Dissertationen zum Thema „Free condition“

The purpose of this project is to evaluate the differences in the wake of a NACA 4412 airfoil in free-flight condition compared to wind tunnel and also investigate wall-interference. This was done using two sets of angles of attack, 5 degrees and 8 degrees. We collected data using Computational Fluid Dynamics to simulate free-flight condition and experimental data gathered from a wind tunnel, there were some key differences between these two cases. The key differences were the size of the area of high velocity deficit as well as the wake thickness and angle.

Aspects of morphological and physiological condition of captive and net-caught dolphins were studied with respect to age, diet, reproduction and seasonal changes in environmental factors. These investigations aimed to provide base-line data on marine mammal physiological and morphological condition indices and to expand the knowledge of condition assessment of small cetaceans. By examining the interactive nature of animal condition and growth, diet and the environment, the study investigated the potential usefulness of animal condition indices to assess and monitor habitat quality. Base-line values for haematological and blood chemistry parameters were established for five captive bottlenose dolphins (Tursiops truncatus), using monthly blood samples, collected between 1992 and 1995, and corresponding measures of body weight and blubber thickness; feeding, dietary energy intake, water temperature and behavioural and medical records. Curves of best fit were used to interpret trends between leukocytic, haematological and blood chemistry parameters and morphology, diet and water temperature. WBC's and WBC differential cell types were related more distinctly to clinical changes in health, than to condition. RBC, HB and PCV were useful as short-term indicators of nutritional condition, with enhanced haematological status associated with greater food intake and improved diet quality. Weight was a more effective long-term indicator of nutritional status. The importance of blubber thickness measurements as a morphological index of condition was reinforced, with relationships between blubber thickness and haematology highlighting interactions between morphological and physiological condition. The complex interactions between haematology, diet, temperature and weight emphasised the need to account for all influential factors when considering haematological condition. The blood chemistry parameters of serum creatinine, BUN, BUN:creatinine and serum albumin provided the best indication of nutritional condition and diet quality in captive dolphins. Creatinine and BUN:creatinine also reflected changes in morphological condition. Reduced ALP was associated with nutritional stress but was more effectively used as an indication of metabolism and growth activity. LDH and CPK were highly variable and fluctuated with changing activity levels, limiting their use as condition indices. Serum sodium was an important indication of diet quality and hydration status. Many of these parameters effectively illustrated that physiological condition is compromised outside of the thermoneutral zone of the species. Bottlenose and common (Delphinus delphis) dolphins, incidentally caught in shark nets, were used to investigate the condition of free-ranging dolphins. Blood samples, taken as soon as possible after capture from drowned animals, were used to analyse physiological parameters. Dissections provided morphological data. Age and dietary status were assessed using growth layer groups in teeth and stomach content analyses, respectively. Morphological measures of net-caught dolphins reflected important interactions with diet, water temperature and reproductive status. Weight, girth and blubber thickness were valuable indicators of condition, although blubber thickness and proportional blubber weight were the best indicators of nutritional status. Condition of net-caught dolphins was difficult to assess in terms of leukocytic and haematological parameters. Stress- and post-mortem-associated changes, and variable data, reduced the usefulness of some parameters. WBC counts reflected on immunological status and served to emphasise changes in health, which may lead to deterioration in condition. WBC's showed potential as indicators of habitat quality, in terms of parasite load and/or pollution. Interactions between RBC, HB, PCV, MCV and dietary, morphological and environmental factors proved valuable in the short-term. Several haematological parameters were related to morphological condition, with weight, girth and blubber thickness, showing potential as non-invasive predictors of haematological status. Relationships between haematology and water temperature implied that dolphins have physiological and environmental "zones of comfort", within which condition is optimised. LDH and CPK were elevated by capture stress and post-mortem changes. Serum sodium and plasma glucose were good indicators of short-term nutritional status, but were altered by stress, which reduced their usefulness as condition indicators. BUN, albumin, globulin, albumin:globulin, total cholesterol and triglycerides appeared to be little affected by these changes and are potentially valuable indicators of condition in net-caught and/or free-ranging dolphins, particularly with respect to nutritional condition, and associated changes in morphology. Although data were limited, these parameters show the greatest potential as physiological indicators of animal condition and environmental health. The limitations of this study are recognised, however, results highlight the feasibility of using net-caught specimens to monitor the condition of free-ranging marine mammals, and the marine habitat as a whole. Relationships established in this study will be used to elucidate further on the interactive nature of marine mammal condition and aid in the development of a non-invasive condition assessment technique.

This thesis is about high–dimensional problems considered under the so{called Kolmogorov condition. Hence, we consider research questions related to random matrices with p rows (corresponding to the parameters) and n columns (corresponding to the sample size), where p > n, assuming that the ratio  converges when the number of parameters and the sample size increase. We focus on the eigenvalue distribution of the considered matrices, since it is a well–known information–carrying object. The spectral distribution with compact support is fully characterized by its moments, i.e., by the normalized expectation of the trace of powers of the matrices. Moreover, such an expectation can be seen as a free moment in the non–commutative space of random matrices of size p x p equipped with the functional . Here, the connections with free probability theory arise. In the relation to that eld we investigate the closed form of the asymptotic spectral distribution for the sum of the quadratic forms. Moreover, we put a free cumulant–moment relation formula that is based on the summation over partitions of the number. This formula is an alternative to the free cumulant{moment relation given through non{crossing partitions ofthe set. Furthermore, we investigate the normalized  and derive, using the dierentiation with respect to some symmetric matrix, a recursive formula for that expectation. That allows us to re–establish moments of the Marcenko–Pastur distribution, and hence the recursive relation for the Catalan numbers. In this thesis we also prove that the , where , is a consistent estimator of the . We consider , where , which is proven to be normally distributed. Moreover, we propose, based on these random variables, a test for the identity of the covariance matrix using a goodness{of{t approach. The test performs very well regarding the power of the test compared to some presented alternatives for both the high–dimensional data (p > n) and the multivariate data (p ≤ n).

Ce travail porte sur l’étude du transfert de chaleur entre un milieu poreux et un milieu libre en utilisant une approche multi-échelle. Dans un premier temps, nous dérivons les conditions limites à imposer à une interface libre-poreux dans le cas des transferts de chaleur à l’équilibre thermique local puis dans le cas du déséquilibre thermique local. Pour les transferts de chaleur turbulent, une simulation numérique directe est réalisée afin d’apporter une meilleur compréhension de la physique existant à l’interface libre poreux. Puis, nous déterminons un modèle turbulent avec des conditions de saut. Ces études répondent à des questions fondamentales liées à la compréhension physique des conditions de saut, des valeurs des paramètres des sauts et de la position de l’interface dans le cadre des transferts de chaleur
This work deals with the study of heat transfer between a porous medium and a free medium, using multi scale approaches. First, we derive the boundary conditions that must be applied at a free-porous interface for laminar heat transfer at local thermal equilibrium and, then, at local thermal non-equilibrium. For turbulent heat transfer, a direct numerical simulation is performed supplying a better understanding of the physic at the free-porous interface. Then, we determine a turbulent model with associated jump conditions. These studies answer fundamental questions regarding the physical meaning of the jump conditions, the values of the jump parameters and the location of the interface for heat transfer

In this work, we have implemented an orbital-free density functional theory (OF-DFT) solver using the finite element method. In OF-DFT, the total ground state energy is minimized directly with respect to the electron density, rather than via orbitals like in the standard Kohn-Sham approach. For this to be possible, one needs an approximation of a universal density functional of the non-interacting kinetic energy. Presently available approximations allow for computation with very low computational expense, but which gives inaccurate energies. A stable OF-DFT code can be used as a testbed for new kinetic energy functionals and provide the necessary tool for investigating the accuracy of OF-DFT calculations for complex systems. We have implemented Thomas-Fermi theory with and without nuclear cusp condition, as well as additional exchange terms of Dirac and Amaldi. The program uses an extended version of the steepest descent in order to find the minimizing density in the variational principle. Our results include convergence tests for the hydrogen atom, weak bonding in the H2 molecule, and accurate results for the lightest noble gases (He, Ne, Ar). For heavier atoms (Kr, Xe, Rn), the results are less accurate. In addition, we consider hydrogen in the simple cubic structure without the cusp condition, which is a first attempt to use the code for periodic systems. Lastly, we discuss some possible improvements for the iterative process towards the minimizing density, as well as other possible directions for future development.

