Approximate calculation of leaky-mode loss coefficients for Ti-diffused LiNbO3waveguides

A hybrid-mode model is developed which allows analytical calculation of the leaky-mode loss coefficient in Ti-diffused LiNbO3waveguides. Field representations correspond to the approximation of geometrical optics. Hybrid-mode effective indexes are approximated utilizing the known anisotropy of LiNbO3. ForX- orY-cut waveguides the leaky mode is shown to be an extraordinary-like hybrid mode with a small ordinary field component which arises from extraordinary to ordinary power conversion at the abrupt index boundary. This ordinary index component is not bound by the graded index boundary, giving rise to the power loss. The theoretical dependence of the loss coefficient on propagation direction is in agreement with experiment.     

A simulation approach to assess the minimal number of real-time PCR replicates for GM quantification

The quantification of genetically modified (GM) ingredients in food and feed typically uses real-time quantitative PCR (RT-QPCR). In recent years a multitude of new RT-QPCR assays have facilitated increased method performance. The level of sample replication within these assays is a fundamental aspect that needs to be considered to produce results with high confidence. In this paper we describe the use of a modelling approach as applied to GM and RT-QPCR data sets, to objectively assesses the effect of different levels of PCR replication in terms of the variability associated with a result, and demonstrate that it is possible to use a reduced level of replication without a subsequent reduction in the confidence of a result. Using an example data set, we show it is possible to reduce the sample level of replication from six to three PCR replicates, without a significant change in the mean value of the result. The use of such an approach can facilitate the use of the minimum number of replicates in order to produce an accurate result, thus saving on important resources involved in quantification assays.     

3D seismic and formation micro-imager (FMI) integrated study to delineate depositional pattern of Abu Madi (Upper Miocene) clastic reservoir rocks in El-Wastani gas field,onshore Nile Delta,Egypt

Ten wells (EW-4, EW-5, EW-6, EW-7, EW-8, EW-9, EW-10, EW-12, EW-13 and EW-15) were interpreted using the composite well logs, data of core analysis, gamma-ray logs, formation micro-imager logs (FMI), and 3D seismic data in SEGY format to understand the stratigraphy of the onshore, Nile Delta, Egypt.The amplitude analysis of 3-D seismic horizon slice of Lower Abu Madi rock unit together with the lithostratigraphic correlation through the study area depending on the gamma-ray log “HSGR” (left to right increasing), and the identification of type of bed geometry, nature of bed contacts, type of the sedimentary structures and the dominant formative paleocurrents by using some available borehole micro-resistivity images (FMI) and core photos. All of these techniques are used together to define the different depositional facies and depositional environment of the Messinian clastics (Lower Abu Madi rock unit), which is considered to be the main reservoir in the El-Wastani gas field, onshore Nile Delta, Egypt.The present study of depositional pattern of the Upper Miocene clastics reservoir (Lower Abu Madi rock unit) revealed that it is represented by high sinuous meandering channels or paleo-valley and three types of fluvial facies were defined; channel fill, channel margin, and floodplain basin.     

Growth of part-through thickness fatigue cracks in sheet polymethylmethacrylate

Fatigue growth data has been obtained for part-through thickness cracks in sheet specimens of polymethylmethacrylate subjected to cyclic tension. Statistical techniques are used to examine the usefulness of linear elastic fracture mechanics for correlating this part-through thickness crack growth data with throughthickness data published previously.     

Monolithic capillary electrophoresis device with integrated fluorescence detector

A monolithic capillary electrophoresis system with integrated on-chip fluorescence detector has been microfabricated on a silicon substrate. Photodiodes in the silicon substrate measure fluorescence emitted from eluting molecules. The device incorporates an on-chip thin-film interference filter that prevents excitation light from inhibiting the fluorescence detection. A transparent AZO conducting ground plane is also used to prevent the high electric fields used for the separation from interfering with the photodiode response. Separations of DNA restriction fragments have been performed in these devices with femtogram detection limits using SYBR Green I intercalating dye.     

Synchronously pumped optical parametric oscillation in periodically poled lithium niobate with 1-w average output power

We report on a rugged all-solid-state laser source of near-IR radiation in the range of 1461-1601 nm based on a high-power Nd:YVO(4) laser that is mode locked by a semiconductor saturable Bragg reflector as the pump source of a synchronously pumped optical parametric oscillator with a periodically poled lithium niobate crystal. The system produces 34-ps pulses with a high repetition rate of 235 MHz and an average output power of 1 W. The relatively long pulses lead to wide cavity detuning tolerances. The comparatively narrow spectral bandwidth of <15 GHz is suitable for applications such as pollutant detection.     

TEM study of the recovery process of cyclically deformed MgO single crystals

Single crystals of MgO were subjected to plastic strain-controlled push-pull cyclic deformation at elevated temperatures. Below 400° C the crystals were very brittle and failed with a few fatigue cycles. At 470° C a large number of cycles could be obtained before failure, and the cyclic stress-strain response showed a period of rapid hardening followed by a period of decreasing hardening rate. TEM investigations of the lower temperature samples show structures of isolated dislocation dipoles, multipoles and debris. At 470° C dense bundles of dislocations were observed aligned perpendicular to the Burgers vector direction. The regions between the bundles were relatively dislocation free, but they contained a high density of debris. Bowed out screw dislocations are observed between the edge dislocation bundles, suggesting that screw dislocations were largely mobile. Comparisons are made with the cyclic deformation and structure of fcc metals and other NaCl structure single crystals.     

Application of CAD to knitting machine design

The development of an interactive computer system for use by industrial knitting machine designers to develop the machine head schematically is outlined. The system extends the manual system in three ways. Nonlinear cams such as double-sine and polynomial can be designed easily. Yarn tension can be displayed to check whether yarns are likely to break and the assembled head can be examined from any viewpoint.     

WCET Analysis of Superscalar Processors Using Simulation With Coloured Petri Nets

Determining a tight WCET of a block of code to be executed on a modern superscalar processor architecture is becoming ever more difficult due to the dynamic behaviour exhibited by current processors, which include dynamic scheduling features such as speculative and out-of-order execution in the context of multiple execution units with deep pipelines. We describe the use of Coloured Petri Nets (CP-nets) in a simulation based approach to this problem. A complex model of a generic processor architecture is described, with emphasis on the modelling strategy for obtaining the WCET and an analysis of the results.     

Authenticating network attached storage

We present an architecture for network-authenticated disks that implements distributed file systems without file servers or encryption. Our system provides network clients with direct network access to remote storage