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582 results on '"Zhang, Hanwen"'

1. Understanding Undergraduate Student Borrowing in China: A Qualitative Analysis

Author

Zhang, Hanwen

Abstract

As China moved from elite to mass higher education, student borrowers as the product of state intervention have surged. Yet little attention has been paid to their voices. This study conducts reflexive thematic analysis with a qualitative inquiry into lived experiences of 41 current borrowers. A five-factor typology of debt attitudes yields a dynamic explanation of debt and repayment complexities. Students perceive borrowing as an investment in human and social capital. They are, however, cautious of consumer credit. Far from being a deterrent or added burden, educational indebtedness grants them a measure of freedom and autonomy in college. And they consider debt repayment manageable, mainly if a family safety net exists.

Published
2023

4. Genetic and phenotypic characterization of Parkinson’s disease at the clinic-wide level

Author

Tropea, Thomas F., Hartstone, Whitney, Amari, Noor, Baum, Dylan, Rick, Jacqueline, Suh, Eunran, Zhang, Hanwen, Paul, Rachel A., Han, Noah, Zack, Rebecca, Brody, Eliza M., Albuja, Isabela, James, Justin, Spindler, Meredith, Deik, Andres, Aamodt, Whitley W., Dahodwala, Nabila, Hamedani, Ali, Lasker, Aaron, Hurtig, Howard, Stern, Matthew, Weintraub, Daniel, Vaswani, Pavan, Willis, Allison W., Siderowf, Andrew, Xie, Sharon X., Van Deerlin, Vivianna, and Chen-Plotkin, Alice S.

Published
2024
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9. Análisis bayesiano para la diferencia de dos proporciones usando R

Author

Zhang, Hanwen and Gutiérrez Rojas, Hugo Andrés

Subjects
estimación, funciones en R, inferencia bayesiana, proporciones, Bayesian inference, estimation, proportions, R functions, Applied mathematics. Quantitative methods, T57-57.97, Mathematics, QA1-939, Business, HF5001-6182
Abstract

Este artículo presenta una colección de funciones computacionales que son utilizadas en la implementación de un análisis bayesiano exhaustivo para la diferencia de dos proporciones. Con este fin, se discute la estimación puntual, la estimación mediante intervalos de credibilidad y la inferencia predictiva desde dos escenarios: el primero basado en las densidades exactas a priori y a posteriori (construidas mediante la primera función hipergeométrica de Appell) y el segundo basado en densidades simuladas (mediante un algoritmo de cadenas de Markov con métodos de Monte Carlo). La implementación de estas funciones se realiza en el programa estadístico R, porque es un software libre, funciona bien en múltiples plataformas y permite enmarcar estas funciones bajo un objeto computacional denominado “paquete”. || In this paper we present a collection of functions that can be used to implement a comprehensive Bayesian analysis of a difference of two proportions. For instance, point estimation, credibility intervals and predictive inference are discussed in both scenarios, the priori and posteriori exact densities(based in the first Appell hypergeometric function) and the simulated densities (based in a Markov chain Monte Carlo algorithm). We have chosento implement the suite of functions using the R statistical software because it is freely available, runs on multiple platforms and allows to compress the functions into a single computational object named “package”.

Published
2009

42. Monotonic, cyclic and post-cyclic shear behaviour of granular material under multi-directional simple shear

Author

Zhang, Hanwen

Subjects
624.1, TA Engineering (General). Civil engineering (General)
Abstract

In most geotechnical applications, soil is subjected to complicated loading conditions. For example, during an earthquake, the soil can be liquefied by randomly oriented ground movements with different loading magnitudes. Currently, this complex in-situ loading conditions can only be duplicated in the multi-directional simple shear devices. With this kind of apparatus, more attentions have been paid on the study of how the multi-directional loading conditions and loading histories can affect the soil behaviour. To undertake a comprehensive investigation on the shear behaviour of granular material subjected to complex loading conditions, in this thesis, several multi-directional simple shear tests were performed by the Variable Direction Dynamic Cyclic Simple Shear (VDDCSS) system. In this testing system, two orthogonal shear actuators can be controlled independently to implement the shear stress in any direction on the horizontal plane. Through this apparatus, the uni- and multi-directional loading paths were conducted on the uniform-sized glass beads in monotonic, cyclic and post-cyclic tests. In the monotonic tests, the effects of relative density and effective vertical stress have been examined in the undrained and drained conditions. More importantly, in another series of tests, the specimens were subjected to two successive shear stresses, between which, the angle varies from 0o to 180o. The results show that the angle between these two shear stresses makes significant impacts on the shear strength, pore pressure buildup, volumetric strain and the level of non-coaxiality. In the cyclic tests, the specimens were cyclically sheared under the uni- and multi-directional loading paths. The results show that the liquefaction resistance is significantly influenced by the relative density, effective vertical stress, shear strain amplitude and loading path. To interpret the difference of liquefaction resistance under different loading paths, an energy dissipation theory is adopted in the discussion, and it is found that the dissipated energy to liquefy a specimen is independent of the loading path. In the post-cyclic tests, two main series of tests were conducted on the glass beads. In the first series of tests, the liquefied specimens were subjected to the undrained monotonic shearing after they were re-consolidated. The effect of the initial liquefaction loading history on the post-liquefaction settlement and shear behaviour have been studied under various relative densities. Conversely, in the second series of tests, the specimens were subjected to the first cyclic shear stress under different liquefaction degrees, loading paths and loading angles (for the uni-directional case). After re-consolidation, the specimens were then subjected to the second cyclic shear stress in the x-direction until liquefaction happened. The results show that the above-mentioned factors in the first cyclic shearing stage can considerably affect the settlement, post-liquefaction shear strength and post-cyclic liquefaction resistance of the tested material.

Published
2020

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