Laser angle measurement system

The design and fabrication of a laser angle measurement system is described. The instrument is a fringe counting interferometer that monitors the pitch attitude of a model in a wind tunnel. A laser source and detector are mounted above the mode. Interference fringes are generated by a small passive element on the model. The fringe count is accumulated and displayed by a processor in the wind tunnel control room. Optical and electrical schematics, system maintenance and operation procedures are included, and the results of a demonstration test are given

Data compression for the First G-APD Cherenkov Telescope

The First Geiger-mode Avalanche photodiode (G-APD) Cherenkov Telescope (FACT) has been operating on the Canary island of La Palma since October 2011. Operations were automated so that the system can be operated remotely. Manual interaction is required only when the observation schedule is modified due to weather conditions or in case of unexpected events such as a mechanical failure. Automatic operations enabled high data taking efficiency, which resulted in up to two terabytes of FITS files being recorded nightly and transferred from La Palma to the FACT archive at ISDC in Switzerland. Since long term storage of hundreds of terabytes of observations data is costly, data compression is mandatory. This paper discusses the design choices that were made to increase the compression ratio and speed of writing of the data with respect to existing compression algorithms. Following a more detailed motivation, the FACT compression algorithm along with the associated I/O layer is discussed. Eventually, the performances of the algorithm is compared to other approaches.Comment: 17 pages, accepted to Astronomy and Computing special issue on astronomical file format

FACT - Monitoring Blazars at Very High Energies

The First G-APD Cherenkov Telescope (FACT) was built on the Canary Island of La Palma in October 2011 as a proof of principle for silicon based photosensors in Cherenkov Astronomy. The scientific goal of the project is to study the variability of active galatic nuclei (AGN) at TeV energies. Observing a small sample of TeV blazars whenever possible, an unbiased data sample is collected. This allows to study the variability of the selected objects on timescales from hours to years. Results from the first three years of monitoring will be presented. To provide quick flare alerts to the community and trigger multi-wavelength observations, a quick look analysis has been installed on-site providing results publicly online within the same night. In summer 2014, several flare alerts were issued. Results of the quick look analysis are summarized.Comment: 2014 Fermi Symposium proceedings - eConf C14102.

Atomic power - its significance to the management of a relief valve company

Thesis (M.B.A.)--Boston Universit

Effects of Small and Normalized Q-Factor Changes and Knee Alignment on Knee Biomechanics During Stationary Cycling

Increasing inter-pedal distance (Q-Factor; QF) in cycling increases peak internal knee abduction moments (KAbM). The effect of smaller, normalized changes in QF has not been investigated, and the effect of static knee alignment at varying QFs is unknown. Purpose: The primary purpose of this study was to see if significant changes in KAbM were detectable with normalized increases in QF that are smaller than what has previously been investigated. The secondary purpose of this study was to investigate whether static knee alignment accounts for any changes in knee biomechanics while cycling at different QFs. Methods: Fifteen healthy participants were included in this study (7 Males, 8 Females, age: 22.7±2.5 years, BMI: 23.95±3.21 kg/m2 ; Mean±STD). Motion capture and instrumented pedals were used to collect kinematic (240 Hz) and pedal reaction force (PRF, 1200 Hz) data, respectively, while cycling at five different QFs. The participant’s mechanical axis angle (MAA) was determined using motion capture. Each participant’s QFs were normalized by starting at 160 mm and increasing by 2% of the participant’s trochanteric leg length (L) where the five QF conditions were (in mm): Q1 (160), Q2 (160 + 0.02*L), Q3 (160 + 0.04*L), Q4 (160 + 0.06*L), and Q5 (160 + 0.08*L). A mixed model analysis of variance was performed to detect differences between QF conditions (α = 0.05). Correlation was calculated between MAA and select variables. Results: KAbM was increased by at least 30% in Q5 from Q1, Q2, Q3, and Q4. Medial PRF was increased by at least 20% in Q5 from Q1, Q2, and Q3. There were no significant changes seen in peak vertical PRF, sagittal-plane moments and angles, or peak abduction angle that were concurrent with significant changes in KAbM. MAA had varying degrees of correlation with the variables of interest. Conclusions: These results suggest that KAbM is more sensitive to changes in QF at greater QF increases. The effect of MAA on frontal-plane knee biomechanics requires further investigation

World squid fisheries

Peer reviewedPublisher PD