As the failure of a bearing could cause cascading breakdowns of the mechanical system and then lead to costly repairs and production delays, bearing condition monitoring has received much attention for decades. One of the primary methods for this purpose is based on the analysis of vibration signal measured by accelerometers because such data are information-rich. The vibration signal collected from a defective bearing is, however, a mixture of several signal components including the fault-generated impulses, interferences from other machine components, and background noise, where fault-induced impulses are further modulated by various low frequency signal contents. The compounded effects of interferences, background noise and the combined modulation effects make it difficult to detect bearing faults. This is further complicated by the nonstationary nature of vibration signals due to speed variations in some cases, such as the bearings in a wind turbine. As such, the main challenges in the vibration-based bearing monitoring are how to address the modulation, noise, interference, and nonstationarity matters. Over the past few decades, considerable research activities have been carried out to deal with the first three issues. Recently, the nonstationarity matter has also attracted strong interests from both industry and academic community. Nevertheless, the existing techniques still have problems (deficiencies) as listed below: (1) The existing enveloping methods for bearing fault feature extraction are often adversely affected by multiple interferences. To eliminate the effect of interferences, the prefiltering is required, which is often parameter-dependent and knowledge-demanding. The selection of proper filter parameters is challenging and even more so in a time-varying environment. (2) Even though filters are properly designed, they are of little use in handling in-band noise and interferences which are also barriers for bearing fault detection, particularly for incipient bearing faults with weak signatures. (3) Conventional approaches for bearing fault detection under constant speed are no longer applicable to the variable speed case because such speed fluctuations may cause “smearing” of the discrete frequencies in the frequency representation. Most current methods for rotating machinery condition monitoring under time-varying speed require signal resampling based on the shaft rotating frequency. For the bearing case, the shaft rotating frequency is, however, often unavailable as it is coupled with the instantaneous fault characteristic frequency (IFCF) by a fault characteristic coefficient (FCC) which cannot be determined without knowing the fault type. Additionally, the effectiveness of resampling-based methods is largely dependent on the accuracy of resampling procedure which, even if reliable, can complicate the entire fault detection process substantially. (4) Time-frequency analysis (TFA) has proved to be a powerful tool in analyzing nonstationary signal and moreover does not require resampling for bearing fault identification. However, the diffusion of time-frequency representation (TFR) along time and frequency axes caused by lack of energy concentration would handicap the application of the TFA. In fact, the reported TFA applications in bearing fault diagnosis are still very limited. To address the first two aforementioned problems, i.e., (1) and (2), for constant speed cases, two morphology-based methods are proposed to extract bearing fault feature without prefiltering. Another two methods are developed to specifically handle the remaining problems for the bearing fault detection under time-varying speed conditions. These methods are itemized as follows: (1) An efficient enveloping method based on signal Fractal Dimension (FD) for bearing fault feature extraction without prefiltering, (2) A signal decomposition technique based on oscillatory behaviors for noise reduction and interferences removal (including in-band ones), (3) A prefiltering-free and resampling-free approach for bearing fault diagnosis under variable speed condition via the joint application of FD-based envelope demodulation and generalized demodulation (GD), and (4) A combined dual-demodulation transform (DDT) and synchrosqueezing approach for TFR energy concentration level enhancement and bearing fault identification. With respect to constant speed cases, the FD-based enveloping method, where a short time Fractal dimension (STFD) transform is proposed, can suppress interferences and highlight the fault-induced impulsive signature by transforming the vibration signal into a STFD representation. Its effectiveness, however, deteriorates with the increased complexity of the interference frequencies, particularly for multiple interferences with high frequencies. As such, the second method, which isolates fault-induced transients from interferences and noise via oscillatory behavior analysis, is then developed to complement the FD-based enveloping approach. Both methods are independent of frequency information and free from prefiltering, hence eliminating the tedious process for filter parameter specification. The in-band vibration interferences can also be suppressed mainly by the second approach. For the nonstationary cases, a prefiltering-free and resampling-free strategy is developed via the joint application of STFD and GD, from which a resampling-free order spectrum can be derived. This order spectrum can effectively reveal not only the existence of a fault but also its location. However, the success of this method relies largely on an effective enveloping technique. To address this matter and at the same time to exploit the advantages of TFA in nonstationary signal analysis, a TFA technique, involving dual demodulations and an iterative process, is developed and innovatively applied to bearing fault identification. The proposed methods have been validated using both simulation and experimental data collected in our lab. The test results have shown that the first two methods can effectively extract fault signatures, remove the interferences (including in-band ones) without prefiltering, and detect fault types from vibration signals for constant speed cases. The last two have shown to be effective in detecting faults and discern fault types from vibration data collected under variable speed conditions without resampling and prefiltering.

This thesis is based on the evidence of the use of range by laying hens from two separate studies that were carried out on commercial flocks. The first study involved a direct observation of 6 flocks of laying hens whereas the second study was carried out on a single flock of laying hens using a still digital camera. Mapping of the outdoor range into three zones, namely; apron (0-10metres), enriched (10-50metres) and range (beyond 50metres), was carried out in both studies determine whether it influenced the distribution, behaviour, nearest neighbour distance (NND) and feather condition of the hens. Based on the estimates of the total number of hens recorded outdoors, it was found that 14.5% of the hens used the range in the first study, with 6.0% of the hens seen in the apron, 4.8% in the enriched and the remaining 3.7% in the outer range zone. This ranging pattern was further confirmed by the quadrat head counts, where the hens used the apron most but showed a significant decrease in the use of other outdoor zones as distance increased from the shed (p < 0.001). The results of the two studies showed that range use peaked in the morning and decreased significantly in the afternoon (p < 0.001). Range use was found to increase significantly with age (p < 0.001) in the first study, although there was a significant decrease in the number of hens outside the shed as the flocks got larger (p < 0.001). The age effect reported in the six-flock study was complemented by the significant positive effect of the week of outdoor access on the ability of the hens to use the range (p < 0.001) in the single flock study. Range use increased as outdoor temperature rose in the six-flock study whereas increased outdoor temperature resulted in a decline in range use in the single flock study. NND of the hens was ii measured in the six-flock study and was found to decrease significantly towards the shed (p < 0.001) and as the hens aged (p < 0.001). There was evidence that the use of distant and less crowded outdoor locations by the hens in the first study was associated with improved feather conditions. The evidence presented in the two studies presented in this thesis showed that the hens were unevenly distributed in the range, with reduced hen density (hen/m2) towards the outer range and that an improvement in the use of distant parts of the range may have beneficial effects on the hens.

This study examined the effects of three fixed-duration free operant access conditions on rates of automatically maintained stereotypic behavior and correct task responding during discrete trial training (DTT) with two children diagnosed with autism. Following a functional analysis, confirming automatic function, interviews/observations were conducted to identify behavioral indicators of satiation and an average satiation level. In this endeavor, participants were exposed to a free operant condition to validate satiation of stereotypic responding. Once satiation level was averaged, two durational conditions were computed: Long (75% access) and Short (25% access). A third condition, Deprivation, involved blocking all attempts at the stereotypic response for the average duration till satiation. An alternating treatment design was used to examine the effects of these three conditions on stereotypy and correct responding during subsequent discrete trial tasks. For both, participants correct responding did not seem to be affected by the length of the pre-session access to the stereotypic behavior prior to the DTT session. For Marcus, the Long condition may have acted as an abolishing operation (AO) during DTT. Following the Short condition he engaged in higher rates of the stereotypic behaviors during his DTT sessions compared to the other conditions. For the Sara, it appears that pre-session access to stereotypy had little effect on stereotypic behavior during DTT sessions.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-106).
The necessity for a highly accurate simulation scheme of free surface flows is emphasized in various industrial and scientific applications. To obtain an accurate response prediction, mass conservation must be satisfied. Due to a continuously moving fluid domain, however, it is a challenge to maintain the volume of the fluid while calculating the dynamic responses of free surfaces, especially when seeking solutions for long time durations. This thesis describes how the difficulty can be overcome by proper employment of an Arbitrary Lagrangian Eulerian (ALE) method derived from the Reynolds transport theorem to compute unsteady Newtonian flows including fluid interfaces and free surfaces. The proposed method conserves mass very accurately and obtains stable and accurate results with very large solution steps and even coarse meshes. The continuum mechanics equations are formulated, and the Navier-Stokes equations are solved using a 'flow-condition-based interpolation' (FCBI) scheme. The FCBI method uses exponential interpolations derived from the analytical solution of the 1-dimensional advection-diffusion equation. The thesis revisits the 2-dimensional FCBI method with special focus on the application to flow problems in highly nonlinear moving domains with interfaces and free surfaces, and develops an effective 3-D FCBI tetrahedral element for such applications. The newly developed 3-D FCBI solution scheme can solve flow problems of a wide range since it can handle highly nonlinear and unsteady flow conditions, even when large mesh distortions occur. Various example solutions are given to show the effectiveness of the developed solution schemes.
by Soyoung You.
Ph. D.

