8. Analytic-numerical matching for gravitational waveform extraction Andrew M. Abrahams; 9. Supernovae, gravitational radiation and the quadrupole formula L. S. Finn; 10. Gravitational radiation from perturbations of stellar core collapse models Edward Seidel and Thomas Moore; 11. General relativistic implicit radiation hydrodynamics in polar sliced space-time Paul J. Schinder; 12. General relativistic radiation hydrodynamics in spherically symmetric spacetimes A. Mezzacappa and R. A. Matzner; 13. Constraint preserving transport for magnetohydrodynamics John F. Hawley and Charles R. Evans; 14. Enforcing the momentum constraints during axisymmetric spacelike simulations Charles R. Evans; 15. Experiences with an adaptive mesh refinement algorithm in numerical relativity Matthew W. Choptuik; 16. The multigrid technique Gregory B. Cook; 17. Finite element methods in numerical relativity P. J. Mann; 18. Pseudo-spectral methods applied to gravitational collapse Silvano Bonazzola and Jean-Alain Marck; 19. Methods in 3D numerical relativity Takashi Nakamura and Ken-ichi Oohara; 20. Nonaxisymmetric rotating gravitational collapse and gravitational radiation Richard F. Stark; 21. Nonaxisymmetric neutron star collisions: initial results using smooth particle hydrodynamics
Macario Galang, Jan Albert; Narod Eco, Rodrigo; Mahar Francisco Lagmay, Alfredo
2015-04-01
The M 7.2 October 15, 2013 Bohol earthquake is the most destructive earthquake to hit the Philippines since 2012. The epicenter was located in Sagbayan municipality, central Bohol and was generated by a previously unmapped reverse fault called the "Inabanga Fault". Its name, taken after the barangay (village) where the fault is best exposed and was first seen. The earthquake resulted in 209 fatalities and over 57 billion USD worth of damages. The earthquake generated co-seismic landslides most of which were related to fault structures. Unlike rainfall induced landslides, the trigger for co-seismic landslides happen without warning. Preparedness against this type of landslide therefore, relies heavily on the identification of fracture-related unstable slopes. To mitigate the impacts of co-seismic landslide hazards, morpho-structural orientations or discontinuity sets were mapped in the field with the aid of a 2012 IFSAR Digital Terrain Model (DTM) with 5-meter pixel resolution and software was then used to identify similar structures including measurement of their dip and dip directions. The chosen discontinuity sets were then keyed into Matterocking software to identify potential rock slide zones due to planar or wedged discontinuities. After identifying the structurally-controlled unstable slopes, the rock mass propagation extent of the possible rock slides was simulated using Conefall. The results were compared to a post-earthquake landslide inventory of 456 landslides. Out the total number of landslides identified from post-earthquake high-resolution imagery, 366 or 80% intersect the structural-controlled hazard areas of Bohol. The results show the potential of this method to identify co-seismic landslide hazard areas for disaster mitigation. Along with computer methods to simulate shallow landslides, and debris flow paths, located structurally-controlled unstable zones can be used to mark unsafe areas for settlement. The method can be further improved with the
Directory of Open Access Journals (Sweden)
Dańko R.
2015-12-01
Full Text Available Experiments of filling the model moulds cavity of various inner shapes inserted in rectangular cavity of the casting die (dimensions: 280 mm (height × 190 mm (width × 10 mm (depth by applying model liquids of various density and viscosity are presented in the paper. Influence of die venting as well as inlet system area and inlet velocity on the volumetric rate of filling of the model liquid - achieved by means of filming the process in the system of a cold-chamber casting die was tested. Experiments compared with the results of simulation performed by means of the calculation module Novacast (Novaflow&Solid for the selected various casting conditions - are also presented in the paper.
Puig-Barberà, Joan; Natividad-Sancho, Angels; Launay, Odile; Burtseva, Elena; Ciblak, Meral A.; Tormos, Anita; Buigues-Vila, Amparo; Martínez-Úbeda, Sergio; Sominina, Anna
2014-01-01
Background The effectiveness of currently licensed vaccines against influenza has not been clearly established, especially among individuals at increased risk for complications from influenza. We used a test-negative approach to estimate influenza vaccine effectiveness (IVE) against hospitalization with laboratory-confirmed influenza based on data collected from the Global Influenza Hospital Surveillance Network (GIHSN). Methods and Findings This was a multi-center, prospective, active surveillance, hospital-based epidemiological study during the 2012–2013 influenza season. Data were collected from hospitals participating in the GIHSN, including five in Spain, five in France, and four in the Russian Federation. Influenza was confirmed by reverse transcription-polymerase chain reaction. IVE against hospitalization for laboratory-confirmed influenza was estimated for adult patients targeted for vaccination and who were swabbed within 7 days of symptom onset. The overall adjusted IVE was 33% (95% confidence interval [CI], 11% to 49%). Point estimates of IVE were 23% (95% CI, −26% to 53%) for influenza A(H1N1)pdm09, 30% (95% CI, −37% to 64%) for influenza A(H3N2), and 43% (95% CI, 17% to 60%) for influenza B/Yamagata. IVE estimates were similar in subjects influenza B/Yamagata were homogenous (I2 = 0.0%). Conclusions These results, which were based on data collected from the GIHSN during the 2012–2013 influenza season, showed that influenza vaccines provided low to moderate protection against hospital admission with laboratory-confirmed influenza in adults targeted for influenza vaccination. In this population, IVE estimates against A(H1N1)pdm09 were sensitive to age group and study site. Influenza vaccination was moderately effective in preventing admissions with influenza B/Yamagata for all sites and age groups. PMID:24945510
Matang, Rex A. S.; Owens, Kay
2014-09-01
The Government of Papua New Guinea undertook a significant step in developing curriculum reform policy that promoted the use of Indigenous knowledge systems in teaching formal school subjects in any of the country's 800-plus Indigenous languages. The implementation of the Elementary Cultural Mathematics Syllabus is in line with the above curriculum emphasis. Given the aims of the reform, the research reported here investigated the influence of children's own mother tongue (Tok Ples) and traditional counting systems on their development of early number knowledge formally taught in schools. The study involved 272 school children from 22 elementary schools in four provinces. Each child participated in a task-based assessment interview focusing on eight task groups relating to early number knowledge. The results obtained indicate that, on average, children learning their traditional counting systems in their own language spent shorter time and made fewer mistakes in solving each task compared to those taught without Tok Ples (using English and/or the lingua franca, Tok Pisin). Possible reasons accounting for these differences are also discussed.
Goldhirsh, Julius; Gebo, Norman; Rowland, John
1988-01-01
In this effort are described cumulative rain rate distributions for a network of nine tipping bucket rain gauge systems located in the mid-Atlantic coast region in the vicinity of the NASA Wallops Flight Facility, Wallops Island, Virginia. The rain gauges are situated within a gridded region of dimensions of 47 km east-west by 70 km north-south. Distributions are presented for the individual site measurements and the network average for the year period June 1, 1986 through May 31, 1987. A previous six year average distribution derived from measurements at one of the site locations is also presented. Comparisons are given of the network average, the CCIR (International Radio Consultative Committee) climatic zone, and the CCIR functional model distributions, the latter of which approximates a log normal at the lower rain rate and a gamma function at the higher rates.
Latkin, Carl A.; Kukhareva, Polina V.; Malov, Sergey V.; Batluk, Julia V.; Shaboltas, Alla V.; Skochilov, Roman V.; Sokolov, Nicolay V.; Verevochkin, Sergei V.; Hudgens, Michael G.; Kozlov, Andrei P.
2014-01-01
We evaluated the efficacy of a peer-educator network intervention as a strategy to reduce HIV acquisition among injection drug users (IDUs) and their drug and/or sexual networks. A randomized controlled trial was conducted in St. Petersburg, Russia among IDU index participants and their risk network participants. Network units were randomized to the control or experimental intervention. Only the experimental index participants received training sessions to communicate risk reduction techniques to their network members. Analysis includes 76 index and 84 network participants who were HIV uninfected. The main outcome measure was HIV sero-conversion. The incidence rates in the control and experimental groups were 19.57 (95 % CI 10.74–35.65) and 7.76 (95 % CI 3.51–17.19) cases per 100 p/y, respectively. The IRR was 0.41 (95 % CI 0.15–1.08) without a statistically significant difference between the two groups (log rank test statistic X2 = 2.73, permutation p value = 0.16). Retention rate was 67 % with a third of the loss due to incarceration or death. The results show a promising trend that this strategy would be successful in reducing the acquisition of HIV among IDUs. PMID:23881187
Cabezudo, Rebeca San José; Izquierdo, Carmen Camarero; Pinto, Javier Rodríguez
2013-11-01
Online opinion networks are areas for social exchange, or conversational networks, made up of individuals actively involved in sharing experiences and opinions concerning matters of mutual interest between consumers or concerning their experience with a given product or service. We pinpoint a gap in the literature regarding how the persuasion process occurs when individuals seek opinions online, including the results process. In an attempt to find an answer, we draw on traditional theories related to information processing. These are mostly taken from the field of psychology and enable us to identify which signals or aspects of communication or opinions the individuals focus their attention on (message and source) and the value attached to such communications as well as how much they impact individuals' purchase decisions, bearing in mind the medium (or online opinion network) in which the opinions are located. Findings from those interviewed support the idea that the quality of information on the Internet, as well as trust in the source of said information, or in the opinion of network users, have an impact on the informational value obtained from involvement in this online opinion seeking and on purchasing decisions. Moreover, depending on the kind of network (firm or brand controlled, review Web sites, and user-controlled nonofficial opinion networks), the quality of the information or trust in the users will have a different bearing in the persuasion process.
Identification of important nodes in directed biological networks: a network motif approach.
Directory of Open Access Journals (Sweden)
Pei Wang
Full Text Available Identification of important nodes in complex networks has attracted an increasing attention over the last decade. Various measures have been proposed to characterize the importance of nodes in complex networks, such as the degree, betweenness and PageRank. Different measures consider different aspects of complex networks. Although there are numerous results reported on undirected complex networks, few results have been reported on directed biological networks. Based on network motifs and principal component analysis (PCA, this paper aims at introducing a new measure to characterize node importance in directed biological networks. Investigations on five real-world biological networks indicate that the proposed method can robustly identify actually important nodes in different networks, such as finding command interneurons, global regulators and non-hub but evolutionary conserved actually important nodes in biological networks. Receiver Operating Characteristic (ROC curves for the five networks indicate remarkable prediction accuracy of the proposed measure. The proposed index provides an alternative complex network metric. Potential implications of the related investigations include identifying network control and regulation targets, biological networks modeling and analysis, as well as networked medicine.
Status of numerical relativity
Indian Academy of Sciences (India)
Numerical relativity; gravitational waves; black hole; neutron star. ... and stellar collapse, emphasizing the well-developed current status of such implementations that enable simulations for several astrophysical phenomena. Some of our latest results for simulation of binary neutron star mergers are briefly presented.
DEFF Research Database (Denmark)
Barosi, Giovanni; Bordessoule, Dominique; Briere, Jean
2005-01-01
The European Myelofibrosis Network (EUMNET), a European research network on myelofibrosis with myeloid metaplasia (MMM), has developed a definition of response for the disease by using clinicohematologic, histologic, and cytogenetic criteria. A core set of 5 clinicohematologic criteria was selected...... (Hb) and spleen size and the presence of constitutional symptoms, while changes in platelet count and white blood cell (WBC) count served as complementary criteria and were of value for defining minor responses. A histologic response was defined by changes in bone marrow fibrosis and cellularity...
Epidemic thresholds for bipartite networks
Hernández, D. G.; Risau-Gusman, S.
2013-11-01
It is well known that sexually transmitted diseases (STD) spread across a network of human sexual contacts. This network is most often bipartite, as most STD are transmitted between men and women. Even though network models in epidemiology have quite a long history now, there are few general results about bipartite networks. One of them is the simple dependence, predicted using the mean field approximation, between the epidemic threshold and the average and variance of the degree distribution of the network. Here we show that going beyond this approximation can lead to qualitatively different results that are supported by numerical simulations. One of the new features, that can be relevant for applications, is the existence of a critical value for the infectivity of each population, below which no epidemics can arise, regardless of the value of the infectivity of the other population.
Numerical Verification of Industrial Numerical Codes
Directory of Open Access Journals (Sweden)
Montan Sethy
2012-04-01
Full Text Available Several approximations occur during a numerical simulation: physical effects mapy be discarded, continuous functions replaced by discretized ones and real numbers replaced by finite-precision representations. The use of the floating point arithmetic generates round-off errors at each arithmetical expression and some mathematical properties are lost. The aim of the numerical verification activity at EDF R&D is to study the effect of the round-off error propagation on the results of a numerical simulation. It is indeed crucial to perform a numerical verification of industrial codes such as developped at EDF R&D even more for code running in HPC environments. This paper presents some recent studies around the numerical verification at EDF R&D. Le résultat d’un code de simulation numérique subit plusieurs approximations effectuées lors de la modélisation mathématique du problème physique, de la discrétisation du modèle mathématique et de la résolution numérique en arithmétique flottante. L’utilisation de l’arithmétique flottante génère en effet des erreurs d’arrondi lors de chaque opération flottante et des propriétés mathématiques sont perdues. Il existe à EDF R&D une activité transverse de vérification numérique consistant à étudier l’effet de la propagation des erreurs d’arrondi sur les résultats des simulations. Il est en effet important de vérifier numériquement des codes industriels et ce d’autant plus s’ils sont éxécutés dans environnements de calcul haute performance. Ce papier présente des études récentes autour de la vérification numérique à EDF R&D.
Kuhlthau, Karen; Orlich, Felice; Hall, Trevor A.; Sikora, Darryn; Kovacs, Erica A.; Delahaye, Jennifer; Clemons, Traci E.
2010-01-01
We examined data collected as a part of the Autism Treatment Network, a group of 15 autism centers across the United States and Canada. Mean Health-Related Quality of Life (HRQoL) scores of the 286 children assessed were significantly lower than those of healthy populations (according to published norms). When compared to normative data from…
Directory of Open Access Journals (Sweden)
Mauro De Marchis
2015-08-01
Full Text Available In many Mediterranean countries, users store water resources in private tanks, which are typically located on rooftops. These local reservoirs are generally connected directly to the water distribution network (WDN. This installation scheme causes a disconnection of the WDN from the users, and thus, the users’ water supply is no longer linked to their consumption, which changes the network operating conditions from the designed conditions. For WDNs characterized by the presence of several private tanks, specific models have to be developed to correctly simulate the operation of the WDN while accounting for reservoirs located between the hydraulic network and users. Some mathematical models that are able to reproduce the tank emptying/filling cycles have already been developed, which combine a tank continuity equation with a float valve emitter law. In the present work, a new emitter law is proposed that improves the predictability of actual models. The new formulation takes into account the variation of the emitter coefficient and of the discharge area during the phases of the filling process of private tanks. Specifically, hyperbolic tangent laws were adopted. A comparison between the proposed mathematical model and the experimental data demonstrated the ability of the new law to estimate the flow discharging into private tanks independently of the float valve branch and of the pressure in the network. The developed model can easily be implemented in hydrodynamic models to take private tanks into account.
