Analysis Of Model And Observation Data For The Development Of A Public Pm2.5 Air-Quality Advisories Tool (Aquat)

Thesis (Ph.D.) University of Alaska Fairbanks, 2012An air-quality advisory tool (AQuAT) that combines mobile measurements of particulate matter less than or equal to 2.5mum in diameter (PM2.5) with air-quality simulations performed with the Alaska adapted version of the Community Multiscale Air Quality (CMAQ) model was developed to interpolate PM2.5-measurements into unmonitored neighborhoods in Fairbanks, Alaska. AQuAT was developed as traditional interpolation methods of interpolating the mobile measurements were unsuccessful. Such a spatially differentiated air-quality advisory is highly desired in Fairbanks due to health concerns of PM2.5, and the need to improve the quality of life. The accuracy of AQuAT depends on the accuracy of the air-quality simulations used for its database. Evaluation of these simulations showed that they captured the observed relationships between PM2.5-concentrations and major meteorological fields (e.g., wind-speed, temperature, and surface-inversions) well. Skill scores for simulated PM2.5-concentrations fell in the range of modern models. The AQuAT database can include information on the nonlinear impacts of various emission sources on PM2.5-concentrations. This benefit was illustrated by investigating the impacts of emissions from point sources, uncertified wood-burning devices, and traffic on the distribution of PM 2.5-concentrations in the neighborhoods. Sensitivity studies on the effects of wood-burning device changeouts on the PM2.5-concentrations suggested that the emission inventory should be updated as soon as possible to capture recent changes in the emission situation in response to the changeout program. The performance of AQuAT was evaluated with PM2.5-measurements from mobile and stationary sites, and with simulated PM2.5-concentrations of winter 2010/2011 which were assumed to be "grand-truth" data. These evaluations showed that AQuAT captured the magnitudes and temporal evolutions of the PM 2.5-measurements and the "grand-truth" data well. The inclusion of wind-speed, wind-direction, and temperature in AQuAT did not improve its accuracy. This result may be explained by the fact that the relationships between meteorology and PM2.5-concentrations were already captured by the database. AQuAT allows quick spatial interpolation after the mobile measurements were made and provides error bars. It also allows for any route within the area for which a database of simulated concentrations exists. It was shown that AQuAT can be easily transferred for applications in other regions

EFFECT OF BLASTING ON THE STABILITY OF LINING DURING EXCAVATION OF NEW TUNNEL NEAR THE EXISTING TUNNEL

In recent years, experimental and numerical researches on the effect of blasting pressure on the stability of existing tunnels was widely obtained. However, the effect of the blasting pressure during excavation a new tunnel or expansion old tunnels on an existing tunnel has disadvantages and still unclear. Some researches were carried out to study the relationship of the observed Peak Particle Velocity (PPV) on the lining areas along the existing tunnel direction, due to either the lack of in situ test data or the difficulty in conducting field tests, particularly for tunnels that are usually old and vulnerable after several decades of service. This paper introduces using numerical methods with the field data investigations on the effect of the blasting in a new tunnel on the surrounding rock mass and on the existing tunnel. The research results show that not only predicting the tunnel lining damage zone under the impact of blast loads but also determination peak maximum of explosion at the same time at the surface of tunnel working

La eficiencia de aplicar muestreo comprimido y resolución múltiple en tomografía por ultrasonido

