Polarization compensator for optical communications

An optical data communication system is provided whereby two orthogonal polarization states of a light beam carrier correspond to digital states. In such a system, automatic polarization compensation is provided by applying a dither modulating voltage to a cell exhibiting the electro-optic effect. The cell controls the relative phase of electric field components of an input light beam enabling the dither frequency component of the difference of the instantaneous powers in the two polarization states to be coherently detected. A signal derived from the coherent detection process is fed back to the cell via an integrator to form polarization bias compensating servo loop ot Type 1

Dynamic polarization compensating system for optical communications receiver

Electro-optic cell is located in optical path of input light beam. Cell includes crystal for controlling phase between two polarization states. Cell axes are rotated 45 deg to receiver axes defined by vertical and horizontal polarization states. Voltage across cell compensates for bias by introducing different phase retardation along crystal axes

Wavelength dependence of laser beam scintillation

Laser beam scintillation and log-amplitude variance evaluation for wavelengths on digital compute

Prelaunch testing of the GEOS-3 laser reflector array

The prelaunch testing performed on the Geos-3 laser reflector array before launch was used to determine the lidar cross section of the array and the distance of the center of gravity of the satellite from the center of gravity of reflected laser pulses as a function of incidence angle. Experimental data are compared to computed results

The Benard problem: A comparison of finite difference and spectral collocation eigen value solutions

The application of spectral methods, using a Chebyshev collocation scheme, to solve hydrodynamic stability problems is demonstrated on the Benard problem. Implementation of the Chebyshev collocation formulation is described. The performance of the spectral scheme is compared with that of a 2nd order finite difference scheme. An exact solution to the Marangoni-Benard problem is used to evaluate the performance of both schemes. The error of the spectral scheme is at least seven orders of magnitude smaller than finite difference error for a grid resolution of N = 15 (number of points used). The performance of the spectral formulation far exceeded the performance of the finite difference formulation for this problem. The spectral scheme required only slightly more effort to set up than the 2nd order finite difference scheme. This suggests that the spectral scheme may actually be faster to implement than higher order finite difference schemes

On the effects of powder morphology on the post-comminution ballistic strength of ceramics

In this paper in order to try and elucidate the effects of particle morphology on ballistic response of comminuted systems, a series of experiments were carried out via the use of powder compacts with differing initial particle morphologies. This approach provided a route to readily manufacture comminuted armour analogues with significantly different microstructural compositions. In this study pre-formed `fragmented-ceramic' analogues were cold-pressed using plasma-spray alumina powders with two differing initial morphologies (angular and spherical). These compacts were then impacted using 7.62-mm FFV AP (Förenade Fabriksverken Armour Piercing) rounds with the subsequent depth-of-penetration of the impacting projectile into backing Al 6082 blocks used to provide a measure of pressed ceramic ballistic response. When material areal density was accounted for via differing ballistic efficiency calculations a strong indication of particle morphology influence on post-impact ceramic properties was apparent. These results were reinforced by a separate small series of plate-impact experiments, whose results indicated that powder morphology had a strong influence on the nature of compact collapse

Are Alcohol-Related Acute Surgical Admission Rates Falling?

BACKGROUND: Alcohol-related admissions (ARA) represent a significant burden on hospital resources. The study objectives were to assess alcohol-related acute surgical admissions to a District General Hospital over a 5-year period, to determine the cost of these admissions and to consider strategies to affect future admission rates. METHODS: A prospective observational study was completed from October 2007 to March 2008. A daily review of acute surgical admissions determined whether alcohol was a factor for patients admitted. Data recorded included patient demographics, clinical presentation, investigations and final outcomes. This data was then compared with a previously completed prospective study between November 2002 and March 2003. RESULTS: Overall emergency surgical admissions during the study period were 1,125 (10.4%) compared to 838 (11.02%) in 2002. There was a 1.1% reduction in ARA from 9.5% (80/838) in 2002 to 8.4% (94/1,125) in 2007. The majority of ARA were male (82.8%) and 59.8% of ARA were under 40 years of age. ARA secondary to road traffic collisions (RTC) were reduced in 2007 compared to 2002 (12.5% to 8.5%). However, head injuries (30.0% to 48.9%) and pancreatitis (3.8% to 19.1%) secondary to alcohol had increased (p=0.27). 79.3% of admissions occurred out of hours. Although use of plain x-rays had decreased (70% to 54.3%, p=0.018), CT imaging (11.3% to 20.2%, p=0.67) and upper GI endoscopy had increased (2.5% to 7.4%, p=0.82). Blood alcohol levels increased with 83.0% of patients in 2007 compared to 60.9% in 2002 admitted with a level greater than 151mg/100mls (p=0.10). The overall cost of ARA over one year was calculated at £341,796. CONCLUSION: Alcohol-related admissions have reduced at this District General Hospital. However, despite recent government initiatives it still remains unclear how these factors affected ARA, as blood alcohol levels, alcohol-related head injuries and pancreatitis admissions all increased. Our findings highlight the relevance of the implementation of an inpatient alcohol policy combined with the availability of an alcohol liaison nurse in all acute surgical units

Advances in Optics for Biotechnology, Medicine and Surgery

The guest editors introduce a Biomedical Optics Express feature issue that includes contributions from participants at the 2013 conference on Advances in Optics for Biotechnology, Medicine and Surgery XIII

Deriving public sector workforce insights: A case study using Australian public sector employment profiles

© Springer International Publishing AG 2016. Effective approaches for measurement of human capital in public sector and government agencies is essential for robust workforce planning against changing economic conditions. To this purpose, adopting innovative hypotheses driven workforce data analysis can help discover hidden patterns and trends about the workforce. These trends are useful for decision making and support the development of policies to reach desired employment outcomes. In this study, the data challenges and approaches to a real life workforce analytics scenario are described. Statistical results from numerous workforce data experiments are combined to derive three hypotheses that are useful to public sector organisations for human resources management and decision making