Berghout, N.A.; Kuramochi, T.; van den Broek, M.A.; Ramirez, C.A.; Faaij, A.P.C.
2013-01-01
This paper evaluated the techno economic performance of several CO2 capture-network configurations for a cluster of sixteen industrial plants in the Netherlands using bottom up analysis. Preliminary findings indicate that centralizing capture equipment instead of capture equipment at plant sites
Energy Technology Data Exchange (ETDEWEB)
Ramdhan, Mohamad [Study Program of Earth Science, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia); Agency for Meteorology, Climatology and Geophysics of Indonesia (BMKG) Jl. Angkasa 1 No. 2 Kemayoran, Jakarta Pusat, 10720 (Indonesia); Nugraha, Andri Dian; Widiyantoro, Sri [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut TeknologiBandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia); Métaxian, Jean-Philippe [Institut de Recherche pour le Développement (IRD) (France); Valencia, Ayunda Aulia, E-mail: mohamad.ramdhan@bmkg.go.id [Study Program of Geophysical Engineering, Institut Teknologi Bandung, Jl. Ganesa 10, Bandung, 40132 (Indonesia)
2015-04-24
DOMERAPI project has been conducted to comprehensively study the internal structure of Merapi volcano, especially about deep structural features beneath the volcano. DOMERAPI earthquake monitoring network consists of 46 broad-band seismometers installed around the Merapi volcano. Earthquake hypocenter determination is a very important step for further studies, such as hypocenter relocation and seismic tomographic imaging. Ray paths from earthquake events occurring outside the Merapi region can be utilized to delineate the deep magma structure. Earthquakes occurring outside the DOMERAPI seismic network will produce an azimuthal gap greater than 180{sup 0}. Owing to this situation the stations from BMKG seismic network can be used jointly to minimize the azimuthal gap. We identified earthquake events manually and carefully, and then picked arrival times of P and S waves. The data from the DOMERAPI seismic network were combined with the BMKG data catalogue to determine earthquake events outside the Merapi region. For future work, we will also use the BPPTKG (Center for Research and Development of Geological Disaster Technology) data catalogue in order to study shallow structures beneath the Merapi volcano. The application of all data catalogues will provide good information as input for further advanced studies and volcano hazards mitigation.
CUFID-query: accurate network querying through random walk based network flow estimation.
Jeong, Hyundoo; Qian, Xiaoning; Yoon, Byung-Jun
2017-12-28
Functional modules in biological networks consist of numerous biomolecules and their complicated interactions. Recent studies have shown that biomolecules in a functional module tend to have similar interaction patterns and that such modules are often conserved across biological networks of different species. As a result, such conserved functional modules can be identified through comparative analysis of biological networks. In this work, we propose a novel network querying algorithm based on the CUFID (Comparative network analysis Using the steady-state network Flow to IDentify orthologous proteins) framework combined with an efficient seed-and-extension approach. The proposed algorithm, CUFID-query, can accurately detect conserved functional modules as small subnetworks in the target network that are expected to perform similar functions to the given query functional module. The CUFID framework was recently developed for probabilistic pairwise global comparison of biological networks, and it has been applied to pairwise global network alignment, where the framework was shown to yield accurate network alignment results. In the proposed CUFID-query algorithm, we adopt the CUFID framework and extend it for local network alignment, specifically to solve network querying problems. First, in the seed selection phase, the proposed method utilizes the CUFID framework to compare the query and the target networks and to predict the probabilistic node-to-node correspondence between the networks. Next, the algorithm selects and greedily extends the seed in the target network by iteratively adding nodes that have frequent interactions with other nodes in the seed network, in a way that the conductance of the extended network is maximally reduced. Finally, CUFID-query removes irrelevant nodes from the querying results based on the personalized PageRank vector for the induced network that includes the fully extended network and its neighboring nodes. Through extensive
Numerical and enumerative results on Okounkov bodies
Pokora, Piotr
2015-01-01
In this note we focus on three independent problems on Okounkov bodies for projective varieties. The main goal is to present a geometric version of the classical Fujita Approximation Theorem, a Jow-type theorem and a cardinality formulae for Minkowski bases on a certain class of smooth projective surfaces.
Belliard, Jean-Philippe; Toffolon, Marco
2013-04-01
Tidal channels represent a major morphological component in tidal wetlands as they transport tidal waters, suspended sediments and nutrients in and out of the marsh platform (e.g., Fagherazzi et al., 2012). Recent studies have helped to get further insights into tidal channel morphodynamics, yet a profound debate still prevails in the scientific community as regards the chief processes governing their formation and further elaboration. The dominant paradigm for tidal channel formation via headcutting of first order channels has been challenged by observations which suggest alternative mechanisms to explain tidal channel origination. Indeed, in view of the abundance and the high diversity of morphology tidal channels depict in worldwide estuarine landscapes, it comes to mind that other models different from the well-documented erosive-based model may be responsible for tidal channel ontogeny and further development. Therefore, models based on the presence of hummocks due to vegetation colonization, or via wind/wave erosion coupled with elongation of salt pans in the marsh surface, or linked to groundwater drainage mediated by crab burrowing activity have been successively proposed to explain origins of tidal channels. Moreover, based on observations of depositional channel network development in prograding deltas, Hood (2006) has suggested a model for tidal channel formation and evolution resulting from depositional processes of delta progradation, leading to the conversion of distributaries into blind tidal channels and creation of meanders occurring concurrently. Depositional channel development was also noticed in other marshes located in different estuarine landscapes. In fact, under conditions of high sediment supply and marsh progradation, depositional tidal channel development may prevail instead of erosional channel development. This diversity in tidal channel formation processes is not reflected in conceptual models of tidal channel evolution as they mostly
Wetherbee, Gregory A.; Latysh, Natalie E.; Burke, Kevin P.
2005-01-01
Six external quality-assurance programs were operated by the U.S. Geological Survey (USGS) External Quality-Assurance (QA) Project for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) from 2002 through 2003. Each program measured specific components of the overall error inherent in NADP/NTN wet-deposition measurements. The intersite-comparison program assessed the variability and bias of pH and specific conductance determinations made by NADP/NTN site operators twice per year with respect to accuracy goals. The percentage of site operators that met the pH accuracy goals decreased from 92.0 percent in spring 2002 to 86.3 percent in spring 2003. In these same four intersite-comparison studies, the percentage of site operators that met the accuracy goals for specific conductance ranged from 94.4 to 97.5 percent. The blind-audit program and the sample-handling evaluation (SHE) program evaluated the effects of routine sample handling, processing, and shipping on the chemistry of weekly NADP/NTN samples. The blind-audit program data indicated that the variability introduced by sample handling might be environmentally significant to data users for sodium, potassium, chloride, and hydrogen ion concentrations during 2002. In 2003, the blind-audit program was modified and replaced by the SHE program. The SHE program was designed to control the effects of laboratory-analysis variability. The 2003 SHE data had less overall variability than the 2002 blind-audit data. The SHE data indicated that sample handling buffers the pH of the precipitation samples and, in turn, results in slightly lower conductivity. Otherwise, the SHE data provided error estimates that were not environmentally significant to data users. The field-audit program was designed to evaluate the effects of onsite exposure, sample handling, and shipping on the chemistry of NADP/NTN precipitation samples. Field-audit results indicated that exposure of NADP/NTN wet-deposition samples
Latkin, Carl; Donnell, Deborah; Liu, Ting-Yuan; Davey-Rothwell, Melissa; Celentano, David; Metzger, David
2013-05-01
Social norms are a key source of influence on health behaviors. This study examined changes in social norms and relationships between HIV injection risk behaviors and social norms among injection drug users (IDUs) involved in an experimental intervention. Randomized clinical trial. An HIV Prevention Trials Network study, Philadelphia, USA. IDUs, called indexes, and their social network members, who were drug or sex partners, were recruited for an HIV prevention intervention and followed for up to 30 months (n = 652). Indexes were randomized into a peer education intervention or control condition. Outcomes of injection-related HIV risk behaviors (sharing needles, sharing cookers, sharing cotton, front-/back-loading) were measured every 6 months and the social norms of these four risk behaviors were assessed every 12 months. There was a statistically significant intervention effect on all four social norms of injection behaviors, with participants in the intervention reporting less risky social norms compared with controls (changes in mean score: needles, -0.24, P = 0.007; cookers, -0.33, P = .004; cottons, -0.28, P = .0165; front-/back-loading, -0.23, P = .002). There was also a statistically significant bidirectional association with social norms predicting injection risk behaviors at the next assessment and risk behaviors predicting social norms at the subsequent visit. Through social network interventions it is feasible to change both injection risk behaviors and associated social norms. However, it is critical that social network interventions focus on publically highlighting behavior changes, as changing social norms without awareness of behaviors change may lead to relapse of risk behaviors. © 2013 The Authors, Addiction © 2013 Society for the Study of Addiction.
Geirsson, Halldor; d'Oreye, Nicolas; Mashagiro, Niche; Syauswa, Muhindo; Celli, Gilles; Kadufu, Benjamin; Smets, Benoît; Kervyn, François
2017-10-01
We present an overview of the installation, operation, and initial results of the 15-station KivuGNet (Kivu Geodetic Network) in the Kivu Region, Central Africa. The network serves primarily as a research and monitoring tool for active volcanic, earthquake, and plate boundary processes in the region. Continuous operation of in-situ measurement networks in naturally and politically harsh environments is challenging, but has proven fruitful in this case. During the operation of the network since 2009, KivuGNet has captured: co-eruptive deformation from two eruptions of Nyamulagira (in 2010 and 2011-2012); inter-eruptive deformation, which we interpret as a combination of plate motion across the Western - East Africa Rift, and decreasing deep-seated magma accumulation under the Nyiragongo-Nyamulagira region; co-seismic deformation from the Mw5.8 August 7, 2015 Lwiro earthquake at the western border of Lake Kivu. We hope that this study will serve as a motivation for further implementation of in-situ geodetic networks in under-monitored and under-studied sections of the East African Rift.
Directory of Open Access Journals (Sweden)
Jöckel Karl
2008-05-01
Full Text Available Abstract Background Social networks and social support are supposed to contribute to the development of unequal health within populations. However, little is known about their socio-economic distribution. In this study, we explore this distribution. Methods This study analyses the association of two indicators of socio-economic position, education and income, with different measures of social networks and support. Cross-sectional data have been derived from the baseline examination of an epidemiological cohort study of 4.814 middle aged urban inhabitants in Germany (Heinz Nixdorf Recall Study. Bivariate and multivariate logistic regression analysis were carried out to estimate the risk of having poor social networks and support across socio-economic groups. Results Socially disadvantaged persons more often report poor social networks and social support. In multivariate analyses, based on education, odds ratios range from 1.0 (highest education to 4.9 (lowest education in a graded way. Findings based on income show similar effects, ranging from 1.0 to 2.5. There is one exception: no association of SEP with close ties living nearby and regularly seen was observed. Conclusion Poor social networks and low social support are more frequent among socio-economically disadvantaged people. To some extent, this finding varies according to the indicator chosen to measure these social constructs.
Sensitive Dependence of Optimal Network Dynamics on Network Structure
Directory of Open Access Journals (Sweden)
Takashi Nishikawa
2017-11-01
Full Text Available The relation between network structure and dynamics is determinant for the behavior of complex systems in numerous domains. An important long-standing problem concerns the properties of the networks that optimize the dynamics with respect to a given performance measure. Here, we show that such optimization can lead to sensitive dependence of the dynamics on the structure of the network. Specifically, using diffusively coupled systems as examples, we demonstrate that the stability of a dynamical state can exhibit sensitivity to unweighted structural perturbations (i.e., link removals and node additions for undirected optimal networks and to weighted perturbations (i.e., small changes in link weights for directed optimal networks. As mechanisms underlying this sensitivity, we identify discontinuous transitions occurring in the complement of undirected optimal networks and the prevalence of eigenvector degeneracy in directed optimal networks. These findings establish a unified characterization of networks optimized for dynamical stability, which we illustrate using Turing instability in activator-inhibitor systems, synchronization in power-grid networks, network diffusion, and several other network processes. Our results suggest that the network structure of a complex system operating near an optimum can potentially be fine-tuned for a significantly enhanced stability compared to what one might expect from simple extrapolation. On the other hand, they also suggest constraints on how close to the optimum the system can be in practice. Finally, the results have potential implications for biophysical networks, which have evolved under the competing pressures of optimizing fitness while remaining robust against perturbations.
Student Collaborative Networks and Academic Performance
Schmidt, David; Bridgeman, Ariel; Kohl, Patrick
2013-04-01
Undergraduate physics students commonly collaborate with one another on homework assignments, especially in more challenging courses. However, there currently exists a dearth of empirical research directly comparing the structure of students' collaborative networks to their academic performances in lower and upper division physics courses. We investigate such networks and associated performances through a mandated collaboration reporting system in two sophomore level and three junior level physics courses during the Fall 2012 and Spring 2013 semesters. We employ social network analysis to quantify the structure and time evolution of networks involving approximately 140 students. Analysis includes analytical and numerical assignments in addition to homework and exam scores. Preliminary results are discussed.
Centrality measures in social networks
Moreau, Michele
Complex networks represent an extensive variety of systems in nature and human interactions. Networks are graphs that describe the structures of interacting systems and give substantial information about the patterns of connections between the nodes in a particular system. In turn, knowing about the structure of networks and their arrangements enables one to make certain types of predictions about their behavior. With that larger motivation, this thesis research emphasizes different measurement metrics such as degree distribution, assortativity and clustering coefficients, transitivity, modularity, network diameter, and the average path length to associate the configurations of the different networks to determine certain types of behavior. The main focus of this thesis is on social networks, where the assortative patterns of social networks were identified. The various parameters used in the study of the networks were calculated and defined using the software packages Networkx and Gephi. The different types of networks are from the Stanford Network Analysis Project (SNAP) website. In particular, the focus is on using the numerical values of the coefficients to infer differences in the forms of contact in different social networks. The ability to do so has implications for detecting preferences when it comes to the relations between groups of people in social networks. As a result of social networks displaying assortative behaviors, the data indicates that these networks could also project some traits of 'narrow-mindedness' due to the formation of different clusters. Another significant repercussion of this research is the ability of a community to thrive successfully based on the interactions of the people with one another.
