Dissertations / Theses on the topic 'Chemical inputs'

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 171-185).
.The fourth industrial revolution is said to be brought about by digitization in the manufacturing sector. According to this understanding, the third industrial revolution which involved computers and automation will be further enhanced with smart and autonomous systems fueled by data and machine learning. At the research stage, an analogous story is being told in how automation and new technologies could revolutionize a chemistry laboratory. Flow chemistry is a technique that contrast with traditional batch chemistry in one aspect as a method that facilitates process automation and in small scales, delivers process improvements such as high heat and mass transfer rates. In addition to flow chemistry, analytical tools have also greatly improved and have become fully automated with potential for remote control. Over the past decade, work utilizing optimization techniques to find optimal conditions in flow chemistry have become more prevalent.
In addition, the scope of reactions performed in these systems have also increased. In the first part of this thesis, the construction of a platform capable of performing a wide range of these reactions on the lab scale is discussed. This platform was built with the capability of performing global optimizations using steady state experiments. The rest of the thesis concerns generating dynamic experiments in flow systems and using these conditions to gain more information about a reaction. The ability to use dynamic experiments to accurately determine reaction kinetics is first detailed. Through these experiments we found that only two orthogonal experiments were needed to sample the experimental space. After this an algorithm that utilizes dynamic experiments for kinetic parameter estimation problems is described. The approach here was to use dynamic experiments to first quickly sample the design space to get a reasonable estimate of the kinetic parameters.
Then steady state optimal design of experiments were used to fine tune these estimates. We observed that after initial orthogonal experiments only three more conditions were needed for accurate estimates of the multi-step reaction example. In a similar fashion, an algorithm for reaction optimization that relies on dynamic experiments is also described. The approach here extended that of adaptive response surface methodology where dynamic orthogonal experiments were performed in place of steady state experiments. When compared to steady state optimizations of multi-step reactions, a reduction by half in time needed to locate the optimum is observed. Finally, the potential issues that arise when using transient experiments in automated systems for reaction analysis are addressed. These issues include dispersion, sampling rate, reactor sizes and the rate of change of transients.
These results demonstrate a way with which technological innovation could further revolutionize the chemistry laboratory. By combining machine learning, clouding computing and efficient, high information experiments reaction data could be quickly collected, and the information gained could be maximized for future predictions or optimizations.
by Kosisochukwu C. Aroh.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering

Doutoramento em Química
Urban soil quality may be severely affected by hydrophobic organic contaminants (HOCs), impairing environmental quality and human health. A comprehensive study was conducted in two contrasting Portuguese urban areas (Lisbon and Viseu) in order to assess the levels and potential risks of these contaminants, to identify sources and study their behaviour in soils. The concentrations of HOCs were related to the size of the city, with much higher contamination levels observed in Lisbon urban area. Source apportionment was performed by studying the HOCs profiles, their relationship with potentially toxic elements and general characteristics of soil using multivariate statistical methods. Lisbon seems to be affected by nearby sources (traffic, industry and incineration processes) whereas in Viseu the atmospheric transport may be playing an important role. In a first tier of risk assessment (RA) it was possible to identify polycyclic aromatic hydrocarbons (PAHs) in Lisbon soils as a potential hazard. The levels of PAHs in street dusts were further studied and allowed to clarify that traffic, tire and pavement debris can be an important source of PAHs to urban soils. Street dusts were also identified as being a potential concern regarding human and environmental health, especially if reaching the nearby aquatic bodies. Geostatistical tools were also used and their usefulness in a RA analysis and urban planning was discussed. In order to obtain a more realistic assessment of risks of HOCs to environment and human health it is important to evaluate their available fraction, which is also the most accessible for organisms. Therefore, a review of the processes involved on the availability of PAHs was performed and the outputs produced by the different chemical methods were evaluated. The suitability of chemical methods to predict bioavailability of PAHs in dissimilar naturally contaminated soils has not been demonstrated, being especially difficult for high molecular weight compounds. No clear relationship between chemical and biological availability was found in this work. Yet, in spite of the very high total concentrations found in some Lisbon soils, both the water soluble fraction and the body residues resulting from bioaccumulation assays were generally very low, which may be due to aging phenomena. It was observed that the percentage of soluble fraction of PAHs in soils was found to be different among compounds and mostly regulated by soil properties. Regarding bioaccumulation assays, although no significant relationship was found between soil properties and bioavailability, it was verified that biota-to-soil bioaccumulation factors were sample dependent rather than compound dependent. In conclusion, once the compounds of potential concern are targeted, then performing a chemical screening as a first tier can be a simple and effective approach to start a RA. However, reliable data is still required to improve the existing models for risk characterization.
A qualidade dos solos urbanos pode ser afetada por contaminantes orgânicos hidrofóbicos (HOCs), prejudicando a saúde ambiental e humana. Este trabalho consistiu em estudar duas áreas urbanas contrastantes (Lisboa e Viseu), com o objetivo de avaliar os níveis de HOCs nos solos e os seus potenciais riscos para a saúde humana e para o ambiente. Pretendia-se ainda identificar as fontes e estudar o comportamento destes contaminantes no solo. Foi possível relacionar as concentrações de HOCs com o tamanho da cidade, sendo os níveis de contaminação muito mais elevados em Lisboa. A identificação das fontes destes contaminantes foi feita através do estudo dos respetivos perfis e da relação com elementos potencialmente tóxicos, utilizando métodos estatísticos multivariados. Lisboa parece ser afetada por fontes próximas (tráfego, indústria e incineração) enquanto em Viseu o transporte atmosférico aparenta ter um papel mais importante. Num primeiro nível da avaliação de risco (RA), foi possível identificar os hidrocarbonetos aromáticos policíclicos (PAHs) nos solos de Lisboa como um perigo potencial. Os níveis de PAHs em poeiras das ruas de Lisboa foram também estudados e permitiram clarificar que o tráfego e os detritos de pneus e de pavimento podem também ser uma importante fonte destes compostos. Utilizaram-se e discutiram-se ferramentas de geoestatística assim como a respetiva utilidade em RA e em planeamento urbano. De modo a obter uma avaliação mais realista dos riscos de HOCs é importante avaliar a fração disponível, que é também a mais acessível para os organismos. Deste modo, foi feita uma avaliação dos processos envolvidos na disponibilidade de PAHs e também dos resultados obtidos pelos diferentes métodos químicos. A adequação dos métodos químicos para prever a biodisponibilidade de PAHs em solos naturalmente contaminados ainda não foi demonstrada, sendo especialmente difícil para os compostos de elevado peso molecular. No presente trabalho também não foi possível estabelecer uma relação significativa entre a disponibilidade química e a biodisponibilidade. No entanto, apesar das elevadas concentrações totais encontradas em alguns solos de Lisboa, tanto a fração solúvel em água como os resíduos acumulados nos ensaios de bioacumulação foram, em geral, muito baixos, o que estará relacionado com os fenómenos de envelhecimento destes contaminantes nos solos. Observou-se que a fração solúvel de PAHs depende do composto em causa e é regulada pelas propriedades do solo. Apesar de não se terem observado correlações entre as propriedades do solo e a biodisponibilidade, observou-se que os fatores de bioacumulação dependem mais da amostra do que do composto. Em conclusão: após a identificação dos contaminantes de interesse uma avaliação química baseada nos teores totais pode ser uma abordagem eficaz no primeiro nível da RA, mas no entanto é necessário melhorar os modelos existentes para a caracterização do risco.

