A Framework to Adjust Dependency Measure Estimates for Chance

Estimating the strength of dependency between two variables is fundamental for exploratory analysis and many other applications in data mining. For example: non-linear dependencies between two continuous variables can be explored with the Maximal Information Coefficient (MIC); and categorical variables that are dependent to the target class are selected using Gini gain in random forests. Nonetheless, because dependency measures are estimated on finite samples, the interpretability of their quantification and the accuracy when ranking dependencies become challenging. Dependency estimates are not equal to 0 when variables are independent, cannot be compared if computed on different sample size, and they are inflated by chance on variables with more categories. In this paper, we propose a framework to adjust dependency measure estimates on finite samples. Our adjustments, which are simple and applicable to any dependency measure, are helpful in improving interpretability when quantifying dependency and in improving accuracy on the task of ranking dependencies. In particular, we demonstrate that our approach enhances the interpretability of MIC when used as a proxy for the amount of noise between variables, and to gain accuracy when ranking variables during the splitting procedure in random forests.Comment: In Proceedings of the 2016 SIAM International Conference on Data Minin

Robust newsvendor games with ambiguity in demand distributions

In classical newsvendor games, vendors collaborate to serve their aggregate demand whose joint distribution is assumed known with certainty. We investigate a new class of newsvendor games with ambiguity in the joint demand distributions, which is represented by a Fréchet class of distributions with some, possibly overlapping, marginal information. To model this new class of games, we use ideas from distributionally robust optimization to handle distributional ambiguity and study the robust newsvendor games. We provide conditions for the existence of core solutions of these games using the structural analysis of the worst-case joint demand distributions of the corresponding distributionally robust newsvendor optimization problem

Dual-Porosity and Dual-Permeability Poromechanics Solutions for Problems in Laboratory and Field Applications

In this work, a study of anisotropic dual-porosity and dual-permeability poromechanics is presented through generalized analytical solutions for selected problems in laboratory and field applications. For example, the solution to the inclined wellbore geometry with standard applications in the oil and gas industry for drilling stability or consolidation in naturally fractured rock formations are derived and illustrated. In addition, the dual-porosity and dual-permeability poromechanics solutions to common laboratory testing setups in geomechanics and biomechanics for purposes of rock and bio-tissue characterization are developed for rectangular strip, solid and hollow cylinder geometries.The behaviors of naturally fractured rock formations or the responses of the well known dual-porosity bone structure are modeled as dual-porosity and dual-permeability poroelastic media that fully couples the secondary porosity medium's deformation, fluid flow and interporosity exchange processes. For chemically active fractured media, e.g., clay, shale, or biomaterial, chemical interaction effects including osmotic and solute transport in both the primary porosity (matrix) and secondary porosity (fracture) are addressed based on non-equilibrium thermodynamics. Thermohydromechanical coupling under non-isothermal condition is incorporated by adopting a "single-temperature" approach in which a single representative thermodynamic continuum is argued to be sufficient to describe the thermally induced responses of a naturally fractured rock formation.The physical and mathematical models are used to find poromechanics analytical solutions for pore pressure, fluid flux, stress, and displacement, in addition to solute flux for chemically active material or temperature for non-isothermal condition to the above problem geometries. These solutions are general and can be tailored to simulate specific field problems or experimental testing. For instance, the inclined wellbore solutions include boundary conditions for simulating openhole drilling and fluid injection or withdrawal. On the other hand, the solutions for laboratory testing of rectangular and cylinder geometries account for two primary axial loading modes, namely, stroke control or stress relaxation and load control or creep test. The rectangular strip solution is also shown to simplify to the classical one-dimensional consolidation in soil mechanics.For non-reactive dual-porous material under isothermal condition, generic dual-poromechanics results are plotted and compared with single-poromechanics counterpart representing a homogenous isotropic medium when applicable. Parametric analyses are also carried out through the responses of a solid cylinder under unconfined compression to evaluate the effects of material anisotropy and dimensionless dual-poroelastic parameters such as permeability ratio, storage ratio, and interporosity coefficient. For chemically active fractured formation, the analyses is focused on the impacts of chemical salinity gradients via osmotic and solute transport on pore pressure and effective stress distributions near the wellbore or fluid/solute flux and displacement of solid cylinder under axial-flow-only oedometer testing setup. Finally, the effects of temperature gradients manifested through thermal expansion/contraction and conductive heat transport are assessed using the analytical solutions for inclined wellbore and rectangular strip geometries. Furthermore, the significance of heat convection is evaluated numerically and displayed.Application-wise, the inclined wellbore solution is used to perform time-dependent wellbore stability analysis for drilling through chemically active fractured rock formations under non-isothermal conditions. The hollow cylinder is applied to study elastic consolidation of a producing naturally fractured reservoir and associated implications on porosity and permeability reduction in the near-wellbore region. Finally, some realistic quasi-static loading conditions commonly encountered in experimental testing and field applications such as cyclic, linear ramping, and exponentially decayed are demonstrated via the solutions of unconfined solid cylinder

The Organizational Structure of the Securities Company Under the Law of Vietnam Current

Purpose: The article researches on the organizational structure of securities company under the Securities Law 2019 in order to point out some limitations and shortcomings and propose for recommendations to improve law about organizational structure on this form of company.   Theoretical framework: Recent literature points out that securities companies play very important role in the development of Vietnam's stock market. However, in the current stage of development, from the influence and impact of international integration and the increasingly fierce competitive pressure, the securities companies have encountered many difficulties to survive. In there, limits and problems in regulations about securities company organizational structures has caused many difficulties for these companies when organization and operation. On the other hand, in the context of judicial reform in Vietnam, the issue of complete law system and expanding the freedom to business has always been paid special attention by the Party and Vietnam State.   Design/methodology/approach: The authors have combined traditional research methods of legal science such as legal analysis method, legal efficiency assessment method and legal comparison method.   Findings: According to research, regulations on the organizational structure of a securities company are directly related to the efficiency of management and administration of this company. In there, Supervisory Board/Internal Audit Committee always ensuring to limit negative and fraudulent acts of the company’s leaders, to better ensure the legitimate rights and interests of the company's members and customers. Therefore, the authors have proposed several solutions such as the need to stipulate the mandatory requirement of a Supervisory Board for the securities trading company under the model of limited liability company, and expand and strengthen the powers of the Supervisory Board/Internal Audit Committee, independent members in securities companies doing business in the form of joint stock company. These are important bases to contribute to perfecting the Law on the organizational structure of securities companies in Vietnam and further enhancing the stability and safety of the Vietnamese stock market.   Research, Practical & Social implications: This research may support many develop future research in Vietnam. At the same time, the research to help foreign investors' activities in Vietnam's stock market.   Originality/value: The research of the freedom to business and organizational structure of securities companies become more and more urgent and very important in Vietnam

Measurement Profile of Surface Revolution by Laser Scan Micrometer Method

Measurement profile of surface revolution by laser scan micrometer method is a non-contact measurement method that allows de-tailed profile measurements with fast measuring speed by using laser scanning and accuracy is much higher than other non-contact scanning methods. This paper presents the mathematical model profile of surface revolution and the application of the laser scan micrometer method for measuring this detailed profile. Fabricating complete equipment model according to the author's proposed method. Compare the results of measuring the profile of surface revolution on a construction measuring device with a roundness meter Jenoptik F315 to prove the feasibility of the construction measurement method