Ziel dieser Arbeit war eine Untersuchung zur Häufigkeit des Wechsels von Legehennen zwischen Innen- und Außenbereichen, einschließlich der Aufenthaltsdauer außerhalb des Stalles, in Relation zum Federpicken und der Beschaffenheit des Integumentes. Der Einfluss der Haltungsbedingungen und der Einfluss des Genotyps wurden untersucht. Die Gruppe, die ohne Grünauslauf war, bewegte sich signifikant häufiger zwischen dem Stall und dem Wintergarten als andere Gruppen mit Grünauslauf. Die Aufenthaltsdauer im Stall und Wintergarten war in der Gruppe ohne Grünauslauf signifikant höher als bei anderen mit Grünauslauf (GA). Hennen, denen eine große Auslauffläche angeboten wurde (10m²/T) bewegten sich signifikant häufiger zu den Außenbereichen als andere mit einem Angebot von 2,5 m²/Tier. Hennen mit einem Angebot von 2,5 m²/Tier hielten sich länger auf dem Grünland auf als Hennen mit einer Besatzdichte von 10m²/T. Die höchsten Federpickaktivitäten waren in der Gruppe ohne GA im Vergleich zu den Gruppen mit GA. Im Vergleich zu anderen Gruppen mit GA, hatte die Gruppe ohne GA einen schlechteren Gefiederzustand. LSL Hennen bewegten sich im Vergleich zu den LT Hennen häufiger zwischen Innen- und Außenbereichen. LSL Hennen hielten sich im Vergleich zu den LT Hennen länger im Wintergarten auf. Dennoch hielten sich die LT Hennen im Vergleich länger auf dem Grünland auf. Die schlechteste Gefiederbeschaffenheit wiesen LSL Hennen im Vergleich zu LT Hennen auf. Die Resultate der vorliegenden Untersuchungen weisen darauf hin, dass die Auslaufnutzung einen positiven Einfluss auf den Gefieder- und Hautzustand hat. Die untersuchten Genotypen unterschieden sich in der Häufigkeit des Ortswechsels und der Aufenthaltsdauer im Grünauslauf
The aim of this work was to investigate the frequency of movement of laying hens between indoor and outdoor enclosures and the time hens spent outside the hen house in relation to feather pecking and condition of the integument. The effect of housing condition and the genotype were studied. Hens that were offered a large space to outside open area (10m²/bird) moved significantly more frequently to the outdoor areas than others (2.5m²/bird). Frequency of movement between poultry house and winter garden was higher in the group without grassland. Hens kept at a higher density outdoors (2.5m²/bird) spent significantly more time in this area than hens were kept at a lower density (10m²/bird) on grassland. The high rates of feather pecking are observed in the group without grassland compared to groups stocked at 2.5m² or 10m² per bird on grassland The group without grassland had poorer feather condition compared to other groups that had 2.5m²/bird and 10m²/bird on grassland Lohmann Selected Leghorn (LSL) hens moved more frequently to the outdoor enclosures compared to Lohmann Tradition (LT). But LT hens spent significantly more time on grassland than LSL.The plumage condition was worse in LSL than LT hens. It is concluded that housing conditions might have a stronger influence on the development of feather pecking than the genetic aspect. Large differences between the genotypes examined were found in respect to the frequency of movement to the outdoor areas, the time spent outside and plumage and skin damage

Approximately half of all reported laminitis cases are the result of “grass founder” (laminitis associated with long-term over consumption of lush, early spring pastures). Elevated body weights (BW), body condition scores (BCS), and blood glucose concentrations have all been associated with the onset of grass founder. Plasma fructosamine concentrations (PFC) have recently been used as an indicator of long-term (14–21 d), mean blood glucose concentrations in horses and numerous authors have reported that elevated PFC were observed in laminitic horses (Murphy et al., 1997; Keen et al., 2004; Knowles et al., 2012). This study was conducted to evaluate the long-term effects of transitioning from an ad-libitum tall fescue hay diet in late winter to an adlibitum tall fescue pasture diet in early spring on parameters associated with grass founder in horses. Five mature stock horse mares were given free choice access to good quality tall fescue hay for 18 weeks before initiation of data collection. Each horse acted as their own control. PFC were determined on day 1, day 128, and then monitored at 14 d intervals for the following 84 d (February 26th through May 21st). Three trained lab technicians evaluated BW and BCS on day 1, 128, 170 and 212 of the trial. The horses were placed in a 20 acre field where their diets consisted of free choice access to hay only for 156 days (DTP1) followed by free choice access to tall fescue hay with minimal access to some early emerging tall fescue pasture for 14 days (DTP2), and finally to free choice access to lush spring tall fescue pasture only for the final 42 days (DTP 3) when the animals refused to eat offered hay. Mean PFC were highest (P < 0.01) for DTP1 and decreased with each successive transition to DTP2 and DTP3. This may have been due to increased insulin secretion associated with the pasture only diet. Mean BCS at the beginning of the trial was 5.7 and increased throughout the trial (P < 0.001) to a value of 7.8. BCS associated with the pasture only diet were higher (P < 0.001) than those associated with the free choice hay and hay plus pasture diets. Mean BW increased (P < 0.05) from 1199 lbs. to 1268.3 lbs. during the 12-week trial. Mean weight gain was 113 lbs. with an average daily gain of 1.35 lbs./day. No incidence of laminitis was observed.

Production, egg quality, behaviour, and physical condition were compared from Wk 20 to Wk 50 among three beak- trimmed commercial laying strains, Lohmann White (LW), H & N White (HN), Lohmann Brown (LB), and a non-commercial Cross between Rhode Island Red (male) and Barred Plymouth Rock (female) in conventional cages and in floor pens. All chicks were reared in their respective environments, and 450 and 432 pullets were housed at 18 and 7 weeks of age in cages and floor pens respectively. Hens in cages were provided with 688 cm2/bird and those in pens with over 6,000 cm2/bird, both of which are more than provided by commercial standards. Body weights and eggshell weights were higher for birds in floor pens than those in cages, and although they increased with age, body weight of hens in cages decreased at Wk 50. White-egg layers (LW, HN) used perches and nest boxes more than Brown-egg layers (LB, Cross). During the laying period, mortality was higher for all strains in cages and during the rearing period mortality was higher in floor pens for LB hens but not other strains. No aggressive behaviours were found, but the frequency of gentle feather pecking and pecking at the enclosure was higher in cages than in floor pens. Feather condition deteriorated over time in cages mainly because of contact with the cage wires whereas in floor pens, feather condition of birds at Wk 20 was not different from that at Wk 50. The frequency of keel bone deformities was higher for White-egg layers than for Brown-egg layers in cages and was higher for Cross hens than other strains in floor pens. Claws were longer in cages than in the floor pens. Foot condition was worse in floor pens than in cages. The welfare indicators used in this study showed that cages restricted the hens' behaviour compared to floor pens and resulted in higher laying period mortality, reduced body weight and deteriorated feather condition than floor pens. Both systems had advantages and disadvantages in regard to the hens’ health and welfare. The use of environmental complexities was strain specific in floor pens. The environment by genotype interactions suggests that the strain should be considered when considering alternative housing systems.

Published Article
A study was conducted to determine the differences between four breeds in respect of coat score, hide-thickness, tick burden and body condition score. The study was comprised of 40 heifers - 10 of each breed, namely Afrikaner, Braford, Charolais and Drakensberger. A subjective system of coat scoring, ranging from extremely short to very woolly, was used. Body condition score was measured subjectively, with 1 being emaciated and 9 being obese. Hide-thickness (in mm) and tick count were also determined. Between August 2007 and early March 2008, measurements were carried out on the same 10 animals of each breed, with highly significant differences in body condition score, hide-thickness and tick count being observed between the breeds in all instances. Coat scores differed significantly between breeds in the earlier and latter stages of the study becoming less significant midway through. A significant difference in body condition score within breeds was also found, while hide-thickness did not differ significantly within breeds.

A non-invasive, on-line method for detection of mechanical (rotor, bearings eccentricity) and stator winding faults in a 3-phase induction motors from observation of motor line current supply input. The main aim is to avoid the consequence of unexpected failure of critical equipment which results in extended process shutdown, costly machinery repair, and health and safety problems. This thesis looks into the possibility of utilizing machine learning techniques in the field of condition monitoring of electromechanical systems. Induction motors are chosen as an example for such application. Electrical motors play a vital role in our everyday life. Induction motors are kept in operation through monitoring its condition in a continuous manner in order to minimise their off times. The author proposes a model free sensor-less monitoring system, where the only monitored signal is the input to the induction motor. The thesis considers different methods available in literature for condition monitoring of induction motors and adopts a simple solution that is based on monitoring of the motor current. The method proposed use the feature extraction and Support Vector Machines (SVM) to set the limits for healthy and faulty data based on the statistical methods. After an extensive overview of the related literature and studies, the motor which is the virtual sensor in the drive system is analysed by considering its construction and principle of operation. The mathematical model of the motor is used for analysing the system. This is followed by laboratory testing of healthy motors and comparing their output signals with those of the same motors after being intentionally failed, concluding with the development of a full monitoring system. Finally, a monitoring system is proposed that can detect the presence of a fault in the monitored machine and diagnose the fault type and severity

Chronic stress can result in elevated circulating levels of glucocorticoid hormones in vertebrates, which can affect their stress response, their immune function, and eventually their fitness. I tested the effect of chronic corticosterone (CORT) elevation on the acute stress responsiveness, immune function, and body condition of free-living painted turtles (Chrysemys picta) in Gatineau Park, using slow-release exogenous CORT administration. While Silastic implants did not predictably elevate circulating CORT concentrations in painted turtles, injections of CORT-laden cocoa butter kept circulating levels elevated for up to 3 weeks, to concentrations likely physiologically and ecologically relevant for the species. I measured the acute CORT stress response, parasitaemia, heterophil-to-lymphocyte ratios, and total leukocyte counts after 1 week and 3 weeks, and determined body condition after 1 week, 3 weeks, and 1 year. Compared to sham and control turtles, I observed no effect of treatment on these hormonal, immune, and body condition metrics of stress, possibly because CORT mediates resource allocation only in the presence of additional immune or energy challenges, because of the masking effect of extrinsic factors, or because free, not total, CORT appears to be biologically active.