Introduction: This publication is the product of  research developed within the research lines of the Smart Sensing, Signal Processing, and Applications (3SPA)  research  group  throughout  2018,  which  supports  the  work  of  a  doctor’s degree at VNU University of Engineering & Technology, Vietnam. Problem: The limitations of diagnostic ultrasound techniques using echo information has motivated the study of new imaging models in order to create additional quantitative ultrasound information in multi-model imaging devices. A promising solution is to use image sound contrast because it is capable of detecting changes in diseased tissue structures. Ultrasound tomography shows speed-of-sound changes in the propagation medium of sound waves. This technique is primarily used for imaging cancer-causing cells in womens’ breasts. The Distorted Born Iterative Method (DBIM), based on the first-order Born approximation, is an efficient diffraction tomography approach. The compressed sensing technique is utilized for DBIM to obtain the high-quality ultrasound image, although the image reconstruction process is quite long. Objective: The objective of the research is to propose an combined method for the efficient ultrasound tomography. Methodology: In this paper, we proposed an approach to enhance the imaging quality and to reduce the imaging time by applying the compressed sensing technique along with the multi-resolution technique for the DBIM. Results: The simulation results indicate that the imaging time is reduced by 33% and the imaging quality is improved by 83%. Conclusion: This project seeks to propose an improvement in ultrasound tomography. The simulated results confirmed the realibility of the propsed method. Originality: Through this research, a combined method of compressed sensing and multiple resolution are formulated for the first time in ultrasound tomography. Limitations: The lack of experiments to confirm the proposed method.Introducción: esta publicación es el producto de la investigación desarrollada dentro de las líneas del grupode investigación Detección Inteligente, Procesamiento de Señales y Aplicaciones (3SPA, Smart Sensing, Signal Processing, and Applications) a lo largo de 2018, que respalda el trabajo de un doctorado en la Universidad deIngeniería y Tecnología de VNU, Vietnam. Problema: las limitaciones de las técnicas de diagnóstico por ultrasonido que utilizan información de eco han motivado el estudio de nuevos modelos de imágenes para crear información cuantitativa adicional de ultrasonidos en dispositivos de imágenes de modelos múltiples. Una solución prometedora es utilizar el contraste de sonido de la imagen porque es capaz de detectar cambios en las estructuras de los tejidos enfermos. La tomografía por ultrasonido muestra los cambios en la velocidad del sonido en el medio de propagación de las ondas sonoras. Esta técnica se usa principalmente para obtener imágenes de células que causan cáncer en los senos de las mujeres.  Objetivo: el objetivo de la investigación es proponer un método combinado para la tomografía de ultrasonido eficiente. Metodología: en este documento se propuso un enfoque para mejorar la calidad de la imagen y reducir el tiempo diante la aplicación de la técnica de detección comprimida junto con la técnica de resolución múltiplepara el DBIM. Resultados: los resultados de la simulación indican que el tiempo de imagen se reduce en un 33 % y la calidad de imagen se mejora en un 83 %. Conclusión: este proyecto busca proponer una mejora en la tomografía por ultrasonido. Los resultados simulados confirmaron la viabilidad del método sugerido. Originalidad: a través de esta investigación, se formula por primera vez un método combinado de detección comprimida y resolución múltiple en la tomografía por ultrasonido. Limitaciones: la falta de experimentos para confirmar el método propuesto

A hierarchical architecture for increasing efficiency of large photovoltaic plants under non-homogeneous solar irradiation

Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under non-homogeneous solar irradiation using Series-Parallel (SP) topology. In the first part of the paper, the authors propose a method containing two key points: a switching matrix to change the connection of PV panels based on SP topology and the proof that the SP-based reconfiguration method can increase the efficiency of the photovoltaic system up to 50%. In the second part, the authors propose the extension of the method proposed in the first part to improve the efficiency of large solar generation systems by means of a two-levels architecture to minimize the cost of fabrication of the switching matrix

Fabrication of Electrochemical Electrodes Based on Platinum and ZnO\text{ZnO} Nanofibers for Biosensing Applications

Platinum (Pt) electrodes were designed in imitation of screen-printed electrodes, and prepared by microelectronic techniques. These electrodes were then modified with zinc oxide (ZnO) nanofibers for biosensing applications. ZnO nanofibers with average length $\sim 20-30\; \mu$ m and diameter $\sim 150$ nm in hexagonal crystalline structure are prepared using electrospinning method. Their surface characteristics were analyzed by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Electrochemical properties of modified Pt electrodes were investigated in comparison with commercial carbon screen-printed electrodes. The results showed that the cyclic voltammogram of modified Pt electrodes was stable, but has much lower resistance compared to that of carbon screen-printed electrodes

A Study on Factors Impacting on Profitability: The Case of Vietnam

This study is conducted to investigate factors influencing the profitability of the Vietnamese food processing firms. Data was collected from audited financial statements from listed food processing firms on the Vietnam Stock Exchange. Panel regression model was applied in this study (PLS). The testing methods used in this research were Pearson model; Modified Wald Test, Wooldridge test (for autocorreclation in panel data), Hausman model, especially the relationship between FEM and REM as well as Multicollinearity test based on VIF coeficient. The results shows that DR, SDR and LDR have negative impacts on profitability. In contrast, TDTELT have positive impacts on the profitability. FATA and SIZE impact return on asset (ROA) without statistical significance. SIZE has positive impact on return on equity (ROE) while it impacts negatively on profit margin (PM). Moreover, AGE, GDP growth, and inflation do not have impact on profitability. Keywords: Factors, Return on assets, Food processing firms, Vietnam DOI: 10.7176/RJFA/11-10-07 Publication date:May 31st 202