Global ETD Search

51	Modelling of Atmospheric Mercury Emission, Transport, Transformation and Deposition in North America Wen, Deyong January 2006 (has links) <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"> </head> <body> A modelling study was conducted to explore the emission, transport, transformation and deposition behaviour of atmospheric Hg. A detailed natural Hg emission model was developed to estimate the natural Hg emissions from soil, water and vegetation. U. S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) Hg model system was improved by incorporating the detailed treatment of natural Hg emissions, adopting boundary conditions from a global Hg model (Seigneur et al. , 2004) and including the calculation of the dry deposition velocity of elemental Hg. The natural Hg emission model and the improved CMAQ-Hg model were validated with some measurements and then applied to North America for a whole year (2002). A detailed natural Hg emission model was developed in this study. This model made use of detailed soil Hg concentration measurements, meteorological data and soil conditions to estimate Hg emissions from soil, water and vegetation. The influence of snow cover and low temperature was also considered in the model. This model was then applied to simulate one-year natural Hg emissions in North America in 2002. The modelled results, compared to some reported natural Hg emission measurements, demonstrated a strong simulation ability. The spatial and temporal variations of emission fluxes were examined through numerical simulations. A pronounced diurnal cycle and a seasonal cycle were found in the emissions from most land uses. Compared with summer, natural Hg emission was significantly limited in winter. Simulation results showed that about 229 metric tons of total natural Hg emission, 1. 8 times anthropogenic Hg emission, was emitted from the simulation domain in 2002. U. S. EPA CMAQ Hg model system was improved and then applied to simulate the emission, transport, transformation and deposition of atmospheric Hg in North America for the year 2002. The simulated results were compared with measured hourly Total Gaseous Hg (TGM) for 3 sites. The good agreement between them demonstrated the good performance of this improved model in modelling the behaviour of emission, transport, transformation and deposition of atmospheric Hg. Hg budget and net evasion of Hg in North America were also investigated. A sensitivity analysis was conducted to assess the effects of emissions, including Hg and non-Hg emissions, on the air concentration and deposition of atmospheric Hg. The results indicated that ambient concentration of TGM was much more sensitive to Hg emissions than non-Hg emissions. Natural Hg emission was more significant than anthropogenic emission to affect ambient concentration of TGM, illustrating natural Hg emission is a key factor influencing TGM ambient concentration. Unlike TGM concentration, Hg dry deposition was not only sensitive to Hg emissions but also to non-Hg emissions such as VOCs and NO<sub>x</sub>. Anthropogenic Hg emission, natural Hg emission and NO<sub>x</sub> emission had almost the same effect on total dry deposition of Hg. The results also illustrated that Hg wet deposition was only sensitive to non-Hg emissions such as NO<sub>x</sub> and VOCs, especially of VOCs emission. Because of the inverse effect of VOCs on Hg wet deposition, reducing NO<sub>x</sub> emission should be an ideal solution to mitigate Hg wet deposition. A possible pathway through which atmospheric Hg was greatly affected by emissions changes was identified: emissions of pollutants, especially VOCs and NO<sub>x</sub>, greatly affect the level of OH in the atmosphere; OH influences the concentration and deposition of Hg by significantly affecting the gas phase reaction between Hg(0) and OH. </body> </html> Chemistry Atmospheric Mercury Modelling Natural Hg emission Sensitivity analysis
52	Modelling a Manufacturing line : Analysis and Decision support based on Discrete Event Simulation Ibrahim, Fady January 2011 (has links) The increasing competition between the companies forces them to develop the production in a continuous manner in order to maintain the competitiveness in the global market, and became as efficient and effective as possible. This master thesis is conducted at Getrag All Wheel Drive Company which is one of the largest suppliers for transmissions and powertrain systems .This Company has worked actively for long time to improve the production flow at the manufacturing departments by using usual methods. Because of the high complex and intersected flow that the company has, the management intended to adopt another approach that takes dynamic information into consideration, therefore, building a simulation model is the