Abstract: A rigorous approach to Statistical Physics issues often produces interesting mathematical questions. This Ph.D. thesis is composed of two different parts. One does not intersect the other, but both research topics lie at the interface between Probability Theory and Statistical Mechanics. • In the first part we deal with reconstruction of a tree-indexedMarkov chain on Galton-Watson trees, improving previous bound byMossel and Peres, both for symmetric and strongly asymmetric chains. Moreover, we give some numerical estimates to compare our bound with those of other authors. We provide a sufficient condition of the form Q(d)c(M) < 1 for the non-reconstructability of tree-indexed q-stateMarkov chains obtained by broadcasting a signal from the root with a given transition matrix M. Here c(M) is a constant depending on the transition matrixM and Q(d) is the expected number of offspring on the Galton-Watson tree. This result is equivalent to proving the extremality of the free boundary condition Gibbs measure within the corresponding Gibbs-simplex. When considering the Potts model case we take this point of view too. Our theorem holds for possibly non-reversible M. In the case of the symmetric Ising model the method produces the correct reconstruction threshold, in the case of the (strongly) asymmetric Ising modelwhere the Kesten-Stigum bound is known to be not sharp the method provides improved numerical bounds. • In the second part of the thesis we give sharp estimates for time uniformpropagation of chaos in some specialsmean field spin-flipmodels exhibiting phase transition. The first model is the dynamical Curie-Weiss model, that can be considered as the most basic mean field model. The second example is a model proposed recently in the context of credit risk in Finance; it describes the time evolution of finantial indicators for a network of interacting firms. Although we have chosen to deal with two specific models, the method we use appear to be rather general, and should work for other classes of models. A substantial limitation of our results is that they are limited to the subcritical case or, in StatisticalMechanical terms, to the high temperature regime.
Sommario: Un approccio rigoroso a questioni di Fisica Statistica spesso produce interessanti problemi matematici. Questa tesi di dottorato è composta da due parti. La prima non interseca la seconda, ma entrambe stanno sul confine tra Teoria della Probabilità e Meccanica Statistica. • La prima parte tratta il problema della ricostruzione per catene di Markov su alberi di tipo Galton-Watson. Miglioriamoi risultati precedentemente ottenuti da Mossel e Peres, sia per catene simmetriche che fortemente asimmetriche. Dimostriamo una condizione sufficiente della forma Q(d)c(M) < 1 per la non ricostruzione di catene diMarkov a q-stati sull’albero. Qui c(M) è una costante che dipende dalla matrice di transizione M e Q(d) è la media del numero di figli per vertice nell’albero di Galton-Watson. Questo risultato è equivalente alla purezza della misura libera di Gibbs. Quando consideriamo il caso del modello di Potts assumiamo anche questo punto di vista. Il teorema è valido anche per catene non reversibili. Nel caso del modello di Ising il nostro risultato produce la correta soglia di ricostruzione, nel caso di catene (fortemente) asimmetriche dove si sa che il bound di Kesten-Stigum non è esatto il metodo usato dà risultati numerici migliori. • Nella seconda parte diamo delle stime uniformi nel tempo per la propagazione del caos in alcuni modelli di spin con interazione a campo medio che presentano transizione di fase. Il primo è il modello dinamico di Curie-Weiss, che può essere considerato come il più semplice esempio di sistema con interazione a campo medio. Il secondo è un modello recentemente impiegato per spiegare i meccanismi del rischio di credito; esso descrive l’evoluzione temporale di indicatori finaziari per un gruppo di aziende interagenti quotate sul mercato. Anche se abbiamo trattato modelli specifici, crediamo che il metodo funzioni piuttosto in generale e che sia applicabile anche ad altre classi di modelli. Una limitazione sostanziale dei nostri risultati è che valgono solo nel caso sottocritico, che corrisponde, nel linguaggio della Meccanica Statistica, al regime di alta temperatura.

A caseína e os ácidos graxos livres (AGL) são importantes componentes do leite relacionados às suas características industriais e sensoriais. Alguns fatores são responsáveis por alterações em suas concentrações, dentre eles, pode-se destacar as condições de armazenamento, além da agitação e, principalmente, a contagem de células somáticas (CCS). Para estudar tais alterações, avaliou-se através do presente estudo o efeito da temperatura de armazenamento (- 20oC e 7oC) e da idade das amostras (3, 6, 9 e 12 dias), assim como da CCS (CCS1: 400 mil, CCS2:400-750 mil e CCS3: 750 mil células somáticas/mL de leite). O efeito das condições de armazenamento sobre a caseína e os AGL foi avaliado no primeiro estudo. O efeito da CCS sobre a caseína e os AGL, por outro lado, foi avaliado no segundo estudo. No primeiro estudo, observou-se aumento nos teores de AGL ao longo do tempo, ou seja, acompanhando o aumento do período de armazenamento, com médias superiores em amostras resfriadas (7oC), em relação às congeladas (-20oC). Desta forma, sugere-se que análises laboratoriais devem ser realizadas em até três dias para este componente, devido ao seu aumento progressivo em amostras resfriadas. Para a caseína, entretanto, não foi identificada interação entre os fatores idade e temperatura. As médias deste componente não diferiram considerando-se as condições de armazenamento avaliadas, indicando que as análises para este componente podem ser realizadas até doze dias após a coleta, independente da temperatura de armazenamento. No segundo estudo, identificou-se interação entre classes de CCS e época de coleta, para caseína. A partir dos resultados de AGL, pode-se concluir que o leite encontra-se com altas concentrações deste componente, quando coletado na propriedade rural, sendo também observada influência da CCS sobre as concentrações de caseína e AGL no leite cru. Os AGL apresentaram incrementos significativos comparando-se amostras coletadas em diferentes locais, no trajeto da fazenda à indústria. Por outro lado, comparando-se os mesmos locais: tanque, rota e silo, as médias de caseína não diferiram. Observou-se correlação entre as variáveis CCS e caseína e CCS e AGL.
The casein and the free fatty acids (FFA) are important milk components related to its industrial and sensory characteristics. Some factors are responsible for changes in their concentration among them can highlight the storage conditions, as well as agitation and, especially, the somatic cell count (SCC). To study such changes, we assessed through the present study the effect of storage temperature (-20oC and 7oC) and the age of samples (3, 6, 9 e 12 days), as well as the CCS (CCS1: 400 mil; CCS2: 400-750 mil; CCS3: 750 mil somatic cells/mL of milk). The effect of CCS storage conditions on casein and FFA was evaluated in the first study. The effect of CCS on casein and FFA moreover, was evaluated in the second study. In the first study, it was observed increased levels the AGL over time, ie, accompanying the increase of the storage period, with means higher in refrigerated samples (7oC), in relation to frozen samples (- 20oC). Thus, it is suggested that laboratory examinations shall be performed up to three days to this component, due to their progressive increase in refrigerated samples. For casein, however, was not identified interaction between the factors age and temperature. The mean of this component did not differ considering the storage conditions, indicating that the analyzes for this component can be made until twelve days after collection, regardless of storage temperature. In the second study, we identified interactions between CCS classes and seasons, for casein. From the FFA results, we can conclude that milk meets with high concentrations of this component, when collected in the rural property, being also observed influence of CCS on concentrations of casein and FFA in raw milk. The FFA showed significant increases compared to samples collected at different locations on the path from farm to industry. On the other hand, comparing the same locations, tank, route and silo, the casein average did not differ. Correlation was observed between the variables casein and CCS and FFA and CCS.

The idea of snow cooling in this case is to save snow from winter to summer and to use it for air conditioning and for saving energy in the production of ice in hockey arenas. Today in Sweden, snow power on a large scale is used only on one place, the hospital in Sundsvall. There you’ll find a pond with 70 000 m3 of snow. The melt water in the pond is heated up while cooling down warm air from the hospital, before circulating back to the pond where it regains a low temperature passing through the snow. The idea was to examine the possibility to use such a system in Västerås, at the multiple sports arenas at Rocklunda, partly for air conditioning and partly for ice production. This work was made possible through gathering information on snow storage and on the Sundsvall snow cooling plant, by interviewing people with insight in the Sundsvall hospital and Rocklunda sports arenas and by calculating the electricity consumption, necessary amount of snow and making an LCC-analysis. For air conditioning the melt water would be used like in Sundsvall but for ice production the melt water would be used for condensing the cooling media in the heat pump at a lower temperature then it would do while cooling with air or river water during summer. Annual electricity savings of 120 and 154 MWh for the arenas were made for 2016 and 2017 when using the snow for ice production. For the air conditioning the saving were estimated to around 55 MWh per year. A snow dispatch hatch in one of the hockey arenas made an alternative to a full-scale snow cooling system. Using this hatch for temporal snow power could save up to 62 MWh per year when used for ice production and 38 MWh when used for air conditioning. The estimated costs for construction of said system proved to be too expensive for making a full-scale snow power system a reality. For ice production a storage of 103 000 m3 of snow was needed which made for a result of -57 MSEK in the LCC-analysis. For the air conditioning alone, a storage of 6 000 m3 was needed which made for a result of -4.2 MSEK. The snow dispose hatch, even without the need of snow storage, resulted in -5.9 MSEK for ice production and -1.6 MSEK for air conditioning. With more thoroughly estimations of the investment costs, together with global warming and thus bigger potential for saving energy, this might be a promising investment in the future.