Opinion evolution in different social acquaintance networks
Chen, Xi; Zhang, Xiao; Wu, Zhan; Wang, Hongwei; Wang, Guohua; Li, Wei
2017-11-01
Social acquaintance networks influenced by social culture and social policy have a great impact on public opinion evolution in daily life. Based on the differences between socio-culture and social policy, three different social acquaintance networks (kinship-priority acquaintance network, independence-priority acquaintance network, and hybrid acquaintance network) incorporating heredity proportion ph and variation proportion pv are proposed in this paper. Numerical experiments are conducted to investigate network topology and different phenomena during opinion evolution, using the Deffuant model. We found that in kinship-priority acquaintance networks, similar to the Chinese traditional acquaintance networks, opinions always achieve fragmentation, resulting in the formation of multiple large clusters and many small clusters due to the fact that individuals believe more in their relatives and live in a relatively closed environment. In independence-priority acquaintance networks, similar to Western acquaintance networks, the results are similar to those in the kinship-priority acquaintance network. In hybrid acquaintance networks, similar to the Chinese modern acquaintance networks, only a few clusters are formed indicating that in modern China, opinions are more likely to reach consensus on a large scale. These results are similar to the opinion evolution phenomena in modern society, proving the rationality and applicability of network models combined with social culture and policy. We also found a threshold curve pv+2 ph=2.05 in the results for the final opinion clusters and evolution time. Above the threshold curve, opinions could easily reach consensus. Based on the above experimental results, a culture-policy-driven mechanism for the opinion dynamic is worth promoting in this paper, that is, opinion dynamics can be driven by different social cultures and policies through the influence of heredity and variation in interpersonal relationship networks. This
Opinion evolution in different social acquaintance networks.
Chen, Xi; Zhang, Xiao; Wu, Zhan; Wang, Hongwei; Wang, Guohua; Li, Wei
2017-11-01
Social acquaintance networks influenced by social culture and social policy have a great impact on public opinion evolution in daily life. Based on the differences between socio-culture and social policy, three different social acquaintance networks (kinship-priority acquaintance network, independence-priority acquaintance network, and hybrid acquaintance network) incorporating heredity proportion ph and variation proportion pv are proposed in this paper. Numerical experiments are conducted to investigate network topology and different phenomena during opinion evolution, using the Deffuant model. We found that in kinship-priority acquaintance networks, similar to the Chinese traditional acquaintance networks, opinions always achieve fragmentation, resulting in the formation of multiple large clusters and many small clusters due to the fact that individuals believe more in their relatives and live in a relatively closed environment. In independence-priority acquaintance networks, similar to Western acquaintance networks, the results are similar to those in the kinship-priority acquaintance network. In hybrid acquaintance networks, similar to the Chinese modern acquaintance networks, only a few clusters are formed indicating that in modern China, opinions are more likely to reach consensus on a large scale. These results are similar to the opinion evolution phenomena in modern society, proving the rationality and applicability of network models combined with social culture and policy. We also found a threshold curve pv+2ph=2.05 in the results for the final opinion clusters and evolution time. Above the threshold curve, opinions could easily reach consensus. Based on the above experimental results, a culture-policy-driven mechanism for the opinion dynamic is worth promoting in this paper, that is, opinion dynamics can be driven by different social cultures and policies through the influence of heredity and variation in interpersonal relationship networks. This finding
Log-periodic oscillations due to discrete effects in complex networks
Sienkiewicz, Julian; Fronczak, Piotr; Hołyst, Janusz A.
2007-06-01
We show how discretization affects two major characteristics in complex networks: internode distances (measured as the shortest number of edges between network sites) and average path length, and as a result there are log-periodic oscillations of the above quantities. The effect occurs both in numerical network models as well as in such real systems as coauthorship, language, food, and public transport networks. Analytical description of these oscillations fits well numerical simulations. We consider a simple case of the network optimization problem, arguing that discrete effects can lead to a nontrivial solution.
Handbook of numerical analysis
Ciarlet, Philippe G
Mathematical finance is a prolific scientific domain in which there exists a particular characteristic of developing both advanced theories and practical techniques simultaneously. Mathematical Modelling and Numerical Methods in Finance addresses the three most important aspects in the field: mathematical models, computational methods, and applications, and provides a solid overview of major new ideas and results in the three domains. Coverage of all aspects of quantitative finance including models, computational methods and applications Provides an overview of new ideas an
Inference of Gene Regulatory Network Based on Local Bayesian Networks.
Liu, Fei; Zhang, Shao-Wu; Guo, Wei-Feng; Wei, Ze-Gang; Chen, Luonan
2016-08-01
The inference of gene regulatory networks (GRNs) from expression data can mine the direct regulations among genes and gain deep insights into biological processes at a network level. During past decades, numerous computational approaches have been introduced for inferring the GRNs. However, many of them still suffer from various problems, e.g., Bayesian network (BN) methods cannot handle large-scale networks due to their high computational complexity, while information theory-based methods cannot identify the directions of regulatory interactions and also suffer from false positive/negative problems. To overcome the limitations, in this work we present a novel algorithm, namely local Bayesian network (LBN), to infer GRNs from gene expression data by using the network decomposition strategy and false-positive edge elimination scheme. Specifically, LBN algorithm first uses conditional mutual information (CMI) to construct an initial network or GRN, which is decomposed into a number of local networks or GRNs. Then, BN method is employed to generate a series of local BNs by selecting the k-nearest neighbors of each gene as its candidate regulatory genes, which significantly reduces the exponential search space from all possible GRN structures. Integrating these local BNs forms a tentative network or GRN by performing CMI, which reduces redundant regulations in the GRN and thus alleviates the false positive problem. The final network or GRN can be obtained by iteratively performing CMI and local BN on the tentative network. In the iterative process, the false or redundant regulations are gradually removed. When tested on the benchmark GRN datasets from DREAM challenge as well as the SOS DNA repair network in E.coli, our results suggest that LBN outperforms other state-of-the-art methods (ARACNE, GENIE3 and NARROMI) significantly, with more accurate and robust performance. In particular, the decomposition strategy with local Bayesian networks not only effectively reduce
A Bi-Projection Neural Network for Solving Constrained Quadratic Optimization Problems.
Xia, Youshen; Wang, Jun
2016-02-01
In this paper, a bi-projection neural network for solving a class of constrained quadratic optimization problems is proposed. It is proved that the proposed neural network is globally stable in the sense of Lyapunov, and the output trajectory of the proposed neural network will converge globally to an optimal solution. Compared with existing projection neural networks (PNNs), the proposed neural network has a very small model size owing to its bi-projection structure. Furthermore, an application to data fusion shows that the proposed neural network is very effective. Numerical results demonstrate that the proposed neural network is much faster than the existing PNNs.
Nikiphorou, Elena; Studenic, Paul; Ammitzbøll, Christian Gytz; Canavan, Mary; Jani, Meghna; Ospelt, Caroline; Berenbaum, Francis
2017-04-01
To explore perceptions, barriers and patterns of social media (SM) use among rheumatology fellows and basic scientists. An online survey was disseminated via Twitter, Facebook and by email to members of the Emerging European League Against Rheumatism Network. Questions focused on general demographics, frequency and types of SM use, reasons and barriers to SM use. Of 233 respondents (47 countries), 72% were aged 30-39 years, 66% female. 83% were active users of at least one SM platform and 71% were using SM professionally. The majority used SM for communicating with friends/colleagues (79%), news updates (76%), entertainment (69%), clinical (50%) and research (48%) updates. Facebook was the dominant platform used (91%). SM was reported to be used for information (81%); for expanding professional networks (76%); new resources (59%); learning new skills (47%) and establishing a professional online presence (46%). 30% of non-SM users justified not using SM due to lack of knowledge. There was a substantial use of SM by rheumatologists and basic scientists for social and professional reasons. The survey highlights a need for providing learning resources and increasing awareness of the use of SM. This could enhance communication, participation and collaborative work, enabling its more widespread use in a professional manner. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
Lu, Tao; Chen, Mingli; Du, Yaping; Qiu, Zongxu
2017-02-01
Lightning location network (LLN) with DF/TOA (direction-finder/time-of-arrival) combined technique has been widely used in the world. However, the accuracy of the lightning data from such LLNs has still been restricted by "site error", especially for those detected only by two DF/TOA sensors. In this paper we practice a statistical approach for evaluation and correction of "site error" for DF/TOA type LLN based on its lightning data. By comparing lightning locations recorded by at least 4 sensors between DF and TOA techniques, the spatial characteristics of "site error" for each sensor in the network can be obtained. The obtained "site error" then can be used to improve the accuracy of lightning locations especially those recorded by only 2 sensors. With this approach, the "site error" patterns for 23 sensors in Yunnan LLN are obtained. The features of these site error patterns are in good consistency with those in literature. Significant differences in lightning locations before and after "site error" corrections indicate that the proposed approach works effectively.
Frank-Bertoncelj, Mojca; Hatemi, Gulen; Ospelt, Caroline; Ramiro, Sofia; Machado, Pedro; Mandl, Peter; Gossec, Laure; Buch, Maya H
2014-01-01
To explore perceptions of, participation in and satisfaction with mentoring programmes among young clinicians and researchers in rheumatology in Europe. To identify mentoring needs and expectations focusing on gender-specific differences. A survey on mentoring in rheumatology was distributed to young clinicians and researchers in rheumatology in Europe through the EMEUNET network. We received 248 responses from 30 European countries. Although 82% of respondents expressed the need for a formal mentoring scheme by EULAR, only 35% participated in mentoring programmes and merely 20% were very satisfied with mentoring. Respondents very satisfied with mentoring were more likely to participate in research, but not clinical mentoring programmes. Career mentoring was perceived as the most beneficial type of mentoring for career development by 46% of respondents, only 35% of respondents, however, declared the existence of career mentoring programmes in their country. There was no gender difference considering participation in mentoring programmes. Women, however, tended to be less satisfied than men with existing mentoring programmes and considered expectations from mentoring as more important for their career development, especially when pertaining to career planning, greater autonomy/responsibility and establishing new networks/collaborations. Career mentoring, especially in the clinical setting, was recognised as a major unmet need of existing mentoring programmes in rheumatology in Europe. Gender-specific differences were identified in the expectations from mentoring. Given this and the importance of mentoring for career prosperity of young physicians and scientists, our survey represents the first step towards developing and refining mentoring programmes in rheumatology in Europe.
IT Department
2009-01-01
A site wide network maintenance has been scheduled for Saturday 28 February. Most of the network devices of the General Purpose network will be upgraded to a newer software version, in order to improve our network monitoring capabilities. This will result in a series of short (2-5 minutes) random interruptions everywhere on the CERN sites along this day. This upgrade will not affect: the Computer centre itself, building 613, the Technical Network and the LHC experiments dedicated networks at the pits. Should you need more details on this intervention, please contact Netops by phone 74927 or email mailto:Netops@cern.ch. IT/CS Group
GS Department
2009-01-01
A site-wide network maintenance operation has been scheduled for Saturday 28 February. Most of the network devices of the general purpose network will be upgraded to a newer software version, in order to improve our network monitoring capabilities. This will result in a series of short (2-5 minutes) random interruptions everywhere on the CERN sites throughout the day. This upgrade will not affect the Computer Centre itself, Building 613, the Technical Network and the LHC experiments, dedicated networks at the pits. For further details of this intervention, please contact Netops by phone 74927 or e-mail mailto:Netops@cern.ch. IT/CS Group
De la Fuente, Ildefonso M; Cortes, Jesus M; Pelta, David A; Veguillas, Juan
2013-01-01
The experimental observations and numerical studies with dissipative metabolic networks have shown that cellular enzymatic activity self-organizes spontaneously leading to the emergence of a Systemic Metabolic Structure in the cell, characterized by a set of different enzymatic reactions always locked into active states (metabolic core) while the rest of the catalytic processes are only intermittently active. This global metabolic structure was verified for Escherichia coli, Helicobacter pylori and Saccharomyces cerevisiae, and it seems to be a common key feature to all cellular organisms. In concordance with these observations, the cell can be considered a complex metabolic network which mainly integrates a large ensemble of self-organized multienzymatic complexes interconnected by substrate fluxes and regulatory signals, where multiple autonomous oscillatory and quasi-stationary catalytic patterns simultaneously emerge. The network adjusts the internal metabolic activities to the external change by means of flux plasticity and structural plasticity. In order to research the systemic mechanisms involved in the regulation of the cellular enzymatic activity we have studied different catalytic activities of a dissipative metabolic network under different external stimuli. The emergent biochemical data have been analysed using statistical mechanic tools, studying some macroscopic properties such as the global information and the energy of the system. We have also obtained an equivalent Hopfield network using a Boltzmann machine. Our main result shows that the dissipative metabolic network can behave as an attractor metabolic network. We have found that the systemic enzymatic activities are governed by attractors with capacity to store functional metabolic patterns which can be correctly recovered from specific input stimuli. The network attractors regulate the catalytic patterns, modify the efficiency in the connection between the multienzymatic complexes, and stably
Directory of Open Access Journals (Sweden)
Ildefonso M De la Fuente
Full Text Available BACKGROUND: The experimental observations and numerical studies with dissipative metabolic networks have shown that cellular enzymatic activity self-organizes spontaneously leading to the emergence of a Systemic Metabolic Structure in the cell, characterized by a set of different enzymatic reactions always locked into active states (metabolic core while the rest of the catalytic processes are only intermittently active. This global metabolic structure was verified for Escherichia coli, Helicobacter pylori and Saccharomyces cerevisiae, and it seems to be a common key feature to all cellular organisms. In concordance with these observations, the cell can be considered a complex metabolic network which mainly integrates a large ensemble of self-organized multienzymatic complexes interconnected by substrate fluxes and regulatory signals, where multiple autonomous oscillatory and quasi-stationary catalytic patterns simultaneously emerge. The network adjusts the internal metabolic activities to the external change by means of flux plasticity and structural plasticity. METHODOLOGY/PRINCIPAL FINDINGS: In order to research the systemic mechanisms involved in the regulation of the cellular enzymatic activity we have studied different catalytic activities of a dissipative metabolic network under different external stimuli. The emergent biochemical data have been analysed using statistical mechanic tools, studying some macroscopic properties such as the global information and the energy of the system. We have also obtained an equivalent Hopfield network using a Boltzmann machine. Our main result shows that the dissipative metabolic network can behave as an attractor metabolic network. CONCLUSIONS/SIGNIFICANCE: We have found that the systemic enzymatic activities are governed by attractors with capacity to store functional metabolic patterns which can be correctly recovered from specific input stimuli. The network attractors regulate the catalytic patterns
Introduction to neural networks
James, Frederick E
1994-02-02
1. Introduction and overview of Artificial Neural Networks. 2,3. The Feed-forward Network as an inverse Problem, and results on the computational complexity of network training. 4.Physics applications of neural networks.
Cortés, J.-C.; Colmenar, J.-M.; Hidalgo, J.-I.; Sánchez-Sánchez, A.; Santonja, F.-J.; Villanueva, R.-J.
