RF-MEMS switch actuation pulse optimization using Taguchi's method

Copyright @ 2011 Springer-VerlagReliability and longevity comprise two of the most important concerns when designing micro-electro-mechanical-systems (MEMS) switches. Forcing the switch to perform close to its operating limits underlies a trade-off between response bandwidth and fatigue life due to the impact force of the cantilever touching its corresponding contact point. This paper presents for first time an actuation pulse optimization technique based on Taguchi’s optimization method to optimize the shape of the actuation pulse of an ohmic RF-MEMS switch in order to achieve better control and switching conditions. Simulation results show significant reduction in impact velocity (which results in less than 5 times impact force than nominal step pulse conditions) and settling time maintaining good switching speed for the pull down phase and almost elimination of the high bouncing phenomena during the release phase of the switch

High Prevalence of Cardiometabolic Risk Factors in Women Considered Low Risk by Traditional Risk Assessment

Background: Cardiovascular disease (CVD) is the leading cause of death in women in the United States. The purpose of this study was to characterize the prevalence and awareness of traditional CVD risk factors, obesity, and coronary heart disease (CHD) risk classification using the Framingham Risk Score (FRS) among women attending the 2006 Sister to Sister National Woman’s Heart Day event. Results: A total of 8936 participants (mean age 49 ± 14 years) were evaluated. There was a modest prevalence of traditional risk factors on screening, including non-high-density lipoprotein-cholesterol (HDL-C) \u3e 160 mg/dL (27%), HDL-C \u3c40 mg/dL (16%), random glucose level \u3e140 mg/dL (6%), uncontrolled blood pressure ≥140/90 mm Hg (12%), current smoking (6%), and a positive family history of CHD (21%). There was a high prevalence of overweight (39%) or obese individuals (35%) (body mass index [BMI] 25–30 and ≥ 30 kg/m2, respectively), as well as those with high waist circumference (≥35 inches) (55%). Women were classified by FRS as low (85%), intermediate (6%), and high risk (9%). When cardiometabolic risk analyses included waist circumference in addition to the FRS, 59% of low-risk and 50% of intermediate-risk women had 1 or 2 risk factors, and 19% and 41% had ≥ 3 risk factors, respectively. Women were often unaware of risk factors on screening; among women without a previous diagnosis of dyslipidemia or hypertension, 48% and 7%, respectively, were given new diagnoses. Conclusions: Women participating in the 2006 Sister to Sister National Woman’s Heart Day event have a high prevalence of cardiometabolic risk factors, especially dyslipidemia, obesity, and high central adiposity, that place them at higher risk for the development of CVD and other comorbidities. The newly identified multiple risk factors in this population support the value of community health screening in women

The Interface Region Imaging Spectrograph (IRIS)

The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona with 0.33-0.4 arcsec spatial resolution, 2 s temporal resolution and 1 km/s velocity resolution over a field-of-view of up to 175 arcsec x 175 arcsec. IRIS was launched into a Sun-synchronous orbit on 27 June 2013 using a Pegasus-XL rocket and consists of a 19-cm UV telescope that feeds a slit-based dual-bandpass imaging spectrograph. IRIS obtains spectra in passbands from 1332-1358, 1389-1407 and 2783-2834 Angstrom including bright spectral lines formed in the chromosphere (Mg II h 2803 Angstrom and Mg II k 2796 Angstrom) and transition region (C II 1334/1335 Angstrom and Si IV 1394/1403 Angstrom). Slit-jaw images in four different passbands (C II 1330, Si IV 1400, Mg II k 2796 and Mg II wing 2830 Angstrom) can be taken simultaneously with spectral rasters that sample regions up to 130 arcsec x 175 arcsec at a variety of spatial samplings (from 0.33 arcsec and up). IRIS is sensitive to emission from plasma at temperatures between 5000 K and 10 MK and will advance our understanding of the flow of mass and energy through an interface region, formed by the chromosphere and transition region, between the photosphere and corona. This highly structured and dynamic region not only acts as the conduit of all mass and energy feeding into the corona and solar wind, it also requires an order of magnitude more energy to heat than the corona and solar wind combined. The IRIS investigation includes a strong numerical modeling component based on advanced radiative-MHD codes to facilitate interpretation of observations of this complex region. Approximately eight Gbytes of data (after compression) are acquired by IRIS each day and made available for unrestricted use within a few days of the observation.Comment: 53 pages, 15 figure