The unimodality of a function seems a simple concept. But in the Euclidean space R^m, m=3,4,..., it is not easy to define. We have an easy tool to find the minimum point of a unimodal function. The goal of this project is to formalize and support distinctive strategies that typically guarantee convergence. Support is given both by analytic arguments and simulation study. Application is envisioned in low-dimensional but non-trivial problems. The convergence of the proposed iterated grid search algorithm is presented along with the results of particular application studies. It has been recognized that the derivative methods, such as the Newton-type method, are not entirely satisfactory, so a variety of other tools are being considered as alternatives. Many other tools have been rejected because of apparent manipulative difficulties. But in our current research, we focus on the simple algorithm and the guaranteed convergence for unimodal function to avoid the possible chaotic behavior of the function. Furthermore, in case the loss function to be optimized is not unimodal, we suggest a weaker condition: almost (noisy) unimodality, under which the iterated grid search finds an estimated optimum point.
Ph. D.

Autologous explant-derived cardiac stem cell (EDC) therapies are a promising therapy for ischemic cardiomyopathy, but straightforward clinical translation is limited by traditional culture conditions which are often supplemented with ill-defined and xenobiotic components such as fetal bovine serum. Therefore, we investigated the influence of a commercially sourced serum-free (SF) xenogen-free medium on human EDC yield, phenotype, in vitro measures of EDC performance, and post-infarct cardiac repair using an immunodeficient mouse model of acute myocardial infarction. Despite reduced production of several pro-cardiogenic cytokines, SF EDCs promoted similar vessel formation, circulating stem cell recruitment and cardiogenic differentiation as compared to standard cultures. Transplant of SF EDCs into immunodeficient mice 1 week after myocardial infarction boosted post-ischemic repair beyond that of standard EDCs by enhancing viable myocardium within the infarct. These findings demonstrate that serum-free culture methods provide a superior cardiac-derived cell product with ready clinical translatability.

Thesis (M.Sc.Eng.)
To determine satellite trajectories in low earth orbit, engineers need to adequately estimate aerodynamic forces. But to this day, such a task su↵ers from inexact values of drag forces acting on complicated shapes that form modern spacecraft. While some of the complications arise from the uncertainty in the upper atmosphere, this work focuses on the problems in modeling the flow interaction with the satellite geometry. The only numerical approach that accurately captures e↵ects in this flow regime—like self-shadowing and multiple molecular reflections—is known as Test Particle Monte Carlo. This method executes a ray-tracing algorithm to follow particles that pass through a control volume containing the spacecraft and accumulates the momentum transfer to the body surfaces. Statistical fluctuations inherent in the approach demand particle numbers on the order of millions, often making this scheme too costly to be practical. This work presents a parallel Test Particle Monte Carlo method that takes advantage of both graphics processing units and multi-core central processing units. The speed at which this model can run with millions of particles enabled the exploration of regimes where a flaw was revealed in the model’s initial particle seeding. A new model introduces an analytical fix to this flaw—consisting of initial position distributions at the boundary of a spherical control volume and an integral for the correct number flux—which is used to seed the calculation. This thesis includes validation of the proposed model using analytical solutions for several simple geometries and demonstrates uses of the method for the aero-stabilization of the Phobos-Grunt Martian probe and pose-estimation for the ICESat mission.
2031-01-01

The aim of this PhD research project was to identify the formulations and to define the process conditions that most influence the quality and the shelf-life of gluten-free (GF) bread. Raw materials that are commonly used in GF bread production were first characterized, in particular as regards the rheological properties of different starchy gels during a short term ageing. Waxy rice flour (WRF) and rice bran (RB), at 25% and 50% substitution level, came out to be very effective in reducing gel stiffness and storage modulus (G’) of the mixtures containing corn starch (CS) or rice flour (RF). The effects of High Hydrostatic Pressure treatments on CS, RF and WRF were also investigated. A partial gelatinization of RF treated at 400MPa and 600MPa was evidenced by the viscoamylographic test and the formation of a more compact structure and a higher water retention capacity were registered for CS treated at 600MPa. The effect of Psyllium (Psy) and sugar beet (SB) fibers on dough and bread properties was also evaluated. The presence of 2.5% Psy generally determined an increase of dough height and CO2 production during leavening. Psy fiber also showed an anti-staling effect, higher than SB fiber. Taking into account all these results, a GF sourdough (SD) containing selected bacteria and yeasts (Lactobacillus sanfranciscensis and Candida humilis) was developed; then it was constantly refreshed and monitored in terms of number and type of microorganisms, capability to produce/retain CO2 and pH variations. When a stable microbial association was achieved, as well as constant SD properties, some breadmaking trials were performed. GF SD combined with compressed yeast resulted an excellent opportunity to improve GF bread quality and shelf-life.

Submitted by Debora de Oliveira Medeiros null (deboraomedeiros@gmail.com) on 2017-06-13T19:08:30Z No. of bitstreams: 1 dissertacao_arquivar.pdf: 4524135 bytes, checksum: 33a027db23ff40bebc026b9090443d53 (MD5)
Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-19T12:58:15Z (GMT) No. of bitstreams: 1 medeiros_do_me_prud.pdf: 4524135 bytes, checksum: 33a027db23ff40bebc026b9090443d53 (MD5)
Made available in DSpace on 2017-06-19T12:58:15Z (GMT). No. of bitstreams: 1 medeiros_do_me_prud.pdf: 4524135 bytes, checksum: 33a027db23ff40bebc026b9090443d53 (MD5) Previous issue date: 2017-04-24
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho é apresentado um estudo das equações de Navier Stokes incompressível com superfície livre e métodos de projeção com uma formulação recente denominada laplaciano superficial. Esta formulação tem como finalidade uma melhor descrição da força de tensão superficial e grandezas, como curvatura e vetores tangencial e normal, descritas sobre a interface. Assim, uma condição de tensão normal alternativa é definida, e esta quando discretizada implicitamente e combinada com o método de projeção, descrevem a formulação laplaciano superficial, cuja sua solução é utilizada como condições de contorno para resolver o sistema de equações que descrevem o escoamento. A nova formulação destina-se a resolver um sistema tridiagonal de equações gerado sobre a interface, e usar a solução deste sistema de equações como uma condição de contorno na superfície livre para o sistema linear da correção da pressão no interior do domínio, que é resultante da aplicação do método de projeção. A nova equação que define a condição de tensão normal conta com grandezas definidas na malha euleriana, no contexto Marker-And-Cell (MAC), que devem ser projetadas sobre a malha lagrangeana e também considera a curvatura e os vetores tangente e normal na sua descrição, sendo importante um estudo detalhado de geometria diferencial. Finalmente, variações da formulação laplaciano superficial com tensão superficial para diferenças finitas são aplicadas para resolver os testes numéricos da oscilação da gota e da gota apoiada que possuem solução de referência, além da simulação de um problema com movimento de interface (fountain flow). Nestes testes, concluímos que a variação mais precisa e estável é aquela que aplica uma discretização da equação da tensão normal utilizando médias de valores alocados na malha MAC.
This work presents a study of the Navier-Stokes equations incompressible with free surface and a projection methods with a recent formulation defined as surface laplacian. The purpose of this formulation is to improve the description of the force of stress tension and quantities, as curvature and tangent and normal vectors, present at the interface. Thus, an alternative normal stress condition is defined, and when this is discretized implicitly and combined with the employ of projection method, describe the surface laplacian formulation, whose solution is used as boundary condition to solve the system of equations describing the flow. The new formulation is intended to solve the tridiagonal system of equations generated at the interface, and to use this solution as a boundary condition at free surface for the linear system of the pressure correction inside of domain, which results of the application of the projection method. The new equation used to define the normal stress condition considers quantities defined in the Eulerian mesh, in the Marker-And-Cell context (MAC), that should be projected on the Lagrangian mesh. In addition, in the new equation, it is also considered the influence of the curvature and normal and tangential vectors in your description, so that a detailed study of differential geometry for this computation is important. Finally, variations of the surface laplacian formulation for finite differences are applied for solving numerical tests of the drop oscillation and sessile drop which have reference solutions, beyond of the simulation of a problem with free surface moving (fountain flow). In these tests, we concluded that the most accurate and stable variation is the one that applies a discretization of the normal stress equation using the mean of values in the MAC mesh.
FAPESP: 2015/01243-0

The baculovirus expression vector system (BEVS) is an effective way to produce recombinant proteins for biopharmaceuticals. However baculovirus stocks are stored in subzero temperatures to maintain virus stability, and fetal bovine serum is commonly used in the storage solution. In an effort to lower transportation and storage costs, a storage formulation that can effectively store the baculovirus in above frozen temperatures without the use of FBS would be beneficial. In this study, DMSO, ethylene glycol, glycerol, sucrose, sorbitol, sucrose-phosphate, and sucrose-phosphate-glutamate were added to baculovirus stock at various concentrations to determine the most effective stabilizer for virus storage at 4°C. Of the seven additives studied, 1 M sorbitol most effectively preserved baculovirus stock over a period of 47 weeks stored in 4°C. Formulations that include sucrose, L-arginine, and Pluronic F68 were created to determine their effectiveness on virus stability in a freeze-dried state stored at room temperature. In a lyophilized state, 0.5 M sucrose maintained baculovirus stock stability after 5 weeks of storage. Lyophilized stocks not containing sucrose were no longer infective after 5 weeks.
Master of Science

