The problem of unwanted noise in buildings has grown continuously over the last twenty years and impact noise through separating floors has been identified as a particularly important problem. One accepted method for improving impact sound insulation is to use floating floors in which the walking surfaces are isolated from the supporting structure by a resilient layer. Traditionally the resilient layers comprise mineral or glass fibre quilts but other materials such as flooring grade polystyrene are increasingly used. Recently, shallow profile floating floors comprising flexible open cell polyurethane foam resilient layers have been developed. These systems are attractive for refurbishment projects since they can simply be placed on existing floors in order to improve their impact sound insulation whilst raising the existing floor level less than systems comprising fibre quilts. Shallow profile floating floors with thin layers of flexible open cell polyurethane foam are the subject of investigation as part of this research work. This thesis reviews the previous research on polyurethane foams and evaluates the usefulness of the Standard Tests on these materials for assisting in the selection of foam for use as resilient layers under lightweight floors. Both the static and dynamic behaviour of flexible open cell polyurethane foam are investigated and recycled polyurethane foam is shown to be particularly useful for use under floating floors Its characteristic behaviour under compressive strain is described for the first time. This thesis shows that by modifying the Standard Method for the determinaf on of the dynamic stiffness of resilient layers under floating floors (BS EN 29052-1), the effect of the air contained in the open cell foam specimens can be included in the Standard laboratory test. The modification makes it possible to evaluate the dynamic stiffness of low airflow resistivity resilient polyurethane resilient layers using the apparatus described in BS EN 29052-1 for the first time. Field measurements of impact sound pressure level conducted using sections of lightweight shallow profile floating floor on a concrete supporting floor are described. The measured improvements in impact sound insulation achieved by using the sections of floating floor are compared with the improvements predicted using the results from the modified Standard laboratory tests on the foams used as resilient layers. It is shown that by compensating for the mass impedance of the Standard tapping machine hammers good correlation between predicted and measured data is achieved. A simple method for predicting the weighted standardised impact sound pressure level (L'nT,w) in the receiving room is proposed which shows excellent correlation with L'nT,w obtained from the measured data. The work shows that BS EN 29052-1 is more widely applicable than the Standard itself states and for the first time identifies a method of predicting the performance of lightweight shallow profile floating floors with polyurethane foam resilient layers. Finally the use of the ISO tapping machine for assessing the impact sound insulation of the very lightweight floating floors of interest to this research is considered. Different methods of correlating perceived and measured the impact sound insulation of floors are reviewed. Experimental results conducted in this research programme, along with searches of the literature confirm that the tapping machine is a suitable source for measuring the impact sound insulation of these floors.

Low frequency noise transmission between dwellings is an increasing problem due to home entertainment systems with enhanced bass responses. The problem is exacerbated since there are not presently available methods of measurement, rating and prediction appropriate for low frequency sound in rooms. A review of the classical theory of sound insulation and room acoustics has shown that both theories are not applicable. In fact, the sound insulation of party walls at low frequencies is strongly dependent on the modal characteristics of the sound fields of the two separated rooms, and of the party wall. Therefore methods originally developed for measurement conditions where the sound field was considered diffuse, may not be appropriate for room configurations with volumes smaller than 50m3 and for frequencies where sound wavelengths are large. An alternative approach is proposed using a Finite Element Method (FEM) to study the sound transmission between rooms. Its reliability depends on the definition of the model, which requires validating measurement. FEM therefore does not replace field or laboratory measurements, but provides complementary parametric surveys not easily obtainable by measurements. The method involves modelling the acoustic field of the two rooms as an Acoustic Finite Element model and the displacement field of the party wall as a Structural Finite Element model. The number of elements for each model was selected by comparing the numerical eigenfrequencies with theoretical values within an acceptable processing time and error. The simulation of a single room and of two coupled rooms, defined by linking the acoustic model with the structural model, were validated by comparing the predicted frequency response with measured response of a 1:4 scale model. The effect of three types of party wall edge condition on sound insulation was investigated: simply supported, clamped, and a combination of clamped and simply supported. It is shown that the frequency trends still can be explained in terms of the classical mechanisms. A thin masonry wall is likely to be mass controlled above 50Hz. A thick wall is stiffness controlled, below 100Hz. A clamped thin wall provides a lower sound insulation than a simply supported, whereas a clamped masonry wall provides greater sound level difference at low frequencies than a simply supported. The sound insulation of masonry walls are shown to be strongly dependent on the acoustical modal characteristics of the connected rooms and of the structural modal characteristics of the party wall. The sound pressure level difference displays a sequence of alternating maxima and minima about a trend, dictated by the properties of the party wall. The sound insulation is lower in equal room than in unequal rooms, whatever the edge conditions and smaller wall areas provide higher sound insulation than large areas. A correction factor is proposed as a function of room configuration and wall area and edge conditions. Attempts to quantify the factor were made using statistical and deterministic analyse, but further work is required.

Using data from co-authorships at the international level in all fields of science in 1990 and 2000, and within six case studies at the sub-field level in 2000, different explanations for the growth of international collaboration in science and technology are explored. We find that few of the explanations within the literature can be supported by a detailed review of the growth of international collaboration during the 1990s. We hypothesize that growth may be due to recognition and rewards as ordering mechanisms within the system. We apply new tools emerging from network science to test whether international collaborations can organize based on rules of recognition and reward. These enquiries show that the growth of international co-authorships can be attributed to self-organizing phenomenon based on preferential attachment among collaborators at the sub-field level. The co-authorship links can be considered as a complex network with sub-dynamics involving features of both competition and cooperation. The analysis suggests that the growth of international collaboration during the 1990s has more likely emerged from dynamics at the sub-field level operating in all fields of science, albeit under institutional constraints. Implications for the management of global scientific collaborations are explored.