solution, where according to Banks et al (2001) the simulation is a duplication of a real-world process or system and its behaviour as it progress during the time, which is a very useful method to evaluate complex systems, instead of using usual mathematical means used tools. The simulation model created by using Banks et al (2001) simulation methodology, and ExtendSim software help. The resulted model used as a tool that provides great assistance to the decision makers, in order to develop the Conwip system which applied in the manufacturing line under study, and to investigate “What if” scenarios. The result of this study obtained after performing two experiments, where the first experiment gives recommendation regarding the optimal upper bound of the total amount of work that can be used in Conwip system, with the use of sensitivity analysis, and the second experiment analyse the overall all effect on the system after separating the paths of high and low volume products. This project proves the powerful side of using the simulation in situations where it’s too hard or even impossible to improve the performance of a manufacturing line i.e. when large number of variables involved and affecting the system. Discrete event simulation Conwip Sensitivity analysis Statistical distribution
53	Modelling of Atmospheric Mercury Emission, Transport, Transformation and Deposition in North America Wen, Deyong January 2006 (has links) <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"> </head> <body> A modelling study was conducted to explore the emission, transport, transformation and deposition behaviour of atmospheric Hg. A detailed natural Hg emission model was developed to estimate the natural Hg emissions from soil, water and vegetation. U. S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) Hg model system was improved by incorporating the detailed treatment of natural Hg emissions, adopting boundary conditions from a global Hg model (Seigneur et al. , 2004) and including the calculation of the dry deposition velocity of elemental Hg. The natural Hg emission model and the improved CMAQ-Hg model were validated with some measurements and then applied to North America for a whole year (2002). A detailed natural Hg emission model was developed in this study. This model made use of detailed soil Hg concentration measurements, meteorological data and soil conditions to estimate Hg emissions from soil, water and vegetation. The influence of snow cover and low temperature was also considered in the model. This model was then applied to simulate one-year natural Hg emissions in North America in 2002. The modelled results, compared to some reported natural Hg emission measurements, demonstrated a strong simulation ability. The spatial and temporal variations of emission fluxes were examined through numerical simulations. A pronounced diurnal cycle and a seasonal cycle were found in the emissions from most land uses. Compared with summer, natural Hg emission was significantly limited in winter. Simulation results showed that about 229 metric tons of total natural Hg emission, 1. 8 times anthropogenic Hg emission, was emitted from the simulation domain in 2002. U. S. EPA CMAQ Hg model system was improved and then applied to simulate the emission, transport, transformation and deposition of atmospheric Hg in North America for the year 2002. The simulated results were compared with measured hourly Total Gaseous Hg (TGM) for 3 sites. The good agreement between them demonstrated the good performance of this improved model in modelling the behaviour of emission, transport, transformation and deposition of atmospheric Hg. Hg budget and net evasion of Hg in North America were also investigated. A sensitivity analysis was conducted to assess the effects of emissions, including Hg and non-Hg emissions, on the air concentration and deposition of atmospheric Hg. The results indicated that ambient concentration of TGM was much more sensitive to Hg emissions than non-Hg emissions. Natural Hg emission was more significant than anthropogenic emission to affect ambient concentration of TGM, illustrating natural Hg emission is a key factor influencing TGM ambient concentration. Unlike TGM concentration, Hg dry deposition was not only sensitive to Hg emissions but also to non-Hg emissions such as VOCs and NO<sub>x</sub>. Anthropogenic Hg emission, natural Hg emission and NO<sub>x</sub> emission had almost the same effect on total dry deposition of Hg. The results also illustrated that Hg wet deposition was only sensitive to non-Hg emissions such as NO<sub>x</sub> and VOCs, especially of VOCs emission. Because of the inverse effect of VOCs on Hg wet deposition, reducing NO<sub>x</sub> emission should be an ideal solution to mitigate Hg wet deposition. A possible pathway through which atmospheric Hg was greatly affected by emissions changes was identified: emissions of pollutants, especially VOCs and NO<sub>x</sub>, greatly affect the level of OH in the atmosphere; OH influences the concentration and deposition of Hg by significantly affecting the gas phase reaction between Hg(0) and OH. </body> </html> Chemistry Atmospheric Mercury Modelling Natural Hg emission Sensitivity analysis
