Fast Response Exhaust Gas Temperature Measurement in IC Engines

The harsh environment presented by engines, particularly in the exhaust systems, often necessitates the use of robust and therefore low bandwidth temperature sensors. Consequently, high frequencies are attenuated in the output. One technique for addressing this problem involves measuring the gas temperature using two sensors with different time-constants and mathematically reconstructing the true gas temperature from the resulting signals. Such a technique has been applied in gas turbine, rocket motor and combustion research. A new reconstruction technique based on difference equations has been developed and its effectiveness proven theoretically. The algorithms have been successfully tested and proven on experimental data from a rig that produces cyclic temperature variations. These tests highlighted that the separation of the thermocouple junctions must be very small to ensure that both sensors are subjected to the same gas temperatures. Exhaust gas temperatures were recorded by an array of thermocouples during transient operation of a high performance two-stroke engine. The results show that the increase in bandwidth arising from the dual sensor technique allowed accurate measurement of exhaust gas temperature with relatively robust thermocouples. Finally, an array of very fine thermocouples (12.5 - 50 microns) was used to measure the in-cycle temperature variation in the exhaust.

Difference equation sensor characterization algorithms for two-thermocouple probes

The characterization of thermocouple sensors for temperature measurement in variable flow environments is a challenging problem. In this paper, novel difference equation-based algorithms are presented that allow in situ characterization of temperature measurement probes consisting of two-thermocouple sensors with differing time constants. Linear and non-linear least squares formulations of the characterization problem are introduced and compared in terms of their computational complexity, robustness to noise and statistical properties. With the aid of this analysis, least squares optimization procedures that yield unbiased estimates are identified. The main contribution of the paper is the development of a linear two-parameter generalized total least squares formulation of the sensor characterization problem. Monte-Carlo simulation results are used to support the analysis.

Concentric split ring element for dual frequency reflectarray antennas

The reflection phase response of a two-layer array of orthogonally oriented concentric split rings is presented. Splitting the ring elements suppresses the interlayer coupling and produces polarisation sensitive scattering. Simulated and measured results at X-band demonstrate that these proper-ties enable the reflection phase coefficients of a reflect-array to be independently optimised at two different frequencies.

Reproduction and fecundity of the Irish pollan (Coregonus autumnalis Pallas, 1776), a threatened lake coregonid

The sex ratio, age at maturation, fecundity, and seasonal development of gonads of pollan (Coregonus autumnalis) in Lough Neagh are described from samples collected between November 1997 and December 1999. Pollan reproductive ecology in the 1990s was similar to that found in the 1970s. Pollan egg size and fecundity differed between years but there were no long-term trends in fecundity despite considerable subsequent eutrophication of the lough and changes in the fish community.

The status of Nathusius' pipistrelle (Pipistrellus nathusii Keyserling & Blasius, 1839) in the British Isles

There are now 91 records of individual Nathusius' pipistrelle Pipistrellus nathusii examined 'in the hand' in the U.K., and bat detector records from a further 36 localities in Britain and Ireland. These records are distributed throughout all months of the year with clear peaks in spring and autumn suggesting migratory movements into and out of the British Isles in autumn and spring, respectively. Three maternity colonies have been located and the species must now also be regarded as a resident breeding species in Britain and Ireland.

Dogs in the paradise: The influence of the cynical philosophy in the construction of the myth of the good savage

This paper studies the influence of cynic philosophy in the construction of the myth of the good savage. In the first part it studies the importance of cynicism in the XVI century and how the cynic influence of Erasmus, More and Montaigne was fundamental to the way that Europe approached the American indigenous. In the second part it studies the cynic motives that could have influenced in the construction of the myth of the good savage.

Tourism changes on a Mediterranean island: experiences from Mallorca

Mediterranean islands exemplify well the interactions between tourism, heritage and culture on islands. After an introduction that considers their heritage and the pressures which might be applied by tourism because of insular characteristics such as scale, the paper considers the Spanish island of Mallorca as a case study. First its history and consequent heritage is identified and then various stages in its tourism development, which might be recognized in Butler’s model, are treated with particular reference to two very different foreigner commentators on the island, George Sand and Robert Trimnell. The mass market tourism exemplified by Trimnell has brought a reaction and in recent decades Mallorca has given much more consideration to its environment and heritage, illustrated here through the example of the district of Calvià and its Local Agenda 21 policies. This has seen a considerable impact on the island’s tourism and marketing initiatives, as well as upon its natural environment.