Thermal decomposition of solid state compounds of lanthanide and yttrium benzoates in CO2 atmosphere

Solid-state Ln-Bz compounds, where Ln stands for trivalent lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetric and differential thermal analysis in a CO2 atmosphere were used to study the thermal decomposition of these compounds.

Thermal behavior of corn starch granules modified by acid treatment at 30 and 50°C

Unprocessed native starches are structurally too weak and functionally too restricted for application in today's advanced food technologies. Processing is necessary to engender a range of functionality. Naturals or natives starches can be modified by using several methods physical, chemical, enzymatic or combined, according industrial purposes. In this work, native corn starch was hydrolyzed by hydrochloric acid solution and investigated by using thermoanalytical techniques (thermogravimetry - TG, differential thermal analysis - DTA and differential scanning calorimetry - DSC), as well as optical microscopy and X-ray diffractometry. After acid treatment at 30 and 50°C, a decrease of gelatinization enthalpy (ΔHgel) was verified. Optical microscopy and X-ray diffractometry allowed us to verify the granules contorn and rugosity typical of cereal starches.

Thermal and spectral properties of di-and trimethoxybenzoates of silver (I)

The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4- and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3.

Thermal stability and thermal decomposition of sucralose

Several papers have been described on the thermal stability of the sweetener, C12H19Cl3O8 (Sucralose). Nevertheless no study using thermoanalytical techniques was found in the literature. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) and infrared spectroscopy, have been used to study the thermal stability and thermal decomposition of sweetener.

Synthesis, characterization and thermal behaviour of solid 2-methoxycinnamylidenepyruvate of some bivalent metal ions in CO2 and N2 atmospheres

Solid State M-2-MeO-CP compounds, where M stands for bivalent metals (Mn, Fe, Co, Ni, Cu and Zn) and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), elemental analysis and complexometry were used to establish the stoichiometry and to study the thermal behaviour of these compounds in CO2 and N2 atmospheres. The results were consistent with the general formula: M(L)2∙H2O. In both atmospheres (CO2, N2) the thermal decomposition occurs in consecutive steps which are characteristic of each compound. For CO2 atmosphere the final residues were: Mn3O4, Fe3O4, Co3O4, NiO, Cu2O and ZnO, while under N2 atmosphere the thermal decomposition is still observed at 1000 º C.

Thermal behaviour of succinic acid, sodium succinate and its compounds with some bivalent transitions metal ions in dynamic N2 and CO2 atmospheres

Thermal stability and thermal decomposition of succinic acid, sodium succinate and its compounds with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA) in nitrogen and carbon dioxide atmospheres and TG-FTIR in nitrogen atmosphere. On heating, in both atmospheres the succinic acid melt and evaporate, while for the sodium succinate the thermal decomposition occurs with the formation of sodium carbonate. For the transition metal succinates the final residue up to 1180 ºC in N2 atmosphere was a mixture of metal and metal oxide in no simple stoichiometric relation, except for Zn compound, where the residue was a small quantity of carbonaceous residue. For the CO2 atmosphere the final residue up to 980 ºC was: MnO, Fe3O4, CoO, ZnO and mixtures of Ni, NiO and Cu, Cu2O.

Analysis and Control of Excitation, Field Weakening and Stability in Direct Torque Controlled Electrically Excited Synchronous Motor Drives

Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor’s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque reference. This method is however parameter sensitive and requires a safety margin between the theoretical torque maximum and the actual torque limit. The DTC modulation principle allows however a direct load angle adjustment without any current control. In this work a direct load angle control method has been developed. The method keeps the drive stabile and allows the maximal utilisation of the drive without a safety margin in the torque limitation.

