Abstract Water level regulation for purposes of hydropower production has caused notable changes in the littoral zones of regulated lakes in northern Finland. Marked geomorphological changes have taken place in the lakes with a raised water level. Lowering of the ice cover during the winter has also caused rapid changes in the littoral. Changes in the environmental conditions and aquatic macrophyte communities were studied largely by comparing the regulated Lake Ontojärvi and the unregulated Lake Lentua in the Kainuu area. The general aims of the study were to analyse environmental effects, to produce information of ecological relationships for remedial measures on the littoral and to apply the restoration methods in the management of regulated lakes. The most obvious effect of regulation was the expanded area of extending ice, which caused an almost complete disappearance of large ice-sensitive isoetids (Isoetes lacustris L., Lobelia dortmanna L.). These species were largely replaced by small erosion resistant isoetids (Ranunculus reptans L., Eleocharis acicularis (L.) Roem. & Schult.). Another significant change was the decreased frequency of large helophytes due to increased erosion. A model based on environmental factors was able to predict roughly the main vegetation types. Permanent plot studies showed no significant differences in the stability of the vegetation between the research lakes, which means that the species pool had adapted to the harsh environment. Restoration techniques based on mechanical protection of shorelines and revegetation were applied to Lake Ontojärvi. The hostile environmental conditions caused a rapid decline of the planted species, but tall Salix phylicifolia L. seedlings and Carex rostrata Stokes were able to survive, although in low abundance. More significant remedial measures were provided by the Ecologically-based Regulation Practices (ERP), which have been applied to several lakes under hydropower production. This procedure, which was largely based on the results of the Kainuu studies, offers a simple way to illustrate the differences between various regulation practices. Two case studies showed that an exceptional year with extremely high or low water levels can largely abolish the positive succession achieved by ERP. The huge financial losses caused by ERP for hydropower production have also promoted the use of other conventional restoration measures.

Recent advances in space geodetic techniques such as Very Long Baseline Interferometry, Global Navigation Satellite Services, Satellite Laser Ranging and advanced numerical weather prediction model simulations, provide huge tropospheric data sets with improved spatial temporal resolution. These data sets exhibit unique fluctuations that have a spatial-temporal structure which are thought to mimic the complex behaviour of the atmosphere. As a result, the analysis of non-stationary structure in the tropospheric parameters derived from geodetic and numerical model simulations could be used to probe the extent of universality in the dynamics of the atmosphere, with applications in space geodesy. In order to identify the physical causes of variability of tropospheric parameters, parametric and nonparametric data analyses strategies which are investigated and reported in this thesis, are used to inform on the geophysical signals embedded in the data structure. In the first task of this research work, it is shown that the fluctuations of atmospheric water vapour over southern Africa are non-linear and non-stationary. Secondly, the tropospheric data sets are transformed to stationarity and the stochastic behaviour of water vapour fluctuations are assessed by use of an automatic algorithm that estimates the model parameters. By using a data adaptive modelling algorithm, an autoregressive-movingaverage model was found to sufficiently characterise the derived stationary water vapour fluctuations. Furthermore, the non-linear and non-stationary properties of tropospheric delay due to water vapour were investigated by use of robust and tractable non-linear approaches such as detrended fluctuation analysis, independent component analysis, wavelet transform and empirical mode decomposition. The use of non-linear approaches to data analysis is objective and tractable because they allow data to speak for themselves during analysis and also because of the non-linear components embedded in the atmosphere system. In the thesis, we establish that the non-linear and non-stationary properties in the tropospheric data sets (i.e., tropospheric delay due to water vapour and delay gradients) could be triggered from strongly non-linear stochastic processes that have a local signature (e.g. local immediate topography, weather and associated systems) and/or exogenous. In addition, we explore and report on the presence of scaling properties (and therefore memory) in tropospheric parameters. This self-similar behaviour exhibit spatial-temporal dependence and could be associated with geophysical processes that drive atmosphere dynamics. Satellite Laser Ranging data are very sensitive to atmospheric conditions, which causes a delay of the laser pulse, hence an apparent range increase. A test for non-linearity is applied within specialised software for these data; it is found that the range residuals (i.e., the observed minus computed residuals) are improved when possible non-linearity of the locally measured meteorological parameters as applied to a range delay model are considered. / Thesis (PhD)--University of Pretoria, 2011. / Geography, Geoinformatics and Meteorology / PhD / Unrestricted

The success of each organisation is derived from its employees. The goal of this thesis is to contribute to eliminating of employees' fluctuation. The theoretical part is dedicated to explanation of the basic activities of the staff department. The practital part is based on research exercised by question forms that were filled by employees. The results of the questionnaire are then analyzed and the recommendations are given based on the needs of the concrete company.