The objective of this research was to determine the effects of conventional inputs on soil chemical and biological properties compared to organic systems in a four year vegetable rotation. Tillage and cover crops were the same in all treatments to avoid confounding factors often present in similar research. Additional experiments investigated plant gene expression in organic and conventional management systems and in soils with decreased microbial diversity. Experimental plots were prepared in the spring of 2004; four replications of three management treatments, organic, low-input and conventional, were arranged in a randomized complete block design. The rotation consisted of edamame soybean, sweet corn, fallow (pastured poultry in organic plots), and potatoes. Soil samples were taken in the spring and fall of each year, along with data for pest damage, weed control, yield and quality. Soil samples were analyzed for enzyme activity (maximum activity under substrate saturation) and basic soil chemical properties. Treatments were compared over time using 2-Way ANOVA. Multiplex terminal-restriction fragment length polymorphism (M-TRFLP) profiles of the soil microbial community were compared using Multiple Response Permutation Procedures (MRPP). Multi-way ANOVA detected significant treatment effects over time in total carbon, nitrogen, Mehlich III K, Exchangeable K and exchangeable Na (p=0.05). Many significant changes in soil properties over time could not be attributed to treatment effects. All treatments produced similar yields, indicating that successful organic production of these vegetables is possible in Kentucky. Input costs for organic were 37% higher than conventional, due to the cost of organic fertilizer. The organic system required nearly 50% more labor hours than conventional or low-input. The low-input system was the most cost effective, with 58% less input expenses than the conventional system. Microarray analysis of approximately 37,500 Glycine max transcripts did not show significant differences in the gene expression between plants grown organically and conventionally, in plots with significant soil chemical and microbial differences. An experiment in progress is investigating changes in plant gene expression using real time RT-PCR in tomatoes grown in autoclaved soil and native field soil.

Bibliography: leaves 109-113.
Dynamic operability reflects the quality with which a plant can be controlled using feedback, and is a function of both the design of the plant and its associated control system. A plant designed on the basis of steady-state considerations alone could exhibit poor dynamic characteristics, leading to a loss of economic performance and a reduced capacity to effectively handle safety and environmental constraints. This motivates the need for the development of quantitative techniques for dynamic operability assessment, as well as its incorporation into procedures for process plant design. Optimization-based approaches to dynamic operability assessment permit simultaneous consideration of performance-limiting factors of nonminimum phase characteristics, input constraints and model uncertainty, and also provide considerable flexibility in the choice of performance criteria, decision variables and constraints. Recent work has incorporated operability requirements as constraints within a single optimal plant design problem formulation (Mohideen et at., 1997; Bahri et at.,1996). Young and Swartz (1997) considered the rigorous inclusion of input saturation effects in optimizing control. Actuator saturation introduces discontinuities in the system model and, to avoid potential problems using a sequential optimization approach, two alternative formulations were proposed for solving the problem within a simultaneous solution framework. Input saturation discontinuities were handled by the introduction of slack variables and their inclusion in either bilinear or mixed-integer constraints resulting in a nonlinear or mixed-integer linear programming problem respectively. The formulations were applied to a linear system with dead time to find the economically optimal operating point for a controller with fixed structure and tunings when disturbance deviations are taken into account. It was shown that using a strictly linear controller in this case would lead to an overly conservative estimate of the feasible operating range and consequently, a suboptimal operating point.

SYNOPSIS Energy/power input in a flotation cell is an important parameter which, if optimised, can increase the flotation rate. The optimum energy/power input within a flotation cell is still a matter of conjecture and there is a need for a better understanding of the effect of energy input on flotation kinetics. This study investigates the effect of energy/power input on flotation kinetics in an oscillating grid flotation cell (OGC). The OGC decouples the processes of solid suspension and bubble generation as well as producing relatively isotropic and homogeneous turbulence with zero mean flow. Due to this, oscillating grids provide a potentially ideal environment for investigating the effects of energy input on flotation kinetics, which cannot be achieved in a mechanical flotation cell. The first objective of this thesis was to determine the effect of energy/power input on the flotation kinetics of sulphide minerals (galena, pyrite & pentlandite) and oxide minerals (apatite & hematite) in a laboratory scale oscillating grid flotation cell. The second objective was to compare the results from the laboratory OGC to comparative studies in the flotation literature and to fundamental models for particle-bubble contacting. The third objective was to determine whether the experimental results from the laboratory OGC are consistent with those from a pilot-scale OGC operating on a platinum ore. Galena, pyrite, pentlandite (-150 μm), apatite (-650 μm) and hematite (-75 μm) were floated in the laboratory OGC at energy inputs from 0.1 to 5.0 W/kg, using 0.13, 0.24, 0.58 and 0.82 mm bubble sizes (d₁₀), and at three collector dosages. Platinum ore (-75 μm) was floated in the pilot-scale OGC at energy inputs from 0 to 2.5 W/kg, using 0.71 and 1.47 mm bubble sizes (d₁₀). The effect of energy input on flotation kinetics was interpreted through trends in experimental flotation rate constants, simulated flotation rate constants and attachment-detachment flotation rate constants. Here, simulated flotation rate constants were calculated using a literature fundamental model for flotation in turbulent systems. This model is based on suitable expressions for the collision frequency, collision efficiency, attachment efficiency and stability efficiency, Attachment-detachment flotation rate constants were calculated using a kinetic model which allows for the two separate processes of bubble-particle collision/attachment and detachment. This model is based on kinetic expressions using empirical correlations for the attachment and detachment rate constants. Experimental flotation results show that the effect of energy input on the flotation rate is strongly dependent on the particle size and particle density and less dependent on bubble size and contact angle. Flotation rates generally increase with increasing particle size, decreasing bubble size and increasing contact angle, as is commonly found in the literature. Increasing energy input generally leads to an increase in the flotation rate for fine particles, an optimum flotation rate for intermediate particles and a decrease in the flotation rate for coarse particles. The optimum in the flotation rate for minerals with higher density is at a lower energy input than that for lower density minerals. The changes (increases/decreases) in the flotation rate with increasing energy input are very large for most of the conditions, indicating that this is an important parameter in flotation. Pilot scale results generally support the trends observed in the laboratory OGC. These findings are attributed to the effect of energy/power input on bubble-particle collection which is a balance between two competing effects, those of bubble-particle collision/attachment and those of bubble-particle detachment. Increasing energy input generally leads to significant increases in the flotation rate of fine particles, due to increased bubble-particle collision/attachment. Increasing energy input generally leads to an optimum flotation rate for intermediate particles, due to a combination of increased bubble-particle collision/attachment and detachment. For coarse particles, increasing energy input leads to significant increases in bubble-particle detachment. The relationship between the flotation rate and energy input is often described as k  ɛᴺ, in the absence of significant bubble-particle detachment. The typical values of N are in the range of 0.44-0.75 for theoretical studies and 0.7-1 for experimental studies. The values of N found in the current study are in the range of 0.7-1, which suggests that bubbleparticle collision/attachment has a stronger dependence on energy input than theory suggests. Simulated flotation results for fine particles compare well to the experimental data in terms of both trends and magnitude. This suggest that the turbulent collision model used is appropriate for fine particles. For intermediate particles there are differences between the simulated flotation rate constants and the experimental data, primarily in terms of trends. For coarse particles there are very large differences between simulated flotation rate constants and the experimental data. This is attributed to under prediction of the collision frequency/efficiency and incorrect prediction of the stability efficiency. Here, the stability efficiency is considered to be under predicted at low energy inputs and over predicted at high energy inputs. This suggests that the stability efficiency has a much stronger dependence on energy input than theory suggests. Attachment-detachment results show that the attachment rate constant has a stronger dependence on energy input than theory suggest, supporting finding from the experimental results and simulated results for coarser particles. In addition, the detachment rate constant has a much stronger dependence on energy input than theory suggests, supporting findings from both the experimental and simulated results. Based on the objectives of this study and literature reviewed, the following hypotheses were made at the outset 1) Increasing energy/power input will increase the rate of flotation of fine particles but will result in an optimum for intermediate and coarse particles. The position of this optimum will depend on the particle density, bubble size and contact angle. 2) Fundamental models based on the RMS turbulent velocity will be appropriate for describing flotation kinetics as turbulence in the oscillating grid cell is relatively homogeneous and isotropic and 3) Trends in flotation results for a laboratory and pilot-scale oscillating grid flotation cell will be comparable as the distribution of turbulence in OGCs at equivalent specific power inputs is scale independent. Hypothesis 1 was found to be valid for both fine and intermediate particles, but for coarse particles increasing energy input resulted in sharp decreases in the flotation rate. In addition, the increase in the flotation rate with increasing energy input was found to be more dependent on the particle size and particle density than the bubble size and contact angle. Hypothesis 2 was found to be valid for fine particles but not for intermediate or coarse particles. Here, it was found that the processes of bubble-particle collision/attachment and detachment have a stronger dependence on energy input than theory suggests. Hypothesis 3 was supported by general trends in results for the laboratory and pilot-scale oscillating grid flotation cells, but was not convincingly demonstrated.

