886 resultados para Resonant Frequency.
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The intensity, duration, and frequency relationship (IDF) of rainfall occurrence may be done through continuous records of pluviographs or daily pluviometer values . The objective of this study was to estimate the intensity-duration-frequency relationships of precipitation, using the method of daily rainfall disaggregation, at weather stations located to the southern half of the state of Rio Grande do Sul; comparing them with those obtained by rain gauge records, in places considered homogeneous from the meteorological point of view. The IDF equation parameters were estimated from daily rainfall disaggregation data, using the method of nonlinear optimization. To validate the equations confidence indices and efficiency and the "t" Student test, among maximum intensity values obtained from the disaggregated daily rainfall durations of 10; 30; 60 min and 6; 12 and 24 h and those extracted from existing IDF equations. For all studied stations and return periods, the trust index values were regarded as "optimal", i.e., greater than 0.85. The maximal intensity of rainfall obtained by daily rainfall disaggregation have similarity with those obtained by relations IDF standards. Thus, the method constitutes a feasible alternative in obtaining the IDF relationships.
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Due to the lack of information concerning maximum rainfall equations for most locations in Mato Grosso do Sul State, the alternative for carrying out hydraulic work projects has been information from meteorological stations closest to the location in which the project is carried out. Alternative methods, such as 24 hours rain disaggregation method from rainfall data due to greater availability of stations and longer observations can work. Based on this approach, the objective of this study was to estimate maximum rainfall equations for Mato Grosso do Sul State by adjusting the 24 hours rain disaggregation method, depending on data obtained from rain gauge stations from Dourado and Campo Grande. For this purpose, data consisting of 105 rainfall stations were used, which are available in the ANA (Water Resources Management National Agency) database. Based on the results we concluded: the intense rainfall equations obtained by pluviogram analysis showed determination coefficient above 99%; and the performance of 24 hours rain disaggregation method was classified as excellent, based on relative average error WILMOTT concordance index (1982).
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ABSTRACTObjective:to compare the frequency and the severity of diagnosed injuries between pedestrians struck by motor vehicles and victims of other blunt trauma mechanisms.Methods:retrospective analysis of data from the Trauma Registry, including adult blunt trauma patients admitted from 2008 to 2010. We reviewed the mechanism of trauma, vital signs on admission and the injuries identified. Severity stratification was carried using RTS, AIS-90, ISS e TRISS. Patients were assigned into group A (pedestrians struck by motor vehicle) or B (victims of other mechanisms of blunt trauma). Variables were compared between groups. We considered p<0.05 as significant.Results:a total of 5785 cases were included, and 1217 (21,0%) of which were in group A. Pedestrians struck by vehicles presented (p<0.05) higher mean age, mean heart rate upon admission, mean ISS and mean AIS in head, thorax, abdomen and extremities, as well as lower mean Glasgow coma scale, arterial blood pressure upon admission, RTS and TRISS. They also had a higher frequency of epidural hematomas, subdural hematomas, subarachnoid hemorrhage, brain swelling, cerebral contusions, costal fractures, pneumothorax, flail chest, pulmonary contusions, as well as pelvic, superior limbs and inferior limbs fractures.Conclusion:pedestrian struck by vehicles sustained intracranial, thoracic, abdominal and extremity injuries more frequently than victims of other blunt trauma mechanism as a group. They also presented worse physiologic and anatomic severity of the trauma.
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In this doctoral thesis, a power conversion unit for a 10 kWsolid oxide fuel cell is modeled, and a suitable control system is designed. The need for research was identified based on an observation that there was no information available about the characteristics of the solid oxide fuel cell from the perspective of power electronics and the control system, and suitable control methods had not previously been studied in the literature. In addition, because of the digital implementation of the control system, the inherent characteristics of the digital system had to be taken into account in the characteristics of the solid oxide fuel cell (SOFC). The characteristics of the solid oxide fuel cell as well the methods for the modeling and control of the DC/DC converter and the grid converter are studied by a literature survey. Based on the survey, the characteristics of the SOFC as an electrical power source are identified, and a solution to the interfacing of the SOFC in distributed generation is proposed. A mathematical model of the power conversion unit is provided, and the control design for the DC/DC converter and the grid converter is made based on the proposed interfacing solution. The limit cycling phenomenon is identified as a source of low-frequency current ripple, which is found to be insignificant when connected to a grid-tied converter. A method to mitigate a second harmonic originating from the grid interface is proposed, and practical considerations of the operation with the solid oxide fuel cell plant are presented. At the theoretical level, the thesis discusses and summarizes the methods to successfully derive a model for a DC/DC converter, a grid converter, and a power conversion unit. The results of this doctoral thesis can also be used in other applications, and the models and methods can be adopted to similar applications such as photovoltaic systems. When comparing the results with the objectives of the doctoral thesis, we may conclude that the objectives set for the work are met. In this doctoral thesis, theoretical and practical guidelines are presented for the successful control design to connect a SOFC-based distributed generation plant to the utility grid.