54	Research on the Financial Model That Promotes Participation in Public Works by the Private Sector ¡V Taking Kaohsiung International Youth Hostel as an Example - Guey, Mei 22 August 2005 (has links) Abstract According to the idea held by the government, ¡§government has limited resources but the private sector has limitless power,¡¨ the Executive Yuan established and promulgated the enactment, ¡§Promoting the Participation by the Private Sector in Public Works,¡¨ in February 2000. This is a policy that depends on the vitality and capital funds of the private sector to be incorporated for use in a timely manner. This has brought positive meanings and benefits in enhancing government performance, reducing government financial burdens, speeding up the construction of public works, improving the quality of public works and services, and promoting economic growth. The scope and target of this dissertation is the process of planning to regard Kaohsiung International Youth Hostel as a dormitory facility of Kaohsiung Chung-Hwa School of Arts. It is expected, with the investigation of this case, to study how to harmony with related existing laws and regulations, analyze the burdens and favors taken by the participants under various situations, and examine the feasibility of its¡¦ cooperation so that unused government assets, in agreement with the original purpose of such assets, can be fully utilized, enthusiastic artists can have a comfortable housing environment and field where they can exchange art, facilitate the art prosperity in the Fine Arts Museum neighborhood, and then bring in commercial opportunity to help local economic development. Moreover, through this case study, it aims to provide government offices concerned with valuable figures when they conduct related operations so that when executing plans of the same essence, the office-in-charge can achieve more economic benefits and policy objectives. This dissertation used ROT mode to introduce the resources of the private sector into the operation of public works, which will effectively solve the difficulty that government has no choice but to implement the operation of public works even under financial deficits. As a consequence, public works would not fall idle in the wake of short government finances and lack of professional operation, and the public would be encouraged to advocate the plan to recycle and to reuse the unused public works so as to achieve energy conservation and the prospect for the sustainable development of Earth. Through sensitivity analysis on the changes in key parameters, this dissertation has clearly noticed the increase and decrease in various hypotheses and parameters, and will present different effects and evaluate the variable effects of all the parameters. Before it is executed, the effects and impact that may be caused by government, chartered companies, students, and banks should be considered. Before the plan is implemented, risk control measures should be formulated according to the results of sensitivity analysis. sensitivity analysis ROT unused asset student dormitory risk control and management
55	The Validity Problem of Reverse Engineering Dynamic Systems Chen, Jian-xun 15 August 2006 (has links) The high-throughput measurement devices for DNA, RNA, and proteins produce large amount of information-rich data from biological dynamic systems. It is a need to reverse engineering these data to reveal parameters/structure and behavior relationships implicit in the data. Ultimately, complex interactions between its components that make up a system can be better understood. However, issues of reverse engineering in bioinformatics like algorithms use, the number of temporal sample, continuous or discrete type of input data, etc. are discussed but merely in the validity problem. We argue that, since the data available in reality are not so perfect, the result of reverse engineering is impacted by the un-perfect data. If this is true, to know how this impacts the results of the reverse engineering and to what extent is an important issue. We choose the parameter estimation as our task of reverse engineering and develop a novel method to investigate this validity problem. The data we used has a minor deviation from real data in each data point and then we compare the results of reverse engineering with its target parameters. It can be realized that