Includes abstract.
Includes bibliographical references (leaves 77-84).
The move to cleaner production has led to the process industry aiming at producing chemicals in a pure form and at the lowest possible cost. In practice this has resulted in a shift from treating processes as "black boxes" towards developing more concise models which reveal what happens within these "black boxes". This shift can be discerned at plant level for better control mechanisms, at a reactor design level to incorporate the effect of hydrodynamics and even at a molecular level when designing a tailor-made catalyst.

Wearable computers allow users the freedom to work in any environment including hazardous environments that may require protective clothing. Past research has shown that protective clothing interferes with manual materials handling tasks, medical tasks, and manual dexterity tasks. However, little information exists regarding how protective clothing affects task performance with wearable input devices. As a result, a study was conducted to address this issue and offer recommendations to enhance the compatibility of chemical protective clothing and wearable input devices. Sixteen active-duty soldiers performed a text-entry task with a wearable mouse and touch pad, while bare handed, wearing 7-mil, 14-mil, and 25-mil chemical protective gloves, wearing a respirator alone, and wearing the respirator and each of three gloves. Upon completion of the experiment, participants rated task difficulty, confidence using the input device, and input device preference. Task completion times were 9% slower with the 25-mil glove than the 7-mil glove. Text entry was not perceived as difficult when bare handed, or wearing the 7-mil and 14-mil gloves, suggesting that thin chemical protective gloves (i.e. 7-mil and 14-mil) are more suitable than thicker gloves for use with wearable input devices. When using the touch pad, task completion times were 17% faster than when using the mouse. Subjective ratings of difficulty, confidence, and preference provide strong support for the use of a touch pad input device rather than a mouse.
Master of Science

Energy is known to play an important role in particle-bubble contacting in flotation. This thesis investigates the effect of energy input (or agitation) on the flotation kinetics of quartz in a novel oscillating grid flotation cell. The effects of bubble size and particle size have been recognized as important variables affecting particle-bubble contacting in turbulent systems and are investigated in this thesis. The research work done in this thesis is a continuation of the work done by the Centre for Minerals Research by Deglon (1998) who investigated the effects of energy in a batch mechanical flotation cell. However, this system has a very complex hydrodynamic environment, resulting from the large disparities in turbulence intensity. Previously Breytenbach (1995) had constructed a hybrid flotation column cell, which was essentially a column flotation cell that could be modified into a Jameson cell or a mechanically agitated column cell. He used this to compare particle collection efficiency in these different particle-bubble contacting environments. The third phase of the work was the oscillating baffle column (OBC), a novel flotation column that attains agitation by oscillating a set of orifice baffles through the slurry, thereby producing a more uniform shear rate distribution than would be obtained in an impeller driven system (Anderson, 2008). The OBC unfortunately has significant oscillatory flow and has high shear rates, which often result in detachment effects becoming appreciable. Oscillating grids generate near ideal hydrodynamic environments, characterised by turbulence that is relatively homogeneous and isotropic. The oscillating grid flotation cell used in this study was based on the oscillatory multi-grid mixer used by Bache and Rasool (2001). The oscillatory multi-grid mixer was purchased from these authors and retrofitted to produce the oscillating grid flotation cell. The novel oscillating grid cell consists of a 10 litre tank agitated by 19 grids with a mesh size of 8 mm and grid spacing of 18 mm. The grids were oscillated at a fixed amplitude, equal to the grid spacing, and over a range of frequencies, using a variable speed drive. Frother was added at 100 ppm to be consistent with the work of Deglon (2002) and Ahmed and Jameson (1985). A low gas flow-rate (100 ml/min) and solids concentration were specifically chosen in order that there was minimal influence on the structure of turbulence in the oscillating grid cell, as Bache and Rasool (2001) took measurements in water. Flotation tests were performed on methylated quartz particles (P80 = 100 μm) over a range of power intensities (0.015–0.60 W/kg) and using three different bubble sizes, generated by sintered glass discs (0.13, 0.24 and 0.82 mm). The flotation rate constant was found to increase approximately linearly with increasing particle size for all three bubble sizes. This was due to the increased probability of collision for larger particles and is well established in the flotation literature. A number of researchers have found that the flotation rate constant for quartz particles increases almost linearly with particle size, at low power intensities. An inverse power relationship was observed between bubble size and flotation rate constant for all fine, middling and coarse particle size ranges. This inverse power relationship was due to the increased probability of collision for smaller bubbles and is also well established in the flotation literature. More significantly, the flotation rate constant was found to increase almost linearly with increasing power intensity for all particle and bubble sizes used in this study. The majority of theoretical and experimental studies have found energy input to have less of an effect than the proportional/linear dependence observed in this study. In addition, the increase in the flotation rate constant with increasing power intensity was observed to depend on particle size, but to be less dependent on bubble size. These findings suggest that energy input and bubble size may respectively play more and less of a role in promoting particle-bubble contacting in turbulent environments than was noted in the flotation literature. However, a recent study by Newell and Grano (2006) done using a stirred tank also noted this linear dependence. Given the findings of this thesis, it is strongly recommended that further work be done to investigate the OGC at higher energy intensities (~3W/kg) and to scale it up so that it can be more comparable to the widely used mechanical flotation cells. The homogeneous and nearly isotropic turbulence generated by the OGC also makes it an ideal environment to characterize floatability for different ores.

Multiple Input-Multiple Output (MIMO) systems are very common in process industries, but can be difficult to control. A phenomenon called coupling occurs in a MIMO system when the controller output from one loop acts as disturbance to other control loops. This thesis studies a solution to coupling by introducing a decoupler to a Proportional Integral Differential (PID) control system. A decoupler is a feed-forward controller added to the traditional feedback loop to cancel out loop disturbance. The effect of a decoupler on the performance of control system was explored by comparing (1) the time it takes to achieve control and (2) the combined error incurred during the control process. In this study, a simulation software, LoopPro is used to model and control two systems; multi-tank system and distillation column. Step test data were used to identify process model and a tuning procedure based on Internal Model Control is illustrated. The extent of loop interaction was also analyzed from the Relative Gain Matrix.