2016-01-01
Academic performance is a concern of paramount importance in Spain, where around of 30 % of the students in the last two courses in high school, before to access to the labor market or to the university, do not achieve the minimum knowledge required according to the Spanish educational law in force. In order to analyze this problem, we propose a random network model to study the dynamics of the academic performance in Spain. Our approach is based on the idea that both, good and bad study habits, are a mixture of personal decisions and influence of classmates. Moreover, in order to consider the uncertainty in the estimation of model parameters, we perform a lot of simulations taking as the model parameters the ones that best fit data returned by the Differential Evolution algorithm. This technique permits to forecast model trends in the next few years using confidence intervals.
Budagov, Yu A; Kulchitskii, Yu A; Rusakovitch, N A; Shigaev, V N; Tsiareshka, P V
2008-01-01
In the course of computational experiments with Monte-Carlo events for ATLAS Combined Test Beam 2004 setup Artificial Neural Networks (ANN) technique was applied for reconstruction of energy losses in dead materials between barrel LAr and Tile calorimeters (Edm). The constructed ANN procedures exploit as their input vectors the information content of different sets of variables (parameters) which describe particular features of the hadronic shower of an event in ATLAS calorimeters. It was shown that application of ANN procedures allows one to reach 40% reduction of the Edm reconstruction error compared to the conventional procedure used in ATLAS collaboration. Impact of various features of a shower on the precision of $Edm$ reconstruction is presented in detail. It was found that longitudinal shower profile information brings greater improvement in $Edm$ reconstruction accuracy than cell energies information in LAr3 and Tile1 samplings.
Directory of Open Access Journals (Sweden)
Rinur H. Bekmansurov
2017-01-01
Full Text Available In work of the Raptor Ringing Center of the Russian Raptor Research and Conservation Network in 2015 participated 35 ornithologists-researchers and birdwatchers who have ringed in total 752 individuals of 22 species of birds of prey and owls. From colour ringed birds the leaders are Steppe Eagle (Aquila nipalensis – 281 ind., Eastern Imperial Eagle (Aquila heliaca – 91 ind., Osprey (Pandion haliaetus – 72 ind., White-Tailed Eagle (Haliaeetus albicilla – 73 ind., and Long-Legged Buzzard (Buteo rufinus – 65 ind. For period from 1 June 2015 – 30 May 2016 the information was received about the registration of 46 birds with rings from which 38 birds were identified. Among recoveries the leaders are Osprey (10 ind., White-Tailed Eagle (10 ind. and Eastern Imperial Eagle (6 ind..
Muntingh, Georg
2014-01-01
This book summarizes research carried out in workshops of the SAGA project, an Initial Training Network exploring the interplay of Shapes, Algebra, Geometry and Algorithms. Written by a combination of young and experienced researchers, the book introduces new ideas in an established context. Among the central topics are approximate and sparse implicitization and surface parametrization; algebraic tools for geometric computing; algebraic geometry for computer aided design applications and problems with industrial applications. Readers will encounter new methods for the (approximate) transition between the implicit and parametric representation; new algebraic tools for geometric computing; new applications of isogeometric analysis, and will gain insight into the emerging research field situated between algebraic geometry and computer aided geometric design.
Berutti, Mariangeles; Nery, Fabiano G; Sato, Rodrigo; Scippa, Angela; Kapczinski, Flavio; Lafer, Beny
2014-06-01
To compare clinical characteristics of bipolar disorder (BD) in patients with and without a family history of mood disorders (FHMD) in a large sample from the Brazilian Research Network of Bipolar Disorders. Four-hundred eighty-eight DSM-IV BD patients participating in the Brazilian Research Network of Bipolar Disorders were included. Participants were divided between those with FHMD (n=230) and without FHMD (n=258). We compared these two groups on demographic and clinical variables and performed a logistic regression to identify which variables were most strongly associated with positive family history of mood disorders. BD patients with FHMD presented with significantly higher lifetime prevalence of any anxiety disorder, obsessive-compulsive disorder, social phobia, substance abuse, and were more likely to present history of suicide attempts, family history of suicide attempts and suicide, and more psychiatric hospitalizations than BD patients without FHMD. Logistic regression showed that the variables most strongly associated with a positive FHMD were any comorbid anxiety disorder, comorbid substance abuse, and family history of suicide. Cross-sectional study and verification of FHMD by indirect information. BD patients with FHMD differ from BD patients without FHMD in rates of comorbid anxiety disorder and substance abuse, number of hospitalizations and suicide attempts. As FHMD is routinely assessed in clinical practice, these findings may help to identify patients at risk for particular manifestations of BD and may point to a common, genetically determined neurobiological substrate that increases the risk of conditions such as comorbidities and suicidality in BD patients. Copyright © 2014 Elsevier B.V. All rights reserved.
The Current Performance of the Third Interplanetary Network
Hurley, K.; Cline, T.; Mitrofanov, I.; Mazets, E.; Golenetskii, S.; Frontera, F.; Montanari, E; Guidorzi, C; Feroci, M.
2002-01-01
The 3rd Interplanetary Network (IPN) has been operating since April 2001 with two distant spacecraft, Ulysses and Mars Odyssey, and numerous near-Earth spacecraft, such as BeppoSAX, Wind, and HETE-II. Mars Odyssey is presently in orbit about Mars, and the network has detected approximately 30 cosmic, SGR, and solar bursts. We discuss the results obtained to date and use them to predict the future performance of the network.
Numerical Optimization in Microfluidics
DEFF Research Database (Denmark)
Jensen, Kristian Ejlebjærg
2017-01-01
Numerical modelling can illuminate the working mechanism and limitations of microfluidic devices. Such insights are useful in their own right, but one can take advantage of numerical modelling in a systematic way using numerical optimization. In this chapter we will discuss when and how numerical...
Energy-aware virtual network embedding in flexi-grid optical networks
Lin, Rongping; Luo, Shan; Wang, Haoran; Wang, Sheng; Chen, Bin
2018-01-01
Virtual network embedding (VNE) problem is to map multiple heterogeneous virtual networks (VN) on a shared substrate network, which mitigate the ossification of the substrate network. Meanwhile, energy efficiency has been widely considered in the network design. In this paper, we aim to solve the energy-aware VNE problem in flexi-grid optical networks. We provide an integer linear programming (ILP) formulation to minimize the power increment of each arriving VN request. We also propose a polynomial-time heuristic algorithm where virtual links are embedded sequentially to keep a reasonable acceptance ratio and maintain a low energy consumption. Numerical results show the functionality of the heuristic algorithm in a 24-node network.
Directory of Open Access Journals (Sweden)
Ursina McCaskey
2018-01-01
Full Text Available Developmental dyscalculia (DD is a learning disability affecting the acquisition of numerical-arithmetical skills. Studies report persistent deficits in number processing and aberrant functional activation of the fronto-parietal numerical network in DD. However, the neural development of numerical abilities has been scarcely investigated. The present paper provides a first attempt to investigate behavioral and neural trajectories of numerical abilities longitudinally in typically developing (TD and DD children. During a study period of 4 years, 28 children (8–11 years were evaluated twice by means of neuropsychological tests and a numerical order fMRI paradigm. Over time, TD children improved in numerical abilities and showed a consistent and well-developed fronto-parietal network. In contrast, DD children revealed persistent deficits in number processing and arithmetic. Brain imaging results of the DD group showed an age-related activation increase in parietal regions (intraparietal sulcus, pointing to a delayed development of number processing areas. Besides, an activation increase in frontal areas was observed over time, indicating the use of compensatory mechanisms. In conclusion, results suggest a continuation in neural development of number representation in DD, whereas the neural network for simple ordinal number estimation seems to be stable or show only subtle changes in TD children over time.
McCaskey, Ursina; von Aster, Michael; Maurer, Urs; Martin, Ernst; O'Gorman Tuura, Ruth; Kucian, Karin
2017-01-01
Developmental dyscalculia (DD) is a learning disability affecting the acquisition of numerical-arithmetical skills. Studies report persistent deficits in number processing and aberrant functional activation of the fronto-parietal numerical network in DD. However, the neural development of numerical abilities has been scarcely investigated. The present paper provides a first attempt to investigate behavioral and neural trajectories of numerical abilities longitudinally in typically developing (TD) and DD children. During a study period of 4 years, 28 children (8-11 years) were evaluated twice by means of neuropsychological tests and a numerical order fMRI paradigm. Over time, TD children improved in numerical abilities and showed a consistent and well-developed fronto-parietal network. In contrast, DD children revealed persistent deficits in number processing and arithmetic. Brain imaging results of the DD group showed an age-related activation increase in parietal regions (intraparietal sulcus), pointing to a delayed development of number processing areas. Besides, an activation increase in frontal areas was observed over time, indicating the use of compensatory mechanisms. In conclusion, results suggest a continuation in neural development of number representation in DD, whereas the neural network for simple ordinal number estimation seems to be stable or show only subtle changes in TD children over time.
Fulton-bennett, K. W.
2011-12-01
As a relatively small organization, the Monterey Bay Aquarium Research Institute has gradually expanded its use of on-line and social media over the past few years. Our web site and expedition blogs have been available for over a decade. In 2009 we established a YouTube channel and RSS feeds. In early 2011 we set up Facebook and Twitter sites that are maintained through automated feeds (e.g. Twitterfeed) as well as by two employees who each spend about two hours a week adding items of interest. Although we do respond to comments, we have not actively encouraged interaction and discussion on our social networking sites, due to limited staff time. Prior to setting up our sites, I studied existing the Facebook pages for a number of marine research institutions and found that the frequency at which a research institution updated its social media site was directly correlated with the number of dedicated followers of that site. For this reason, MBARI set goals for keeping our sites updated on a regular basis-at least monthly for YouTube, and three to five times a week for Facebook and Twitter. While expanding our social media activities, we have also expanded our monitoring of all our on-line media. This monitoring has revealed some surprising findings. For example, although we have a steadily growing list of followers (over 1,000 "likes" on Facebook and almost 2,500 "subscribers" YouTube), the use of social media has not significantly increased traffic to our main institutional web site. For the last three years, this site has maintained fairly consistent traffic at 1,000 to 2,000 visits/day. We do see a few extreme spikes in traffic, which can be up to an order of magnitude above normal, when a major web site links to one of our news releases. Since initiating our social networking sites, we have seen an increase in these types of spikes, but it is too early to establish cause and effect in this case. Another unexpected finding is that we are reaching very different
Universal Numeric Segmented Display
Azad, Md. Abul Kalam; Sharmeen, Rezwana; S. M. Kamruzzaman
2010-01-01
Segmentation display plays a vital role to display numerals. But in today's world matrix display is also used in displaying numerals. Because numerals has lots of curve edges which is better supported by matrix display. But as matrix display is costly and complex to implement and also needs more memory, segment display is generally used to display numerals. But as there is yet no proposed compact display architecture to display multiple language numerals at a time, this paper proposes uniform...
Evon, Donna M; Wahed, Abdus S; Johnson, Geoffrey; Khalili, Mandana; Lisker-Melman, Mauricio; Fontana, Robert J; Sarkar, Souvik; Reeve, Bryce B; Hoofnagle, Jay H
2016-04-01
Fatigue is a common symptom of liver disease but not well characterized in patients with chronic hepatitis B virus (HBV). We assessed the rate of fatigue using a validated instrument in patients with HBV and identified demographic, virologic, and clinical features associated with fatigue in a cross-sectional cohort study from the Hepatitis B Research Network. Participants were English- and Spanish-speaking adults with chronic HBV who were not pregnant nor on treatment. Fatigue was measured using the PROMIS® Fatigue 7-item Short Form. The sample included 948 adults: median age 42; 51 % female; 71 % Asian; 74 % college educated; 77 % employed; 41 % inactive HBV carriers; 36 % with active chronic disease; and 2 % with advanced fibrosis, defined as AST-platelet ratio index (APRI) > 1.50. Patients with chronic HBV had a mean fatigue T-score of 46.8 ± SD = 7.9, compared to a mean fatigue T-score of 50.0 ± 10 in the US general population (p fatigue was associated with demographic and clinical features such as female sex, lower income, more comorbidities, higher APRI score, and poorer mental health (p fatigue in this large cohort of North American chronic HBV patients may be equal to or lower than that reported in the US general population. Patients with advanced fibrosis, more comorbidities, and poorer mental health report worse fatigue.
Directory of Open Access Journals (Sweden)
Margaret E. Mattson
2015-01-01
Full Text Available Case reports in medical literature suggest that the atypical antipsychotic quetiapine, a medication not previously considered to have abuse potential, is now being subject to misuse and abuse (MUA; ie, taken when not prescribed for them or used in a way other than instructed by their health professional. Here we present systematic, nationally representative data from the 2005 to 2011 Drug Abuse Warning Network (DAWN for prevalence of emergency department (ED visits among the U.S. general population involving quetiapine and related to MUA, suicide attempts, and adverse reactions. Nationally, quetiapine-related ED visits increased 90% between 2005 and 2011, from 35,581 ED visits to 67,497. DAWN data indicate that when used without medical supervision for recreational/self-medication purposes, quetiapine poses health risks for its users, especially among polydrug users and women. These findings suggest that the medical and public health communities should increase vigilance concerning this drug and its potential for MUA.
Numerical modeling of economic uncertainty
DEFF Research Database (Denmark)
Schjær-Jacobsen, Hans
2007-01-01
Representation and modeling of economic uncertainty is addressed by different modeling methods, namely stochastic variables and probabilities, interval analysis, and fuzzy numbers, in particular triple estimates. Focusing on discounted cash flow analysis numerical results are presented, comparisons...
Fullerton, Stephanie M; Wolf, Wendy A; Brothers, Kyle B; Clayton, Ellen Wright; Crawford, Dana C; Denny, Joshua C; Greenland, Philip; Koenig, Barbara A; Leppig, Kathleen A; Lindor, Noralane M; McCarty, Catherine A; McGuire, Amy L; McPeek Hinz, Eugenia R; Mirel, Daniel B; Ramos, Erin M; Ritchie, Marylyn D; Smith, Maureen E; Waudby, Carol J; Burke, Wylie; Jarvik, Gail P
2012-04-01
Return of individual genetic results to research participants, including participants in archives and biorepositories, is receiving increased attention. However, few groups have deliberated on specific results or weighed deliberations against relevant local contextual factors. The Electronic Medical Records and Genomics (eMERGE) Network, which includes five biorepositories conducting genome-wide association studies, convened a return of results oversight committee to identify potentially returnable results. Network-wide deliberations were then brought to local constituencies for final decision making. Defining results that should be considered for return required input from clinicians with relevant expertise and much deliberation. The return of results oversight committee identified two sex chromosomal anomalies, Klinefelter syndrome and Turner syndrome, as well as homozygosity for factor V Leiden, as findings that could warrant reporting. Views about returning findings of HFE gene mutations associated with hemochromatosis were mixed due to low penetrance. Review of electronic medical records suggested that most participants with detected abnormalities were unaware of these findings. Local considerations relevant to return varied and, to date, four sites have elected not to return findings (return was not possible at one site). The eMERGE experience reveals the complexity of return of results decision making and provides a potential deliberative model for adoption in other collaborative contexts.
