Journey to freedom

The purpose of this thesis is to investigate imagery that encompasses my early memories of Vietnam, my immigration to a new country, and my current situation in America. This investigation will also include both my use of Rostow & Jung\u27s water-based intaglio inks, and non-toxic printmaking techniques to help illustrate my imagery. I will discuss not only the similarities and differences of artists who have influenced my work but also my source material. The latter, gained through the observation and documentation of my family, friends, and environmental images

The emerging business of science in Vietnam

Manh-Tung Ho, Khanh-Linh Hoang, Minh-Hoang Nguyen, Manh-Toan Ho (2019). Chapter 8. The emerging business of science in Vietnam. In Quan-Hoang Vuong, Trung Tran (Eds.), The Vietnamese Social Sciences at a Fork in the Road (pp. 163–177). Warsaw, Poland: De Gruyter. DOI:10.2478/9783110686081-013. Online ISBN: 9783110686081 © 2019 Sciendo / De Gruyte

The Impacts of U.S. - China Trade on U.S. Manufacturing Unemployment

The U.S.-China economic ties have expanded over the past three decades with a substantial growth in both imports and exports. The total trade amount rose from only 2 billion in 1979 to over 457 billion in 2011. Although total trade increased over time, U.S. imports from China rose at a much higher rate than U.S. exports, and thus have caused a trade deficit since 1974, making China the U.S.’s biggest source of imports and second largest U.S. trading partner

Sand and silty-sand soil stabilization using bacterial enzyme induced carbonate precipitation (BEICP)

The concept of bio-geotechnics represents an innovative, new technical merger between three traditional disciplines: geotechnical, material, and environmental engineering. As originally conceived decades ago, biogeotechnology mechanism uses live micro-organisms to improve and stabilize soils, by which their suitability for construction realizes engineering, environmental, and economical benefits. More recently, though, this concept has been broadened to include a suite of possible strategies, including: 1) using whole-cell microorganisms to secure ‘Microbial Induced CaCO3 Precipitation’ (MICP), 2) using cell-free, free-‘Enzyme Induced CaCO3 Precipitation’ (EICP), and 3) using ‘Microbial Induced Desaturation and Precipitation’ (MIDP). Although none of these biogeotechnical methods have yet reached a pragmatic level of commercial application, promising results have been achieved within laboratory, and in limited instances of large-scale and field-scale evaluation. This dissertation documents the outcomes achieved during an investigation of a novel modification of the latter ‘EICP’ method which could be similarly employed to secure bio-mediated soil improvement. In this case, however, the operative catalytic enzyme (i.e., urease) was extracted from a bacterial source and then used in its free-enzyme form to secure a so-called ‘Bacterial Enzyme Induced Carbonate Precipitation’ (BEICP). A sonication method was applied to lyse living cells of S. pasteurii to obtain the desired urease solution. The urease activity rate of this bacterial extracted enzyme was higher, at an approximate 2X magnification, even though the volume of the sonicated solution had only been reduced one-fourth as compared to that of the original bacterial solution. Furthermore, extending beyond this benefit realized with producing an even higher rate of enzymatic activity, the performance results obtained when using BEICP soil processing demonstrated several additional performance-based benefits. This dissertation consequently documents the engineering properties achieved with BEICP-treated sand processing, as well as comparing these findings against that of traditional MICP treatment. These lab-level research results offer positive evidence for two possible benefits with the BEICP method: 1) mechanical stabilization of sands, and even including that of loose sandy soil materials, and 2) an ability to retain post-treatment permeability of the bio-cemented sands (i.e., as compared to MICP’s typically higher reduction in treated soil permeability). The advantage of BEICP’s free-enzyme processing approach stems from its nano-sized (water-soluble) catalyst dimension, where these nano-enzymes are far more easily able to penetrate the small pore space of a silty sand matrix. In turn, this BEICP method was successfully applicable to the solidification of silty-sand soil. The measurement of unconfined compression strength of BEICP-treated samples ranged from 0.4 to 1.1 MPa, and from 0.23 to 0.84 MPa with silt-sand mixtures at silt levels of 10 and 20 %, respectively. These results accordingly validated the biological treatment process BEICP as a prospectively applicable means of successfully solidifying natural sand and silty-sand soil systems. As previous mentioned, BEICP treated is a new bio-based method, and this dissertation’s accompanying research has further evaluated a variety of processing factors which might impact the resultant engineering properties of bio-cemented sand. Notably, a series of test-tube experiments was conducted to investigate the effects between the bacterial cell and urease in the chemical conversion ratio. The results showed that the precipitation ratio reduced when the concentration of chemical agents increased. These experiments also characterized the urease activity of biological sources and chemical concentration for sand column tests. Two types of sand, including both coarse- and fine-grained sands, were examined in order to evaluate how these size factors impacts product strength and permeability with BIECP treatment. These findings correlated with previous studies on MICP and EICP, where the size of particle and the CaCO3 content played a vital contributing factor relative to both strength increase and permeability reduction. However, more engineering factors, such as injection flow, temperature, chemical concentration, etc., needs to be studied in order to optimize the BEICP-treatment process. Another significant aspect of BEICP-treated soil is that of the durability of the biocemented soil under the freeze-thaw cycling. Sandy soil and silty-sand soils which were originally packed in a loose condition were treated with BEICP processing as well as with commercial Portland cement and fly ash additions. The strength reduction following freeze-thaw cycling was examined on treated samples. This investigation revealed that the BEICP-treated samples retained higher strengths than that in Portland and fly ash cemented samples after freeze-thaw cycling. This approach suggests that this method may have beneficial use when applied to stabilize sub-grade and sub-base materials underlying pavement layers within cold regions. This research effort subsequently started with the development of a sonication technique to lyse viable S. pasteurii bacteria cells in order to release their intracellular urease materials. A particular advantage of using this new method is that it produces distinctly higher levels of urease activity. The extracted enzyme was then used to treat a group of test columns bearing different percentages of coarse- and fine-grained soils by weight. The engineering properties of BEICP-treated soil were evaluated via a series of lab tests. Another clear advantage for BEICP processing is that this method can form calcium-bearing crystals as bridges between fine (silt) and coarse (sand) soil grains, which then increases the overall strength of our silty-sand columns, while at the same time not unduly decreasing matrix permeability