COMPARISON OF PROCEDURES FOR IMMEDIATE CHEMICAL ANALYSIS OF CHARCOAL

ABSTRACT The climate change, the quest for sustainability and the strong environmental pressures for alternatives to traditional fossil fuels have increased the interest in the search and use of renewable energy sources. Among them stands out the biomass of charcoal coming from renewable forests, widely used as a thermal reductant in the steel industry in the detriment of the use of mineral coal coke. This study aimed to compare different operating procedures of immediate chemical analysis of charcoal. Seven essays to immediate chemical analysis were compared, spread between procedures performed by Brazilian companies and laboratories, the test described by NBR 8112 and one realized with a thermogravimetric analyzer (TGA) using the parameters of the NBR 8112. There were significant differences in the volatiles matter content and consequently in the fixed carbon contents found. The differences between the procedures and the NBR 8112 were caused by an excess burning time, a mass sample above or below the standard or inappropriate container used for burning. It observed that the TGA appraisal of the volatiles content must be carried out with a burning time equal to 2 minutes to obtain results similar to those of the NBR 8112 norm. Moreover, the ash content values were statistically identical and the particles size did not influence the differences between means.

Computer tools applied to analysis of solar water heaters

The simulation programs are important tools to analyze the different energetic alternatives, including the use of renewable energy. The objective of this study was to analyze comparatively the different computer tools available for modeling of solar water heaters. Among the main simulation software of solar thermal systems, there are: RETScreen International, EnergyPlus, TRNSYS, SolDesigner, SolarPro, e T*SOL. Among the tools mentioned, only EnergyPlus and RETScreen International are free, but they allow obtaining interesting results when applied together. The first one has a detailed module of energy analysis of solar water heaters, while the second one provides an detailed economic feasibility study and an assessment of emissions of greenhouse gases. RETScreen International and EnergyPlus programs are aimed at a diverse audience, including designers, researchers and energy planners.

Integrated multivariate analysis to evaluate effects of pre-slaughter handling on pork quality

The aim of this study was to investigate the effect of pre-slaughter handling on the occurrence of PSE (Pale, Soft, and Exudative) meat in swine slaughtered at a commercial slaughterhouse located in the metropolitan region of Dourados, Mato Grosso do Sul, Brazil. Based on the database (n=1,832 carcasses), it was possible to apply the integrated multivariate analysis for the purpose of identifying, among the selected variables, those of greatest relevance to this study. Results of the Principal Component Analysis showed that the first five components explained 89.28% of total variance. In the Factor Analysis, the first factor represented the thermal stress and fatiguing conditions for swine during pre-slaughter handling. In general, this study indicated the importance of the pre-slaughter handling stages, evidencing those of greatest stress and threat to animal welfare and pork quality, which are transport time, resting period, lairage time before unloading, unloading time, and ambience.

Behavior of chicks subjected to thermal challenge

In the first week of a chick life, broilers are very sensitive to different conditions outside their thermoneutral zone. Thus, the goal of this study was to evaluate the behaviors and productive responses of broilers subjected to conditions of thermal comfort or challenge at different intensities (27, 30, 33 and 36ºC) and durations (1, 2, 3 and 4 days starting on the second day of life). In the experiment, ten minutes of images from each hour of each treatment were analyzed to evaluate the key behaviors of the birds. Similar behavior at different dry-bulb air temperatures were identified by using Ward's method of cluster analysis. These behaviors were grouped by dendograms in which the similarity of these data was qualified. Feed intake, water intake and body mass of these animals were evaluated and used to support the observed behaviors. Thus, a similar huddling behavior was observed in the birds from the 2nd to the 5th day of life subjected to 27ºC and 30ºC, while at 30ºC and 33ºC the behavior of accessing feeders and drinkers was also similar. Chicks subjected to 33ºC presented the best performance, and at 30 and 36ºC showed intermediate development.

Environment in poultry production covered with thermal and aluminum roofing tiles

Brazil is a country of tropical climate, a fact that hinders the poultry production in the aspect of thermal comfort. Thus, we aimed to evaluate the thermal environment in commercial poultry houses with different covers during the months of December 2012 to May 2013, in the municipality of Rio Verde, Goiás. The experimental design was completely randomized in split plots with factorial arrangement of treatments 2x3, being two shed models (thermal and aluminum roof tiles) and three sections within each shed (initial, central and final) for 182 days, having the days as replicates. The thermal environment was assessed through thermal comfort indices: Temperature and Humidity Index, Black Globe Temperature and Humidity Index, Radiant Heat Load and Enthalpy. The data was analyzed by SISVAR 5.1., through the analysis of variance, the Scott Knott test used to compare the means, considering a significance level of 1%. The results showed a significant statistical difference between the sheds and the points assessed (P < 0.05). The thermal shed had the lowest values for the environmental variables (Dbt and Bgt) and thermal indices studied, but larger values for the RH compared to the shed with aluminum covering. The use of thermal covers minimizes the difference in temperature range throughout various times of the day, being at 14:00 o'clock the prominence time to others.