Electrospun dye-doped fiber networks: lasing emission from randomly distributed cavities
DEFF Research Database (Denmark)
Krammer, Sarah; Vannahme, Christoph; Smith, Cameron
2015-01-01
Dye-doped polymer fiber networks fabricated with electrospinning exhibit comb-like laser emission. We identify randomly distributed ring resonators being responsible for lasing emission by making use of spatially resolved spectroscopy. Numerical simulations confirm this result quantitatively....
Energy Technology Data Exchange (ETDEWEB)
Shakhashiro, Abdulghani [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-1400 Vienna (Austria)], E-mail: a.shakhashiro@iaea.org; Trinkl, Alexander; Sansone, Umberto [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-1400 Vienna (Austria)
2008-11-15
The International Atomic Energy Agency (IAEA) coordinates the work of a world-wide network of analytical laboratories, the Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) network. A proficiency test for ALMERA members was organized in 2006 based on the determination of gamma-emitting radionuclides ({sup 54}Mn, {sup 60}Co, {sup 65}Zn, {sup 109}Cd, {sup 134}Cs, {sup 137}Cs, {sup 241}Am and {sup 210}Pb) in three matrices: water, soil and grass. This paper presents the methodology applied in this proficiency test and discusses the results of the analytical performance evaluation for 38 participating laboratories. The paper also addresses some technical root causes, which could explain low performances in the determination of {sup 109}Cd and {sup 210}Pb.
Chan, Christopher T; Chertow, Glenn M; Daugirdas, John T; Greene, Tom H; Kotanko, Peter; Larive, Brett; Pierratos, Andreas; Stokes, John B
2014-01-01
End-stage renal disease is associated with reduced heart rate variability (HRV), components of which generally are associated with advanced age, diabetes mellitus and left ventricular hypertrophy. We hypothesized that daily in-center hemodialysis (HD) would increase HRV. The Frequent Hemodialysis Network (FHN) Daily Trial randomized 245 patients to receive 12 months of six versus three times per week in-center HD. Two hundred and seven patients had baseline Holter recordings. HRV measures were calculated from 24-h Holter electrocardiograms at both baseline and 12 months in 131 patients and included low-frequency power (LF, a measure of sympathetic modulation), high-frequency power (HF, a measure of parasympathetic modulation) and standard deviation (SD) of the R-R interval (SDNN, a measure of beat-to-beat variation). Baseline to Month 12 change in LF was augmented by 50% [95% confidence interval (95% CI) 6.1-112%, P =0.022] and LF + HF was augmented by 40% (95% CI 3.3-88.4%, P = 0.03) in patients assigned to daily hemodialysis (DHD) compared with conventional HD. Changes in HF and SDNN were similar between the randomized groups. The effects of DHD on LF were attenuated by advanced age and diabetes mellitus (predefined subgroups). Changes in HF (r = -0.20, P = 0.02) and SDNN (r = -0.18, P = 0.04) were inversely associated with changes in left ventricular mass (LVM). DHD increased the LF component of HRV. Reduction of LVM by DHD was associated with increased vagal modulation of heart rate (HF) and with increased beat-to-beat heart rate variation (SDNN), suggesting an important functional correlate to the structural effects of DHD on the heart in uremia.
Directory of Open Access Journals (Sweden)
C. Pellet
2017-06-01
Full Text Available Besides its important role in the energy and water balance at the soil–atmosphere interface, soil moisture can be a particular important factor in mountain environments since it influences the amount of freezing and thawing in the subsurface and can affect the stability of slopes. In spite of its importance, the technical challenges and its strong spatial variability usually prevents soil moisture from being measured operationally at high and/or middle altitudes. This study describes the new Swiss soil moisture monitoring network SOMOMOUNT (soil moisture in mountainous terrain launched in 2013. It consists of six entirely automated soil moisture stations distributed along an altitudinal gradient between the Jura Mountains and the Swiss Alps, ranging from 1205 to 3410 m a.s.l. in elevation. In addition to the standard instrumentation comprising frequency domain sensor and time domain reflectometry (TDR sensors along vertical profiles, soil probes and meteorological data are available at each station. In this contribution we present a detailed description of the SOMOMOUNT instrumentation and calibration procedures. Additionally, the liquid soil moisture (LSM data collected during the first 3 years of the project are discussed with regard to their soil type and climate dependency as well as their altitudinal distribution. The observed elevation dependency of LSM is found to be non-linear, with an increase of the mean annual values up to ∼ 2000 m a.s.l. followed by a decreasing trend towards higher elevations. This altitude threshold marks the change between precipitation-/evaporation-controlled and frost-affected LSM regimes. The former is characterized by high LSM throughout the year and minimum values in summer, whereas the latter typically exhibits long-lasting winter minimum LSM values and high variability during the summer.
Pellet, Cécile; Hauck, Christian
2017-06-01
Besides its important role in the energy and water balance at the soil-atmosphere interface, soil moisture can be a particular important factor in mountain environments since it influences the amount of freezing and thawing in the subsurface and can affect the stability of slopes. In spite of its importance, the technical challenges and its strong spatial variability usually prevents soil moisture from being measured operationally at high and/or middle altitudes. This study describes the new Swiss soil moisture monitoring network SOMOMOUNT (soil moisture in mountainous terrain) launched in 2013. It consists of six entirely automated soil moisture stations distributed along an altitudinal gradient between the Jura Mountains and the Swiss Alps, ranging from 1205 to 3410 m a.s.l. in elevation. In addition to the standard instrumentation comprising frequency domain sensor and time domain reflectometry (TDR) sensors along vertical profiles, soil probes and meteorological data are available at each station. In this contribution we present a detailed description of the SOMOMOUNT instrumentation and calibration procedures. Additionally, the liquid soil moisture (LSM) data collected during the first 3 years of the project are discussed with regard to their soil type and climate dependency as well as their altitudinal distribution. The observed elevation dependency of LSM is found to be non-linear, with an increase of the mean annual values up to ˜ 2000 m a.s.l. followed by a decreasing trend towards higher elevations. This altitude threshold marks the change between precipitation-/evaporation-controlled and frost-affected LSM regimes. The former is characterized by high LSM throughout the year and minimum values in summer, whereas the latter typically exhibits long-lasting winter minimum LSM values and high variability during the summer.
Energy Technology Data Exchange (ETDEWEB)
Kaiser, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-07-01
The use of an analogue ictometer poses technical problems for measuring low count rates. These latter call for time constants of up to 1000 sec. The numerical technique is better adapted and makes it possible to increase the time constant to 1000 sec. or over. The equipment described consists of 6 numerical ictometers fitted in a 3 U 3 drawer. By means of a clock it is possible to vary the counting time from 1 second to 1000 seconds, using values at 5, 10, 50, 100 and 500 seconds. The corresponding values of the frequency are 500 c/sec, 100, 50 10. 5. 1 and 0.5 c/sec with a resolving power of 0.2 per cent. The result appears on an indicator panel (galvanometer) and is available in the form of an analogue voltage suitable for a 50 mV MECI recorder. (author) [French] En utilisant un ictometre analogique, la mesure des taux de comptages faibles pose des problemes techniques. Les faibles taux de comptage exigent des constantes de temps allant jusqu'a 1000 s. La technique numerique se montre mieux adaptee et permet d'augmenter la constante de temps a 1000 s ou plus. L'ensemble decrit comporte 6 ictometres numeriques loges dans un tiroir 3 U 3. Une horloge permet de varier le temps de comptage de 1 seconde a 1000 secondes, passant par 5, 10, 50, 100, 500 secondes. Les gammes de frequences correspondantes sont 500, 100, 50, 10, 5, 1, 0,5 c/s avec une resolution de 2 pour 1000. Le resultat est affiche par un indicateur de tableaux (galvanometre) et est disponible en tension analogique pour l'enregistrement sur MECI (50 mV). (auteur)
Attentional networks in developmental dyscalculia
Directory of Open Access Journals (Sweden)
Henik Avishai
2010-01-01
Full Text Available Abstract Background Very little is known about attention deficits in developmental dyscalculia, hence, this study was designed to provide the missing information. We examined attention abilities of participants suffering from developmental dyscalculia using the attention networks test - interactions. This test was designed to examine three different attention networks--executive function, orienting and alerting--and the interactions between them. Methods Fourteen university students that were diagnosed as suffering from developmental dyscalculia--intelligence and reading abilities in the normal range and no indication of attention-deficit hyperactivity disorder--and 14 matched controls were tested using the attention networks test - interactions. All participants were given preliminary tests to measure mathematical abilities, reading, attention and intelligence. Results The results revealed deficits in the alerting network--a larger alerting effect--and in the executive function networks--a larger congruity effect in developmental dyscalculia participants. The interaction between the alerting and executive function networks was also modulated by group. In addition, developmental dyscalculia participants were slower to respond in the non-cued conditions. Conclusions These results imply specific attentional deficits in pure developmental dyscalculia. Namely, those with developmental dyscalculia seem to be deficient in the executive function and alertness networks. They suffer from difficulty in recruiting attention, in addition to the deficits in numerical processing.
Green corridors and network design
DEFF Research Database (Denmark)
Panagakos, George
2016-01-01
major overhaul of the EU transportation infrastructure policy is outlined and the basic differences with the past are pinpointed. The provisions of the new TEN-T Guidelines are scrutinized so as to check whether the TEN-T core network corridors exhibit the characteristics of a green corridor......The purpose of this chapter is to investigate the relation between the Trans-European Transport Network (TEN-T) and the green corridor concept. First, the need is established for a corridor governance structure that enables the close cooperation among the numerous stakeholders from both the public......, as they have been identified in the previous chapter. Based on the results of this analysis, it is concluded that the TEN-T core network is, as far as its freight dimension is concerned, a network of green corridors....
Zhang, Songchuan; Xia, Youshen; Wang, Jun
2015-12-01
In this paper, we present a complex-valued projection neural network for solving constrained convex optimization problems of real functions with complex variables, as an extension of real-valued projection neural networks. Theoretically, by developing results on complex-valued optimization techniques, we prove that the complex-valued projection neural network is globally stable and convergent to the optimal solution. Obtained results are completely established in the complex domain and thus significantly generalize existing results of the real-valued projection neural networks. Numerical simulations are presented to confirm the obtained results and effectiveness of the proposed complex-valued projection neural network.
Wols, B.A.; Van Daal, K.; Van Thienen, P.
2014-01-01
Climate change may result in lowering of ground water levels and consolidation of the soil. The resulting (differential) settlements, associated with soil property transitions, may damage underground pipe infrastructure, such as drinking water distribution sys- tems. The work presented here offers
Adaptive bridge control strategy for opinion evolution on social networks.
Qian, Cheng; Cao, Jinde; Lu, Jianquan; Kurths, Jürgen
2011-06-01
In this paper, we present an efficient opinion control strategy for complex networks, in particular, for social networks. The proposed adaptive bridge control (ABC) strategy calls for controlling a special kind of nodes named bridge and requires no knowledge of the node degrees or any other global or local knowledge, which are necessary for some other immunization strategies including targeted immunization and acquaintance immunization. We study the efficiency of the proposed ABC strategy on random networks, small-world networks, scale-free networks, and the random networks adjusted by the edge exchanging method. Our results show that the proposed ABC strategy is efficient for all of these four kinds of networks. Through an adjusting clustering coefficient by the edge exchanging method, it is found out that the efficiency of our ABC strategy is closely related with the clustering coefficient. The main contributions of this paper can be listed as follows: (1) A new high-order social network is proposed to describe opinion dynamic. (2) An algorithm, which does not require the knowledge of the nodes' degree and other global∕local network structure information, is proposed to control the "bridges" more accurately and further control the opinion dynamics of the social networks. The efficiency of our ABC strategy is illustrated by numerical examples. (3) The numerical results indicate that our ABC strategy is more efficient for networks with higher clustering coefficient.
Constrained target controllability of complex networks
Guo, Wei-Feng; Zhang, Shao-Wu; Wei, Ze-Gang; Zeng, Tao; Liu, Fei; Zhang, Jingsong; Wu, Fang-Xiang; Chen, Luonan
2017-06-01
It is of great theoretical interest and practical significance to study how to control a system by applying perturbations to only a few driver nodes. Recently, a hot topic of modern network researches is how to determine driver nodes that allow the control of an entire network. However, in practice, to control a complex network, especially a biological network, one may know not only the set of nodes which need to be controlled (i.e. target nodes), but also the set of nodes to which only control signals can be applied (i.e. constrained control nodes). Compared to the general concept of controllability, we introduce the concept of constrained target controllability (CTC) of complex networks, which concerns the ability to drive any state of target nodes to their desirable state by applying control signals to the driver nodes from the set of constrained control nodes. To efficiently investigate the CTC of complex networks, we further design a novel graph-theoretic algorithm called CTCA to estimate the ability of a given network to control targets by choosing driver nodes from the set of constrained control nodes. We extensively evaluate the CTC of numerous real complex networks. The results indicate that biological networks with a higher average degree are easier to control than biological networks with a lower average degree, while electronic networks with a lower average degree are easier to control than web networks with a higher average degree. We also show that our CTCA can more efficiently produce driver nodes for target-controlling the networks than existing state-of-the-art methods. Moreover, we use our CTCA to analyze two expert-curated bio-molecular networks and compare to other state-of-the-art methods. The results illustrate that our CTCA can efficiently identify proven drug targets and new potentials, according to the constrained controllability of those biological networks.