Statistical physics has been the foundation for much of our understanding about plasma physics. Often, plasma physics phenomena are explained using statistical physics principles and theories. Here, I reverse this paradigm to instead use plasma experiments to test statistical physics principles. In this thesis, I test statistical physics principles with an experimental dusty plasma, which is a four-component mixture of micron-sized ``dust'' particles, electrons, ions, and neutral gas molecules. When immersed in the plasma, the dust particles acquire large negative charges, since they accumulate more electrons than ions. Due to their large electric charges, the dust particles have interparticle potential energies that greatly exceed their kinetic energies, so that the collection of dust particles is considered to be a strongly coupled plasma. Like other strongly coupled plasma, the collection of dust particles can exhibit solid-like or liquid-like behavior. A key advantage offered by dusty plasma experiments is the ability to track the motion of individual dust particles. Dust particles are sufficiently large to allow for direct imaging using a video camera, so that time series data can be obtained for particle positions and velocities. These particle-level data provide a richer description of the dynamics and structure than can be obtained for most other strongly coupled plasmas, simple liquids, or solid materials. In particular, the particle-level data of positions and velocities are often required inputs for testing statistical physics theories or principles. The dusty plasma data I analyze are from the experiment of Haralson~\textit{et al.} [1,2], where dust particles were electrically levitated in a single horizontal layer within a vacuum chamber. The collection of dust particles initially settled into a crystalline lattice with solid-like behavior. To reach a liquid-like state, or to drive a shear flow, dust particles were manipulated using the radiation pressure force of lasers. In this thesis, I test three different statistical physics principles using an experimental dusty plasma. First, I test the fluctuation theorem, which was first was presented in 1993 by Evans, Cohen, and Morriss [3]. The fluctuation theorem, which is one of the most important recent developments in statistical physics, quantifies the probability that the entropy production rate will temporarily fluctuate to negative values in ``violations'' of the second law of thermodynamics. The original formulation of the fluctuation theorem described the entropy production due to viscous heating in a shear flow; this version of the fluctuation theorem had never been experimentally demonstrated in a liquid of any kind. In Chapter 2, I provide the first such demonstration by showing that the entropy production rate in a liquid-like dusty plasma shear flow satisfies the fluctuation theorem. This result also serves as the first demonstration that a strongly coupled plasma obeys the fluctuation theorem. Second, I measure the Einstein frequency $\Omega_E$, which describes the stochastic process of collisions in a strongly coupled plasma, and I compare my measurement to predictions made in the literature that used simulation data. Often, for weakly coupled plasma, a collision frequency is obtained to provide a measure of the strength of particle-particle interactions. However, for strongly coupled plasma (and likewise for liquids and solids), a collision frequency is not well defined since collisions are multibody and occur continuously. Another quantity is needed to describe the strength of particle-particle interactions. I propose that the Einstein frequency $\Omega_E$, a concept more commonly used in solid physics, is better suited for describing particle-particle interactions in a strongly coupled plasma. In Chapter 3, I present and use a new method to obtain the Einstein frequency of a 2D dusty plasma in both a liquid-like state and a crystalline state. My measurement of the Einstein frequency, which serves as a proxy for a collision frequency, is consistent with simulation predictions in the literature. Third, I present particle-coordination survival functions, which provide a richer description of microscopic dynamics in a liquid than the commonly used relaxation time. Relaxation times have been used, for example the Maxwell relaxation time, to describe the characteristic time scale for the crossover between elastic and viscous behavior in viscoelastic liquids. However, relaxation times are single-value measures that cannot fully describe the complexity of a liquid. In Chapter 4, using a survival function that retains temporal information about the local structural in a liquid, I discover that the microscopic arrangements in a liquid-like 2D dusty plasma have multiple time scales. Unexpectedly, non-defects have two time scales, while defects have one. My survival functions are time-series graphs of the probability that a particle's number of nearest neighbors, i.e., its coordination, remains the same. The two time scales for non-defects are revealed by an elbow in their survival-function curve. As a spinoff with a considerable amount of importance, I performed the simplest fluctuation theorem experiment to date, using an aerosol. An aerosol is simply a particle that is immersed in air. In Chapter 5, I show that the fluctuation theorem is applicable for an aerosol particle undergoing free-fall in air due to gravity. While the particle typically fell downwards, it is observed to occasionally fall upwards, against the force of gravity. For such upward displacements, the work done on the particle is negative, which is a temporary violation of the second law. I find that the probability of these temporarily violations obeys the work fluctuation theorem. This result also allowed an application: a novel diagnostic method to measure the mass of aerosol particles.