In this thesis the influence of stress-state on ductile damage in free cutting steel under hot forming conditions is examined. The industrial motivation for the project focuses on edge cracking in hot rolling. A brief outline of the hot rolling process conditions is necessary to define the important parameters affecting edge cracking. Triaxiality was, thus, identified as the key parameter relating to damage under hot rolling conditions. Based on a detailed literature review, the appropriate testing and modelling methodology were identified for this body of work. A high temperature, uniaxial tension test program was implemented to identify the effect of triaxiality on damage under hot forming conditions. Double notched bars with varying notch radii were utilised, thus inducing different stress triaxialities due to geometrical constraints. Based on the resultant stress-strain data the effect of triaxiality on ductility and the strain to failure was investigated. Subsequently, unbroken notches from tested double notched samples were sectioned and optically examined to reveal damage initiation sites. Interesting damage features were identified and correlated with sample geometry (i.e. triaxiality) and testing conditions. Finite element analysis of the double notched samples revealed the effect of triaxiality on the local stress-state. The accuracy of the mechanical analysis from such simulations was improved by incorporating the thermal gradients induced during high temperature Gleeble tests. Three stress parameters were examined in relation to their effect on the experimentally observed damage; maximum principal stress, effective stress and hydrostatic stress. The maximum principal stress and equivalent stress were most clearly correlated to damage development under multiaxial conditions for this particular free cutting steel. Based on the results of the stress-state investigation of the double notched samples, a multiaxial damage expression was developed that reproduced the experimentally observed damage characteristics. The new multiaxial damage model was calibrated using a combination of uniaxial and multiaxial stress-strain data and damage profiles. The model was shown to have good accuracy in predicting both the stress-strain data and the damage initiation sites as a function of geometry and damage conditions. Finally, an extensive range of temperature and strain rate conditions were simulated for all tested sample geometries, and an additional sample geometry, to fully understand how testing conditions affect damage characteristics and under what triaxialities this is prone to happen.

We introduce two different properties of representations of the free group of rank 2 into the group of hyperbolic isometries PSL(2,C): BQ conditions and primitive stability. We investigate relations between the sets of characters satisfying these conditions, and study certain slices of the character variety separately. The results we get are in line with the conjecture that these two sets actually coincide. We also show that in the diagonal slice of the character variety, namely the set of representations with associated trace triple (z, z, z), z E C, there exists a large class of primitive stable representations which are not discrete and faithful.

This thesis is divided in two main parts. The first part compares and contrasts early experiments with non-slave labour in Cuba and Sao Paulo. The second part considers projects for the gradual abolition of slavery and the transition to free labour. The objective is to examine how Cuban and Brazilian planters solved the problem of labour supply triggered by a rapid growth of plantation exports during the nineteenth century. At this time sugar and coffee plantations came to characterize economic development in the two areas. Continued expansion was threatened by international pressures to end the trans- Atlantic slave trade. Challenged by international demands to terminate the "African trade" Cuba and Brazil sought to solve the labour problem by means of immigration. From the mid-century until the end of slavery in the 1880s, planters would experiment with several labour systems, involving a variety of labour relations. Besides slaves, Europeans, Chinese, Mexican Indians, Canary Islanders, and free domestic workers (white and coloured) would be employed on the plantations. Substituting "free" labour for slave labour was not simply a matter of labour supply. For Cuba there was the question of the relationship with Spain and its consequences for the defense of slavery and the impact on immigration. For Brazil there was the question of forging a national identity. What would be the place of slaves, freedmen and immigrants in the new nation. In both regions these considerations had a racial dimension. Also planters were anxious to secure a cheap disciplined workforce. What labour system would best meet these requirements? As this thesis demonstrates this was a time of experimentation. From the first, in Brazil alternative supplies of labour were regarded as a means of transition to free labour. In Cuba new supplies of workers were viewed as complementing slavery. But the first experiments with non-slave labour affected the processes of the abolition of slavery and the transition to free labour while the meaning of "free labour” and “transition” also changed over time.

>Magister Scientiae - MSc
In this thesis, we investigate the HIV/AIDS epidemic in a population which experiences a significant flow of immigrants. We derive and analyse a math- ematical model that describes the dynamics of HIV infection among the im- migrant youths and intervention that can minimize or prevent the spread of the disease in the population. In particular, we are interested in the effects of public-health education and of parental care.We consider existing models of public-health education in HIV/AIDS epidemi-ology, and provide some new insights on these. In this regard we focus atten-tion on the papers [b] and [c], expanding those researches by adding sensitivity analysis and optimal control problems with their solutions.Our main emphasis will be on the effect of parental care on HIV/AIDS epidemi-ology. In this regard we introduce a new model. Firstly, we analyse the model without parental care and investigate its stability and sensitivity behaviour.We conduct both qualitative and quantitative analyses. It is observed that in the absence of infected youths, disease-free equilibrium is achievable and is asymptotically stable. Further, we use optimal control methods to determine the necessary conditions for the optimality of intervention, and for disease eradication or control. Using Pontryagin’s Maximum Principle to check the effects of screening control and parental care on the spread of HIV/AIDS, we observe that parental care is more effective than screening control. However, the most efficient control strategy is in fact a combination of parental care and screening control. The results form the central theme of this thesis, and are included in the manuscript [a] which is now being reviewed for publication. Finally, numerical simulations are performed to illustrate the analytical results.

Dissertação para obtenção do Grau de Mestre em Engenharia Informática
Software has become widespread, being used and relied upon on nearly every domain. Furthermore, as this globalization of software took place and multi-core architectures became the norm, several programs are now expected to run on a given device at the same time in a timely fashion. Attending this need, concurrent and distributed systems are a well known way of dealing with performance and scalability of computation. Although several such systems exist in the devices and services we depend on, it is frequent for those systems to be exploited or go wrong. Because most complex programs are built in modules and lack a formal specification of what they do, it is hard to prevent the emerging system from failing or being exploited. Therefore, one of the most sought after results by software industry is a way of reasoning about programs that prevents undesired behavior. Formal methods contribute to a rigorous specification, analysis, and verification of programs, having proven to be quite effective in this regard. Program logics,in particular, are able to verify validity of user-specified formulas and are the solution we propose to tackle this issue. Regarding concurrent programs, locks are a mechanism that make reasoning easier by serializing access to shared resources, taming concurrency. Since lock-free programs offer a better way of taking advantage of concurrency, we are especially interested in them. In this context, the LL/SC pair of primitives have proven to be more expressive than their widely used CAS counterpart. The goal of our work is then to develop a proof system capable of proving correctness of lock-free programs based on LL/SC primitives. In this dissertation we present a new program logic, based on those of concurrent separation logic and RGSep, which establishes a solid theoretical basis for reasoning about such programs.

