No description available.

A study was conducted to investigate and compare the nutritional status and physical work performance of children of Brazilian migrant agricultural workers with Brazilian children from wel1-to-do backgrounds. The relationship between nutritional status and physical work performance was also investigated. Dietary analysis was conducted using the 24-hour diet recall method. Evidence was found that intakes of energy, calcium, thiamin, riboflavin, niacin, and vitamin C may have been inadequate among migrant worker children. Their diet was generally monotonous and consisted mainly of rice, beans, and coffee with sugar. Diets of well-to-do children were considerably more varied with good representation from all major food groups. Anthropometric assessment indicated that migrant worker children had values for weight and triceps skinfold thickness that were low compared to American standards. Values for height, arm circumference, and arm muscle circumference were average compared to American standards. Well-to-do children exceeded American standards for all anthropometric parameters measured. Biochemical investigations of protein and iron status were also conducted. Serum total protein and albumin levels were normal in most subjects in both groups. However, many migrant worker, children had low values for hematocrit, serum iron, and transferrin saturation. Most well-to-do children had normal values for these parameters. Hemoglobin levels were adequate in most subjects. Physical work performance was found to be impaired in migrant worker children. Exercise heart rates and post-exercise blood lactic acid levels in response to a standardized bicycle-ergometer work test were significantly higher in migrant worker compared to wel1-to-do children. In addition, a significant correlation was found between anthropometric indicators of nutritional status and parameters of physical work performance. Finally, socio-economic and ecological assessment indicated that the living conditions of migrant worker children were impoverished and unsanitary. This probably aggravated health problems such as infections that were found to occur among these children. Well-to-do children did not share these conditions. / Land and Food Systems, Faculty of / Graduate

The growing shares of renewable energy sources in the market and solar thermal power applications have set higher requirements on steam turbine operation.These requirements are related to flexibility during transients. A key aspect sought of such flexibility is the capability for fast starts. Due to the varying temperature gradients during start-up, the speed at which the turbine can start is constrained by thermal stresses and differential expansion. These phenomena either consume component lifetime or may result in machine failure if not carefully controlled. In order to accomplish faster starts while ensuring that lifing requirements are preserved, it is important to analyze the thermal behavior of the machine. For this, a transient thermal model was developed with a focus on adaptability to different turbine sizes and geometries. The model allows for simple and fast prediction of thermo-mechanical properties within the turbine metal, more importantly, of the temperature distribution and the associated thermal expansion. The next step of this work was to validate the assumptions and simplifications of the model. This was done through the study and comparison of two turbines against measured operational data from their respective power plants. Furthermore,validation studies also included comparisons concerning the geometric detail level of the model. Overall, comparison results showed a large degree of agreement with respect to the measured data and between the geometric detail levels. The validated model was then implemented in studies related to reducing start-up times and peak differential expansion. For this, the potential effects of turbine temperature maintaining modifications were investigated and quantified.The modifications studied included: increasing gland steam pressure, increasing back pressure and increasing barring speed. Results yielded significant improvements starting from 9.5% in the start-up times and 7% in the differential expansion. / <p>QC 20141128</p>

For a long time voltage spikes has been seen in measurement data from accelerator magnets during current ramps. These has been believed to be caused by movements, but has never before been studied in depth. The purpose of this thesis is therefore to prove, or disprove, that these events are caused by movements and to analyse what kind of displacements that actually occur. Measurement data from coil voltage, magnetic pick-up coils and current during transients has been acquired and analysed for the Nb3Sn-dipole magnets FRESCA2 and 11T models—named MBHSP107 and MBHSP109. The measurement data is compared to movement simulations that was done with the ROXIE-program, which is used to calculate mutual inductance change for a number of different movement types. The study strongly suggests that the transients are caused by movements, and also indicates that the maximal length of a single slip-stick motion can be up to around 10 micrometers, mostly in the direction of the magnet’s internal forces. The study has proven that transients in measurement data occur due to coil movements, and that these can be quantified—a discovery that can possibly affect future construction and design of accelerator magnets.

This thesis presents the theory, analysis, testing and implementation of a scheme to reduce shunt compensation capacitor switching transients. The described method is switch the capacitors very near the instant when the bus voltage is at a power frequency zero. This was accomplished with a vacuum breaker on a 230 kV shunt capacitor bank.