Hurtado-Cardador, Manuel; Urrutia-Fucugauchi, Jaime
2006-12-01
Since 1947 Petroleos Mexicanos (Pemex) has conducted oil exploration projects using potential field methods. Geophysical exploration companies under contracts with Pemex carried out gravity anomaly surveys that were referred to different floating data. Each survey comprises observations of gravity stations along highways, roads and trails at intervals of about 500 m. At present, 265 separate gravimeter surveys that cover 60% of the Mexican territory (mainly in the oil producing regions of Mexico) are available. This gravity database represents the largest, highest spatial resolution information, and consequently has been used in the geophysical data compilations for the Mexico and North America gravity anomaly maps. Regional integration of gravimeter surveys generates gradients and spurious anomalies in the Bouguer anomaly maps at the boundaries of the connected surveys due to the different gravity base stations utilized. The main objective of this study is to refer all gravimeter surveys from Pemex to a single new first-order gravity base station network, in order to eliminate problems of gradients and spurious anomalies. A second objective is to establish a network of permanent gravity base stations (BGP), referred to a single base from the World Gravity System. Four regional loops of BGP covering eight States of Mexico were established to support the tie of local gravity base stations from each of the gravimeter surveys located in the vicinity of these loops. The third objective is to add the gravity constants, measured and calculated, for each of the 265 gravimeter surveys to their corresponding files in the Pemex and Instituto Mexicano del Petroleo database. The gravity base used as the common datum is the station SILAG 9135-49 (Latin American System of Gravity) located in the National Observatory of Tacubaya in Mexico City. We present the results of the installation of a new gravity base network in northeastern Mexico, reference of the 43 gravimeter surveys
Maddah, Heydar; Ghasemi, Nahid
2017-12-01
In this study, heat transfer efficiency of water and iron oxide nanofluid in a double pipe heat exchanger equipped with a typical twisted tape is experimentally investigated and impacts of the concentration of nanofluid and twisted tape on the heat transfer efficiency are also studied. Experiments were conducted under the laminar and turbulent flow for Reynolds numbers in the range of 1000 to 6000 and the concentration of nanofluid was 0.01, 0.02 and 0.03 wt%. In order to model and predict the heat transfer efficiency, an artificial neural network was used. The temperature of the hot fluid (nanofluid), the temperature of the cold fluid (water), mass flow rate of hot fluid (nanofluid), mass flow rate of cold fluid (water), the concentration of nanofluid and twist ratio are input data in artificial neural network and heat transfer is output or target. Heat transfer efficiency in the presence of 0.03 wt% nanofluid increases by 30% while using both the 0.03 wt% nanofluid and twisted tape with twist ratio 2 increases the heat transfer efficiency by 60%. Implementation of various structures of neural network with different number of neurons in the middle layer showed that 1-10-6 arrangement with the correlation coefficient 0.99181 and normal root mean square error 0.001621 is suggested as a desirable arrangement. The above structure has been successful in predicting 72% to 97%of variation in heat transfer efficiency characteristics based on the independent variables changes. In total, comparing the predicted results in this study with other studies and also the statistical measures shows the efficiency of artificial neural network.
Gómez-Rivas, J; Rodríguez-Socarrás, M E; Tortolero-Blanco, L; Garcia-Sanz, M; Alvarez-Maestro, M; Ribal, M J; Cózar-Olmo, M
2017-04-01
To measure social network activity during the 81th National Congress of the Spanish Urological Association (AEU) and to compare it with the activity during other congresses of national and international urological associations. We designed and registered the official hashtag #AEU16 for the 81 th National Congress of the AEU on the Symplur website. The following measurements were recorded: number of participants, number of tweets, tweets by participant, tweets per hour and views. The number of participants in the social network activity during the congress was 207. The measurements of activity in Twitter consisted of a total of 1866 tweets, a mean rate of 16 tweets/h, 9 tweets per participant and 1,511,142 views. The activity during the international congresses is as follows: 2016 American Urological Association annual congress (views: 28,052,558), 2016 European Association of Urology annual congress (views: 13,915,994), 2016 Urological Society of Australia and New Zealand (views: 4,757,453), 2015 Société Internationale d'Urologie annual congress (views: 1,023,038). The activity during the national congresses was recorded as follows: 2016 Annual Conference of The British Association of Urological Surgeons (views: 2,518,880), 81th National Congress of the AEU (views: 1,511,142), 109th Congress of l'Association Française d'Urologie (views: 662,828), 67th German Congress of Urology (views: 167,347). We found 10 posts in Facebook and 2 communications via Periscope TV related to #AEU16. The social network activity during the 81 th National Congress of the AEU was notable given the results of this study. The use of social networks has expanded among urological associations, congresses and meetings, giving them a global character. Copyright © 2016 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.
Numerical prediction of shoreline adjacent to breakwater
Digital Repository Service at National Institute of Oceanography (India)
Mahadevan, R.; Chandramohan, P.; Nayak, B.U.
Existing mathematical models for prediction of shoreline changes in the vicinity of a breakwater were reviewed The analytical and numerical results obtained from these models have been compared Under the numerical approach, two different implicit...
Wols, B.A.; van Daal, K.; van Thienen, P.
2014-01-01
Climate change may result in lowering of ground water levels and consolidation of the soil. The resulting (differential) settlements, associated with soil property transitions, may damage underground pipe infrastructure, such as drinking water distribution sys- tems. The work presented here offers an approach for the prediction of pipe failure under conditions of differential settlement. A probabilistic model for pipe failure has been implemented in a geographical information system (GIS) env...
A numerical reference model for themomechanical subduction
DEFF Research Database (Denmark)
Quinquis, Matthieu; Chemia, Zurab; Tosi, Nicola
2010-01-01
response to systematic variations in input parameters, numerical studies often start from a 'reference' subduction model. However, the reference model often varies between different numerical studies, making it difficult to compare results directly. We aim therefore to define a numerical reference model......, and initial temperature distribution. We will show results of the evolution and dynamics of the subduction reference model using different numerical codes: a finite element code, SULEC, and two finite difference codes, YACC and FDcon....
When are networks truly modular?
Reichardt, Jörg; Bornholdt, Stefan
2006-12-01
The study of cluster or community structure of complex networks contributes to the understanding of networks at a functional level. In many networks, latent classes of nodes are suspected which manifest themselves as communities, i.e. groups of nodes with a high link density among the nodes of the same class and low link density between nodes of different classes. Community detection algorithms are used to infer these classes, e.g. by finding a partition of the network which maximizes a quality function such as the network modularity Q [M. Newman, M. Girvan, Finding and evaluating community structure in networks, Phys. Rev. E 69 (2004) 026113]. However, it is known from numerical experiments that even purely random networks display intrinsic modularity and may be partitioned yielding high values of Q. Extending on our earlier results [J. Reichardt, S. Bornholdt, Statistical mechanics of community detection, Phys. Rev. E 74 (2006) 016110], the mapping of the community detection problem onto finding the ground state of a spin glass is exploited in order to derive analytical expressions for the expected modularity in random graphs and assess the theoretical limits to community detection. The results are independent of any specific community detection algorithm and allow for differentiation between modularity arising purely due to the search process in the large configuration space of possible partitionings on the one hand, or due to the actual presence of different classes of nodes on the other hand.
Attentional networks in developmental dyscalculia.
Askenazi, Sarit; Henik, Avishai
2010-01-07
Very little is known about attention deficits in developmental dyscalculia, hence, this study was designed to provide the missing information. We examined attention abilities of participants suffering from developmental dyscalculia using the attention networks test - interactions. This test was designed to examine three different attention networks--executive function, orienting and alerting--and the interactions between them. Fourteen university students that were diagnosed as suffering from developmental dyscalculia--intelligence and reading abilities in the normal range and no indication of attention-deficit hyperactivity disorder--and 14 matched controls were tested using the attention networks test-interactions. All participants were given preliminary tests to measure mathematical abilities, reading, attention and intelligence. The results revealed deficits in the alerting network--a larger alerting effect--and in the executive function networks--a larger congruity effect in developmental dyscalculia participants. The interaction between the alerting and executive function networks was also modulated by group. In addition, developmental dyscalculia participants were slower to respond in the non-cued conditions. These results imply specific attentional deficits in pure developmental dyscalculia. Namely, those with developmental dyscalculia seem to be deficient in the executive function and alertness networks. They suffer from difficulty in recruiting attention, in addition to the deficits in numerical processing.
Minimum network constraint on reverse engineering to develop biological regulatory networks.
Shao, Bin; Wu, Jiayi; Tian, Binghui; Ouyang, Qi
2015-09-07
Reconstructing the topological structure of biological regulatory networks from microarray expression data or data of protein expression profiles is one of major tasks in systems biology. In recent years, various mathematical methods have been developed to meet this task. Here, based on our previously reported reverse engineering method, we propose a new constraint, i.e., the minimum network constraint, to facilitate the reconstruction of biological networks. Three well studied regulatory networks (the budding yeast cell cycle network, the fission yeast cell cycle network, and the SOS network of Escherichia coli) were used as the test sets to verify the performance of this method. Numerical results show that the biological networks prefer to use the minimal networks to fulfill their functional tasks, making it possible to apply minimal network criteria in the network reconstruction process. Two scenarios were considered in the reconstruction process: generating data using different initial conditions; and generating data from knock out and over-expression experiments. In both cases, network structures are revealed faithfully in a few steps using our approach. Copyright © 2015 Elsevier Ltd. All rights reserved.
Jani, Yashvant
1992-01-01
As part of the RICIS activity, the reinforcement learning techniques developed at Ames Research Center are being applied to proximity and docking operations using the Shuttle and Solar Max satellite simulation. This activity is carried out in the software technology laboratory utilizing the Orbital Operations Simulator (OOS). This report is deliverable D2 Altitude Control Results and provides the status of the project after four months of activities and outlines the future plans. In section 2 we describe the Fuzzy-Learner system for the attitude control functions. In section 3, we provide the description of test cases and results in a chronological order. In section 4, we have summarized our results and conclusions. Our future plans and recommendations are provided in section 5.
Epidemics on interconnected networks
Dickison, Mark; Havlin, S.; Stanley, H. E.
2012-06-01
Populations are seldom completely isolated from their environment. Individuals in a particular geographic or social region may be considered a distinct network due to strong local ties but will also interact with individuals in other networks. We study the susceptible-infected-recovered process on interconnected network systems and find two distinct regimes. In strongly coupled network systems, epidemics occur simultaneously across the entire system at a critical infection strength βc, below which the disease does not spread. In contrast, in weakly coupled network systems, a mixed phase exists below βc of the coupled network system, where an epidemic occurs in one network but does not spread to the coupled network. We derive an expression for the network and disease parameters that allow this mixed phase and verify it numerically. Public health implications of communities comprising these two classes of network systems are also mentioned.
Softening in random networks of non-identical beams
Ban, Ehsan; Barocas, Victor H.; Shephard, Mark S.; Picu, R. Catalin
2016-02-01
Random fiber networks are assemblies of elastic elements connected in random configurations. They are used as models for a broad range of fibrous materials including biopolymer gels and synthetic nonwovens. Although the mechanics of networks made from the same type of fibers has been studied extensively, the behavior of composite systems of fibers with different properties has received less attention. In this work we numerically and theoretically study random networks of beams and springs of different mechanical properties. We observe that the overall network stiffness decreases on average as the variability of fiber stiffness increases, at constant mean fiber stiffness. Numerical results and analytical arguments show that for small variabilities in fiber stiffness the amount of network softening scales linearly with the variance of the fiber stiffness distribution. This result holds for any beam structure and is expected to apply to a broad range of materials including cellular solids.
Softening in Random Networks of Non-Identical Beams.
Ban, Ehsan; Barocas, Victor H; Shephard, Mark S; Picu, Catalin R
2016-02-01
Random fiber networks are assemblies of elastic elements connected in random configurations. They are used as models for a broad range of fibrous materials including biopolymer gels and synthetic nonwovens. Although the mechanics of networks made from the same type of fibers has been studied extensively, the behavior of composite systems of fibers with different properties has received less attention. In this work we numerically and theoretically study random networks of beams and springs of different mechanical properties. We observe that the overall network stiffness decreases on average as the variability of fiber stiffness increases, at constant mean fiber stiffness. Numerical results and analytical arguments show that for small variabilities in fiber stiffness the amount of network softening scales linearly with the variance of the fiber stiffness distribution. This result holds for any beam structure and is expected to apply to a broad range of materials including cellular solids.
Ganas, A.; Marinou, A.; Anastasiou, D.; Paradissis, D.; Papazissi, K.; Tzavaras, P.; Drakatos, G.
2013-07-01
Ionian Sea (western Greece) is a plate-boundary region of high seismicity and complex tectonics, dominated by frequent earthquake activity along the right-lateral Cephalonia transform fault. We present an analysis of 30-s GPS data from five (5) continuous stations of NOANET (NOA permanent GPS network) spanning the period 2007-2010. Our results show N-S crustal shortening onshore Lefkada island of the order of 2-3 mm/yr which is probably related to increased locking on the offshore Lefkada fault. We also calculated a large difference (1:3) in the principal strain rate amplitude between extension and shortening for the central Ionian Sea.
Learning Bayesian networks for discrete data
Liang, Faming
2009-02-01
Bayesian networks have received much attention in the recent literature. In this article, we propose an approach to learn Bayesian networks using the stochastic approximation Monte Carlo (SAMC) algorithm. Our approach has two nice features. Firstly, it possesses the self-adjusting mechanism and thus avoids essentially the local-trap problem suffered by conventional MCMC simulation-based approaches in learning Bayesian networks. Secondly, it falls into the class of dynamic importance sampling algorithms; the network features can be inferred by dynamically weighted averaging the samples generated in the learning process, and the resulting estimates can have much lower variation than the single model-based estimates. The numerical results indicate that our approach can mix much faster over the space of Bayesian networks than the conventional MCMC simulation-based approaches. © 2008 Elsevier B.V. All rights reserved.
Estimation of Conditional Quantile using Neural Networks
DEFF Research Database (Denmark)
Kulczycki, P.; Schiøler, Henrik
1999-01-01
The problem of estimating conditional quantiles using neural networks is investigated here. A basic structure is developed using the methodology of kernel estimation, and a theory guaranteeing con-sistency on a mild set of assumptions is provided. The constructed structure constitutes a basis...... for the design of a variety of different neural networks, some of which are considered in detail. The task of estimating conditional quantiles is related to Bayes point estimation whereby a broad range of applications within engineering, economics and management can be suggested. Numerical results illustrating...... the capabilities of the elaborated neural network are also given....
Reinforcement learning account of network reciprocity.
Directory of Open Access Journals (Sweden)
Takahiro Ezaki
Full Text Available Evolutionary game theory predicts that cooperation in social dilemma games is promoted when agents are connected as a network. However, when networks are fixed over time, humans do not necessarily show enhanced mutual cooperation. Here we show that reinforcement learning (specifically, the so-called Bush-Mosteller model approximately explains the experimentally observed network reciprocity and the lack thereof in a parameter region spanned by the benefit-to-cost ratio and the node's degree. Thus, we significantly extend previously obtained numerical results.