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PURPOSE: To evaluate the frequency of fear of needles and the impact of a multidisciplinary educational program in women with pre-gestational and gestational diabetes taking insulin during pregnancy. METHODS: The short Diabetes Fear of Injecting and Self-testing Questionnaire (D-FISQ), composed by two subscales that access fear of self injection (FSI) and fear of self testing (FST), was administered twice during pregnancy to 65 pregnant women with pre-gestational and gestational diabetes: at the first endocrine consult and within the last two weeks of pregnancy or postpartum. An organized multidisciplinary program provided diabetes education during pregnancy. Statistical analysis was carried out by Wilcoxon and McNemar tests and Spearman correlation. A p<0.05 was considered to be significant. RESULTS: Data from the short D-FISQ questionnaire shows that 43.1% of pregnant women were afraid of needles in the first evaluation. There was a significant reduction in scores for FSI and FST subscales between the first and second assessments (first FSI 38.5% compared with second 12.7%, p=0.001; first FST 27.7% compared with second FST 14.3%, p=0.012). CONCLUSIONS: The fear of needles is common in pregnant women on insulin therapy and an organized multidisciplinary educational diabetes program applied during pregnancy reduces scores of such fear.
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Transportation of fluids is one of the most common and energy intensive processes in the industrial and HVAC sectors. Pumping systems are frequently subject to engineering malpractice when dimensioned, which can lead to poor operational efficiency. Moreover, pump monitoring requires dedicated measuring equipment, which imply costly investments. Inefficient pump operation and improper maintenance can increase energy costs substantially and even lead to pump failure. A centrifugal pump is commonly driven by an induction motor. Driving the induction motor with a frequency converter can diminish energy consumption in pump drives and provide better control of a process. In addition, induction machine signals can also be estimated by modern frequency converters, dispensing with the use of sensors. If the estimates are accurate enough, a pump can be modelled and integrated into the frequency converter control scheme. This can open the possibility of joint motor and pump monitoring and diagnostics, thereby allowing the detection of reliability-reducing operating states that can lead to additional maintenance costs. The goal of this work is to study the accuracy of rotational speed, torque and shaft power estimates calculated by a frequency converter. Laboratory tests were performed in order to observe estimate behaviour in both steady-state and transient operation. An induction machine driven by a vector-controlled frequency converter, coupled with another induction machine acting as load was used in the tests. The estimated quantities were obtained through the frequency converter’s Trend Recorder software. A high-precision, HBM T12 torque-speed transducer was used to measure the actual values of the aforementioned variables. The effect of the flux optimization energy saving feature on the estimate quality was also studied. A processing function was developed in MATLAB for comparison of the obtained data. The obtained results confirm the suitability of this particular converter to provide accurate enough estimates for pumping applications.
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Tämän pro gradu– tutkielman tavoitteena oli testata täytettyjen taukojen (er ja erm) esiintymistiheyttä, sijaintia kieliopillisessa rakenteessa sekä funktioita Kjellmerin (2003) korpus-tutkimuksessa. Materiaalina käytin viiden yhdysvaltalaisen poliitikon puhetta keskusteluohjelmasta Larry King Live. Tutkimuksessani sovelsin Kjellmerin tutkimusmenetelmiä, joita muokkasin huomattavasti suppeampaan materiaaliini sopiviksi. Lähestymistapani oli täten induktiivinen toisin kuin testatussa tutkimuksessa. Materiaalini oli tarkoituksellisesti rajattu, sillä halusin selvittää, kuvaavatko Kjellmerin laajaan materiaaliin perustuvat tutkimustulokset myös täytettyjen taukojen käyttöä suppeammassa materiaalissa. Materiaalini (kokonaisuudessaan 101 minuuttia) transkriboin ortografisesti. Analyysissäni arvioin täytettyjen taukojen esiintymistiheyden puhujakohtaisesti ja koko ryhmälle suhteuttamalla täytettyjen taukojen lukumäärän kokonaissanamäärään. Tämän jälkeen tein perinteisen kielioppianalyysin rakenteista, joita edeltää tai joissa esiintyy täytetty tauko, ja täytettyjen taukojen sijainnin perusteella luokittelin ne sana-, lauseke-, ja lausetasolle. Lopuksi analysoin täytettyjen taukojen käyttöä soveltaen Kjellmerin ehdottamia funktioita (hesitaatio, vuorottelujäsennyksen merkitseminen, huomion herättäminen ja kontaktin luominen, korostus ja korjaus) ja niiden piirteitä omaan materiaaliini. Tutkimukseni perusteella täytetyt tauot esiintyvät tutkitun viiden poliitikon puheessa suhteellisen usein. Puhujakohtaiset eroavaisuudet olivat kuitenkin huomattavat. Kieliopillisen luokitteluni mukaan sana-, lauseke- ja lausetasot eivät täysin kuvaa täytettyjen taukojen sijoittumista, sillä täytetyt tauot edelsivät mm. määre-lauseita, jotka eivät vastaa lausetasoa englannin kielessä. Materiaalini funktioanalyysi osoitti, että täytetyt tauot yleensä vastaavat yhtä tai useampaa Kjellmerin ehdottamaa funktioita. Lisäksi tutkimukseni mukaan täytetyillä tauoilla on ainakin yksi rakenteellinen funktio. Analyysini perusteella Kjellmerin tutkimustulokset ovat siis pääosin sovellettavissa suppeampaan materiaaliin. Puutteiksi hänen tutkimuksessaan osoittautuivat funktioanalyysille tärkeän kontekstuaalisen informaation puute sekä keskittyminen täytettyihin taukoihin, jotka esiintyvät vain tietyissä kielioppirakenteissa. Yleisesti voin tutkimukseni pohjalta todeta, että täytetyt tauot ovat vielä vajaasti tunnettuja ja että kieliopillisen sijoituksen ja funktioiden lisätutkimus on tarpeellista.