[pt] A finalidade primordial deste trabalho é apresentar um modelo estatístico para a troposfera e tendo-o como base caracterizar os efeitos de cintilação (flutuação aleatória de amplitude e fase) observados em ligações de microondas em visibilidade. O problema a ser estudado é a solução da equação de onda para um meio não homogêneo onde o parâmetro índice de refração é uma função aleatória. Por fim são apresentados resultados experimentais que justificam o enfoque teórico utilizado. / [en] The purpose of this work is to present a statistical model of te troposphere and based upon it characterize the amplitude and phase scintillation effects observed on line- of-sight microwave links. The problem to be dealt with is the solution of the wave equation for a non-homogeneous medium where the refractive index is a random function. Experimental results are presented in order to justify the theoretical approach.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21546号 / 理博第4453号 / 新制||理||1639(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 池田 隆介, 教授 前野 悦輝, 教授 川上 則雄 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

The task of diploma´s thesis is trying to find answers to questions that will focus mainly on motivation and stabilization of employees one unnamed company. Through certain activities that invent and some of them even realize, I will try to achieve a lower turnover, and also that employees feel motivated to be part of the employer.

The influence of the distributor configuration on the mass transfer and bubble sizes in a 2-D FBR was studied for two types of distributor configurations: <ul><li> A novel multi-vortex (MV) distributor with tuyéres directed vertically and horizontally at different heights. </li><li> A standard perforated plate distributor (baseline). </li></ul> The ozone decomposition reaction over FCC catalyst was used as an indirect meas-ure of the interphase mass transfer in the bed. The ranged between 0.1 m/s and 0.35 m/s, with air as a fluidizing medium at ambient conditions. The MV distributor displayed a significant improvement in the conversion cies (χmeasured / χPFR). For all velocities an improvement of between 0% and 30% was measured (average improvement of 14.7%). At Uo ≤ 0.2 m/s the improvement distributed evenly about the mean improvement, with a minimum improvement of 10%. The Uc for the respective distributors were determined using absolute pressure fluctuations (baseline distributor) and visual observations (MV distributor) and it was found that the Uc for the MV distributor was lower than that for the baseline: <ul><li> Uc Baceline = 0.30 m/s.</li><li> Uc MV distributor = 0.25 m/s.</li></ul> The decrease in Uc indicated that the MV distributor induces faster onset of turbulent behaviour in the FBR which negates interphase mass transfer limitations in the FBR. The bubble sizes were measured visually and compared to a pressure signal decomposition technique. The bubble size growth for the MV distributor was estimated at .14 times that of the baseline. Two models were compared to the experimental results, the Kunii-Levenspiel three-phase model and the Thompson generalized bubble-turbulent model. The fitting parameters showed that the mass transfer for the MV distributor is significantly larger than that of the baseline. In addition the MV distributor decreased the axial dispersion in the FBR as Uo → Uoo, which improved the reactor performance to that of an ideal PFR. This phenomenon was observed at Uo > 0.33 m/s. / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

There are today many areas and types of water storage. The uses to which these are put are many, and the prospect for the future can only be that there will be an increase in the number of these reservoirs. These areas are usually operated with regard only for power production, irrigation, or storage, but there is a growing concern about the effects on wildlife which this type of operation may have. Fluctuating water levels, and falling water levels are not restricted to man-made impoundments tut are characteristic of many of then. Biologists have observed that these variations in water levels are often harmful to some forms of wildlife. Fluctuating water levels generally were found to cause damage to waterfowl nests. The amount of damage, the amount of water rise and the time involved are values which have generally remained unknown, largely perhaps because some other aspects was of greater importance in the nesting studies. There is a descending scale of values which have been placed on natural resources, and it is generally agreed that the waterfowl concerned would rank below the value derived from the impounded waters. Where it is practical, the management of these impoundments should take wildlife into consideration. To have intentions of good management is not sufficient to effect conservation; these intentions must be implemented with the proper tools. This study was designed to discover magnitudes of cause and effect, and perhaps it will point the way to a more efficient utilization of associated resources. It was possible that the results of this study would show that there was little damage to waterfowl. On the other hand, if significant damage were to be discovered, contributing causes could be more closely delimited and so point the way toward corrective measures.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19473号 / 理博第4133号 / 新制||理||1594(附属図書館) / 32509 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)講師 市川 正敏, 教授 佐々 真一, 教授 山本 潤 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM