346 resultados para Multiplier
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Traditional rectifier circuit can convert AC to DC, but some disadvantages can't be avoided, such as small output current, high power consumption, low conversion efficiency. This paper designs a new type of rectifier voltage-multiplier circuit named MR MOS circuit. It uses a low let-through resistance MOS tube to replace the conventional rectifier diode, and adds the voltage-multiplying factor to the synchronous input port. Therefore, it can improve the rectifier effect and increase the output voltage. By the simulation result of Synopsys Saber Platform, it shows that the new type circuit can implement the rectification and voltage-multiplying by the simulating output pulse voltage of nano fiber made in Deakin University as the source of excitation. It can provide the basic theoretical of the piezoelectric energy harvester (PEH) development, and has certain reference significance to the development of piezoelectricity technology. © (2014) Trans Tech Publications.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A low-voltage, low-power four-quadrant analog multiplier with optimized current-efficiency is presented. Its core corresponds to a pseudodifferential cascode, gain-boosting triode-transconductor. According to a low-voltage 1.2μm CMOS n-well process, operand differential-amplitudes are 1.0Vpp and 0.32Vpp for a 1.3V-supply. Common-mode voltages are properly chosen to maximize current-efficiency to 58%. Total quiescent dissipation is 260μW. A range of PSPICE simulation supports theoretical analysis. Excellent linearity is observed on dc characteristic. Assuming a ±0.5% mismatch on (W/L) and VTH THD at full-scale is 0.93% and 1.42%, for output frequencies of 1MHz and 10MHz, respectively.
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Background: The Swiss pig population enjoys a favourable health situation. To further promote this, the Pig Health Service (PHS) conducts a surveillance program in affiliated herds: closed multiplier herds with the highest PHS-health and hygiene status have to be free from swine dysentery and progressive atrophic rhinitis and are clinically examined four times a year, including laboratory testing. Besides, four batches of pigs per year are fattened together with pigs from other herds and checked for typical symptoms (monitored fattening groups (MF)). While costly and laborious, little was known about the effectiveness of the surveillance to detect an infection in a herd. Therefore, the sensitivity of the surveillance for progressive atrophic rhinitis and swine dysentery at herd level was assessed using scenario tree modelling, a method well established at national level. Furthermore, its costs and the time until an infection would be detected were estimated, with the final aim of yielding suggestions how to optimize surveillance. Results: For swine dysentery, the median annual surveillance sensitivity was 96.7 %, mean time to detection 4.4 months, and total annual costs 1022.20 Euro/herd. The median component sensitivity of active sampling was between 62.5 and 77.0 %, that of a MF between 7.2 and 12.7 %. For progressive atrophic rhinitis, the median surveillance sensitivity was 99.4 %, mean time to detection 3.1 months and total annual costs 842.20 Euro. The median component sensitivity of active sampling was 81.7 %, that of a MF between 19.4 and 38.6 %. Conclusions: Results indicate that total sensitivity for both diseases is high, while time to detection could be a risk in herds with frequent pig trade. From all components, active sampling had the highest contribution to the surveillance sensitivity, whereas that of MF was very low. To increase efficiency, active sampling should be intensified (more animals sampled) and MF abandoned. This would significantly improve sensitivity and time to detection at comparable or lower costs. The method of scenario tree modelling proved useful to assess the efficiency of surveillance at herd level. Its versatility allows adjustment to all kinds of surveillance scenarios to optimize sensitivity, time to detection and/or costs.
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OBJECTIVE: This research was aimed to determine the occurrence of Brachyspira (B.) hyodysenteriae in Swiss multiplier pig herds. MATERIALS AND METHODS: In a pilot study a direct real-time polymerase chain reaction (PCR) method for B. hyodysenteriae was compared to culture followed by PCR on 106 samples from three herds. Subsequently 40 multiplier herds were epidemiologically characterized and analysed for the presence of B. hyodysenteriae using direct PCR on 1412 rectal swabs. For external validation 20 swabs obtained from two positive conventional herds were analysed. RESULTS: The comparison of direct PCR with culture followed by PCR resulted in a moderate agreement (kappa index: 0.58). In the two conventional herds, 35% of the samples (7/20) tested positive. Samples from 39 multipliers tested negative. In one multiplier herd, 25% (9/36) of the samples tested PCR positive. Risk factors in the multiplier herd may have been rodents or birds, but not pig purchase. CONCLUSION AND CLINICAL RELEVANCE: B. hyodysenteriae have been detected in a Swiss multiplier herd, which underlines the threat of potential spread by replacement pigs. Consequently, a Brachyspira monitoring programme was established for Swiss multiplier herds.
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Includes bibliography.
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Mode of access: Internet.
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Bibliographical footnotes.
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"UIUCDCS-R-74-640"
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Supported in part by: Atomic Energy Commission contract no. AT (11-1)-415.
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Bibliography: p. 31.
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Includes bibliographical references.
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Datos de ed. preceden a la mención de tomo.