Postbuckling of thick FGM cylindrical panels with tangential edge constraints and temperature dependent properties

This paper investigates postbuckling behavior of thick  FGM cylindrical panels resting on elastic foundations and subjected to  thermal, mechanical and thermomechanical loading conditions. Material  properties are assumed to be temperature dependent, and graded in the  thickness direction according to a simple power law distribution in terms of  the volume fractions of constituents. Governing equations are based on  higher order shear deformation shell theory incorporating von Karman-Donnell  geometrical nonlinearity, initial geometrical imperfection, tangential edge  constraints and Pasternak type elastic foundations. Approximate solutions  are assumed to satisfy simply supported boundary conditions and Galerkin  procedure is applied to derive expressions of buckling loads and  load-deflection relations. In thermal postbuckling analysis, an iteration  algorithm is employed to determine critical buckling temperatures and  postbuckling temperature-deflection equilibrium paths. The separate and  simultaneous effects of tangential edge restraints, elastic foundations and  temperature dependence of material properties on the buckling and  postbuckling responses of higher order shear deformable FGM cylindrical  panels are analyzed and discussed

Performance analysis with wireless power transfer constraint policies in full-duplex relaying networks

In practice, full-duplex (FD) transmission mode not only helps extend the coverage but also lengthen network lifetime. In this paper, we develop wireless power supply policies, namely separated power (SP) and harvested power (HP) to propose a flexible architecture at the relay node in FD decode-and-forward (DF) relaying networks considering time switching-based relaying protocol (TSR) to achieve optimal time used for a communication process. This transmission mode requires more processing procedure at the relay, i.e. antenna installations and radio frequency (RF) self-interference cancellation. We evaluate the optimal power constraints in case of SP and HP to achieve better power consumption efficiency at the relay node. More importantly, closed-form expressions for outage probability and throughput are provided, and we also use numerical and simulation results to compare SP with HP.Web of Science234767

Improving Bayesian statistics understanding in the age of Big Data with the bayesvl R package

The exponential growth of social data both in volume and complexity has increasingly exposed many of the shortcomings of the conventional frequentist approach to statistics. The scientific community has called for careful usage of the approach and its inference. Meanwhile, the alternative method, Bayesian statistics, still faces considerable barriers toward a more widespread application. The bayesvl R package is an open program, designed for implementing Bayesian modeling and analysis using the Stan language’s no-U-turn (NUTS) sampler. The package combines the ability to construct Bayesian network models using directed acyclic graphs (DAGs), the Markov chain Monte Carlo (MCMC) simulation technique, and the graphic capability of the ggplot2 package. As a result, it can improve the user experience and intuitive understanding when constructing and analyzing Bayesian network models. A case example is offered to illustrate the usefulness of the package for Big Data analytics and cognitive computing