2013/2014
Subject to high-intensity ultra-short light pulses, solid materials are driven into short-living states of extremely high temperatures and pressures. Creating such unique states under controlled laboratory conditions and addressing their physical properties with an adequate time resolution to follow their fast-evolving dynamics has been a primary objective of pump-and-probe studies employing the high-peak-power femtosecond optical lasers that have become of increasingly widespread availability during the last three decades. Operative since few years, free electron lasers (FELs) add - to the desired properties of high brilliance, short time duration and coherence proper of those lasers - the tunable energy up to the extreme ultraviolet (EUV) and X-ray spectral ranges which is typical of synchrotron light sources, thus offering a number of advantages on both the fronts of pumping and probing. This thesis describes the efforts that have been undertaken towards the establishment of a new experimental ground for the study of matter under extreme transient conditions at the TIMEX beamline of the free electron laser FERMI in Trieste and discusses my understanding of a number of seminal investigations. Characterization of the exotic states swiftly reached by FEL-excited metallic samples is addressed through single-shot measurements of their EUV reflectance and absorbance. In particular, we provide the first demonstration of EUV absorption near edge spectroscopy at high energy densities and with sub- 100 fs time resolution. The combination of these features is only possible at FEL sources, but makes FERMI truly unique when further considering that here it comes without a need for monochromatization thanks to its seeded nature which makes the delivered pulses almost Fourier-transform limited in bandwidth. The measured dependence on irradiation fluence of the transient absorbance and reflectance of Ti for selected wavelengths across the M2,3 absorption edge and near the plasma frequency respectively is reported, revealing an ultrafast modification of the electronic structure compatible with a single FEL pulse having turned within about 100 fs room-temperature solid-density Ti into a hot free electron gas coexisting in highly non-equilibrium conditions with a cold ion lattice. An interpretive perspective is proposed that - based on simplified, yet reasonable, Drude-like models - allows to gain information on the average free electron temperature and density and the average ionization state of the generated dense plasma. Ultra-fast high-energy-density self-transmission measurements on Al at a few photon energies between the plasma frequency and the L2,3 absorption edge are presented, evidencing for the first time a non-monotonic trend of the EUV transmission as a function of fluence, that are seen to be interpretable - within a three-channel model - as resulting from an interplay between saturation effects and absorption cross-section variations due to electron heating. Higher fluence conditions are shown to induce almost full transparency in an Al-Mg-Al stack over an entire energy region across the Mg L2,3 absorption edge. An analytical model is formulated, that tentatively permits to deduce from the data an estimate for the first ionization energy of warm dense Mg. The responses of insulator and semiconductor samples to FEL and laser excitations - from the initial non-equilibrium stage, through the subsequent relaxation dynamics, to possible phase transformations - are explored through pump-and-probe experiments. Here, FEL pulses are exploited in combination with pulses from the same infrared laser that serves to initiate the FEL emission process, which ensures a natural synchronization between the two radiation sources, - again - a unique feature of seeded FELs. Measurements of transient optical reflectivity on FEL-pumped Si3N4 samples are offered as a demonstration of the nearly jitter-free pump-probe capabilities of FERMI, thus far unbeaten among FEL facilities. The results of a systematic study of the optical response of this material to FEL irradiation for different pump wavelengths and intensities, probe polarizations, sample thicknesses and types of substrate in both reflection and transmission simultaneously are discussed, hinting at the role of interference effects at play due to the different penetration depths of the EUV FEL and infrared laser pulses. Transient EUV transmissions for Ge at its M4,5 edge within a laser pump / FEL probe configuration and for Si at its L2,3 edge within a FEL pump / FEL probe configuration yield a time and energy -resolved view on femtosecond pulse -induced melting of semiconductors. We show that, while able to follow the excitation and de-excitation dynamics of the electronic population in the valence band through below- absorption edge data, we can infer dynamical structural information through on- absorption edge data, in which we recognize the fingerprint of a partial band gap closure associated with the transition to a liquid state of increased metallic character. ---
--- Sottoposti ad impulsi luminosi ultra-intensi ed ultra-brevi, i materiali solidi sono temporaneamente portati ad altissime temperature e pressioni. Generare tali stati in controllate condizioni di laboratorio ed investigarne le proprietà fisiche con una risoluzione temporale adeguata a seguirne la rapida evoluzione è stato un obiettivo primario degli esperimenti di tipo ``pump-and-probe'' facenti uso dei laser ottici al femtosecondo ed elevate potenze di picco che sono divenuti di crescentemente diffusa disponibilità nel corso degli scorsi tre decenni. Operativi soltanto da pochi anni, i laser ad elettroni liberi (FEL) uniscono - alle desiderate proprietà di alta brillanza, breve durata temporale e coerenza propri di questi laser - l'energia variabile fin negli intervalli spettrali dell'estremo ultravioletto (EUV) e dei raggi X che è tipica delle sorgenti di sincrotrone, offrendo in tal modo una serie di vantaggi sia per quanto riguarda la generazione che la caratterizzazione dei suddetti stati. Questa tesi descrive gli sforzi che sono stati intrapresi verso il consolidamento di una nuova piattaforma sperimentale per lo studio della materia in condizioni estreme e transienti presso la linea di luce TIMEX del laser ad elettroni liberi FERMI in funzione a Trieste e discute la raggiunta comprensione di un certo numero di indagini pionieristiche. Stati esotici istantaneamente raggiunti da campioni metallici in seguito ad eccitazione FEL sono caratterizzati attraverso misure a singolo impulso delle loro riflettanza ed assorbanza EUV. In particolare, diamo la prima dimostrazione di spettroscopia di assorbimento EUV vicino soglia ad alte densità energetiche e con risoluzione temporale inferiore ai 100 fs. La combinazione di queste caratteristiche è disponibile solamente presso sorgenti FEL, ma rende FERMI unico qualora, in aggiunta, si consideri che qui si presenta senza bisogno di monocromatizzazione grazie alla natura ``seeded'' che rende gli impulsi rilasciati quasi Fourier-transform limited in larghezza di banda. Viene riportata la dipendenza dalla fluenza di irraggiamento dell' assorbanza e della riflettanza transienti del Ti per selezionate lunghezze d'onda sulla soglia M2,3 di assorbimento e vicino alla frequenza di plasma, rispettivamente. Essa rivela una modificazione ultraveloce della struttura elettronica compatibile con uno scenario in cui un singolo impulso FEL, entro la sua durata di circa 100 fs, trasforma il titanio a temperatura ambiente in un gas caldo di elettroni liberi coesistente in condizioni altamente fuori dall'equilibrio con un reticolo freddo di ioni. Si propone una prospettiva interpretativa che, basata su semplificati ma ragionevoli modelli simil-Drude, permette di ricavare informazioni sulla temperatura e sulla densità elettronica medie e sullo stato di carica medio del plasma denso generato. Sono presentate misure di trasmissione di impulsi ultra-veloci e ad alta densità di energia su un campione di Al ad alcune energie fotoniche tra la frequenza di plasma e la soglia di assorbimento L2,3. Queste evidenziano per la prima volta un andamento non-monotonico della trasmissione EUV in funzione della fluenza, che giudichiamo interpretabile – nell'ambito di un modello a tre canali – come risultante da un effetto di saturazione congiunto ad una variazione della sezione d'urto d'assorbimento dovuta al riscaldamento elettronico. Si mostra come condizioni di ancora più elevata fluenza inducono una trasparenza quasi completa in un campione Al-Mg-Al sull'intero intervallo di energie a cavallo della soglia di assorbimento L2,3 dell'Mg. Viene formulato un modello analitico che, tentativamente, permette di dedurre dai dati una stima per l'energia di prima ionizzazione dell'Mg in condizioni di plasma denso. Le risposte di campioni isolanti e semiconduttori ad eccitazioni FEL e laser - dall'iniziale fase di non-equilibrio, attraverso le successive dinamiche di rilassamento, alle possibili trasformazioni di fase - sono esplorate attraverso misure pump-and-probe. In questo caso, gli impulsi FEL sono sfruttati in combinazione con impulsi dallo stesso laser infrarosso che funge da iniziatore del processo di emissione FEL, il che assicura una naturale sincronizzazione tra le due sorgenti di radiazione, una caratteristica - di nuovo - esclusiva dei FEL seeded. Misure di riflettività ottica transiente su campioni di Si3N4 pompati dal FEL sono offerte come dimostrazione della capacità ad oggi imbattuta di FERMI di offrire una coppia di impulsi laser / FEL praticamente liberi da jitter. Sono discussi i risultati di uno studio sistematico della risposta ottica di questo materiale all'irraggiamento FEL a diverse lunghezze d'onda ed intensità di pump, diverse polarizzazioni di probe, diversi spessori del campione e diversi tipi di substrato, sia in riflessione che in trasmissione simultaneamente. Essi conducono a riconoscere il ruolo giocato da effetti di interferenza a causa delle differenti lunghezze di penetrazione tra impulsi EUV FEL ed infrarossi. Le trasmissioni EUV transienti collezionate per il Ge alla sua soglia M4,5 in una configurazione laser pump / FEL probe e per il Si alla sua soglia L2,3 in una configurazione FEL pump / FEL probe restituiscono una visione risolta sia in tempo che in energia del fenomeno di fusione dei semiconduttori indotto da impulsi al femtosecondo. Mostriamo come sia possibile seguire le dinamiche di eccitazione e diseccitazione della popolazione elettronica nella banda di valenza attraverso dati sotto soglia di assorbimento e come possiamo invece inferire informazioni di dinamica strutturale da dati sulla soglia di assorbimento, negli quali riteniamo di riconoscere l'impronta della chiusura parziale della “band gap” associata alla transizione verso uno stato liquido di aumentato carattere metallico.
XXVI Ciclo
1986

L'orientation des fibres myocardiaque est à la base du comportement électro-mécanique du cœur, et connue pour être altérée dans diverses maladies cardiaques telles que la cardiopathie ischémique et l'hypertrophie ventriculaire. Cette thèse porte principalement sur l'imagerie in vivo du tenseur de diffusion (diffusion tensor imaging—DTI) en vue d’obtenir la structure des fibres myocardiques du cœur humain dans des conditions de respiration libre. L'utilisation de DTI pour l'étude du cœur humain in vivo est un grand défi en raison du mouvement cardiaque. En particulier, l’acquisition DTI avec respiration libre sans recourir au gating respiratoire est très difficile à cause des mouvements à a fois respiratoire et cardiaque. Pour aborder ce problème, nous proposons de nouvelles approches consistant à combiner des acquisitions à retards de déclenchement multiples (trigger delay—TD) et des méthodes de post-traitement. D’abord, nous réalisons des acquisitions avec multiples TD décalés en fin de diastole. Ensuite, nous développons deux méthodes de post-traitement. La première méthode s’attaque au problème d’effets de mouvement physiologique sur DTI cardiaque in vivo en utilisant les techniques de recalage et de PCATMIP (Principal Components Analysis filtering and Temporal Maximum Intensity Projection). La deuxième méthode traite le problème de mouvement par l’utilisation d’un algorithme de fusion d’images basé sur l’ondelette (wavelet-based image fusion-WIF) et d’une technique de débruitage PCA (Principal Components Analysis). Enfin, une comparaison des mesures DTI entre la méthode PCATMIP et la méthode WIF est réalisée ; les champs de tenseurs sont calculés, à partir desquels les propriétés de l’architecture des fibres in vivo sont comparées. Les résultats montrent qu’en utilisant les approches proposées, il est possible d’étudier l’impact du mouvement cardiaque sur les paramètres de tenseur de diffusion, et d’explorer les relations sous-jacentes entre les propriétés de tenseur de diffusion mesurées et le mouvement cardiaque. Nous trouvons aussi que la combinaison des acqusiitions avec des TD multiples décalés and des post-traitements d’images peut compenser les effets de mouvement physiologique, ce qui permet d’obtenir l’architecture 3D du cœur humain dans des conditions de respiration libre. Les résultats suggèrent de nouvelles solutions au problème de perte du signal due au mouvement, qui sont prometteuses pour obtenir les propriétés de l’architecture des fibres myocardiques du cœur humain in vivo, dans des conditions cliniques
The orientation of cardiac fibers underlies the electro-mechanical behavior of the heart, and it is known to be altered in various cardiac diseases such as ischemic heart disease and ventricular hypertrophy. This thesis mainly focuses on in vivo diffusion tensor imaging (DTI) to obtain the myocardial fiber structure of the human heart under free-breathing conditions. The use of DTI for studying the human heart in vivo is challenging due to cardiac motion. In particular, free-breathing DTI acquisition without resorting to respiratory gating is very difficult due to both respiratory and cardiac motion. To deal with this problem, we propose novel approaches that combine multiple shifted trigger delay (TD) acquisitions and post-processing methods. First, we perform multiple shifted TD acquisitions at end diastole. Then, we focus on two different post-processing methods. The first method addresses physiological motion effects on in vivo cardiac DTI using image co-registration and PCATMIP (Principal Components Analysis filtering and Temporal Maximum Intensity Projection). The second method is a wavelet-based image fusion (WIF) algorithm combined with a PCA noise removing method. Finally, a comparison of DTI measurements between the PCATMIP and WIF methods is also performed; tensor fields are calculated, from which the in vivo fiber architecture properties are compared. The results show that using the proposed approaches, we are able to study the cardiac motion effects on diffusion tensor parameters, and investigate the underlying relationship between the measured diffusion tensor properties and the cardiac motion. We also find that the combination of multiple shifted TD acquisitions and dedicated image post-processing can compensate for physiological motion effects, which allows us to obtain 3D fiber architectures of the human heart under free-breathing conditions. The findings suggest new solutions to signal loss problems associated with bulk motion, which are promising for obtaining in vivo human myocardial fiber architecture properties in clinical conditions