the more error in data will introduce more serious validity problem in reverse engineering. Three artificial systems are used as test bed to demonstrate our approach. The results of the experiments show, a minor deviation in data may introduce large parameter deviation in the parameter solutions. We conclude that we should not ignore the data error in reverse engineering. To have more knowledge of this phenomenon, we further develop an analytical procedure to analyze the dynamic of the systems to see which characteristic will contribute to this impact. The sensitivity test, propagation analysis and impact factor analysis are applied to the systems. Some qualitative rules that describe the relationship between the results of reverse engineering and the dynamics of the system are summarized. All the finding of this exploration research needs more study to confirm its results. Along this line of research, the biological meaning and the possible relationship between robustness and the variation in parameters in reverse engineering is worth to study in the future. The better reverse algorithm to avoid this validity problem is another topic for future work. System Dynamics Sensitivity Analysis Validity Reverse Engineering Genetic algorithm
56	Computer-Aided Analysis and Design of the Steering System of Front Wheels for Vehicle Li, Wei-Chun 04 July 2007 (has links) Four wheeler is one type of the transportation vehicle which be widely used. Good or bad performance of the vehicle steering system has the decisive influence regarding security of the driver operation and the vehicle travel. Therefore, the purpose of this article is to establish the kinematic analysis theories of the vehicle steering system. And an improvement design theory of size synthesis are proposed to develop a set of user-friendly computer aided analysis and design program. At First, this article collects the related literatures and papers to understand the research technique and the design direction of vehicle steering mechanism. Second, establish the location analysis theory, the rotation torque analysis theory, the mechanical advantage theory and other performance¡¦s calculation formula with regard to ¡§Rocker Shaft Type Connecting Rod Vehicle Steering¡¨ and ¡§Rack and Pinion Type Connecting Rod Vehicle Steering¡¨ which are the most widely used. Third, establish a set of user-friendly computer aided kinematic analysis program by using the VB.NET computer programming language. And then propose a systematized movement design procedure, and establish the optimization size synthesis design theory by using the gene calculation method. Afterwards, carry on the sensitivity analysis in view of the each design variable of the steering mechanism with the orthogonal array table, and establish the kinematic improvement design program. Finally, separately aim at the two Vehicle Steering mechanisms, design a new group mechanism¡¦s size, whose steering performance is better than the original mechanism¡¦s size. Kinematic improvement design Sensitivity analysis Kinematic analysis Vehicle steering system
57	脊柱特発性側彎症の治療法に関する検討（座屈説に基く感度解析）竹内, 謙善, TAKEUCHI, Kenzen, 笹岡, 竜, SASAOKA, Ryu, 畔上, 秀幸, AZEGAMI, Hideyuki, 川上, 紀明, Kawakami, Noriaki 07 1900 (has links) No description available. Sensitivity Analysis Buckling Finite Element Method Medical Engineering
58	Application of Monitored Natural Attenuation and Risk Assessment at a Chlorinated-compound Contaminated Site for Risk anagement Tsai, Wei-anne 03 August 2009 (has links) Contamination by dense non aqueous phase liquids (DNAPLs) [e.g., trichloroethylene (TCE)] in soil and groundwater has become an issue of great concern in many industrialized counties. In this study, a chlorinated-compound spill site was selected as the case study site to evaluate the possible risk to site workers and local residents caused by the contaminated soil and groundwater. The contaminants of concern at this site were TCE and 1,1-Dichloroethylene (1,1-DCE). The detected concentrations for TCE and 1,1-DCE exceeded the control standards of 0.05 and 0.07 mg/L, respectively. In this study, the Risk-based Corrective Action (RBCA) protocol developed by American Society for Testing and Materials (ASTM), health and risk assessment methods for soil and groundwater contaminated sites developed by Taiwan Environmental Protection Administration were applied for risk calculation and quantification. Monte Carlo analysis using @RISK software was applied for uncertainty analysis to calculate the cumulative risk at 95% probability distribution. Moreover, a natural attenuation model (BIOCHLOR) was used to evaluate the effectiveness of natural attenuation mechanisms on the chlorinated compounds. Results from this study show that the occurrence of natural attenuation for the chlorinated compounds