This dissertation describes several studies of groundwater quality, the fate and transport of nutrients and atrazine in groundwater systems and physical processes at the sediment-water interface which impact on groundwater discharge. Groundwater monitoring wells were installed at the Goodwins Island and Catlett Island NERRS sites in Virginia and agricultural, suburban and forest land use sites in the York and James River Basins. Groundwater was analyzed for nutrients, pH, salinity and trace organics. Shoreline land use, associated nutrient loading and an estimate of total groundwater flux suggest that groundwater contributes up to 30% of the total nitrogen input to the Chesapeake Bay. Batch isotherm K&\sb{lcub}\rm d{rcub}& values for &\sp{14}&C-labelled atrazine sorption to low organic carbon (OC) aquifer solids ranged from 0.08 to 0.61 L/kg, much lower than for soil and other, higher carbon, solids. Kd was dependent on the surface area (SA) and surface iron (SFe), and can be described by:&&\rm K\sb{lcub}d{rcub} = 0.046(SA)+ 0.61(SFe) + 0.83&&. Kinetics of atrazine sorption onto low OC sediments showed an initial rapid reaction accounting for &>&95% of sorption within a few minutes at about 2 &\mu&g kg&\sp{lcub}-1{rcub}& min&\sp{lcub}-1{rcub}& followed by a slower (0.003 &\mu&g kg&\sp{lcub}-1{rcub}& min&\sp{lcub}-1{rcub}&) reaction. Comparison of homogeneous and heterogeneous atrazine hydrolysis reaction rates at elevated temperature showed no evidence for catalysis by aquifer solids. A physical mechanism for passive ventilation of relict biological structures in the benthic boundary layer is presented, a mathematical model of circulation in surrounding sediments was solved analytically and MODFLOW used to numerically determine induced hydraulic gradients and flow. Hydraulic head in surrounding sediments can be reduced by several centimeters in a zone extending over several hundred cm&\sp2&, and pore velocities of &>&10&\sp{lcub}-3{rcub}& cm/s and flux rates of tens to hundreds of mL/hr induced. Flume and field studies showed that large variability and poor repeatability of seepage meter measurements may be due to surface water flow across the meter. Pressure gradients in the boundary layer reduce hydraulic head within the meter and induce augmented seepage flow. Covering the seepage meter collection bag to isolate it from flow can reduce or eliminate this error.

This study examines a reflex mechanism involved in mediating the inhibition of nociceptive input at a heterosegmental spinal level. This heterosegmental inhibitory mechanism is activated by noxious stimulation of a peripheral body region and is regulated by afferent fibers, local spinal neuronal circuitry and supraspinal structures.
A conditioning stimulus, consisting of immersion of one paw of the lightly anesthetized rat in water at a noxious temperature for 90 s elicited an inhibition of a spinal nociceptive reflex in response to a noxious thermal test stimulus in the tail flick test. The magnitude of this antinociception varied with the intensity of the noxious conditioning stimulus, as immersion in water at 40$ sp circ$C, an innocuous temperature, did not evoke an increase in tail flick latency. The antinociceptive response to noxious conditioning stimuli persisted for 3 to 6 min. The response was observed with noxious thermal stimulation of either the hindpaw or the forepaw. Adult animals treated neonatally with capsaicin, which inhibits development of small diameter unmyelinated afferent fibers, did not show this response, suggesting that unmyelinated afferent fibers mediated the input of the conditioning stimulus. Furthermore, in rats transected at the thoracic level, the antinociception following noxious stimulation of the forepaw was blocked while that following hindpaw stimulation was attenuated, indicating that the conditioning stimulus activated heterosegmental inhibitory mechanisms controlled in part by supraspinal structures and in part by spinal structures.
Systemic preadministration of substance P (NK-1) receptor antagonists blocked the antinociceptive effect. These results support an earlier hypothesis that substance P is involved in the transmission of nociceptive information in the spinal cord. Systemic as well as intrathecal preadministration of opiate receptor antagonists blocked the response in a dose-dependent fashion. Therefore, this study suggests that both substance P and endogenous opioids are involved in mediating heterosegmental inhibitory mechanisms.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第18696号
農博第2093号
新制||農||1029(附属図書館)
学位論文||H27||N4890(農学部図書室)
31629
京都大学大学院農学研究科農学専攻
(主査)教授 稲村 達也, 教授 白岩 立彦, 教授 廣岡 博之
学位規則第4条第1項該当

Fibre-to-board is a simulation model developed at Stora Enso Research Centre Karlstad. Within this model isotropic hand sheet properties are used as input data for prediction of the final multi ply board properties. In order to improve and verify the calculations from simulations in Fibre-to-board so that these will correspond better with the results from the measurements on the paper/board machine, it was requested at RCK to investigate the possibility to optimize the input data to the model.

Standardized hand sheet forming always results in sheets with properties far away from those produced on a machine. Therefore the aim with this Master thesis was to modify the laboratory procedure to receive hand sheets with properties closer to machine sheets. To achieve this, it was investigated how different parameters affect the sheet properties and if the hand sheet making process could be improved.

When freely dried sheets were investigated it was found that sheets pressed with a wire clothing between the blotting paper and the hand sheet were less cockled than sheets pressed against only blotting papers. These sheets also tend to have a higher density. The cockling i.e. as a result from shrinkage was also reduced when the sheets were dried between slightly weighted wire clothing. Neither wire clothing nor orientated blotting papers during pressing eliminate the influence of anisotropic blotters on the shrinkage for isotropic hand sheets.

It was also examined how the fine material influences sheet properties. The results showed that an increase in fines content result in higher shrinkage, higher density, increased TSI, more cockling and decreased air permeability.

Different pressing loads and an increased density did not have much influence on the shrinkage. The density for freely dried sheets increased with higher load, but the results did not reach machine sheet densities, when the laboratory platen press was used. It might be difficult to receive freely dried hand sheets with higher densities. This is because fibres in freely dried sheets tend to relax after pressing, which will influence the density. Another press than the platen press used in these studies might compensate this matter. An increased pressing load resulted in less cockled sheets.

The basis weight did not seem to have that large affect on the shrinkage when using machine chest furnish, therefore the basis weight on hand sheets used as input data to the simulation model Fibre-to-board might not be that important.

It was studied how different plies and SW/CTMP pulp in a mixture affect the shrinkage. The results showed that the shrinkage increased with a higher SW content. It was also found that there is a linear relation between the total shrinkage of a SW/CTMP pulp mixture and the shrinkage for each individual pulp.

In order to verify the Fibre-to-board model a simulation finally was performed. Furnishes and CD profiles of board were collected from a particular board machine within the Stora Enso Group. Properties from hand sheets made of furnishes were used as input data and the machine CD profiles were used as references. The CD TSI value corresponded with the value received from measurements on the machine board, but the MD TSI value did not. The shrinkage calculated on machine sheets did not coincide with the shrinkage from the simulation in Fibre-to-board.

There are insecurities in the results from shrinkage measurement on the board CD profile due to the lack of width measurement during the process, which complicates the validation of the Fibre-to-board model.

Fibre to board är en simulerings modell framtagen vid Stora Enso Research Centre Karlstad. Modellen används för att prediktera krympning och styrkeegenskaper hos en bestämd kartongbana. Indata till modellen hämtas ifrån isotropa laboratorieark. För att förbättra och verifiera erhållna resultat från simuleringsmodellen så att de korresponderar bättre med värden från kartongmaskinen fanns det ett önskemål från RCK om att undersöka möjligheten att optimera indata till modellen.