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A case-control study was carried out in litters of 1 to 7-day-old piglets to identify the main infectious agents involved with neonatal diarrhea in pigs. Fecal samples (n=276) from piglets were collected on pig farms in the State of Rio Grande do Sul, Brazil, from May to September 2007. Litters with diarrhea were considered cases (n=129) and normal litters (n=147) controls. The samples were examined by latex agglutination test, PAGE, conventional isolating techniques, ELISA, PCR, and microscopic methods in order to detect rotavirus, bacterial pathogens (Escherichia coli, Clostridium perfringens type A and C, and Clostridium difficile), and parasites (Coccidian and Cryptosporidium spp.). Outbreaks of diarrhea were not observed during sampling. At least one agent was detected in fecal samples on 25 out of 28 farms (89.3%) and in 16 farms (57.1%) more than one agent was found. The main agents diagnosed were Coccidia (42.86%) and rotavirus (39.29%). The main agents identified in litters with diarrhea were Clostridium difficile (10.6%), Clostridium perfringens type A (8.8%) and rotavirus (7.5%); in control litters, Clostridium difficile (16.6%) and Coccidian (8.5%). Beta hemolytic Escherichia coli and Clostridium perfringens type C were not detected. When compared with controls, no agent was significantly associated with diarrhea in case litters. These findings stress the need for caution in the interpretation of laboratorial diagnosis of mild diarrhea in neonatal pigs, as the sole detection of an agent does not necessarily indicate that it is the cause of the problem.
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The study aimed to evaluate the risk factors associated with the frequency of IgG antibodies against Babesia bovis and B. bigemina in cattle in southern Mozambique. Eight hundred and nine serum samples were collected from cattle in three provinces namely Maputo, Gaza and Inhambane, and tested by indirect enzyme-linked immunosorbent assay (i-ELISA) to assess the humoral immune response towards B. bovis and B. bigemina. The chi-square test at 5% significance was used to determine whether there was an association between gender, age and geographic origin of seropositive animals. The overall prevalence was 78.8% (548/695) for B. bovis and 76.0% (528/695) for B. bigemina. The origin of the animals showed a significant association (p<0.05) with seropositivity to both agents, while gender and age was not associated (p>0.05). Maputo province had the highest rate of positive animals, with 93.7% (118/126) for B. bovis and 97.6% (123/126) for B. bigemina. In Gaza province 77.3% (321/415) of the animals were positive for B. bovis and 67.5% (280/415) for B. bigemina, while in the province of Inhambane the levels of seropositivity were 70.8% (109/154) and 81.2% (125/154) for B. bovis and B. bigemina respectively. In the present study, the frequency of cattle positive for B. bovis and B. bigemina was shown to increase among older age groups, suggesting that infection and re-infection persisted even after the primary infection. Thus, this region is considered to be in a state of enzootic stability with regards to B. bovis and B. bigemina.
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Leptospirosis is a worldwide anthropozoonosis that infects livestock, including sheep as the carriers to other animals and humans. The present study aimed to determine the prevalence of Leptospira spp. in sheep from two slaughterhouses in the state of São Paulo, Brazil and its association with epidemiological variables. Serum samples from 182 sheep were evaluated for Leptospira spp. antibodies by microscopic agglutination test (MAT). Results indicated 34/182 (18.68%; CI95% 13.70-24.98%) positive serum samples, mainly to the serovar Copenhageni (17/34; 50%; CI95% 33.99-66.01%). Bacterial growth in the Fletcher medium was detected for 13/34 (38.24%; CI95% 23.87-55.08%) animals, and confirmed by Polymerase Chain Reaction (PCR) and sequencing for only two kidney samples from two animals. Thus, treatment and vaccination of sheep, besides rodent control, can be useful to prevent the infection in the studied region since sheep are important Leptospira spp. carriers, and its transmission to slaughterhouse workers is mainly through the manipulation of visceral tissues.
