Improved performance of motor-drive systems by SAW shaft torque feedback

The paper describes the application of a non-contact, high bandwidth, low cost, SAW-based torque measuring system for improving the dynamic performance of industrial process motor-drive systems. Background to the SAW technology and its motor integration is discussed and a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor is proposed. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. The control structures are experimentally validated and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins

Investigation of Underground Water Resources of Texas

A report of an investigation of underground water resources of several areas in Texas. Describes modern methods of investigation and shows evolution methods of investigation

Igneous Rocks of the Balcones Fault Region of Texas

Mode of access: Internet

Origin of Analcite in Igneous Rocks of the Terlingua District, Texas

Many of the igneous rocks of the Terlingua district in west Texas contain analcite as an important mineral. The analcite-bearing rocks generally are assemblages of andesine or labradorite, alkali feldspar, augite or aegirite-augite, olivine, iron ores, and analcite. Biotite is present in some types but absent in others. Important types are analcite syenogabbro, analcite trachybasalt porphyry, analcite trachycdolerite, and analcite syenite. Analcite was formed in these rocks through an extended period from late magmatic to definitely post magmatic stages. Reaction between the analcitic liquid and earlier formed minerals resulted in a series of reaction products including analcite aegirite-augite, serpentine, albite, and zeolites

The Plantersville Meteorite, Grimes County, Texas

The Plantersville meteorite fell on the afternoon of September 4, 1930, at a point three and one-half miles southwest of Plantersville, Grimes County, Texas. The locality of the fall is forested but several men were working nearby and recovered the specimen within a few minutes of its fall. The phenomena of fall included rumbling explosions and a noise like an airplane in flight. This find is a light-gray friable aerolite, weighing 2084.9 grams, with a dense black crust showing oriented thread lines. The shape is sub-conoid faceted with a well-developed brutseit. The dimensions are 5¾” X 4 X 3¾” measured in three directions at right angles

Green space and child weight status : does outcome measurement matter? Evidence from an Australian longitudinal study

Taren Sanders is supported by an Australian Postgraduate Award. Thomas Astell-Burt is supported by a Fellowship with the National Heart Foundation of Australia.Objective. To examine whether neighbourhood green space is beneficially associated with (i) waist circumference (WC) and (ii) waist-to-height ratio (WtHR) across childhood. Methods. Gender-stratified multilevel linear regressions were used to examine associations between green space and objective measures of weight status in the Longitudinal Study of Australian Children, a nationally representative source of data on 4,423 children aged 6 y to 13 y. WC and WtHR were measured objectively. Percentage green space within the local area of residence was calculated. Effect modification by age was explored, adjusting for socioeconomic confounding. Results. Compared to peers with 0-5% green space locally, boys and girls with >40% green space tended to have lower WC (βboys -1.15, 95% CI -2.44, 0.14; βgirls -0.21, 95% CI -1.47, 1.05) and WtHR (βboys -0.82, 95% CI -1.65, 0.01; βgirls -0.32, 95% CI -1.13, 0.49). Associations among boys were contingent upon age (p valuesage green space40% green space at 73.85 cm and 45.75% compared to those with 0-5% green space at 75.18 cm and 46.62%, respectively. Conclusions. Greener neighbourhoods appear beneficial to alternative child weight status measures, particularly among boys.Publisher PDFPeer reviewe

Large-scale structure in a new deep IRAS galaxy redshift survey

We present here the first results from two recently completed, fully sampled redshift surveys comprising 3703 IRAS Faint Source Survey (FSS) galaxies. An unbiased counts-in-cells analysis finds a clustering strength in broad agreement with other recent redshift surveys and at odds with the standard cold dark matter model. We combine our data with those from the QDOT and 1.2 Jy surveys, producing a single estimate of the IRAS galaxy clustering strength. We compare the data with the power spectrum derived from a mixed dark matter universe. Direct comparison of the clustering strength seen in the IRAS samples with that seen in the APM-Stromlo survey suggests b_O/b_I=1.20+/-0.05 assuming a linear, scale independent biasing. We also perform a cell by cell comparison of our FSS-z sample with galaxies from the first CfA slice, testing the viability of a linear-biasing scheme linking the two. We are able to rule out models in which the FSS-z galaxies identically trace the CfA galaxies on scales 5-20h^{-1}Mpc. On scales of 5 and 10h^{-1}Mpc no linear-biasing model can be found relating the two samples. We argue that this result is expected since the CfA sample includes more elliptical galaxies which have different clustering properties from spirals. On scales of 20h^{-1}Mpc no linear-biasing model with b_O/b_I < 1.70 is acceptable. When comparing the FSS-z galaxies to the CfA spirals, however, the two populations trace the same structures within our uncertaintie

Plausible responses to the threat of rapid sea-level rise for the Thames Estuary

This paper considers the perceptions and responses of selected stakeholders to a scenarion of rapid rise in sea-level due to the collapse of the West Antarctic ice sheet, which could produce a global rise in sea-level of 5 to 6 metres. Through a process of dialogue involving one-to one interviews and a one-day policy exercise, we addressed influences on decision-making when information is uncertain and our ability to plan, prepare for and implement effective ways of coping with this extreme scenario. Through these interactions we hoped to uncover plausible responses to the scenario and identify potential weaknesses in our current flood management approaches to dealing with such an occurrence. By undertaking this exploratory exercise we hoped to find out whether this was a feasible way to deal with such a low probability but high consequence scenario. It was the process of finding a solution that interested us rather than the technical merits of one solution over another. We were not intending to produce definitive set of recommendations on how to respond but to gain insights into the process of making a decision, specifically what influences it and what assumptions are made.Sea level rise, London