Hydrological assessment and biogeochemical advancement of the Noah-MP land surface model

textLand surface models (LSMs) simulate the energy, momentum, water, and carbon balance of the soil-vegetation-atmosphere system. As a key component of weather and climate models, LSMs play an important role in weather prediction and climate projections. Rapid growth in LSM development has resulted in both the improvement of existing process representation and the addition of new processes and functionalities. However, it is a challenge to evaluate the accuracy of energy, water, and nutrient fluxes simulated by LSMs, due to the lack of observational data and the complexity of interactions and feedback among different processes. Additionally, climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading nutrient for causing eutrophication in water bodies. However, few LSMs include nitrogen dynamics and nitrogen leaching is usually not well parameterized; hence these LSMs are not feasible for applications-based modeling, particularly for land management and agricultural impacts. Therefore, this dissertation uses the Noah-MP LSM to study the following three questions. (1) How do recent developments in Noah-MP improve its performance in hydrological modeling, based on a case study for the Mississippi River Basin? (2) Compared to other similar LSMs, what are the advantages and disadvantages of Noah-MP in assessing the water balance over the conterminous U.S.? (3) After coupling the Fixation and Uptake of Nitrogen plant model and the Soil and Water Assessment Tool soil nitrogen dynamics into Noah-MP, can this coupled model characterize the major nitrogen fluxes and how the nitrogen dynamics affect the carbon and water simulations? The main scientific findings are as follows. (1) Noah-MP shows significant improvement in modeling the major hydrological variables such as runoff, groundwater, evapotranspiration, soil moisture, and terrestrial water storage (TWS), which is very likely due to the incorporation of some major improvements into Noah-MP, particularly an unconfined aquifer storage layer for groundwater dynamics and an interactive vegetation canopy for dynamic leaf phenology. (2) Compared to other three LSMs, Noah-MP provides the best performance in simulating soil moisture and is among the best in simulating TWS. (3) The new Noah-MP with nitrogen dynamics performs well in capturing the major nitrogen state/flux variables (e.g., soil nitrate and nitrate leaching). (4) The addition of nitrogen dynamics in Noah-MP improves the modeling of the carbon and water cycles (e.g., net primary productivity and evapotranspiration).Geological Science

Integrated automotive exhaust engineering : uncertainty management

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2006.Includes bibliographical references (p. 104-108).The global automotive industry has entered a stagnating period. Automotive OEMs and their tier suppliers are struggling for business growth. One of the most important strategies is to improve the engineering efficiency in the product development process. The engineering uncertainties have been identified as the main obstacles in the Lean Engineering practices. This study will be focused on the engineering development process of ArvinMeritor Emission Technologies. The lean engineering principles and techniques are applied to the current product development process. The Value Stream Mapping and Analysis method is used to identify the information flow inside the current engineering process. Based on the value stream map, the uncertainties at various development stages in the process are identified. The Design Structure Matrix is used to identify any unplanned design iteration, which results in lower engineering efficiency. The House of Quality is used to prioritize the importance of the iterations. The suggested excel program can effectively evaluate the effect of task duration, probability, impact and learning curve assumption.(cont.) In order to quantitatively predict the effects of the uncertainties, a System Dynamic model is specifically developed for the current engineering of Emission Technologies. The results clearly indicate the control factors for on-time delivery, efficient resource allocation, and cost reduction. This study has integrated the techniques from system engineering, system project management, and system dynamics. An improved automotive exhaust engineering process is proposed.by Xitian Fang and Deming Wan.S.M

Coulomb Oscillations of Indium-doped ZnO Nanowire Transistors in a Magnetic Field

We report on the observation of Coulomb oscillations from localized quantum dots superimposed on the normal hopping current in ZnO nanowire transistors. The Coulomb oscillations can be resolved up to 20 K. Positive anisotropic magnetoresistance has been observed due to the Lorentz force on the carrier motion. Magnetic field-induced tunneling barrier transparency results in an increase of oscillation amplitude with increasing magnetic field. The energy shift as a function of magnetic field indicates electron wavefunction modification in the quantum dots.Comment: 16 pages, 6 figure

Unveiling Hidden Physics in the 215-Kelvin Superconducting Calcium Hydride: Temperature, Quantum and Defect Effects