Best, M.; Johnson, F.; Moran, K.; Pirenne, B.; Founding Scientists Of Neptune Canada
2011-12-01
NEPTUNE Canada completed the installation and is now operating an 800 km, 5-node, regional cabled ocean network that spans the northern Juan de Fuca tectonic plate and continental shelf/slope in the northeastern Pacific. The NEPTUNE Canada network is part of the Ocean Networks Canada Observatory. Public data flow started in 2009 and interactive instruments continue to be added to this technically advanced system which provides continuous power and high bandwidth for enabling the collection of real-time physical, chemical, geological, and biological oceanographic data at resolutions relevant for furthering our understanding of the dynamics of the earth-ocean system. Here we present an overview and some initial results of the early installed real-time experiments, developed through workshops and international competitions, at five offshore locations. Inshore at Folger Passage, Barkley Sound, observations are focused on understanding biological productivity and the effects that marine processes have on fish and marine mammals. Experiments around Barkley Canyon allow quantification of changes in benthic activity with nutrient and sediment transport. There and north along the mid-continental slope near ODP Site 889, instruments are monitoring changes in the distribution, structure, related biotas and venting of gas hydrates. A Circulation Obviation Retrofit Kit (CORK) at our mid-plate site (ODP 1026) monitors real-time changes in crustal temperature and pressure, particularly related to events such as earthquakes, tsunamis, hydrothermal convection; these data are also important for understanding regional plate strain. At Endeavour on the Juan de Fuca Ridge, complex interactions among volcanic, tectonic, hydrothermal and biological processes are being observed. Across the NEPTUNE Canada network, high resolution acoustic and seismic monitoring elucidates tectonic processes such as earthquakes, and a tsunami detection system allows for the determination of open ocean
Amory-Mazaudier, C.; Fleury, R.; Petitdidier, M.; Soula, S.; Masson, F.; Davila, J.; Doherty, P.; Elias, A.; Gadimova, S.; Makela, J.; Nava, B.; Radicella, S.; Richardson, J.; Touzani, A.; Girgea Team
2017-12-01
This paper reviews scientific advances achieved by a North-South network between 2006 and 2016. These scientific advances concern solar terrestrial physics, atmospheric physics and space weather. This part B is devoted to the results and capacity building. Our network began in 1991, in solar terrestrial physics, by our participation in the two projects: International Equatorial Electrojet Year IEEY [1992-1993] and International Heliophysical Year IHY [2007-2009]. These two projects were mainly focused on the equatorial ionosphere in Africa. In Atmospheric physics our research focused on gravity waves in the framework of the African Multidisciplinary Monsoon Analysis project n°1 [2005-2009 ], on hydrology in the Congo river basin and on lightning in Central Africa, the most lightning part of the world. In Vietnam the study of a broad climate data base highlighted global warming. In space weather, our results essentially concern the impact of solar events on global navigation satellite system GNSS and on the effects of solar events on the circulation of electric currents in the earth (GIC). This research began in the framework of the international space weather initiative project ISWI [2010-2012]. Finally, all these scientific projects have enabled young scientists from the South to publish original results and to obtain positions in their countries. These projects have also crossed disciplinary boundaries and defined a more diversified education which led to the training of specialists in a specific field with knowledge of related scientific fields.
Directory of Open Access Journals (Sweden)
Lan Liu
2017-01-01
Full Text Available As the adoption of Software Defined Networks (SDNs grows, the security of SDN still has several unaddressed limitations. A key network security research area is in the study of malware propagation across the SDN-enabled networks. To analyze the spreading processes of network malware (e.g., viruses in SDN, we propose a dynamic model with a time-varying community network, inspired by research models on the spread of epidemics in complex networks across communities. We assume subnets of the network as communities and links that are dense in subnets but sparse between subnets. Using numerical simulation and theoretical analysis, we find that the efficiency of network malware propagation in this model depends on the mobility rate q of the nodes between subnets. We also find that there exists a mobility rate threshold qc. The network malware will spread in the SDN when the mobility rate q>qc. The malware will survive when q>qc and perish when q
The theory of pattern formation on directed networks.
Asllani, Malbor; Challenger, Joseph D; Pavone, Francesco Saverio; Sacconi, Leonardo; Fanelli, Duccio
2014-07-31
Dynamical processes on networks have generated widespread interest in recent years. The theory of pattern formation in reaction-diffusion systems defined on symmetric networks has often been investigated, due to its applications in a wide range of disciplines. Here we extend the theory to the case of directed networks, which are found in a number of different fields, such as neuroscience, computer networks and traffic systems. Owing to the structure of the network Laplacian, the dispersion relation has both real and imaginary parts, at variance with the case for a symmetric, undirected network. The homogeneous fixed point can become unstable due to the topology of the network, resulting in a new class of instabilities, which cannot be induced on undirected graphs. Results from a linear stability analysis allow the instability region to be analytically traced. Numerical simulations show travelling waves, or quasi-stationary patterns, depending on the characteristics of the underlying graph.
Equivalence of Conventional and Modified Network of Generalized Neural Elements
Directory of Open Access Journals (Sweden)
E. V. Konovalov
2016-01-01
Full Text Available The article is devoted to the analysis of neural networks consisting of generalized neural elements. The first part of the article proposes a new neural network model — a modified network of generalized neural elements (MGNE-network. This network developes the model of generalized neural element, whose formal description contains some flaws. In the model of the MGNE-network these drawbacks are overcome. A neural network is introduced all at once, without preliminary description of the model of a single neural element and method of such elements interaction. The description of neural network mathematical model is simplified and makes it relatively easy to construct on its basis a simulation model to conduct numerical experiments. The model of the MGNE-network is universal, uniting properties of networks consisting of neurons-oscillators and neurons-detectors. In the second part of the article we prove the equivalence of the dynamics of the two considered neural networks: the network, consisting of classical generalized neural elements, and MGNE-network. We introduce the definition of equivalence in the functioning of the generalized neural element and the MGNE-network consisting of a single element. Then we introduce the definition of the equivalence of the dynamics of the two neural networks in general. It is determined the correlation of different parameters of the two considered neural network models. We discuss the issue of matching the initial conditions of the two considered neural network models. We prove the theorem about the equivalence of the dynamics of the two considered neural networks. This theorem allows us to apply all previously obtained results for the networks, consisting of classical generalized neural elements, to the MGNE-network.
Numerical Propulsion System Simulation
Naiman, Cynthia
2006-01-01
The NASA Glenn Research Center, in partnership with the aerospace industry, other government agencies, and academia, is leading the effort to develop an advanced multidisciplinary analysis environment for aerospace propulsion systems called the Numerical Propulsion System Simulation (NPSS). NPSS is a framework for performing analysis of complex systems. The initial development of NPSS focused on the analysis and design of airbreathing aircraft engines, but the resulting NPSS framework may be applied to any system, for example: aerospace, rockets, hypersonics, power and propulsion, fuel cells, ground based power, and even human system modeling. NPSS provides increased flexibility for the user, which reduces the total development time and cost. It is currently being extended to support the NASA Aeronautics Research Mission Directorate Fundamental Aeronautics Program and the Advanced Virtual Engine Test Cell (AVETeC). NPSS focuses on the integration of multiple disciplines such as aerodynamics, structure, and heat transfer with numerical zooming on component codes. Zooming is the coupling of analyses at various levels of detail. NPSS development includes capabilities to facilitate collaborative engineering. The NPSS will provide improved tools to develop custom components and to use capability for zooming to higher fidelity codes, coupling to multidiscipline codes, transmitting secure data, and distributing simulations across different platforms. These powerful capabilities extend NPSS from a zero-dimensional simulation tool to a multi-fidelity, multidiscipline system-level simulation tool for the full development life cycle.
Banwart, Steven; Menon, Manoj; Bernasconi, Stefano M.; Bloem, Jaap; Blum, Winfried E. H.; Souza, Danielle Maia de; Davidsdotir, Brynhildur; Duffy, Christopher; Lair, Georg J.; Kram, Pavel; Lamacova, Anna; Lundin, Lars; Nikolaidis, Nikolaos P.; Novak, Martin; Panagos, Panos; Ragnarsdottir, Kristin Vala; Reynolds, Brian; Robinson, David; Rousseva, Svetla; de Ruiter, Peter; van Gaans, Pauline; Weng, Liping; White, Tim; Zhang, Bin
2012-11-01
Growth in human population and demand for wealth creates ever-increasing pressure on global soils, leading to soil losses and degradation worldwide. Critical Zone science studies the impact linkages between these pressures, the resulting environmental state of soils, and potential interventions to protect soil and reverse degradation. New research on soil processes is being driven by the scientific hypothesis that soil processes can be described along a life cycle of soil development. This begins with formation of new soil from parent material, development of the soil profile, and potential loss of the developed soil functions and the soil itself under overly intensive anthropogenic land use, thus closing the cycle. Four Critical Zone Observatories in Europe have been selected focusing research at sites that represent key stages along the hypothetical soil life cycle; incipient soil formation, productive use of soil for farming and forestry, and decline of soil due to longstanding intensive agriculture. Initial results from the research show that soil develops important biogeochemical properties on the time scale of decades and that soil carbon and the development of favourable soil structure takes place over similar time scales. A new mathematical model of soil aggregate formation and degradation predicts that set-aside land at the most degraded site studied can develop substantially improved soil structure with the accumulation of soil carbon over a period of several years. Further results demonstrate the rapid dynamics of soil carbon; how quickly it can be lost, and also demonstrate how data from the CZOs can be used to determine parameter values for models at catchment scale. A structure for a new integrated Critical Zone model is proposed that combines process descriptions of carbon and nutrient flows, a simplified description of the soil food web, and reactive transport; all coupled with a dynamic model for soil structure and soil aggregation. This approach
Jani, Yashvant
1992-01-01
The reinforcement learning techniques developed at Ames Research Center are being applied to proximity and docking operations using the Shuttle and Solar Maximum Mission (SMM) satellite simulation. In utilizing these fuzzy learning techniques, we also use the Approximate Reasoning based Intelligent Control (ARIC) architecture, and so we use two terms interchangeable to imply the same. This activity is carried out in the Software Technology Laboratory utilizing the Orbital Operations Simulator (OOS). This report is the deliverable D3 in our project activity and provides the test results of the fuzzy learning translational controller. This report is organized in six sections. Based on our experience and analysis with the attitude controller, we have modified the basic configuration of the reinforcement learning algorithm in ARIC as described in section 2. The shuttle translational controller and its implementation in fuzzy learning architecture is described in section 3. Two test cases that we have performed are described in section 4. Our results and conclusions are discussed in section 5, and section 6 provides future plans and summary for the project.
DEFF Research Database (Denmark)
Hendriksen, Rene S.; Vieira, Antonio; Karlsmose, Susanne
2011-01-01
most frequently identified serovars of Salmonella isolated from humans from 2001 to 2007 in laboratories from 37 countries that participated in World Health Organization Global Foodborne Infections Network and demonstrated serotyping proficiency in the Global Foodborne Infections Network External...
The PM2.5 Fine Particle Background Network of the German Meteorological Service-First Results
Directory of Open Access Journals (Sweden)
Uwe Kaminski
2013-04-01
Full Text Available Since 2009, the measurement of the background concentration of the fine particle fraction has been a part of the climate-monitoring program of the German Meteorological Service (DWD. These particles are of high health relevance as a critical air pollutant affecting processes like the scattering and absorption of solar radiation and influencing cloud formation and visibility. At 12 weather stations, the coarse (2.5 to 10 l m and the fine particle fractions (PM2.5 are measured by means of passive and active samplers. First results are presented for the mass concentrations of coarse and fine particles as well as for the black carbon (BC content and the concentration of certain inorganic ions of fine particles. There is not only a seasonal correlation between the fraction of fine and coarse particles, but also a correlation with the location (urban background or rural background. With the help of light microscopy, coarse particles can be differentiated for a geogenic (predominantly wind blown mineral and sea salt particles of natural origin and road abrasion and for an anthropogenic opaque component (combustion residues, e.g. fly ash and non-exhaust vehicle emissions, e.g. abrasion particles of brakes and tires. Measuring the fine fraction and the coarse fraction separately instead of PM10 allows for a better source allocation and thus is a more appropriate method for the improvement of the air quality in, e.g. low emission zones.
Directory of Open Access Journals (Sweden)
Olson Matthew D
2012-08-01
Full Text Available Abstract Background Medical records that do not accurately reflect the patient’s current medication list are an open invitation to errors and may compromise patient safety. Methods This cross-sectional study compares primary care provider (PCP medication lists and pharmacy claims for 100 patients seen in 8 primary care practices and examines the association of congruence with demographic, clinical, and practice characteristics. Medication list congruence was measured as agreement of pharmacy claims with the entire PCP chart, including current medication list, visit notes, and correspondence sections. Results Congruence between pharmacy claims and the PCP chart was 65%. Congruence was associated with large chronic disease burden, frequent PCP visits, group practice, and patient age ≥45 years. Conclusion Agreement of medication lists between the PCP chart and pharmacy records is low. Medication documentation was more accurate among patients who have more chronic conditions, those who have frequent PCP visits, those whose practice has multiple providers, and those at least 45 years of age. Improved congruence among patients with multiple chronic conditions and in group practices may reflect more frequent visits and reviews by providers.
Schüler, G; Klaes, L; Rommel, A; Schröder, H; Köhler, T
2013-08-01
Demographic change, advances in medicine, and innovative health care services are leading to changes in the professional qualification requirements for nursing and care staff. Detecting future trends in relation to these requirements was the focus of a Delphi study developed as part of the BMBF FreQueNz initiative. After qualitative expert interviews, data collection was organized in three consecutive steps, with 243 interviews realized in the second wave. It was found that home care will further diversify in the fields of supporting and counseling services as well as in palliative care, resulting in the necessary expansion of specific qualifications (e.g., intensive care). Moreover, there will be an increased need for interprofessional, intersectoral, and intercultural coordination and communication skills. As a consequence of the delegation of medical tasks, new duties for nonmedical professions in inpatient and outpatient care will also arise. For instance, qualifications need to be tailored to the new demands of assessment, diagnostics, therapy, and patient education and they should take into account evidence-based knowledge as well as clinical practice guidelines. Consequently, the system of care professionals will further diversify through advanced training programs and the continued academization of nursing.
Navigability of multiplex temporal network
Wang, Yan; Song, Qiao-Zhen
2017-01-01
Real world complex systems have multiple levels of relationships and in many cases, they need to be modeled as multiplex networks where the same nodes can interact with each other in different layers, such as social networks. However, social relationships only appear at prescribed times so the temporal structures of edge activations can also affect the dynamical processes located above them. To consider both factors are simultaneously, we introduce multiplex temporal networks and propose three different walk strategies to investigate the concurrent dynamics of random walks and the temporal structure of multiplex networks. Thus, we derive analytical results for the multiplex centrality and coverage function in multiplex temporal networks. By comparing them with the numerical results, we show how the underlying topology of the layers and the walk strategy affect the efficiency when exploring the networks. In particular, the most interesting result is the emergence of a super-diffusion process, where the time scale of the multiplex is faster than that of both layers acting separately.
Continuum Modeling of Biological Network Formation
Albi, Giacomo
2017-04-10
We present an overview of recent analytical and numerical results for the elliptic–parabolic system of partial differential equations proposed by Hu and Cai, which models the formation of biological transportation networks. The model describes the pressure field using a Darcy type equation and the dynamics of the conductance network under pressure force effects. Randomness in the material structure is represented by a linear diffusion term and conductance relaxation by an algebraic decay term. We first introduce micro- and mesoscopic models and show how they are connected to the macroscopic PDE system. Then, we provide an overview of analytical results for the PDE model, focusing mainly on the existence of weak and mild solutions and analysis of the steady states. The analytical part is complemented by extensive numerical simulations. We propose a discretization based on finite elements and study the qualitative properties of network structures for various parameter values.
