THE 1990 LAURENCE BISHOP SILVER MEDAL LECTURE* THE DESIDERATUM FOR FLAVOUR CONTROL

Flavour is arguably the most important aspect of the quality of foods and beverages. Beer, however, is an extremely complex mixture of volatile and non-volatile components, and the measurement and control of beer flavour is one of the greatest challenges in brewing research. Recent progress towards understanding the contributions of raw materials and processing conditions to the aroma and taste of beer is reviewed.     

Physical ergonomic hazards in highway tunnel construction: overview from the Construction Occupational Health Program

This report provides an overview of physical ergonomic exposures in highway construction work across trades and major operations. For each operation, the observational method “PATH” (Posture, Activity, Tools and Handling) was used to estimate the percentage of time that workers spent in specific tasks and with exposure to awkward postures and load handling. The observations were carried out on 73 different days, typically for about 4 h per day, covering 120 construction workers in 5 different trades: laborers, carpenters, ironworkers, plasterers, and tilers. Non-neutral trunk postures (forward or sideways flexion or twisting) were frequently observed, representing over 40% of observations for all trades except laborers (28%). Kneeling and squatting were common in all operations, especially tiling and underground utility relocation work. Handling loads was frequent, especially for plasterers and tilers, with a range of load weights but most often under 15 pounds. The results of this study provide quantitative evidence that workers in highway tunnel construction operations are exposed to ergonomic factors known to present significant health hazards. Numerous opportunities exist for the development and implementation of ergonomic interventions to protect the health and safety of construction workers.     

Design study of a 120-keV,3He neutral beam injector

We describe a design for a 120-keV, 2.3-MW,³He neutral beam injector for use on a D-³He fusion reactor. The constraint that limits operating life when injecting He is its high sputtering rate. The sputtering is partly controlled by using an extra grid to prevent ion flow from the neutralizer duct to the electron suppressor grid, but a tradeoff between beam current and operating life is still required. Hollow grid wires functioning as mercury heat pipes cool the grid and enable steady state operation. Voltage holding and radiation effects on the acceleration grid structure are discussed. We also briefly describe the vacuum system and analyze use of a direct energy converter to recapture energy from unneutralized ions exiting the neutralizer. Of crucial importance to the technical feasibility of the³He-burning reactor are the injector efficiency and cost; these are 53% and $5.5 million, respectively, when power supplies are included.The beam is composed of 91 separate, parallel currents that flow in the gaps between the elements or wires of a grid. Each such flow is referred to as a beamlet. The current densities in Figs. 5, 8, and 9 are values within a beamlet, as measured at the beam-forming grid. They are not values averaged over the entire beam cross-section.     

Sustainable Disposal of Domestic Sanitary Waste

The study presented is an example of the assessment of the relative sustainability of either option for disposal of domestic sanitary waste, either via the toilet or via the solid waste route. This required an evaluation of the total (social, economic, environmental, and technical) benefit/cost of implementing and adopting the alternative routes and an assessment of public responsiveness to encouragement to change sanitary waste disposal practices. It illustrates how, even for an apparently straightforward either/or question, the assessment of relative sustainability is complex and the amount of data needed to quantify sustainability indicators is prodigious. The study also provides an appraisal of the effectiveness of public campaigns to reduce waterborne disposal. Important information regarding public attitude and behavior in relation to wastewater systems has been acquired and lessons for ways of encouraging behavioral change to more sustainable ways of living have been gleaned.     

Speech and noise power estimation using Gamma modeling

In speech enhancement, having an accurate estimation of the power of the speech and noise signals forming the noisy observation is critical, as it can highly affect the performance of the enhancement algorithm. A method is introduced in which the distributions of the power of the speech and noise periodograms are modeled using the Gamma distribution to extract their shape parameters. These shape parameters are later used in the observed noisy speech to estimate the power when forming speech and noise periodograms. This method results in more accurate and faster power estimation with respect to the well‐known minimum statistics power estimation algorithm and together with the maximum a posteriori speech enhancement algorithm exhibits good speech enhancement performance.     

Toeplitz matrices for LTI systems,an illustration of their application to Wiener filters and estimators

The Wiener–Kolmogorov theory of filtering has been with us since the first half of the twentieth century. A later matrix-based approach which was more general was derived with the steady-state Kalman filter. This approach uses a novel method of representing causal and uncausal systems in the form of convolution matrices and leads to a Wiener solution which is much easier to calculate than either the Kalman or Wiener approaches. For coloured additive noise, it avoids the use of Diophantine equations. The key idea missing in previous work is the close link between polynomials and Toeplitz matrices which are lower triangular in form. There is already a reasonably sized literature in the mathematics field on such matrices and so the area is ripe for exploration. Although the method does not offer a different or better solution, it shows a completely new way of defining linear time-invariant (LTI) systems which is neither transfer-function nor state-space-based. This is achieved by exploiting the connection between polynomials and Toeplitz matrices. The application here is the Wiener filter but there could well be many more as this is a generic approach.     

Filtering,smoothing and prediction using a control‐loop spectral factorization method for coloured noise

A method for the linear least‐squares estimation of random signals contaminated with random noise that uses a new method of spectral factorization is shown. It is shown that the optimal filter can be written entirely in terms of the two spectral factors of signal plus noise and noise‐alone, and can be applied to the general case of coloured and white additive noise. The method of spectral factorization used is novel and uses control‐system methodology. Copyright © 2012 John Wiley & Sons, Ltd.     

Location of sources of variation in forage digestibility

Data from tables of composition of animal feedstuffs in which there were entries for digestibility (digestible dry matter or digestible organic matter) and cell wall were classified into different categories—grass or legume, stage of growth, leaf or stem, and forage species. No conclusions were drawn about legumes, because of insufficient data. After removing the effect of different categories, all the grass species behaved similarly with respect to digested cell walls, In contrast, within-species variation in digested cell walls was large, as shown by the high residual standard deviation of ± 4.0 in a simple linear regression of in-vivo digestibility on cell-wall content. There was a small effect which was due to the lignin content of the cell wall, but the source of most of the variation was not located. While it remains undiscovered, there is a danger that experiments involving forage might merely be testing the effect of treatment on random variation in the digested cell wall.