Effectiveness of UK motorway services areas in reducing sleep-related and other collisions

In the UK, motorway service areas (MSAs) are believed to be helpful in reducing sleep (‘fatigue’) related collisions (SRCs), however, their actual effectiveness has yet to be evaluated. During a 2-3-year period, and over two sections of UK motorways comprising 14 MSA sites, assessments were undertaken of all fatal and injury road traffic collisions (RTCs), especially SRCs. Analyses examined whether there was: (i) a reduction in collisions 16 km beyond MSAs compared with the same distance beforehand; (ii) accumulation of collisions with increasing inter-MSA distances. Within the 16 km regions there was a non-significant fall in all RTCs from 355 before MSAs, to 304 afterwards. However, the 22% decrease in SRCs (108 vs. 84) was significant. Cars comprised the greatest reduction in SRCs possibly attributable to a MSA. Including and beyond these 16 km regions, there was no correlation between inter-MSA distances and accumulated RTCs or SRCs (n = 682 of which 181 were SRCs [26%]). There were obvious differences between MSAs in all these respects. Of the 23 fatal RTCs, 17 were SRCs. Whilst SRCs had their greatest daily incidence between 02:00 h and 06:00 h, as expected, MSAs seemed to have their least beneficial effect on SRCs during this vulnerable period, which is a matter for concern.     

Noninvasive measurement of electrostatic-discharge-inducedphenomena in electronic systems

The design of a high-speed measurement system consisting of an electric (E)-field detector and a magnetic (H)-field detector coupled to an optoelectronic transmission system is described. A laser diode transmitter, a fiber-optic link, and a laser diode receiver were used to isolate the detected signal from a high-speed transient digitizer, which was utilized to acquire experimental data for signal processing. Experiments were conducted to measure E- and N-field-induced signals within a typical electronic enclosure subjected to radiated interference from a spark-gap source. The results have application in the development of an integrated electromagnetic interference (EMI) detector for use in electronic systems     

Parasitic bipolar gain reduction and the optimization of 0.25-μmpartially depleted SOI MOSFETs

An in-depth analysis of the role of parasitic bipolar gain reduction in 0.25-μm partially depleted SOI MOSFETs is presented, considering both dc characteristics as well as circuit operation. The effect of channel doping, silicide proximity, and germanium implantation on the lateral bipolar gain are characterized for optimal performance and manufacturability. Channel doping has the expected impact on bipolar gain. Silicide proximity is shown also to have a large impact. Germanium implantation into the source/drain regions reduces the lateral bipolar gain due to the introduction of defects that act as recombination centers in the source, reducing emitter efficiency. Further, germanium implantation serves to finely control the silicidation process, leading to good manufacturing control of the lateral silicide encroachment. Analysis of MOSFET dc I-V characteristics shows that threshold voltages for SOI have to be set only 30-50 mV higher for comparable dc off current to bulk CMOS. Finally, the impact of bipolar gain on floating-body-induced hysteretic effects and on alpha-particle-induced SRAM soft error rates are described     

Investigation of the optical and electrical characteristics of aspark gap

A spark-gap apparatus and a high-speed optoelectronic measurement system were used to examine the optical and electrical characteristics of spark discharges. Parameters studied included the magnitude and polarity of the discharge voltage, gap length, and the impedance of the discharge circuit. Analyses were performed to compare the measured optical signatures as a function of the discharge current. Results of the experimentally measured parameters compare well with theoretically computed values. The work has application in the study of electrostatic discharge (ESD) events     

Calibration of a calorimeter for measuring the spark energy of an electrostatic discharge