Laboratoriearktillverkning enligt standard resulterar alltid i ark med egenskaper som ligger långt från maskin arkens. Därför är syftet med detta examensarbete att modifiera arktillverkningsmetoden så att laboratorieark med egenskaper närmare de för maskinark kan erhållas. För att lyckas med detta undersöktes det hur olika parametrar påverkar pappersegenskaperna och om tillverkningsmetoden kunde förbättras.

Vid undersökning av fritorkade ark upptäcktes att ark som pressats med viraduk mellan läskark och laboratorieark blev mindre buckliga än ark som pressats med enbart läskark. Dessa ark hade också en något högre densitet. Buckligheten som är en följd av krympningen reducerades också när arken torkades mellan viraduk under lätt belastning. Läskarkens inverkan på de isotropa arken kunde inte elimineras genom att använda viraduk vid pressning, inte heller genom att växla läskarken så att deras MD riktning orienterades olika.

Även finmaterialets inverkan på pappersegenskaperna undersöktes. Resultaten visade att ett ökat finmaterial innehåll ger ökad krympning, högre densitet, ökat dragstyvhetsindex, buckligare ark och en minskad luft permeabilitet.

Det visade sig att olika presstryck ger arken en högre densitet men krympningen påverkades inte märkbart. Densitet i samma nivå som på maskinark kunde däremot inte erhållas med laboratorieplanpress. Detta kan bero på att fibrerna i fritorkade ark relaxerar efter pressning, vilket ger en lägre densitet. För att kunna få högre densitet kanske en annan press än den planpress som användes i dessa studier kan införas. Det kunde även konstateras att ett ökat presstryck ger mindre buckliga ark.

I dessa studier, där ark tillverkades av färdiga skiktblandningar från maskinkar, hade inte ytvikten på arken någon större inverkan på krympningen. Detta tyder på att ytvikten på arken som används som indata inte har så stor inverkan vid simulering i modellen Fibre-to-board.

Det undersöktes även hur skikten i ett två-skikts ark och en blandning av LF/CTMP massa påverkar krympningen. Resultaten visade att krympningen ökar med en högre andel LF och att det finns ett linjärt samband mellan den totala krympningen för en blandning av LF/CTMP massa och krympningen för de enskilda massorna.

För att kunna verifiera beräkningsmodellen Fibre-to-board utfördes slutligen en simulering. Skiktblandningar och tvärsprofiler från kartong togs ut från en specifik pappers maskin inom Stora Enso koncernen. Egenskaperna på laboratorieark gjorda av skiktblandningarna användes som indata till simuleringsprogrammet och kartongprofilerna från pappersmaskinen användes som referens. Dragstyvhetsindex i CD stämde bra överens med de mätningar som gjordes på maskinarken, men dragstyvhetsindex i MD skiljde sig. Krympningen som beräknades på maskinarken överensstämde inte med det simulerade resultatet. Det förekommer en osäkerhet i krympmätningarna som gjordes på kartong profilerna, då det idag inte förekommer någon mätutrustning på pappersmaskinen, som bestämmer bredden mellan press- och torkpartiet. Detta komplicerar valideringen av Fibre-to-board modellen.

