Assessment And Prediction Of Potentially Mineralizable Organic Nitrogen For Subarctic Alaska Soils

Thesis (Ph.D.) University of Alaska Fairbanks, 2011The objective of this study was to identify a rapid laboratory technique to predict potentially mineralizable organic N for subarctic Alaska soils. Soil samples were taken from major agricultural area of subarctic Alaska. Laboratory incubation followed by kinetic model fit was first used to select a best model to estimate potential soil N mineralization. By correlating the model estimated organic N pool sizes and different chemical extracted organic N, I then found the best chemical method to estimate soil potentially mineralizable N. Spectroscopic properties of water extractable organic matter were also determined and correlated with model estimated organic N pool sizes in order to improve the estimation of soil mineralizable N pool. Finally, the best chemical method and spectroscopic property were used in the selected best kinetic model for the prediction of soil N mineralization in field incubation. Model comparisons showed that models with fixed rate constants were better than that the ones with rate constants estimated from simulation. Among models with fixed rate constants, fixed double exponential model was best. This model differentiated active mineralizable organic N pool with a fixed rate constant of 0.693 week-1 and slow mineralizable organic N pool with a fixed rate constant of 0.051 week-1. By correlating model estimated organic N pool size and chemical extracted organic N amount, I found that the potentially mineralizable organic N size was closely correlated with hot (80 �C) water extractable organic N or 1 M NaOH hydrolysable organic N. By correlating model estimated organic N size and spectroscopic characteristics of water extractable organic matter, I found that the active mineralizable organic N pool was correlated with humification index in cold (22 �C) water extraction (R 2=0.89, p<0.05), which indicates that characterizing extracted organic matter was a useful tool to improve the estimation of soil organic N pools. In summary, potential mineralizable organic N in soils from subarctic Alaska can be estimated by hot water extractable organic matter or 1 M NaOH hydrolysable organic N, which accounted for 70% and 63% of the variation in potentially mineralizable organic N, respectively. This approach will provide fundamental insight for farmers to manage N fertilizer application in agricultural land and also provide some basic information for ecologists on predicting N release from Alaska soil that can be used for assessing the N impact on ecosystem

Modeling Risk Behavior of Agricultural Production in Chinese Small Households

This paper analyzed Chinese small-scale farmer's response to agricultural risks by using MOTAD model. Based on the household's data from the two villages Wangjia and Damao in Zhejiang province, we established "representative rural household" for each of the sampling villages. The results show that farmers in Zhejiang are quite sensitive to agricultural risks. However, different farming systems, the ratio of agricultural income to total family income, as well as the size of arable land, differentiates their risk response. The decision maker's risk preference not only affects the type of agricultural activities and corresponding scales they selected, but also have further effects on the micro agricultural production structure and stable growth of household's income. Given the amount of productive resources such as arable land, capital and labor force, the combination of production activities with a higher level of expected income/risk would be selected if the decision maker is willing to take risks. In a higher level of risks, capital is invested prior to manpower, implying that the latter has a much higher opportunity cost. For those combinations with a lower risk level, diversification might reduce risks to some extent at a cost of total return. Current agriculture structure needs to be adjusted and improved.Farming household, agricultural risks, risk response, MOTAD Model, Farm Management, Risk and Uncertainty, D1, C6, D2,

Study on Structural Optimization Design of Heat Exchangers of Hot air furnace

AbstractSpraying heat exchanger and tubular radiation recuperator are common equipment of the drying hot air furnace. To study the way of reducing the investment cost for the heat exchanger of high-temperature and high-capacity hot air furnace, the heat exchange area of the two heat exchangers was calculated by LMTD method when air temperature rose from 0°C,100°Cand 200°C to different temperature points, and the figure of the relationship between the temperature difference and average heat exchange area was given. According to the analysis, the economical temperature range of the heat exchangers is narrower as the inlet air temperature rises. When the air temperature difference keeps constant, the average heat exchange area increases as the inlet air temperature rises. When the inlet air temperature keeps constant, the average heat exchange area increases gradually as the air temperature difference rises. Then the average heat exchange area exceeds the economical temperature range and approaches infinity quickly. The analytical method of economic performance can be applied to the design and model selection of two-stage heat exchanger of high-temperature and high-capacity hot air furnace

Optical and sensing properties of various shaped gold nanoplates and highly controlled asymmetric gold nanoplate/nanosphere coupled assemblies.

With the development of a strategy to correlate the dark-field light scattering spectra of individual nanostructures with scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the same nanostructures, we were able to investigate several interesting optical properties of Au nanoplates (NPs) and asymmetrically-coupled Au nanospheres (NSs) attached to Au NPs with a high level of control. The light scattering spectra of the NP/NS coupled structures depend strongly on the location of NS attachment on the NP. Attachment of multiple NSs at the edge/vertex sites leads to a unique synergistic effect. In contrast to the uniform distribution of NSs, asymmetric distributions of multiple NSs attached to the sides of a NP result in complex, broadened, multi-peaked spectra with larger plasmonic shifts. Simulations using the discrete dipole approximation (DDA) method verified all of the experimental results. The positive shift in the dipolar plasmon mode of the NP/NS assembly relative to the original NP increases with increasing NS size for those attached on the side of the NP in the order of 9±2 nm, 24±4 nm, and 98±16 nm for the 13, 24, and 51 nm average diameter NSs, respectively. For a NS attached to the top terrace of a NP, the shift in the dipolar plasmon mode is 1±1 nm, 3±1 nm, and 14±4 nm for the 13, 24, and 51 nm NS, respectively, and the spectra become more broad. The attachment of a Au NS to a hexagonal or circular Au NP through a cysteamine (Cys) linker shows different light scattering properties compared to attachment through 4-aminothiophenol (4-ATP). The shorter length of Cys leads to stronger dipolar plasmon coupling along the long axis of the NP/NS structure. This leads to a larger red-shift compared to linking with 4-ATP. The geometric shape of the NPs dramatically affects their sensitivity to refractive index changes in the environment and sensitivity to the attachment of a Au NS. The sensitivity of λmax to a change in the refractive index of the environment followed the order of triangles \u3e hexagons \u3e circles. This research provides new fundamental information and a better understanding of shape-dependent optical properties and plasmon coupling of asymmetric metallic nanostructures with potential use in three-dimensional spatial sensing and other plasmonic applications

Research on the Relationship Network in Customer Innovation Community based on Text Mining and Social Network Analysis

Relationship is the focus of the current study in the social phenomenon with social network theory, which is mainly about its meaning and strength. However, a different object, different relationship. Social network theory insists that the actor\u27s behavior is the result of the limitations and opportunities of many relationships that occur simultaneously and interaction. The behavior and characteristics of the whole group are also dependent on the integration of multi-dimensional relationships. There are multi-dimensional relationships among customers participated product innovation in the customer innovation community. Since the huge number of customers in customer innovation community and the complex relationships among the customers, the method is different in traditional ways. Therefore, this paper combines associated crawler algorithm, text mining, and social network analysis to study network relationship types, network structure and the relevance of the customer innovation community. Firstly, this paper analyzes the relationship type and the relationship network according to previous studies. Secondly, reptile technology is used to obtain structured data in the customer community. After cleaning and pre-processing, the data is transformed into relational data from the original structure, with format 1069 × 1069 size matrix. Analyzing the structure of relationship network using social network analysis methods and tools, the results show that interactive network, social network, and knowledge-sharing networks are all sparse network. Thirdly, the correlation among the relationship networks is studied. The results demonstrate that it is higher than the correlation between the interactive network and the knowledge-sharing network and lower than the social network correlated with the other two networks