This thesis is an introduction to the solution of electromagnetic transients by a combination of the Bergeran method of characteristics and the application of trapezoidal rule of integration. Three test examples solved by digital computer illustrate the step by step solution and computer programming. To compare this method with the Laplace transformation technique, a test problem solved by both methods and also digital computer is illustrated. In conclusion, the advantages and disadvantages of both methods are compared

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19288号 / 工博第4085号 / 新制||工||1630(附属図書館) / 32290 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 細田 尚, 教授 戸田 圭一, 教授 後藤 仁志 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

A methodology to obtain design guidelines for gate oxide input pin protection and high voltage output pin protection in Electrostatic Discharge (ESD) time frame is developed through measurements and Technology Computer Aided Design (TCAD). A set of parameters based on transient measurements are used to define Transient Safe Operating Area (TSOA). The parameters are then used to assess effectiveness of protection devices for output and input pins. The methodology for input pins includes establishing ESD design targets under Charged Device Model (CDM) type stress in low voltage MOS inputs. The methodology for output pins includes defining ESD design targets under Human Metal Model (HMM) type stress in high voltage Laterally Diffused MOS (LDMOS) outputs. First, the assessment of standalone LDMOS robustness is performed, followed by establishment of protection design guidelines. Secondly, standalone clamp HMM robustness is evaluated and a prediction methodology for HMM type stress is developed based on standardized testing. Finally, LDMOS and protection clamp parallel protection conditions are identified

Load transients are prevalent in every electronic device including semiconductor memory, card readers, microprocessors, disc drives, piezoelectric devices, and digitally based systems. They are capable of producing voltage stress, introducing noise, and degrading device functionality. In order to avoid damage to the device, a feedback control loop is implemented with system compensation to regulate the output voltage deviations by the converter. Because designing compensation networks can be rather complicated, DC-DC converters with integrated feedback control topologies help minimize design time and complexity of converter compensation at the expense of design flexibility. This thesis widens the limitations of an integrated DC-DC converter with a stability optimization technique that utilizes the feedback network to create a phase boost centered at the bandwidth of the converter to increase the phase margin and improve its transient response. Ideal modeling verifies stability optimization while non-ideal modeling that introduces PCB parasitics to the control loop suggest an additional phase boost in the feedback network. Experimental data confirms this non-deal model for parasitic capacitances higher than calculated. The modified non-ideal model shows more accuracy compared to the experimental data which indicates that there may be PCB parasitics that is unaccounted for. Modeling the modified non-ideal model to high orders may yield more accuracy. This thesis gives both DC-DC converter and PCB layout designers insight and considerations into PCB effects on the stability of DC-DC converters and the optimization of integrated compensation.

This thesis primarily focuses on studying the impact of Distributed Generation (DG) on the electromechanical transients in the electric grid (distribution, transmission or combined transmission and distribution (TandD) systems) using a Three Phase Dynamics Analyzer (hereafter referred to as TPDA). TPDA includes dynamic models for electric machines, their controllers, and a three-phase model of the electric grid, and performs three-phase dynamic simulations without assuming a positive sequence network model. As a result, TPDA can be used for more accurate investigation of electromechanical transients in the electric grid in the presence of imbalances. At present, the Electromagnetic Transient Program (EMTP) software can be used to perform three-phase dynamic simulations. This software models the differential equations of the entire electric network along with those of the machines. This calls for solving differential equations with time constants in the order of milliseconds (representing the fast electric network) in tandem with differential equations with time constants in the order of seconds (representing the slower electromechanical machines). This results in a stiff set of differential equations, making such an analysis extremely time consuming. For the purpose of electromechanical transient analysis, TPDA exploits the difference in the order of time constants and adopts phasor analysis of the electric network, solving differential equations only for the equipment whose dynamics are much slower than those of the electric network. Power Flow equations are solved using a graph trace analysis based approach which, along with the explicit partitioned method adopted in TPDA, can eventually lead to the use of distributed computing that will further enhance the speed of TPDA and perhaps enable it to perform dynamic simulation in real time . In the work presented here, first an overview of the methodology behind TPDA is provided. A description of the object oriented implementation of TPDA in C++/C# is included. Subsequently, TPDA is shown to accurately simulate power system dynamics of balanced networks by comparing its results against those obtained using GE-PSLF®. This is followed by an analysis that demonstrates the advantages of using TPDA by highlighting the differences in results when the same problem is analyzed using a three-phase network model with unbalances and the positive sequence network model as used in GE-PSLF®. Finally, the impact of rapidly varying DG generation is analyzed, and it is shown that as the penetration level of DG increases, the current and voltage oscillations throughout the transmission network increase as well. Further, rotor speed deviations are shown to grow proportionally with increasing DG penetration. / Master of Science