Orientador: Fabiano Tomazini da Conceição
Resumo: O processo de denudação continental é controlado por fatores exógenos como intemperismo químico e erosão dos solos. Nesse processo, os sistemas fluviais desempenham um papel fundamental ao transportar os materiais sólidos e dissolvidos de seu local origem até atingir os oceanos. Visando investigar o balanço de denudação no Planalto Alcalino de Poços de Caldas – MG, adotou-se o método de balanço de massa geoquímico aplicado em escala de bacia hidrográfica, cuja análise quantitativa foi baseada nos fluxos de entrada e saída de elementos/compostos químicos em duas pequenas bacias hidrográficas situadas na borda noroeste do planalto. A média da descarga fluvial de sólidos dissolvidos foi estimada em 32,5 t km-2 ano-1 sendo que cerca de 40 % desse fluxo foi atribuído à deposição atmosférica (14,0 t km-2 ano-1) enquanto o restante foi associado ao intemperismo químico das rochas (18,5 t km2 ano-1), enquanto a descarga sólida, estimada em 5,4 t km-2 ano-1, demostra um sistema fluvial de baixo fluxo de sedimento. A taxa de intemperismo químico de fonólitos, tinguaítos e nefelina sienito de Poços de Caldas (2,1 m Ma) foi inferior à taxa de remoção dos solos do planalto (4,0 m Ma), revelando uma tendência de exumação das rochas do maciço a uma velocidade de 1,9 m Ma. A taxa de denudação do Planalto de Poços de Caldas foi reduzida com o passar do tempo geológico e sob o clima atual o relevo de Poços de Caldas tende a se manter na paisagem com pouca alteração em sua forma em um lento pro... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The continental denudation process is controlled by exogenous factors such as chemical weathering and soil erosion. In this process, river systems play a key role in transporting solid and dissolved materials from their source site to the oceans. In order to investigate the denudation balance in the Poços de Caldas Alkaline Plateau - MG, the geochemical mass balance method applied in a watershed scale was adopted, whose quantitative analysis was based on the input and output flows of chemical elements / compounds in two small watersheds situated on the northwest edge of the plateau. The average fluvial discharge of dissolved solids was estimated at 32.5 t km-2 year-1 and about 40% of this flow was attributed to atmospheric deposition (14.0 t km-2 year-1) while the remainder was associated with the chemical weathering of the rocks (18.5 t km-2 year-1), while the solid discharge estimated at 5.4 t km-2 year-1 demonstrates a low sediment flow river system. The chemical weathering rate of phonolites, tinguaites and nepheline syenite from Poços de Caldas (2.1 m Ma) was lower than the removal rate from the plateau soils (4.0 m Ma), revealing a tendency for rock mass exhumation at a speed of 1.9 m Ma. The denudation rate of the Poços de Caldas Plateau has been reduced over time and under current weather the relief of Poços de Caldas tends to remain in the landscape with little change in its form in a slow process of exhumation of the rocks.
Doutor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This study was conducted at an experimental area at Aroeira Farm, belonging to Votorantim Celulose e Papel company, under the geographic coordinates 31° 45 50.7 S e 53° 50 34.9 W, located in Candiota county. In the area there is an experimental field, where some production factors involved in an agroflorestry system are being monitored, with four different treatments (T 1 = eucalyptus planted in 3 m x 2 m spacing; T2= native grass; T3 agroforestry system planted in double line and T4 agroforestry system planted in triple line). Because of this, this study was divided in four chapters, that are: 1) Biomass and nutrients in the agroforestry components in the south of Rio Grande do Sul, Brazil, where the above ground biomass from eucalyptus, sorghum and sunflower was quantified, as well as the nutrients in it. As above ground biomass, sorghum showed a total of 9.876 kg ha-1 (17,67% in the leaves, 47,74% in the stem and 34,61% in grains. In sunflower, the total biomass above the gound was 11.968 kg ha-1 (21,62% in blossom, 24,03% in the leaves, 21,32% in grains and 22,03% in the stem). Eucalyptus total above ground biomass totalized 10.974 kg ha-1 (45,28% in wood, 26,31% in branches, 19,96% in leaves and 8,45% in bark). The total amount of nutrients in sorghum followed this magnitude for total: C > N > K > Ca > P > Mg > S > Fe > Al > Na > Mn. In sunflower the total amount followed this magnitude: C > K > N > Ca > Mg > P > S > Na > Fe > Al > Mn. In eucalyptus the magnitude for total was: C > N > Ca > K > Mg > P > S > Na > Mn > Al > Fe; 2) Inputs through precipitation in área in south Rio Grande do Sul, Brazil, where in native grass area are installed 10 plastic rain gauges (23 cm of diameter). The volume quantification as well as the composed sampling collections for pH, electrical conductivity, nitrate, nitrite, ammonium, phosphorus, sulphur, chlorine, calcium, magnesium, potassium and calcium analysis were collected every fifteen days. The total precipitation during the studied period was 1.605,79 mm, being 13, 56% higher than the average for the region (from September, 3006 to August, 2007). The average pH was 6,59, being the lowest value as 5,66 and this is not considered as acid rain. The average electrical conductivity was 52,84. Sodium showed an average concentration of 2,52 mg/L; potassium 1,07 mg/L; calcium 1,15 mg/L; magnesium 0,17 mg/L; nitrate 0,13 mg/L of N; nitrite 0,52 mg/L of N; ammonium 1,14 mg/L of N; phosphorus 0,66 mg/L; sulphur 0, 19 mg/L, and chlorine 1,60 mg/L. The input through rain precipitation followed this magnitude: Na > Cl > N > K > Ca > S > P >Mg; 3) Soil solution chemical characteristics in an agroforestry system in south Rio Grande do Sul, where the objective was to chemically evaluate the soil solution, in two differend depths (30 cm and 80 cm), in four different treatments )T1 = eucalyptus planted in 3 m x 2 m spacing; T2= native grass; T3 agroforestry system planted in double line and T4 agroforestry system planted in triple line). For sampling collections, lisimeters were used (8 in each depth and in each treatment), accionated by vacuum pumps (through timers), every four hours, kept turned on for 10 minutes. The soil solution samples were collected every fifteen days and sent to pH, electrical conductivity, nitrate, nitrite, ammonium, phosphorus, sulphur, chlorine, calcium, magnesium, potassium and calcium analysis. Soil solution behavior, in different depths and different treatments, showed to be highly variable, considering the kind of crop involved; 4) This chapter had as objective to demonstrate a partial summary from the biogeochemical in the agroforestry system studied, showing the macronutrients distribution in above ground biomass and in the soil. For this, as inputs, it was considered the rain and dust and also fertilizations done for sorghum, sunflower and eucalyptus. Through a scheme, al the fraction and parts that would be evaluated in these system during the 7 years of this study. The calculations were based on the water precipitation samples and on vegetal tissues analysis; for soil calculations it was used the soil analysis. In this study it was possible to quantify the macronutrients inputs and its absorption through the crops and also the amounts of these nutrients in soil; next year it is going to be possible to quantify the nutrients inputs through stem flow, internal precipitation and litter. The runoff is also going to be calculated through soil solution samples collected through lisimeters already installed in the field The inputs of nitrogen totalized 179, 76 kg ha-1 through precipitation and fertilization; phosphorus totalized 74, 31 kg ha-1 through precipitation and fertilization, potassium through precipitation and fertilization totalized 79, 37 kg ha-1 ,calcium 14,12 kg ha-1 and magnesium 2,09 kg ha-1. Soil had 432, 49 kg ha-1 of nitrogen, 63,61 kg ha-1 of phosphorus, 1.656 kg ha-1 of potassium, 65.250 kg ha-1 of calcium and 5.439,60 kg ha-1magnesium.
Este estudo foi realizado em área experimental da Fazenda Aroeira, pertencente a empresa Votorantim Celulose e Papel, unidade Rio Grande do Sul, sob coordenadas geográficas 31° 45 50.7 S e 53° 50 34.9 W, localizada no município de Candiota. Na área, existe uma base de pesquisa,onde estão sendo monitorados os fatores de produção envolvidos em um sistema agroflorestal, com quatro diferentes tratamentos (T1 = eucalipo solteiro plantado em espaçamento 3 m x 2 m; T2 = campo nativo (testemunha); T3 = SAF (eucalipto plantado em linha dupla), T4 = SAF (eucalipto plantado em linha tripla)). Para tanto, este estudo foi dividido em quatro capítulos, os quais são: 1) Biomassa e nutrientes nos componentes de um sistema agroflorestal no sul do Rio Grande do Sul, onde foi quantificada a biomassa acima do solo dos componentes eucalipto, sorgo e girassol, bem como os nutrientes nela contidos. Como biomassa acima do solo, o sorgo apresentou um total de 9.876 kg ha-1 (17,67% nas folhas, 47,74% no colmo e 34,61% nos grãos. No girassol, a biomassa total acima do solo totalizou 11.968 kg ha-1 (21,62% no capítulo, 24,03% nas folhas, 21,32% nos grãos e 22,03% no caule). A biomassa acima do solo total no eucalipto, aos 16 meses, totalizou 10.974 kg ha-1 (45,28% na madeira, 26,31% nos galhos, 19,96% nas folhas e 8,45% na casca). O conteúdo de nutrientes na cultura do sorgo apresentou-se na seguinte magnitude para o total: C > N > K > Ca > P > Mg > S > Fe > Al > Na > Mn. Na cultura do girassol, a magnitude de distribuição dos nutrientes na biomassa total, foi: C > K > N > Ca > Mg > P > S > Na > Fe > Al > Mn. No eucalipto, a magnitude da distribuição do total de nutrientes foi: C > N > Ca > K > Mg > P > S > Na > Mn > Al > Fe; 2) Entrada de nutrientes via precipitação pluviométrica em área no sul do Rio Grande do Sul, onde em área de campo nativo estão instalados 10 funis plásticos, de 23 centímetros de diâmetro, coletores de água da chuva. A quantificação do volume de água armazenado, bem como coleta de amostras compostas para determinação de pH, condutividade elétrica, nitrato, nitrito, amônia, fósforo, enxofre, cloro, cálcio, magnésio, potássio e cálcio foram realizadas quinzenalmente. A precipitação total ocorrida no período de setembro de 2006 a agosto de 2007 foi de 1605,79 mm, sendo 13,56% maior que a média para a região. O pH médio da água da chuva foi 6,59, sendo o menor valor o de 5,66 e este não é considerado como de ocorrência de chuva ácida. A condutividade elétrica média foi 52, 84. O sódio apresentou concentração média de 2,52 mg/L; o potássio 1,07 mg/L; o cálcio 1,15 mg/L, o magnésio 0,17 mg/L, o nitrato 0,13 mg/L de N; o nitrito 0,52 mg/L de N; a amônia 1,14 mg/L de N, o fósforo 0,66 mg/L; o enxofre 0,19 mg/L; e o cloro 1,60 mg/L. O aporte de nutrientes ao sistema agroflorestal em estudo, via precipitação pluviométrica, ocorreu na seguinte magnitude: Na > Cl> N > K > Ca > S > P > Mg; 3) Características químicas da solução do solo em um sistema agroflorestal no sul do Rio Grande do Sul, onde se teve por objetivo avaliar quimicamente a solução do solo, em duas diferentes profundidades (30 cm e 80 cm), em quatro diferentes tratamentos. Para a coleta das amostras, foram utilizados lisímetros (8 em cada profundidade e em cada tratamento,), acionados por bombas de vácuo (através de timers), a cada 4 horas, permanecendo ligados durante 10 minutos. As amostras de solução do solo foram coletadas a cada quinze dias e encaminhadas para análise de: pH, condutividade elétrica, sódio, potássio, cálcio, magnésio, fosfato, sulfato, cloreto, nitrito, nitrato e amônia.O comportamento da solução do solo, nas diferentes profundidades e diferentes tratamentos, apresenta-se bastante variável, considerando o tipo de cultura envolvida (eucalipto solteiro, campo nativo ou sistema agroflorestal); 4) Este capítulo teve por objetivos demonstrar um resumo parcial da biogeoquímica do sistema agroflorestal em estudo, mostrando a distribuição dos macronutrientes na biomassa acima do solo e no solo. Para tanto, foram considerados como entradas no sistema, a poeira e precipitação pluviométrica e a adubação realizada nas culturas agrícolas, sorgo e girassol e para o eucalipto. Através de um esquema, demonstrou-se todas as frações e partes que serão avaliados nesse sistema agroflorestal nos 7 anos de duração desse estudo. Os cálculos foram realizados com base nas análises realizadas em laboratório, das amostras de água da chuva e dos tecidos vegetais; para o cálculo dos nutrientes no solo, utilizou-se a análise de solo realizada para o mesmo. No presente estudo, foi possível quantificar as entradas de macronutrientes, a absorção dos mesmos pelas culturas e o conteúdo destes no solo; futuramente; será possível quantificar as entradas provenientes do gotejamento das copas, precipitação interna, escorrimento pelo tronco e serapilheira. Também será possível avaliar a lixiviação, com base nos dados provenientes da solução do solo coletados através de lisímetros já instalados. As entradas de nitrogênio totalizaram 179, 76 kg ha-1 pela precipitação e adubação; o fósforo totalizou 74, 31 kg ha-1 pela precipitação e adubação, o potássio via precipitação e adubação totalizou 79, 37 kg ha-1 ,o cálcio via precipitação e adubação totalizou 14,12 kg ha-1 e o magnésio via precipitação e adubação totalizou 2,09 kg ha-1. O solo apresenta 432, 49 kg ha-1 de nitrogênio, 63,61 kg ha-1 de fósforo, 1.656 kg ha-1 de potássio, 65.250 kg ha-1 de cálcio e 5.439,60 kg ha-1de magnésio.