This thesis is concerned with the development and application of reliable, creative and efficient computational tools for the analysis and structural optimization of 2D and 3D trusses under static and free vibration conditions and prismatic structures under static and free vibration conditions. The first part of the thesis deals with the analysis and optimization of 2D and 3D trusses under static and free vibration conditions. The second part of the thesis deals with prismatic structures under static and free vibration conditions which are idealised as effectively one-dimensional problems. The procedures used to define the structural shape and incorporating automatic mesh generation are described and the basic formulations of curved, Mindlin-Reissner finite elements and finite strips are presented for prismatic shells. The accuracy of the elements and strips is verified using several benchmark tests. The basic algorithm of structural shape optimization is then presented and several examples are carried out. In both parts the optimization analysis is carried out using two different algorithms: sequential quadratic programming (SQP) and genetic algorithms (GAs). The optimized structures are not checked for buckling. Six main computer FORTRAN programs are developed, documented and tested.

The thesis develops a new model of the small open economy emphasizing financial constraints, based on the notion of liquidity preference as a constraining tendency on the income adjustment process. Preference for liquid assets results in a number of financial states of constraint, such as financial vulnerability, financial exclusion and financial fragility. These are explored in a regional and international context. Openness brings with it new opportunity as well as potential constraints. Models of small open economies have in general assumed away the latter and have neglected the consequences of financial openness. This is reflected in the absence of a means to identify economies as small and open on the basis of their financial exposure. The financial vulnerability index is developed to address this deficit. Applied to twenty-one countries, the index reveals that emerging countries can be classified as small open economies constrained by preference for liquid assets. Policies designed with the conventional approach to constraints in mind appear to be inappropriate for these countries. The concept of constraints has rarely been dealt with explicitly and a possible categorisation of constraints for mainstream and Post Keynesian schools is developed. It proves to be a useful point of entry for grasping ontological differences between schools. It also provides insights into the constraining tendencies facing the small open economy, and how they can be managed. When these insights are applied to the South African economy, the current macroeconomic policy, and critiques thereof, are found to be wanting.

Ce travail de these est consacre a l'application des methodes integrales aux frontieres a la simulation numerique des ecoulements non-lineaires a frontieres libres. Deux principales parties peuvent etre distinguees. L'une, est consacree au probleme de la progression en temps dans le cadre d'une approximation potentielle et plus precisement l'etablissement d'une procedure de suivi d'interfaces fondee sur des schemas explicites d'ordres eleves issus de developpements en serie de taylor. L'autre, propose une methode generale pour resoudre les equations de navier-stokes fondee sur une formulation entierement integrale. Basee sur la decomposition de helmholtz, notre demarche porte sur l'etablissement de conditions aux limites et de projection associees a l'equation de transport du tourbillon. Cette etude met en evidence les avantages d'une formulation integrale qui ne sont pas seulement theoriques et numeriques. Ils apportent en effet un eclairage sur la comprehension des phenomenes de la genese et la propagation de la vorticite.

Published Articles
Increased waste generation and poor waste disposal strategies are a global problem. In South Africa most provinces, and the larger municipalities and metros, seems to have the waste disposal and the landfills reasonably organized. This cannot be said of the landfills in the Free State Province, which could only be called dump sites. In the Free State Province a high unemployment level exists and a lack of finances is experienced by many members of the communities, especially in rural areas. Poverty levels is shown in a study by Adventist Development and Relief Agency (ADRA SA), where it was recorded that 1.8 million (68%) of the people in the Free State Province are living in poverty and living on less than R15 per day. Data on the state of the landfill, types of waste generated which have potential to be recycled, were recorded to assess if recycling could be increased to relieve the economic burden of the poor communities. Attention was paid to the following aspects: assessing the current status of each landfill and identifying the types of waste generated in the area which ended up at the landfills. The extent of recycling and the waste handling and disposal of the waste were recorded. Non-compliance with the prescribed legislative guidelines were noted and aspects such as the state of the landfills, proper enclosure, burning of waste, recycling and products being recycled were identified and recorded. The waste disposal practices at most landfills were poor and very limited recycling was taking place. None of the landfills in the province complied with the minimum requirements for landfilling. Recommendations to improve waste disposal and identification of products with recycling potential were made. Alternative waste strategies which could be economically beneficial for the communities were recommended

Thesis (Ph. D.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains viii, 76 p. : ill. Includes abstract. Includes bibliographical references (p. 72-76).

In this thesis we prove the following: The semigroup which is a disjoint union of two or three copies of a group is a Clifford semigroup, Rees matrix semigroup or a combination between a Rees matrix semigroup and a group. Furthermore, the semigroup which is a disjoint union of finitely many copies of a finitely presented (residually finite) group is finitely presented (residually finite) semigroup. The constructions of the semigroup which is a disjoint union of two copies of the free monogenic semigroup are parallel to the constructions of the semigroup which is a disjoint union of two copies of a group, i.e. such a semigroup is Clifford (strong semilattice of groups) or Rees matrix semigroup. However, the semigroup which is a disjoint union of three copies of the free monogenic semigroup is not just a strong semillatice of semigroups, Rees matrix semigroup or combination between a Rees matrix semigroup and a semigroup, but there are two more semigroups which do not arise from the constructions of the semigroup which is a disjoint union of three copies of a group. We also classify semigroups which are disjoint unions of two or three copies of the free monogenic semigroup. There are three types of semigroups which are unions of two copies of the free monogenic semigroup and nine types of semigroups which are unions of three copies of the free monogenic semigroup. For each type of such semigroups we exhibit a presentation defining semigroups of this type. The semigroup which is a disjoint union of finitely many copies of the free monogenic semigroup is finitely presented, residually finite, hopfian, has soluble word problem and has soluble subsemigroup membership problem.

The recent development of free-electron lasers operating at XUV and X-ray wavelengths are proving vital for the exploration of matter in extreme conditions. The ultra-short pulse length and high peak brightness these light sources provide, combined with a tunable X-ray wavelength range, makes them ideally suited both for creating high energy density samples and for their subsequent study. In this thesis I describe the work done on the XUV free-electron laser FLASH in Hamburg, aimed at creating homogeneous samples of warm dense matter through the process of volumetric XUV photo-absorption, and the theoretical work undertaken to understand the process of high-intensity laser-matter interactions. As a first step, we have successfully demonstrated intensities above 10¹⁷ Wcm-2 at a wavelength of 13.5 nm, by focusing the FEL beam to micron and sub-micron spot sizes by means of a multilayer-coated off-axis parabolic mirror. Using these record high intensities, we have demonstrated for the first time saturable absorption in the XUV. The effect was observed in aluminium and magnesium samples and is due to the bleaching of a core-state absorption channel by the intense radiation field. This result has major implications for the creation of homogeneous high energy density systems, as a saturable absorption channel allows for a more homogeneous heating mechanism than previously thought possible. Further, we have conducted soft X-ray emission spectroscopy measurements which have delivered a wealth of information on the highly photo-excited system under irradiation, immediately after the excitation pulse, yet before the system evolves into the warm dense matter state. Such strongly photo-excited samples have also been studied theoretically, by means of density functional theory coupled to molecular dynamics calculations, yielding detailed electronic structure information. The use of emission spectroscopy as a probe for solid-density and finite-temperature systems is discussed in light of these results. Theoretical efforts have further been made in the study of the free-free absorption of aluminium as the system evolves from the solid state to warm dense matter. We predict an absorption peak in temperature as the system heats and forms a dense plasma. The physical significance of this effect is discussed in terms of intense light-matter interactions on both femtosecond and picosecond time-scales.