A transformation in the functions of university, industry, and government, the â triple helix,â is taking place as each institution can increasingly assume the role of the other. The Triple Helix thesis states that the knowledge infrastructure can be explained in terms of these changing relationships. Arrangements and networks among the three institutional spheres provide input and sustainance to science-based innovation processes. In this new configuration, academia can play a role as a source of firm-formation, technological, and regional development, in addition to its traditional role as a provider of trained persons and basic knowledge.

5 pp. / In this publication we make a recount of basic terms and acronyms used in describing the functionality and capabilities of precision agriculture technologies. Growers seeking to acquire new systems or upgrade their existing equipment need to be fluent in terminology used in communications, hardware, software, and other areas in order to make good decisions at the time of buying equipment. This information is also useful to educate equipment operators in the in-and-outs of this technology and this way be able to maximize the use of these expensive upgrades.

This study investigates the issue of gender differences in computer-based foreign language activities. The experiment, conducted at the University of Arizona in the Fall of 1992, used as subjects students (N = 60) enrolled in intermediate French classes. Students were assigned to mixed- or same-gender dyads. All dyads engaged in a French cooperative task at the computer. The software-based pre- and posttests were composed of two parts: (1) vocabulary pertaining to description of people, and (2) geographical knowledge. Gain scores indicated no significant difference in overall learning between genders and dyad types. Further analysis of subscores revealed that females outperformed males significantly (p =.02) in learning vocabulary pertaining to description of people. Males outperformed females numerically in learning geographical facts. Differences between mixed- and same-gender dyads suggest that females tend to acquiesce to male factual preferences in mixed-gender dyads. The analysis of interaction patterns at the computer revealed that females tended to share keyboard control more than males in same-gender dyads. And, males tended to use more management statements with female partners than with male partners. Results from the MBTI personality test indicated that males and females tended to have different learning profiles. The analysis of gain scores indicated that overall, NFs and NTs learned significantly more than STs. Personality profiles also showed a significant effect (p =.03) on keyboard control. EJs controlled the keyboard significantly more than the other types. Likewise, results revealed a significant effect of personalities on overall amount of talk (p =.04), management statements (p =.02), and task statements (p =.06). EJs spoke more and used more management statements than the other types when in control of the keyboard. When not in control of the keyboard, EPs and IJs spoke more than the other types. Interestingly 'non-keyboard controllers' tended to compensate for the lack of keyboard control with verbal control. The overall results of this study established that learning achievement and interaction patterns were more strongly related to personality differences than to gender differences.

The characteristics of passivated iron particles have been examined with flow microcalorimetry to determine the acidic nature of the surface sites. The molar heat of adsorption of pyridine from hexane was measured with a FMC and a differential refractive index detector, at 23 and 40°C. The adsorption data were found to obey the assumptions of the Freundlich isotherm. The adsorption densities at different temperatures were used to calculate the isosteric heat of adsorption. The molar heat of adsorption of triethylamine from hexane was also measured and combined with the data for pyridine in order to calculate the Drago constants for the iron particles. A static adsorption method was used for the adsorption of pyridine from hexane onto the iron particles, for comparison with the dynamic method. The heat of wetting for the iron particles, with hexane, has also been measured. The iron particles were examined with X-ray diffraction. Mossbauer spectroscopy, XPS, SEM, TEM, and electrophoresis to characterize the surface layer. These techniques have revealed that the iron particles are coated with ferric oxide and this surface is amphoteric in aqueous solutions.

The performance of four immunochemical test kits in detecting aflatoxin contamination in cottonseed under non-laboratory conditions was evaluated. Naturally contaminated cottonseed was analyzed at cotton gins, ammoniation plants, cotton oil processing plants, a dairy farm and at the University of Arizona. Evaluation was based on the ability to determine aflatoxin concentrations as more or less than 20 ppb when analyzed on-site and in the laboratory using a common extract. Comparison of results from both locations showed excellent agreement (Afla-20 Cup 86 ± 6%, (n = 188); Agri-Screen I, 75 ± 9%, (n = 56); Agri-Screen II, 93 ± 5%, (n = 106); Agri-Chek, 93 ± 4%, (n = 156) and Aflatest-10, 90 ± 4%, (n = 178)). Overall agreement between on-site and laboratory results was 88%. Comparison of kit results to those of TLC demonstrated a low potential for obtaining false negative values. From these results the kits can reliably be used to screen cottonseed for aflatoxin contamination under non-laboratory conditions.

A dynamic model of fresh beef packaged under modified atmospheres has been developed. This model links the change in meat color with the permeation of gases (O₂, CO₂, N₂) through the packaging film. Its viability is demonstrated with experimental data using muscle semimembranosus with which it was shown that color change of the meat surface and the change of headspace gas concentration were well described by the model. Moreover, the model parameters were obtained independently of the model itself through the literature. A major result of the model showed that surface color is independent of oxygen concentration above 5%. Moreover, under aseptic conditions and ambient atmosphere concentrations, shelf-life of muscle semimembranosus was shown to be 11 days with this value possibly being a minimum.

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