Parametrization of stochastic inputs using generative adversarial networks with application in geology

We investigate artificial neural networks as a parametrization tool for stochastic inputs in numerical simulations. We address parametrization from the point of view of emulating the data generating process, instead of explicitly constructing a parametric form to preserve predefined statistics of the data. This is done by training a neural network to generate samples from the data distribution using a recent deep learning technique called generative adversarial networks. By emulating the data generating process, the relevant statistics of the data are replicated. The method is assessed in subsurface flow problems, where effective parametrization of underground properties such as permeability is important due to the high dimensionality and presence of high spatial correlations. We experiment with realizations of binary channelized subsurface permeability and perform uncertainty quantification and parameter estimation. Results show that the parametrization using generative adversarial networks is very effective in preserving visual realism as well as high order statistics of the flow responses, while achieving a dimensionality reduction of two orders of magnitude

A machine learning approach for efficient uncertainty quantification using multiscale methods

Several multiscale methods account for sub-grid scale features using coarse scale basis functions. For example, in the Multiscale Finite Volume method the coarse scale basis functions are obtained by solving a set of local problems over dual-grid cells. We introduce a data-driven approach for the estimation of these coarse scale basis functions. Specifically, we employ a neural network predictor fitted using a set of solution samples from which it learns to generate subsequent basis functions at a lower computational cost than solving the local problems. The computational advantage of this approach is realized for uncertainty quantification tasks where a large number of realizations has to be evaluated. We attribute the ability to learn these basis functions to the modularity of the local problems and the redundancy of the permeability patches between samples. The proposed method is evaluated on elliptic problems yielding very promising results.Comment: Journal of Computational Physics (2017

Currency attack/defense with two-sided private information

A currency attack fails on its own when the speculator suffers from her financial problem. This paper extends the existing models and argues that the monetary authority?s willingness to peg and the speculator?s cost of attack are private information. Our model thus accounts for the duration of currency attack/defense, and more importantly, allows for failed attack. We employ an asymmetric war of attrition and gauge the time when the speculator stops attacking, or when the monetary authority de-pegs. Comparative static results throw light on the interest rate policy amidst the Exchange Rate Mechanism Crisis and the Asian Currency CrisisAsymmetric war of attrition; Credibility of policymakers; Failed speculative attack; Persistent effect; Two-sided private information

Attractiveness of a Religious Theme Site: The A-Ma Cultural Village in Macau, China

Specific attributes of a destination and visitors’ perceived value are two major and complementary components of tourism destination attractiveness. Based on 329 questionnaires, this study evaluates the level of attractiveness and specificity of A-Ma Cultural Village in Macau, China in the context of the emerging significance of Mazu-related heritage and religious tourism in Asia. Also, the similarities and differences between visitors from Hong Kong, China and Taiwan, regarding visit motives, satisfaction, needs and preferences are examined. The statistical tools of analysis used in this study include descriptive statistics, ANOVA and chi-square test. The survey found that the A-Ma Cultural Village’s existing resources and created resources are reputable destination attributes, but the upstream factor needs to be greatly improved. Sightseeing is the most popular reason to visit the site amongst visitors from Hong Kong, Taiwan and China. Hong Kong and China groups showed a comparatively higher level of satisfaction than the Taiwan group which expressed the strongest sense of dissatisfaction about the services and facilities of the site. The A-Ma Cultural Village’s attractive attributes or features and its weaknesses or limitations provide points of departure for further research and discussion on the emerging Mazu theme-site tourism in general, and a useful reference for the operator to enhance and strengthen its theme attractions to visitors in particular

Simulation And Modelling Of Thin Film Phi(rho-z) Curves For Electron Probe Microanalysis

Quantitative analysis of homogeneous bulk unknowns using an electron probe microanalyzer requires the accurate knowledge of the depth distributions of x-ray production ({dollar}\phi{dollar}({dollar}\rho{dollar}z) curves). Straight line behaviour is observed in the plot of ln{dollar}\phi{dollar}({dollar}\rho{dollar}z) versus ({dollar}\rho{dollar}z){dollar}\sp2{dollar} for most experimentally measured data. Monte Carlo calculations can be used to simulate {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves. However, ln {dollar}\phi{dollar}({dollar}\rho{dollar}z) versus ({dollar}\rho{dollar}z){dollar}\sp2{dollar} plots of these {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves, in general, are nonlinear and concave downward. By introducing the concept of electron straggling into a multiple scattering Monte Carlo model, agreement with the behaviour of experimental curves is achieved.;Electron probe microanalysis can also be used for the characterization of thin films on substrates. The multiple scattering Monte Carlo program was used to simulate more than 300 thin film {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves with different film/substrate combinations. The simulations were made at normal electron incidence in the energy range from 10-30 keV. Using these data and based on the concept of the ratio of {dollar}\phi{dollar}({dollar}\rho{dollar}z) values from the thin film to the corresponding bulk {dollar}\phi{dollar}({dollar}\rho{dollar}z) value at the same thickness, general equations were developed which allow prediction of thin film {dollar}\phi{dollar}({dollar}\rho{dollar}z) curves for any film/substrate combination at any electron energy. The equations can used with any bulk {dollar}\phi{dollar}({dollar}\rho{dollar}z) model. Comparisons were made with literature values of measured k-ratios in order to confirm the validity of the present model

An East and West Debate on Human Rights

In an East and West debate on human rights, scholars from different cultures disagree on whether all civil and political rights are human rights. While they generally agree that basic civil rights such as rights against torture and slavery (i.e., physical security rights) are human rights, some of them argue that traditional political rights in the West such as freedom of speech and political participation (i.e., liberal rights) are not human rights. Some scholars, such as Daniel A. Bell, argue that liberal rights are not human rights because liberal rights conflict with some East Asian cultures. In this dissertation, I argue that both physical security rights and liberal rights are human rights, and explain the relationship between these rights and East Asian cultures. First, I argue that if liberal rights are not human rights because they conflict with some East Asian cultures, then physical security rights are also not human rights because physical security rights also conflict with some East Asian cultures. Next, I discuss the idea from Daniel Bell and Michael Walzer that physical security rights are human rights because they are minimal values. Based on their idea, I explain what minimal values are, and why it is possible to develop some maximal theories of physical security rights in East Asian cultures. I argue that since physical security rights are minimal values, they are still human rights even they conflict with some East Asian cultures. I then argue that liberal rights, similar to physical security rights, are also minimal values, and it is possible to develop some maximal theories of them in East Asian cultures. Therefore, similar to physical security rights, liberal rights are also human rights even they also conflict with some East Asian cultures. I also discuss other human rights debates, especially the debates between Daniel Bell and other philosophers. Charles Taylor argues for an overlapping consensus approach on human rights; Jack Donnelly argues for a Western liberalist approach on human rights. I explain the relationship between these approaches and my arguments, and how my arguments can help them to reply to the challenges from Daniel Bell