Design of salient pole PM synchronous machines for a vehicle traction application – Analysis and

This doctoral thesis presents a study on the development of a liquid-cooled frame salient pole permanent-magnet-exited traction machine for a four-wheel-driven electric car. The emphasis of the thesis is put on a radial flux machine design in order to achieve a light-weight machine structure for traction applications. The design features combine electromagnetic and thermal design methods, because traction machine operation does not have a strict operating point. Arbitrary load cycles and the flexible supply require special attention in the design process. It is shown that accurate modelling of the machine magnetic state is essential for high-performance operation. The saturation effect related to the cross-saturation has to be taken carefully into account in order to achieve the desired operation. Two prototype machines have been designed and built for testing: one totally enclosed machine with a special magnet module pole arrangement and another through-ventilated machine with a more traditional embedded magnet structure. Both structures are built with magnetically salient structures in order to increase the torque production capability with the reluctance torque component. Both machine structures show potential for traction usage. However, the traditional embedded magnet design turns out to be mechanically the more secure one of these two machine options.

Conservative Treatment of Stress Urinary Incontinence: A Systematic Review with Meta-analysis of Randomized Controlled Trials

We performed a systematic review and meta-analysis of randomized controlled trials that studied the conservative management of stress urinary incontinence (SUI). There were 1058 results after the initial searches, from which 37 studies were eligible according to previously determined inclusion criteria. For the primary outcomes, pelvic floor muscle training (PFMT) was more efficacious than no treatment in improving incontinence-specific quality of life (QoL) scales (SMD = [1]1.24SDs; CI 95% = [1]1.77 to [1]0.71SDs). However, its effect on pad tests was imprecise. Combining biofeedback with PFMT had an uncertain effect on QoL (MD = [1]4.4 points; CI 95% = [1]16.69 to 7.89 points), but better results on the pad test, although with elevated heterogeneity (MD = 0.9g; 95%CI = 0.71 to 1,10g); group PFMT was not less efficacious than individual treatment, and home PFMT was not consistently worse than supervised PFMT. Both intravaginal and superficial electrical stimulation (IES and SES) were better than no treatment for QoL and pad test. Vaginal cones had mixed results. The association of IES with PFMT may improve the efficacy of the latter for QoL and pad test, but the results of individual studies were not consistent. Thus, there is evidence of the use of PFMT on the treatment of SUI, with and without biofeedback.

Analysis of emergency braking performance with particular consideration of temperature effects on brakes

During vehicle deceleration due to braking there is friction between the lining surface and the brake drum or disc. In this process the kinetic energy of vehicle is turned into thermal energy that raises temperature of the components. The heating of the brake system in the course of braking is a great problem, because besides damaging the system, it may also affect the wheel and tire, which can cause accidents. In search of the best configuration that considers the true conditions of use, without passing the safety limits, models and formulations are presented with respect to the brake system, considering different braking conditions and kinds of brakes. Some modeling was analyzed using well-known methods. The flat plate model considering energy conservation was applied to a bus, using for this a computer program. The vehicle is simulated to undergo an emergency braking, considering the change of temperature on the lining-drum. The results include deceleration, braking efficiency, wheel resistance, normal reaction on the tires and the coefficient of adhesion. Some of the results were compared with dynamometer tests made by FRAS-LE and others were compared with track tests made by Mercedes-Benz. The convergence between the results and the tests is sufficient to validate the mathematical model. The computer program makes it possible to simulate the brake system performance in the vehicle. It assists the designer during the development phase and reduces track tests.