This paper deals with the factors that influence the accuracy of the measurements performed with a calorimeter, developed to detect the optical signal emitted by the spark generated to facilitate experiments with electrostatic discharge. Experiments are described which were performed with a special calorimeter and a compound optical source consisting of a spark gap, a human-body-model electrostatic discharge (ESD) signal generator, and four LEDs. The spark gap was used as a versatile and more powerful source of optical emission than the human-body-model circuit; the LED source was used for calibration and alignment. For control, the spectrum of the spark discharge was measured with a spectrometer and a broadband photodetector. The calorimeter was used as a means for the determination of the energy contained in the optical signal, yielding the value of the spark-gap emission in the fundamental units for energy. The long-term stability of the system was measured, and the system response was studied for threshold optical signals. The calorimeter detectivity, defined as the overall instrument sensitivity, measured in volts per joule, was D=4.3/spl times/10/sup 7/ V.J/sup -1/ and its detection limit 2.3/spl times/10/sup -13/ J. The system's response to the IEC standard human-body-model circuit was consistent with the measurements of the system's detectivity. Most parts of the developed apparatus have been tested in an industrial environment.     

Mechanistic features of molten salt corrosion in coal fired boilers

In general, the hottest outlet sections of both superheaters and reheaters in modern CEGB boilers are tubed in austenitic stainless steels. Experience over the last 10–15 years has indicated that molten salt fireside corrosion can significantly reduce design lives, corrosion rates being a function of

• (i) metal temperature
• (ii) gas temperature
• (iii) coal chlorine content
• (iv) the tube's aerodynamic position

The characteristic visual features of this form of corrosion such as “classical” wastage flats, honeycomb pitting, and localised pitting at tube geometrical features such as weld beads, and lugs is described. Also discussed are some of the metallographic features of molten salt corrosion, including substrate carburization, internal oxidation/sulphidation and corrosion scale morphology. Whilst uncertainty remains in understanding the precise mechanism, the CEGB have adopted a pragmatic approach using new/alternative materials such as shields, coatings and co-extruded tubes. However, such a policy may not be the most economic: for example, in some circumstances the alloy 50 Cr 50 Ni is required to give a guaranteed degree of protection. What is still required is the quantification of the role of Na, K, Cl etc. in fuel on deposition and corrosion rates, and the source and influence of carburization so that further operational control of this molten salt corrosion is available.     

Noninvasive optoelectronic system for measurement of electrostaticdischarge (ESD)-induced phenomena

The design of a high-speed optoelectronic system consisting of an electrically floating detector/transmitter module coupled to a receiver by a fiber-optic link is described. Typical applications of this optical decoupled system involving electrostatic discharge (ESD) are described. These include the optical signature characterization of discharges and the measurement of conducted and radiated electromagnetic interference (EMI) due to ESD. Results of experiments conducted to demonstrate the qualitative performance characteristics of the measurement system are presented     

Calorimetric measurements of optical signals in electrostaticdischarge studies

A method based on calorimetry and an instrument are described for the absolute measurement of the energy contained in optical radiation, especially in the optical signatures of electrostatic discharge. The optical emission of a spark gap, comprised of two stainless-steel spheres, was collected by an optical condenser system and focused on the calorimeter sensor. The system was calibrated using a set of light-emitting diodes and tested using either single-pulse discharge or a continuously operating optical source. The calorimeter system detectivity, in terms of output voltage related to the input energy, was determined to be 4.3 × 10⁷ V·J^-1 and its detection limit was 2.3 × 10^-13 J. The system has application for nonintrusive characterization of optical emissions associated with discharge events     

Establishing Geomorphic Reference Criteria for Design of River Diversions Around Mine Pits in the Pilbara,Western Australia

The poor condition of river diversion channels can prevent mining companies from relinquishing their mine to the government after mining has ceased. Many regions lack a locally derived template for integrating appropriate geomorphic and hydraulic conditions from unmodified river channels into river diversion designs to help guide post-mining closure activities. Establishing baseline geomorphic reference criteria for unmodified catchments can guide restoration efforts to allow recovery and stability of the fluvial system. Design-wise, channels should be built so that flow conditions are able to move sediment, but not high enough to accelerate erosion in the channel. We used natural headwater channels to inform a regional guide for geomorphic criteria for artificial channels constructed in the Pilbara, Western Australia. We provide guideline hydraulic criteria for specific channel types, including velocity, stream power, and bed shear stress values for five key channel types: alluvial single thread (≥ cobble) and single thread (sand), bedrock/confined channel sections, island-barform channels, and heavily vegetated channels.