Browsing by Subject "MIXER"
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Item An investigation of effects of flow conditioning on straight tube Coriolis meter(2009-05-15) Shukla, ShashankCoriolis meter, despite being very accurate in single phase conditions, fails to accurately measure two-phase flows. It poses a complex fluid-structure interaction problem in case of two-phase operation; there is a scarcity of theoretical models available to predict the errors reported by Coriolis meter in aforementioned conditions, hence the need for experimental research. Experiments are conducted in both single and two-phase flow conditions. Meter accuracy is excellent in single phase conditions and no significant effect is observed on use of flow conditioners, namely inlet swirl and inline mixer. Operational two-phase envelope is determined through experiments at different flowrates. Flow conditioners are used to study the effect of phase segregation and homogenization on accuracy of the meter. Testing is done to cover two-phase flows from both extreme ends, namely aerated liquids and wet gas. Use of flow conditioners show slight improvement in meter accuracy on use of inline mixer, and reduction in accuracy in case of inlet swirl, when both former and latter are compared to results obtained from experiments with no flow conditioners. The difference in accuracies between results with flow conditioner and without flow conditioners is attributed to relative motion between the phases, which is more in case of inlet swirl, due to larger bubble sizes. Flow conditioners show an insignificant effect on meter accuracy during wet gas tests. The reason proposed is annular flow regime, which is not highly affected by flow conditioners. Single phase tests demonstrate that Coriolis meter gives accurate measurement even in presence of severe flow disturbances. There is no need for flow conditioning before the meter to obtain accurate readings from it, which would be the case in other metering technologies like orifice and turbine. In two phase flows, the meter reports negative errors, which is consistent with previous experimental works available in literature. Use of flow conditioners clearly affects the reading of the meter in aerated liquids. This phenomenon can be used to get fairly accurate estimate of flow rate in low gas volume fraction liquid flows.Item Design of a 3.1-4.8 GHZ RF front-end for an ultra wideband receiver(Texas A&M University, 2006-08-16) Sharma, PushkarIEEE 802.15 High Rate Alternative PHY task group (TG3a) is working to define a protocol for Wireless Personal Area Networks (WPANs) which makes it possible to attain data rates of greater than 110Mbps. Ultra Wideband (UWB) technology utilizing frequency band of 3.168 GHz ? 10.6 GHz is an emerging solution to this with data rates of 110, 200 and 480 Mbps. Initially, UWB mode I devices using only 3.168 GHz ? 4.752 GHz have been proposed. Low Noise Amplifier (LNA) and I-Q mixers are key components constituting the RF front-end. Performance of these blocks is very critical to the overall performance of the receiver. In general, main considerations for the LNA are low noise, 50 broadband input matching, high gain with maximum flatness and good linearity. For the mixers, it is essential to attain low flicker noise performance coupled with good conversion gain. Proposed LNA architecture is a derivative of inductive source degenerated topology. Broadband matching at the LNA output is achieved using LC band-pass filter. To obtain high gain with maximum flatness, an LC band-pass filter is used at its output. Proposed LNA achieved a gain of 15dB, noise figure of less than 2.6dB and IIP3 of more than -7dBm. Mixer is a modified version of double balanced Gilbert cell topology where both I and Q channel mixers are merged together. Frequency response of each sub-band is matched by using an additional inductor, which further improves the noise figure and conversion gain. Current bleeding scheme is used to further reduce the low frequency noise. Mixer achieves average conversion gain of 14.5dB, IIP3 more than 6dBm and Double Side Band (DSB) noise figure less than 9dB. Maximum variation in conversion gain is desired to be less than 1dB. Both LNA and mixers are designed to be fabricated in TSMC 0.18??m CMOS technology.