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Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, an obligate intracellular parasite protozoan. A large percentage of animals presents specific antibodies caused by a previous exposition, resulting in a chronic infection. Felides are the definitive hosts and the other warm-blooded animals, including primates, are the intermediate hosts. This study was aimed to determine the prevalence of T. gondii infection in free-living tufted capuchin monkeys (Cebus apella nigritus) from an ecological station located on Mata de Santa Teresa, Ribeirão Preto, SP, Brazil. T. gondii antibodies were analyzed by modified agglutination test (MAT) in serum samples of 36 tufted capuchin monkeys, considering eight as cut-off titer. From the studied animals, 3/36 (8.33%; CI95% 3.0-21.9%) presented T. gondii antibodies, all with titer 32. No significative difference was observed relating to the sex (1/3 male and 2/3 female), and to the age (1/3 young and 2/3 adult) (P>0.05). Thus, these results demonstrate the presence of T. gondii antibodies in primates from São Paulo state.
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From a cross-sectional observational study with convenience samples, 347 blood samples from horses were collected from different physiographic regions, as follows: Santa Catarina Plateau (Santa Catarina State - SC), Médio Paraíba do Sul (São Paulo State - SP and Rio de Janeiro State RJ), Mountainous and Metropolitan regions (Rio de Janeiro State - RJ). Samples were tested for the presence of antibodies (IgG) anti Neorickettsia risticii by indirect immunofluorescence assay (IFA). The frequency obtained in this study corroborates with the ones obtained in the U.S.A., which refers to endemic regions. Fisher's exact test showed significant differences in the number of positive animals between regions, indicating that the probability of an animal becoming infected varies depending on the area. The CI 95% revealed no association between infection and geopolitical space. Moreover, Odds ratio test showed differences of an animal getting infected in different regions. This event could be influenced by the type of treatment used in each area, as the seasonal frequency of injury or even potential vectors. Therefore, there are seropositive animals for N. risticii in the studied areas, suggesting that this agent may be circulating in those regions. Future studies mainly based on molecular analyzes are needed to confirm these serological findings.
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This paper investigates defect detection methodologies for rolling element bearings through vibration analysis. Specifically, the utility of a new signal processing scheme combining the High Frequency Resonance Technique (HFRT) and Adaptive Line Enhancer (ALE) is investigated. The accelerometer is used to acquire data for this analysis, and experimental results have been obtained for outer race defects. Results show the potential effectiveness of the signal processing technique to determine both the severity and location of a defect. The HFRT utilizes the fact that much of the energy resulting from a defect impact manifests itself in the higher resonant frequencies of a system. Demodulation of these frequency bands through use of the envelope technique is then employed to gain further insight into the nature of the defect while further increasing the signal to noise ratio. If periodic, the defect frequency is then present in the spectra of the enveloped signal. The ALE is used to enhance the envelope spectrum by reducing the broadband noise. It provides an enhanced envelope spectrum with clear peaks at the harmonics of a characteristic defect frequency. It is implemented by using a delayed version of the signal and the signal itself to decorrelate the wideband noise. This noise is then rejected by the adaptive filter that is based upon the periodic information in the signal. Results have been obtained for outer race defects. They show the effectiveness of the methodology to determine both the severity and location of a defect. In two instances, a linear relationship between signal characteristics and defect size is indicated.
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This paper describes an electronic transducer for multiphase flow measurement. Its high sensitivity, good signal to noise ratio and accuracy are achieved through an electrical impedance sensor with a special guard technique. The transducer consists of a wide bandwidth and high slew rate differentiator where the lead inductance and stray capacitance effects are compensated. The sensor edge effect is eliminated by using a guard electrode based on the virtual ground potential of the operational amplifier. A theoretical modeling and a calibration method are also presented. The results obtained seem to confirm the validity of the proposed technique.
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The nonlinear interaction between Görtler vortices (GV) and three-dimensional Tollmien-Schlichting (TS) waves nonlinear interaction is studied with a spatial, nonparallel model based on the Parabolized Stability Equations (PSE). In this investigation the effect of TS wave frequency on the nonlinear interaction is studied. As verified in previous investigations using the same numerical model, the relative amplitudes and growth rates are the dominant parameters in GV/TS wave interaction. In this sense, the wave frequency influence is important in defining the streamwise distance traveled by the disturbances in the unstable region of the stability diagram and in defining the amplification rates that they go through.