L'objectif principal de ce travail a été d'apporter une nouvelle contribution quant à l'approche de contrôle optimal pendant la phase d'identification. Il s'agissait de trouver la commande à appliquer pendant l'expérience qui permet d'optimiser un critère qui est fonction des sensibilités des sorties par rapport aux paramètres du modèle à identifier. Cette approche couplant contrôleur prédictif sous contraintes et estimateur a résolu en ligne le problème d'identification à chaque instant en utilisant l'observateur. En ce sens, c'est une approche permettant d'automatiser et d'optimiser le design d'expérience, tout en réalisant conjointement l'identification d'un paramètre du modèle spécifié. L'aspect temps réel a été pris en compte dans la formulation de la solution apportée. Dans ce contexte, nous avons introduit deux stratégies de commande pour l'identification optimale. La première était basée sur un modèle de prédiction non linéaire et la seconde sur un modèle linéaire temps variant. Si le temps devient un paramètre critique pour l'implémentation de l'approche, cette dernière vise à réduire le temps alloué à l'optimisation. L'approche d'identification optimale en ligne a été appliquée à deux problèmes concrets du Génie des Procédés (réaction de saponification et cuisson de peintures). Ces exemples ont permis de vérifier en simulation, l'efficacité et la faisabilité de cette approche.

This thesis examines climate-related risk behaviours among small-scale citrus farmers and their decision to adoption certified seedlings and use of agrochemical inputs in East Java, Indonesia. The analysis is important for understanding citrus farmers’ behaviours regarding climate change issues. Understanding farm households climate related behaviours is key to designing appropriate smallholder support and advisory services. Given the importance of climate change to rural agricultural communities in developing countries, governments, NGOs and international development agencies continue to make substantial efforts to improve the ability of small-scale farmers to adapt. Yet, too often, national adaptation policies and programs ignore insights from existing smallholder adaptation practices. Previous studies show that behavioural insights are critical in developing an understanding of climate risk management by farmers. An important aim of this thesis is to understanding climate-related influences on smallholders’ decisions. The research objectives are to: (i) understand the extent of perceptions of risk among small-scale citrus farmers related to a range of climate change events and to identify the drivers of their risk perception at aggregated and disaggregated levels; (ii) provide analytical insights into the adoption of certified citrus seedlings by small-scale farmers by analysing the extent to which they value the certification of citrus seedlings and the role of this factor in influencing the adoption of higher-yielding, climate-risk resilient and disease-free citrus varieties; and (iii) explore the extent of use of chemical inputs and the role of risk preferences, intrahousehold dynamics and social networks on the household expenditure spent on chemical inputs. The research uses data from a household survey of 500 citrus farmers with interviews of both the male and female household heads. The first research objective was analysed by employing seemingly unrelated regression models (SUR) and ordered logistic regression models (OLM), the second objective was estimated using a multinomial logit model, and the third objective employed joint modelling of risk, intrahousehold dynamics and spatial factors in a spatial regression model. Among the key contributions of this thesis is integrating the research on complex patterns of risk behaviours, from both the economics and psychology literatures, into climate research on risk perceptions through a straight-forward extension of current approaches to the analysis of the risk perception index. An important result is the disadvantage of using only the aggregate approach in analysing risk perception because it could underestimate and simplify the complex representation of climate risk behaviours. This study also presents empirical support for the use of information and communication technology based extension as an efficient extension tool to reach more farmers than in traditional methods. A second result highlights how farmers' beliefs about the yield and production risks of particular seedling types, along with risk preferences, were significantly related to farmers’ intentions to adopt particular seedling types. This study also found the relationship between climate-related variables (i.e. climate information source and climate extension) and farmers’ decisions to use certified seedlings. Lastly, this thesis finds that more risk-averse households tend to have lower spending on insecticides and the use of this input is also significantly associated with higher profit variability. A wife’s leadership could lead to a considerably lower expenditure for fungicides, but higher herbicide expenses; and a higher disagreement between spouses is associated with more insecticides and fungicides costs. The pattern of chemical inputs usage is spatially dependent on endogenous effects, while spatial disturbance effect existed for the use of chemical fertilisers and herbicides.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2020