Shiokawa, Kazuo
2012-07-01
Whistler-mode waves in the VLF/ELF frequency range interact with high-energy (~10 keV) electrons to cause diffuse and pulsating auroras, and with MeV electrons in the radiation belts. However, simultaneous high-time resolution measurements of aurora and these waves have previously not been done sufficiently. We made a campaign observation of such high-time resolution measurements at Athabasca (54.72N, 246.69E, MLAT=61.3) and Fort Vermillion (58.38N, 243.99E, MLAT=64.5) using two loop antennas and several auroral cameras for February 16-26, 2012. The loop antennas at both stations measure east-west and north-south magnetic field variations with a sampling rate of 100 kHz. The panchromatic all-sky cameras at both stations measure auroras with a sampling rate of 30 Hz. The sampling timings of both instruments are corrected by GPS receivers. In addition we installed an oblique looking narrow-FoV EMCCD camera at Athabasca with a sampling rate of 100 Hz, to measure height variation of pulsating aurora. At Athabasca, routine measurements by an induction magnetometer, a proton photometer, an all-sky airglow imager, LF standard wave receiver, were also carried out. We also tried to compare these observations with satellite measurements by REIMEI, THEMIS, NOAA, and DMSP. In this presentation we will show initial results obtained from this comprehensive campaign of aurora and radio wave measurements at subauroral latitudes.
Gómez-Batiste, Xavier; Caja, Carmen; Espinosa, Jose; Bullich, Ingrid; Porta-Sales, Josep; Sala, Carme; Limón, Esther; Trelis, Jordi; Pascual, Antonio; Luisa Puente, M
2010-10-01
A wide range of palliative care services has been implemented in Catalonia over the past 20 years. Quantitative and qualitative differences in the organization of palliative care services between districts and settings can result in wide variability in the quality of these services, and their accessibility. We implemented a benchmark methodology to compare dimensions of care and organization, to identify aspects requiring improvement, and to establish indicators to measure progress. The overall aim was to generate a consensus document for submission to the Department of Health (DoH) of the Government of Catalonia. A Steering Committee convoked a meeting in Barcelona (Catalonia, Spain) and representatives (n = 114) of all the 37 districts within our health care remit (rural, urban, intermediate, and metropolitan) and settings of the health care system (hospitals, social health centers, community, and nursing homes) attended and took part in plenary sessions and workshops to define areas that, in their experience, were considered weak. Twenty-one consensus recommendations achieving high levels of consensus were generated for submission to the DoH. These included the formal definition of the model of care and organization of palliative care services at all levels in the region, the implementation of measures for improvement in different settings and scenarios, systems for continuous care, and facilities for the continuing training of health care personnel. These proposals have since been implemented in a trial region and, depending on the outcomes, will be applied throughout our health service. We conclude that benchmark methodology is valuable in acquiring data for use in improving palliative care organization for patients' benefit.
Parallel computing: numerics, applications, and trends
National Research Council Canada - National Science Library
Trobec, Roman; Vajteršic, Marián; Zinterhof, Peter
2009-01-01
... and/or distributed systems. The contributions to this book are focused on topics most concerned in the trends of today's parallel computing. These range from parallel algorithmics, programming, tools, network computing to future parallel computing. Particular attention is paid to parallel numerics: linear algebra, differential equations, numerica...
Numerical Analysis on the Stability of Hydraulic Fracture Propagation
Directory of Open Access Journals (Sweden)
Zhaobin Zhang
2015-09-01
Full Text Available The formation of dense spacing fracture network is crucial to the hydraulic fracturing treatment of unconventional reservoir. However, one difficulty for fracturing treatment is the lack of clear understanding on the nature of fracture complexity created during the treatment. In this paper, fracture propagation is numerically investigated to find the conditions needed for the stable propagation of complex fracture network. Firstly, starting from a parallel fracture system, the stability of fracture propagation is analyzed and a dimensionless number M is obtained. Then, by developing a hydraulic fracturing simulation model based on displacement discontinuity method, the propagation of parallel fractures is simulated and a clear relation between M and the stability of parallel fractures is obtained. Finally, the investigation on parallel fractures is extended to complex fracture networks. The propagation of complex fracture networks is simulated and the results show that the effects of M on complex fracture networks is the same to that of parallel fractures. The clear relation between M and fracture propagation stability is important for the optimization of hydraulic fracturing operation.
Critical behavior of the contact process in annealed scale-free networks
Noh, Jae Dong; Park, Hyunggyu
2008-01-01
Critical behavior of the contact process is studied in annealed scale-free networks by mapping it on the random walk problem. We obtain the analytic results for the critical scaling, using the event-driven dynamics approach. These results are confirmed by numerical simulations. The disorder fluctuation induced by the sampling disorder in annealed networks is also explored. Finally, we discuss over the discrepancy of the finite-size-scaling theory in annealed and quenched networks in spirit of...
Multi-mode clustering model for hierarchical wireless sensor networks
Hu, Xiangdong; Li, Yongfu; Xu, Huifen
2017-03-01
The topology management, i.e., clusters maintenance, of wireless sensor networks (WSNs) is still a challenge due to its numerous nodes, diverse application scenarios and limited resources as well as complex dynamics. To address this issue, a multi-mode clustering model (M2 CM) is proposed to maintain the clusters for hierarchical WSNs in this study. In particular, unlike the traditional time-trigger model based on the whole-network and periodic style, the M2 CM is proposed based on the local and event-trigger operations. In addition, an adaptive local maintenance algorithm is designed for the broken clusters in the WSNs using the spatial-temporal demand changes accordingly. Numerical experiments are performed using the NS2 network simulation platform. Results validate the effectiveness of the proposed model with respect to the network maintenance costs, node energy consumption and transmitted data as well as the network lifetime.
Modeling and Analysis of New Products Diffusion on Heterogeneous Networks
Directory of Open Access Journals (Sweden)
Shuping Li
2014-01-01
Full Text Available We present a heterogeneous networks model with the awareness stage and the decision-making stage to explain the process of new products diffusion. If mass media is neglected in the decision-making stage, there is a threshold whether the innovation diffusion is successful or not, or else it is proved that the network model has at least one positive equilibrium. For networks with the power-law degree distribution, numerical simulations confirm analytical results, and also at the same time, by numerical analysis of the influence of the network structure and persuasive advertisements on the density of adopters, we give two different products propagation strategies for two classes of nodes in scale-free networks.
Bipartite quantum states and random complex networks
Garnerone, Silvano; Giorda, Paolo; Zanardi, Paolo
2012-01-01
We introduce a mapping between graphs and pure quantum bipartite states and show that the associated entanglement entropy conveys non-trivial information about the structure of the graph. Our primary goal is to investigate the family of random graphs known as complex networks. In the case of classical random graphs, we derive an analytic expression for the averaged entanglement entropy \\bar S while for general complex networks we rely on numerics. For a large number of nodes n we find a scaling \\bar {S} \\sim c log n +g_{ {e}} where both the prefactor c and the sub-leading O(1) term ge are characteristic of the different classes of complex networks. In particular, ge encodes topological features of the graphs and is named network topological entropy. Our results suggest that quantum entanglement may provide a powerful tool for the analysis of large complex networks with non-trivial topological properties.
3rd International Conference on Network Analysis
Kalyagin, Valery; Pardalos, Panos
2014-01-01
This volume compiles the major results of conference participants from the "Third International Conference in Network Analysis" held at the Higher School of Economics, Nizhny Novgorod in May 2013, with the aim to initiate further joint research among different groups. The contributions in this book cover a broad range of topics relevant to the theory and practice of network analysis, including the reliability of complex networks, software, theory, methodology, and applications. Network analysis has become a major research topic over the last several years. The broad range of applications that can be described and analyzed by means of a network has brought together researchers, practitioners from numerous fields such as operations research, computer science, transportation, energy, biomedicine, computational neuroscience and social sciences. In addition, new approaches and computer environments such as parallel computing, grid computing, cloud computing, and quantum computing have helped to solve large scale...
Approach of Complex Networks for the Determination of Brain Death
Sun, Wei-Gang; Cao, Jian-Ting; Wang, Ru-Bin
2011-06-01
In clinical practice, brain death is the irreversible end of all brain activity. Compared to current statistical methods for the determination of brain death, we focus on the approach of complex networks for real-world electroencephalography in its determination. Brain functional networks constructed by correlation analysis are derived, and statistical network quantities used for distinguishing the patients in coma or brain death state, such as average strength, clustering coefficient and average path length, are calculated. Numerical results show that the values of network quantities of patients in coma state are larger than those of patients in brain death state. Our findings might provide valuable insights on the determination of brain death.
Complex-linear invariants of biochemical networks.
Karp, Robert L; Pérez Millán, Mercedes; Dasgupta, Tathagata; Dickenstein, Alicia; Gunawardena, Jeremy
2012-10-21
The nonlinearities found in molecular networks usually prevent mathematical analysis of network behaviour, which has largely been studied by numerical simulation. This can lead to difficult problems of parameter determination. However, molecular networks give rise, through mass-action kinetics, to polynomial dynamical systems, whose steady states are zeros of a set of polynomial equations. These equations may be analysed by algebraic methods, in which parameters are treated as symbolic expressions whose numerical values do not have to be known in advance. For instance, an "invariant" of a network is a polynomial expression on selected state variables that vanishes in any steady state. Invariants have been found that encode key network properties and that discriminate between different network structures. Although invariants may be calculated by computational algebraic methods, such as Gröbner bases, these become computationally infeasible for biologically realistic networks. Here, we exploit Chemical Reaction Network Theory (CRNT) to develop an efficient procedure for calculating invariants that are linear combinations of "complexes", or the monomials coming from mass action. We show how this procedure can be used in proving earlier results of Horn and Jackson and of Shinar and Feinberg for networks of deficiency at most one. We then apply our method to enzyme bifunctionality, including the bacterial EnvZ/OmpR osmolarity regulator and the mammalian 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase glycolytic regulator, whose networks have deficiencies up to four. We show that bifunctionality leads to different forms of concentration control that are robust to changes in initial conditions or total amounts. Finally, we outline a systematic procedure for using complex-linear invariants to analyse molecular networks of any deficiency. Copyright © 2012 Elsevier Ltd. All rights reserved.
Thampi, Smitha V.; Yamamoto, Mamoru
2010-03-01
A chain of newly designed GNU (GNU is not UNIX) Radio Beacon Receivers (GRBR) has recently been established over Japan, primarily for tomographic imaging of the ionosphere over this region. Receivers installed at Shionomisaki (33.45°N, 135.8°E), Shigaraki (34.8°N, 136.1°E), and Fukui (36°N, 136°E) continuously track low earth orbiting satellites (LEOS), mainly OSCAR, Cosmos, and FORMOSAT-3/COSMIC, to obtain simultaneous total electron content (TEC) data from these three locations, which are then used for the tomographic reconstruction of ionospheric electron densities. This is the first GRBR network established for TEC observations, and the first beacon-based tomographic imaging in Japanese longitudes. The first tomographic images revealed the temporal evolution with all of the major features in the ionospheric electron density distribution over Japan. A comparison of the tomographically reconstructed electron densities with the ƒ o F 2 data from Kokubunji (35°N, 139°E) revealed that there was good agreement between the datasets. These first results show the potential of GRBR and its network for making continuous, unattended ionospheric TEC measurements and for tomographic imaging of the ionosphere.
Heinrich, Steffen; Sommerfeld, Ulrike; Michalowsky, Bernhard; Hoffmann, Wolfgang; Thyrian, Jochen René; Wolf-Ostermann, Karin; Roes, Martina
2017-07-01
Despite its high relevance, scientific evidence often fails to be disseminated into practice. Information websites can be a successful information dissemination tool, but very little is known about the processes involved in the interdisciplinary development of such websites. This article aims to demonstrate the processes, barriers, and facilitators during the development and publication of a practice-friendly information website grounded in scientifically based research findings about dementia care networks obtained by the DemNet-D study. The qualitative data of this article are based on a work progress protocol and a recorded interview with the project's science journalist. The interview was transcribed, analyzed, and coded based on structured content analysis. Quantitative data were extracted to display the website usage rate. The results indicate that interdisciplinary teamwork is an essential factor for successful website development. Furthermore, the use of a formalized model can help to organize the development structure. To transform scientific content, a specialized expert in the field is needed. Continuous evaluations and marketing strategies are vital for the success of a website. The final website had a high access rate 1 month after launch. Crucial processes, barriers, and facilitators during the development of a practice-related information website about dementia care networks are presented and discussed. These findings can help people who aim to disseminate research findings to other practitioner-associated priority groups as well as public health-related groups.
Fu, Hongyun; VanLandingham, Mark J
2012-05-01
Although the existing literature on immigrant mental health is extensive, major substantive and methodological gaps remain. Substantively, there is little population-based research that focuses on the mental health consequences of migration for Vietnamese Americans. More generally, although a wide range of mental health problems among immigrants has been identified, the potential causal or mediating mechanisms underlying these problems remain elusive. This latter substantive shortcoming is related to a key methodological challenge involving the potentially confounding effects of selection on migration-related outcomes. This article addresses these challenges by employing a "natural experiment" design, involving comparisons among three population-based samples of Vietnamese immigrants, never-leavers, and returnees (N=709). Data were collected in Ho Chi Minh City and in New Orleans between 2003 and 2005. The study investigates the long-term impact of international migration on Vietnamese mental health, and the potential mediating effects of social networks and physical health on these migration-related outcomes. The results reveal both mental health advantages and disadvantages among Vietnamese immigrants relative to the two groups of Vietnamese nationals. Selection can be ruled out for some of these differences, and both social networks and physical health are found to play important explanatory roles.
Supertasks and Numeral Systems
Rizza, Davide
2016-01-01
Physical supertasks are completed, infinite sequences of events or interactions that occur within a finite amount of time. Examples thereof have been constructed to show that infinite physical systems may violate conservation laws. It is shown in this paper that this conclusion may be critically sensitive to a selection of numeral system. Weaker numeral systems generate physical reports whose inaccuracy simulates the violation of a conservation law. Stronger numeral systems can confirm this e...
Numerical Study of Atmospheric Icing on Non Rotating Circular Cylinders in Tandem Arrangement
Directory of Open Access Journals (Sweden)
Muhammad S. Virk
2013-03-01
Full Text Available Numerical study of atmospheric ice accretion on two non-rotating circular cylinders in tandem arrangement was carried out at different operating and geometric conditions. To validate the numerical model, initially the results of ice accretion on single circular cylinder were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT [1, 2]. A good agreement was found between experimental and numerical results. Numerical analyses of ice accretion on two circular cylinders in tandem arrangement showed that accreted ice loads decreases with the increase in distance between the cylinders and also affects the rate and shape of ice accretion. Parametric study at different droplet sizes and temperatures showed a significant change in ice accretion. This research work provides a useful base for better understanding and further investig