Temperature and quantum effects induce the structural complexity of condensed hydrogen, and therefore they are expected to impact nontrivially the structures of clathrate hydrides. Exemplified by clathrate calcium hydride, we show through ab initio (path-integral) molecular dynamics simulations that these effects are indeed pivotal at 100-200 GPa. The quantum equation of states derived at 300 K suggests that the synthesized samples in previous experiments were berthollide-like CaH$_{6-\delta}$, with the stoichiometric defect $\delta$ increasing smoothly during decompression. The change of composition provides an explanation for the experimental observation of positive pressure dependence of superconducting T$_c$ below 165 GPa. Furthermore, we find significant proton diffusion in CaH$_{6-\delta}$ at 150-300 K, with the diffusion coefficient reaching 10$^{-7}$ cm$^{2}$/s. This suggests a coexistence of superconductivity and proton diffusion in clathrate hydrides. Our findings underline the importance of temperature, quantum and defect effects to the understandings of the structure and pertinent physics in high-T$_c$ superconducting clathrate hydrides.Comment: 9 pages, 3 figure

Defining SSO Power and Characterizing SSO Propagation in Power System with Wind Farms Integration

This paper studies the characteristics of subsynchronous oscillation (SSO) power propagation in power systems with a large-scale wind farm integration. Based on the instantaneous power theory, a novel definition of SSO power is proposed to characterize its propagation. The SSO power contains both DC power components and AC power components. Utilizing SSO power, SSO propagation is quantitatively studied in single oscillation source systems, and further studied in multiple oscillation sources systems. Theoretical analysis reveals that in addition to the recognized impact of line impedance, power flow also affects SSO power propagation significantly. Hence, propagation impact factor is proposed for the determination of the dominant influencing element. To reveal SSO power propagation paths in a network, shunt coefficients of DC power components and AC power components are expressed respectively. Test cases under different operating conditions and a practical case are carried out to demonstrate analysis and conclusions in this paper

The Monte Carlo Simulation of the Electronic Local Properties in the Two-Dimensional Disordered System

AbstractUsing Monte Carlo simulation method, we studied the influence of the disorder, eigenenergy and bandwidth on the localization length in disordered system. The results reveal that electronic states of system exhibited localization phenomena with the increase of degree of disorder and the localization length can be reduced by the increasing of disorder degree. Moreover the incremental range of localization length had a trend to descend with increase of bandwidth

Soil C:N:P stoichiometry in tropical forests on Hainan Island of China: Spatial and vertical variations

Soil carbon (C), nitrogen (N), and phosphorus (P) are three important elements. The study of stoichiometric relationships of soil C, N, and P in tropical forests on Hainan Island, China could improve our understanding of nutrient cycling and provide valuable information for forest management. Soil samples were collected at five different depths from 0 to 100 cm at 100 sites among four different forest types on Hainan Island, and total C, N, and P concentrations were measured. Soil C and N concentrations and soil C:P and N:P ratios declined from the surface soil layer to the deeper soil layers and soil P and C:N ratio had relatively small variations among different depths, due to that soil C and N were mostly controlled by biological processes such as photosynthesis and N2-fixation, while P was more influenced by bedrock. Large spatial variations were found for soil C, N, P concentrations and their ratios. Soil C and N concentrations were significantly influenced by longitude and vegetation cover, while soil P concentration and C:P and N:P ratios were significantly controlled by latitude. This study produced a comprehensive data set of soil C, N, and P stoichiometry, and their variation patterns and controls in the tropical forests. The information generated here could help improve ecosystem models for better understanding of forest element stoichiometry, ecosystem productivity, and plant-environment relationships

Daya Antibakteri Estrak Kulit Dan Biji Buah Pulasan (Nephelium Mutabile) Terhadap Staphylococcus Aureus Dan Escherichia Coli Secara in Vitro

Traditional medicine from drug crop has more than a pharmacological effect so that its use should be acurate and correct. The mistake in traditional medicine USAge and or drug crop can be dangerous for health. Therefore, it is required a complete scientific information to avoid it. It had been done the research of anti-bacteria activity test from crude extract of ethyl acetate and ethanol from skin and seed of Pulasan to bacterium Staphylococcus aureus and Escherichia coli with dilution method to determine Minimum Inhibitory Concentration (MIC) and Minimum Bakterisidal Concentration (MBC). The biggest MIC and MBC was respectively obtained from ethyl acetate extract that was 0,76 mg/ml, and ethanol extract that was 156,13 mg/ml. In general, skin and fruit seed extract of pulasan (Nephelium mutabile) has bigger resistance ones to bacterium Staphylococcus aureus compared to Escherichia coli