A simulator developed for a twin-pod AUV,the Marport SQX-500

A vertically arranged twin-pod autonomous underwater vehicle (AUV) is presently under development in St. John’s Newfoundland. A large separation of the centre of gravity (CG) and the centre of buoyancy (CB) can be achieved by placing heavy batteries and payloads in the lower pod and placing the light controller and communication electronics on the upper pod. With the large vertical separation between CG and CB the twin-pod vehicle becomes highly stable in pitch and roll and thus provides an ideal platform for obtaining photos, video and sonar images of the seabed. This paper presents the vehicle motion simulations that have been done in support of this novel AUV design and development.

     

Applying open-source software to laboratory data management

The rise of new experimental techniques, such as high-throughput combinatorial methods, and the availability of large data sets by means of the Internet have greatly increased the amount of data that must be managed by relatively small projects. Scientific data management systems developed for large projects are often not available, suitable, nor affordable for projects with lesser resources. Increasing numbers of open-source frameworks have made available numerous options for smaller facilities to build for themselves effective and robust data management solutions. We will present considerations of these options and a case study.     

Prior negative experiences: their impact on computer training outcomes

This study examined how a person's negative experiences with computers prior to a training class interacted with their motivation to predict their performance in a computer class. Participants were 384 students who completed a computer course that was designed to introduce them to personal computers and a popular software package. Questionnaires were administered to the participants on the first day of the course to assess their prior negative experiences with computers, along with their computer attitudes, achievement motivation, and computer knowledge. Performance was measured objectively throughout the course with tests over the relevant material. Results indicated some evidence that the participants' pre-training motivation was moderated by their prior negative experiences when predicting test performance.     

Hand-held microanalytical instrument for chip-based electrophoretic separations of proteins

The design, fabrication, and demonstration of a hand-held microchip-based analytical instrument for detection and identification of proteins and other biomolecules are reported. The overall system, referred to as muChemLab, has a modular design that provides for reliability and flexibility and that facilitates rapid assembly, fluid and microchip replacement, troubleshooting, and sample analysis. Components include two independent separation modules that incorporate interchangeable fluid cartridges, a 2-cm-square fused-silica microfluidic chip, and a miniature laser-induced fluorescence detection module. A custom O-ring sealed manifold plate connects chip access ports to a fluids cartridge and a syringe injection port and provides sample introduction and world-to-chip interface. Other novel microfluidic connectors include capillary needle fittings for fluidic connection between septum-sealed fluid reservoirs and the manifold housing the chip, enabling rapid chip priming and fluids replacement. Programmable high-voltage power supplies provide bidirectional currents up to 100 microAlpha at 5000 V, enabling real-time current and voltage monitoring and facilitating troubleshooting and methods development. Laser-induced fluorescence detection allows picomolar (10(-11) M) detection sensitivity of fluorescent dyes and nanomolar sensitivity (10(-9) M) for fluorescamine-labeled proteins. Migration time reproducibility was significantly improved when separations were performed under constant current control (0.5-1%) as compared to constant voltage control (2-8%).     

A comparison of phase equilibria in some II-IV-VI compounds based on PbTe

The solubilities of the group II elements Cd, Zn, Hg, Ca and Mg in PbTe are compared over the temperature range 250 to 800° C. Cd, Zn and Mg have retrograde solubilities whilst Hg and Ca are virtually insoluble in “as-grown” material. A consequence of these solubilities is a change in the properties of the alloys compared with PbTe. Thus the phase widths of the Cd/PbTe, Mg/PbTe and Zn/PbTe systems differ from that of PbTe. With the exception of the Zn/PbTe system, (where there is reasonable evidence to support the solubility of Zn in PbTe) there is a significant change in all measured electrical properties compared with PbTe.     

Estimation of section thickness,etc. by quantitative electron microscopy

Methods have been developed for the estimation of section thickness, and of the mass-thicknesses, and hence the masses, of material embedded in sections. They are based on the current densities measured with a Faraday-cage or on a new approximation for the relationship between exposure and optical density (OD) of the electron microscopical plate, which is valid for OD < 5. This relationship is quite distinct from the response to light, and also from an approximation for electrons which was only valid for OD < 1.2, and which was the basis for an earlier method. The old methods and the two groups of new ones were tested, and also compared with the interference microscope. It was found that all but one of the new methods, in both groups, were homogeneous; the older methods and the interference microscope differed very significantly between themselves and with the homogeneous methods. The errors in the interference microscopical estimations were almost certainly due to the presence of embedded material in the sections, which could not be detected with the interference microscope because of its low resolution and the poor contrast in the thin sections. (A second set of experiments using only pure resin gave a good agreement between the homogeneous methods and the interference microscope.) The orders of accuracy of the methods are quite high. A measurement repeated twelve to thirty-five times will yield a value which has a 95% chance of being within 5% of the true value, while a single observation has a 95% chance of being within ～ 25% of the true value with most methods, while some place it within ～ 10%. Simplified, but less accurate, applications of the methods are also suggested.     

Dynamic Response and Fatigue of Steel Tied-Arch Bridge

The Toutle River Bridge is a steel tied-arch bridge, one that vibrates extensively and has sustained significant fatigue cracking. An experimental study into the cause of this behavior is described. Computer analyses of the bridge behavior are used to estimate the expected response and to establish appropriate locations for instrumentation. The instruments were installed and field tests were performed. Controlled tests were performed with trucks of known axle weight and spacing. Some controlled tests were performed with trucks traveling at known speed and in a specific driving lane with no other traffic on the bridge. Controlled tests were used to calibrate the instrumentation and establish the basic bridge behavior. The results showed that composite action had been lost in the heavily loaded stringers, and little amplification of dynamic response was noted. The measured periods of vibration generally compared well with computer predictions. Uncontrolled truck traffic was then measured for approximately one month. This data was used to establish load spectra and to estimate the fatigue life of critical components. Fatigue, which is caused by calculated stress ranges, should not be important on this bridge for another 20 to 30 years. Existing fatigue damage is driven by distortional fatigue caused by the large bridge deformations. Several options for dealing with the problem are presented.