was confirmed through the anaerobic biodegradation processes. The calculated cumulative risk at 95% cumulative probability via ingestion route was 2.61¡Ñ10-5 through the Monte Carlo analysis. The calculated cumulative risk at 95% cumulative probability via inhalation route and ambient (outdoor) vapor inhalation diffusion channels were 1.461¡Ñ10-5 and 2.17¡Ñ10-6, respectively. Because the calculated risk levels were higher than the target cancer risk is 1¡Ñ10-6 described in Taiwan¡¦s ¡§Soil and Groundwater Remediation Act¡¨, appropriate remedial actions are required to lower the risk to below the target level. Results also show that the calculated hazard index (HI) values of the contaminated site are lower than the acceptable level (HI < 1) described in the ¡§Soil and Groundwater Remediation Act.¡¨ To meet the target level of cancer risk of 1¡Ñ10-6, TCE contaminated groundwater needs to be remediated to below the site specific target level (SSTL) for inhalation exposure routes in a confined space volume, which is 6.91 ¡Ñ 10-2 mg/L. Based on the results of risk assessment, it is very important for the decision makers to incorporate remedial activities including institutional controls, engineering controls, and remediation programs from RBCA results. This study provides a streamlined process and guidelines of developing the risk-based decision-making strategy for contaminated sites in Taiwan. sensitivity analysis Monte Carlo analysis trichloroethylene exposure assessment risk assessment
59	Modeling the Sensitivity of a Seasonalized Semi-arid Aquifer to the Quantity of Recharge and Evapotranspiration Neff, Kirstin Lynn January 2013 (has links) The Upper San Pedro River aquifer in Southern Arizona has been modeled using MODFLOW several times. The current model improves upon previous models by switching stream packages, adding a third season to represent the summer monsoon, and thereby creating a seasonalized steady-state oscillatory model. Recharge was seasonalized using a method to develop seasonal recharge estimates using ratios of seasonal precipitation to seasonal actual or potential evapotranspiration (ET). Maximum ET was seasonalized according to estimates of riparian groundwater consumption by vegetation in the study area. The model was run with inputs of 80%, 100% and 120% of base values for recharge and maximum ET rates to assess the sensitivity of the groundwater system and river to the seasonal timing and quantity of recharge and ET. The greatest amount of baseflow, 47%, occurred during the wet winter season, 35% occurred during the dry summer, and 18% during the wet summer (monsoon) season. hydrogeology modeling recharge seasonalization sensitivity analysis Hydrology evapotranspiration
60	Land Surface Processes In Natural and Artificial Tropical Ecosystems Rosolem, Rafael January 2010 (has links) Land Surface Parameterization (LSP) schemes have evolved from simple tipping-bucket models to fully interactive models, including parameterizations which account for exchanges of momentum, energy, mass, and biogeochemistry. As the demand for greater realism has increased, so has the complexity of LSPs which now includes some parameters that may not be universally relevant to all regions of the globe. The performance of LSP schemes depends on the magnitude of structural, data-related (input and output), and parameter uncertainties in the model. Parameter estimation uncertainty can be reduced by calibrating LSPs against measurements available at field sites. Given the multiple outputs of the models, multi-objective optimization approaches are performed. Some of the parameter values used in LSPs have originally obtained from laboratory studies which analyzed plant behavior under a range of conditions in enclosed chambers. The research described in this dissertation takes advantage of currently available data from several eddy covariance flux towers located mainly in the Brazilian Amazon basin to estimate parameter values of a widely-used LSP scheme, version 3 of the Simple Biosphere model (SiB3). Background climatological data was used to assess the representativeness of the data collection period that might have affected model calibration. Variance-based sensitivity analysis was then used to investigate potential structural deficiencies in SiB3 and to reduce the dimensionality of the subsequent optimization by identifying those model parameters that merit calibration. Finally, some structural and conceptual aspects of SiB3 were tested inside Biosphere 2 Tropical Rain Forest biome (B2-TRF) under meteorological conditions that resemble those predicted in future climate scenarios for the Amazon basin. Amazon Biosphere2 Hydrometeorology Land Surface Modeling Optimization Sensitivity Analysis

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