Management-induced degradation of soil chemical and microbial quality is one of the most pressing concerns and a considerable threat to the sustainability of agroecosystems. However, information on this important issue is limited and largely based on short-term studies. A long-term experiment initiated in 1939 at the University of Pretoria provided a unique opportunity to assess the direct and residual effects of manure and inorganic fertilizers on soil chemical properties, microbial components and maize yield in rotation with field pea. Long-term addition of manure resulted in increased total organic C (TOC), total N and available P levels in the soil. Seasonally, these nutrients exhibited variations that appeared to be related to influences of crop rotation. Soil N content in an adjacent native site remained relatively constant but tended to increase in the control and manured plots. Soil microbial biomass C, N and P and microbial populations were affected by previous manure application as well as by crop rotation. Microbial biomass and numbers were generally higher in the manured plots. Manure application also had substantial residual effects and resulted in maize grain yields higher than in the control. Long-term NPK application resulted in decreased TOC and basic cation contents, and lowering of soil pH. The decrease in TOC was greater in single fertilizer treatments whereas basic cation contents and pH declined more in the balanced fertilizer treatments. Soil microbial biomass and numbers were influenced by, and exhibited qualitative changes in response to, long-term fertilization. Crop rotation also exerted effects on chemical and microbial properties of the soil. Maize grain yield showed significant increases in response to balanced fertilizer treatments. Response of maize to simple fertilizer applications was not beneficial in terms of yield returns. These results suggest that judicious use of inorganic fertilizers may, in the long-term, maintain soil quality and productive capacity. A comparison of the effects of residual manure and NPK fertilizers on the content of selected nutrients, microbial properties, C and N inputs, tissue nutrient concentration and crop yield showed differences due to treatments. TOC, total N and available P levels were increased due to residual manure alone or in combination with NPK fertilizers. C and N inputs and tissue P concentration were also generally higher in manured than in the NPK treatment. However, the higher increase in nutrient contents of manured plots was not reflected in microbial properties of the soil. Despite lower nutrient levels, the NPK treatment resulted in relatively greater increases in microbial properties of the soil. The differential responses were largely due to differences in quality and decomposability of organic material. Organic material in the NPK treatment appeared to have a higher decomposition and turnover rate than in other treatments, suggesting that C limitation in soils of low C but good nutrient supply may be compensated by high turnover rates of the available organic materials. The beneficial effect of residual manure on microbial properties and crop yield was decreased by application of supplemental N fertilizer but remained unaffected by application of supplemental K fertilizer. The depressive effect of excess soil P levels on soil microbial properties and crop yield was exacerbated by supplemental N fertilizer and mitigated by supplemental manure and K fertilizer applied to residual P. The decrease in available P levels due to supplemental K application implies that this may serve as a viable alternative to ameliorate soils with excess P levels.
Thesis (PhD (Plant Production and Soil Science))--University of Pretoria, 2003.
Plant Production and Soil Science
unrestricted

Management-induced degradation of soil chemical and microbial quality is one of the most pressing concerns and a considerable threat to the sustainability of agroecosystems. However, information on this important issue is limited and largely based on short-term studies. A long-term experiment initiated in 1939 at the University of Pretoria provided a unique opportunity to assess the direct and residual effects of manure and inorganic fertilizers on soil chemical properties, microbial components and maize yield in rotation with field pea. Long-term addition of manure resulted in increased total organic C (TO C), total Nand available P levels in the soil. Seasonally, these nutrients exhibited variations that appeared to be related to influences of crop rotation. Soil N content in an adjacent native site remained relatively constant but tended to increase in the control and manured plots. Soil microbial biomass C, Nand P and microbial populations were affected by previous manure application as well as by crop rotation. Microbial biomass and numbers were generally higher in the manured plots. Manure application also had substantial residual effects and resulted in maize grain yields higher than in the control. Long-term NPK application resulted in decreased TOC and basic cation contents, and lowering of soil pH. The decrease in TOC was greater in single fertilizer treatments whereas basic cation contents and pH declined more in the balanced fertilizer treatments. Soil microbial biomass and numbers were influenced by, and exhibited qualitative changes in response to, long-term fertilization. Crop rotation also exerted effects on chemical and microbial properties of the soil. Maize grain yield showed significant increases in response to balanced fertilizer treatments. Response of maize to simple fertilizer applications was not beneficial in terms of yield returns. These results suggest that judicious use of inorganic fertilizers may, in the long-term, maintain soil quality and productive capacity. A comparison of the effects of residual manure and NPK fertilizers on the content of selected nutrients, microbial properties, C and N inputs, tissue nutrient concentration and crop yield showed differences due to treatments. TOC, total N and available P levels were increased due to residual manure alone or in combination with NPK fertilizers. C and N inputs and tissue P concentration were also generally higher in manured than in the NPK treatment. However, the higher increase in nutrient contents of manured plots was not reflected in microbial properties of the soil. Despite lower nutrient levels, the NPK treatment resulted in relatively greater increases in microbial properties of the soil. The differential responses were largely due to differences in quality and decomposability of organic material. Organic material in the NPK treatment appeared to have a higher decomposition and turnover rate than in other treatments, suggesting that C limitation in soils of low C but good nutrient supply may be compensated by high turnover rates of the available organic materials. The beneficial effect of residual manure on microbial properties and crop yield was decreased by application of supplemental N fertilizer but remained unaffected by application of supplemental K fertilizer. The depressive effect of excess soil P levels on soil microbial properties and crop yield was exacerbated by supplemental N fertilizer and mitigated by supplemental manure and K fertilizer applied to residual P. The decrease in available P levels due to supplemental K application implies that this may serve as a viable alternative to ameliorate soils with excess P levels.
Thesis (PhD)--University of Pretoria, 2010.
Plant Production and Soil Science
unrestricted

碩士
國立交通大學
機械工程系所
95
Chemical-Mechanical Polish is an extremely complicated process because it involves physical, chemical, and mechanical field [1]. There are many complicated factors which may affect only one output parameter such as removal rate. For non-planarization index alone, it is necessary to consider more than two input parameters at the same time. In semiconductor industry, run-to-run process control is used extensively to control process outputs, such as non uniformity and removal rate. Run-to-run process control uses the previous run process recipe to predict the next run process recipe to control the next run product quality on the target. This research has proposed multi-input, multi-output wafer-to-wafer Dual Mode Adaptive Control. Dual Mode Adaptive Control （DMAC）[2][3] utilizes adaptive model following control mode and adaptive model identification mode to achieve the control target. The experiment is carried out based on conditioning the pad every wafer. According to literature [4], wafer non-uniformity can be minimized when the wafer polishing pad and the wafer carrier are rotated at the same speed in CMP process. In one two-inputs, two-outputs CMP process, the inputs are down force and rotation speed of the wafer, the outputs are removal rate and non-planarization index. This multiple–input, multiple–output system uses down force and rotational speed of the wafer to control removal rate and non-planarization index. This research proposes decoupled controller to turn this two-inputs, two-outputs system into two single input single output systems. In adaptive model following control, according to simulations and experiments, control system with decoupled controller can do a better job in controlling removal rate and non-planarization index than control system without decoupled controller. In adaptive model following control simulations, decoupled controller of this research improves the target error SAE（summation of absolute error）by 35.9％, SSE （summation of squared error）by 48.9％, MAE（maximum of absolute error）by 23.5％. In adaptive model following control experiments, decoupled controller of this research improves the target error SAE（summation of absolute error）by 7.6％, SSE （summation of squared error）by 32.6％, MAE（maximum of absolute error）by 29.7％. There is difference in improvement of SAE between simulation and experiment. The actual CMP plant is a nonlinear system in experiment, but a linear model is used in simulation. The improvement of SAE in experiment is not so ideal as it is in simulation. In adaptive model identification mode, if there shows more than 20% drift in system parameter, the CMP equipment will be shut down for diagnosis, this is one additional monitoring capability provided by DMAC than conventional single mode adaptive control(SMAC).

Certain properties of back-propagation neural networks have been found to be useful in structuring models for multiple-input, multiple-output (MIMO) processes. The network's simplicity and its ability to identify the non-linearity can have wide impacts on the construction of model-based control system. Care must be taken to train the network with consistent data that contains sufficient dynamic information. A predictive control system based on the network model was proposed. Although the controller is relatively simple in terms of concept and computation, it shows excellent performances both in servo and regulator problems. Model prediction error sometimes causes a cyclic behavior in process responses; however, it can be stabilized by imposing certain constraints of controller action. The constraints are also effective for noisy measurements. Use of neural networks for modeling and control of MIMO system appears to be very promising with its ability to treat non-linearity and process interactions.