Electromechanical resonators as measuring transducers

With the increasing use of digital computers for data acquisition and digital process control, frequency domain transducers have become very attractive due to their virtual digital output. Essentially they are electrically maintained oscillators where the sensor is the controlling resonator.They are designed to make the frequency a function of the physical parameter being measured. Because of their high quality factor, mechanical resonators give very good frequency stability and are widely used as sensors. For this work symmetrical mechanical resonators such as the tuning fork were considered, to be the most promising. These are dynamically clamped and can be designed to have extensive regions where no vibrations occur.This enables the resonators to be robustly mounted in a way convenient for various applications. Designs for the measurement of fluid density and tension have been produced. The principle of the design of the resonator for fluid density measurement is a thin gap (trapping a lamina of fluid) between its two members which vibrate in antiphase.An analysis of the inter­ action between this resonator and the fluid lamina has carried out.In gases narrow gaps are needed for a good sensitivity and the use of the material fused quartz, because of its low density and very low temperature coefficient, is ideally suitable. In liquids an adequate sensitivity is achieved even with a wide lamina gap. Practical designs of such transducers have been evolved. The accuracy for liquid measurements is better than 1%. For gases it was found that, in air, a change of atmospheric pressure of 0.3% could be detected. In constructing a tension transducer using such a mechanical sensor as a wire or a beam, major difficulties are encountered in making an efficient clamping arrangement for the sensor. The use of dynamically clamped beams has been found to overcome the problem and this is the basis of the transducer investigated.

Vibrational methods applied to NDT testing and fluid density measurement

A system for the NDI' testing of the integrity of conposite materials and of adhesive bonds has been developed to meet industrial requirements. The vibration techniques used were found to be applicable to the development of fluid measuring transducers. The vibrational spectra of thin rectangular bars were used for the NDT work. A machined cut in a bar had a significant effect on the spectrum but a genuine crack gave an unambiguous response at high amplitudes. This was the generation of fretting crack noise at frequencies far above that of the drive. A specially designed vibrational decrement meter which, in effect, measures mechanical energy loss enabled a numerical classification of material adhesion to be obtained. This was used to study bars which had been flame or plasma sprayed with a variety of materials. It has become a useful tool in optimising coating methods. A direct industrial application was to classify piston rings of high performance I.C. engines. Each consists of a cast iron ring with a channel into which molybdenum, a good bearing surface, is sprayed. The NDT classification agreed quite well with the destructive test normally used. The techniques and equipment used for the NOT work were applied to the development of the tuning fork transducers investigated by Hassan into commercial density and viscosity devices. Using narrowly spaced, large area tines a thin lamina of fluid is trapped between them. It stores a large fraction of the vibrational energy which, acting as an inertia load reduces the frequency. Magnetostrictive and piezoelectric effects together or in combination enable the fork to be operated through a flange. This allows it to be used in pipeline or 'dipstick' applications. Using a different tine geometry the viscosity loading can be predoninant. This as well as the signal decrement of the density transducer makes a practical viscometer.

The role of formulation excipients in the development of lyophilised fast-disintegrating tablets

Despite recent Success, many fast-disintegrating tablets (FDTs) still face problems of low mechanical strength, poor mouth-feel and higher disintegration times. This Study aimed to optimise FDTS using a progressive three-stage approach. A series of hardness, fracturability and disintegration time tests were performed on the formulations at each stage. During Stage 1, tablets were prepared in concentrations between 2% and 5% w/w, and were formulated at each concentration as single and combination bloom strength gelatin (BSG) using 75 and 225 BSGs. Analysis revealed that both hardness and disintegration time increased with an increase in gelatin concentration. A combination (5% gelatin) FDT comprising a 50:50 ratio of 75:225 BSGs (hardness: 13.7 +/- 0.9 N and disintegration time: 24.1 +/- 0.6 s) was judged the most ideal, and was carried forward to Stage II: the addition of the saccharides sorbitol, mannitol and sucrose in concentrations between 10% and 80% w/w. The best properties were exhibited by mannitol-containing formulations (50%-hardness: 30.9 +/- 2.8 N and disintegration time: 13.3 +/- 2.1 s), which were carried forward to the next stage: the addition of viscosity-modifying polymers to improve mouth-feel and aid pre-gastric retention. Addition of carbopol 974P-NF resulted in the enhancement of viscosity with a compromise of the hardness of the tablet, whereas Pluronic F127 (6%) showed an increase in disintegration time and viscosity with retention of mechanical propel-ties. (C) 2008 Elsevier B.V. All rights reserved.

Comprehensive human urine standards for comparability and standardization in clinical proteome analysis

Urine proteomics is emerging as a powerful tool for biomarker discovery. The purpose of this study is the development of a well-characterized "real life" sample that can be used as reference standard in urine clinical proteomics studies.

Mechanisms of drying of skin forming materials

The literature relating to evaporation from single droplets of pure liquids, and to the drying of droplets containing solids and of droplet sprays has been reviewed. The heat and mass transfer rates for a single droplet suspended from a nozzle were studied within a 42mm I.D. horizontal wind tunnel designed to supply hot dry air, to simulate conditions encountered in a practical spray dryer. A novel rotating glass nozzle was developed to facilitate direct measurements of droplet weight and core temperature. This design minimised heat conduction through the nozzle. Revised correlations were obtained for heat and mass transfer coefficients, for evaporation from pure water droplets suspended from a rotating nozzle. Nu = 2.0 + 0.27 (l/B)°-18Re°-5Pr°-83 Sh = 2.0 + 0.575 ((T0-T.)/Tomfc) -o.o4Reo.5 ^0.33 Experimental drying studies were carried out on single droplets of different types of skin-forming materials, namely, custard, gelatin, skim milk and fructose at air temperatures ranging from 19°C to 198°C. Dried crusts were recovered and examined by Scanning Electron Microscopy. Skin-forming materials were classified into three types according to the mechanisms of skin formation. In the first type (typified by droplets of custard and starch) skin formed due to gelatinisation at high temperatures. Increasing the drying temperature resulted in increased crust resistance to mass transfer due to increased granule swelling and the crust resistance was completely transferred to a skin resistance at drying temperatures > 150°C. In the second type e.g. gelatin droplets the skin formed immediately drying had taken place at any drying temperature. At drying temperature > 60° C a more resistant skin was formed. In the third type (typified by droplets of skim milk and fructose) the skin appeared on the droplet surface at a certain stage of the drying process under any drying conditions. As the drying temperature was increased the resistance of the skin to mass transfer increased. The drying rate history of any material depended upon the nature of the skin formed which, in turn, depended upon the drying conditions. A mathematical model was proposed for the drying of the first type of skin-forming material. This was based on the assumption that, once all the granules gelatinised at the gelatinisation temperature, a skin appeared instantaneously on the droplet surface. The experimentally-observed times at which the skin appeared on the droplets surfaces were in excellent agreement with those predicted from the model. The work should assist in understanding the fundamentals of paniculate drying processes, particularly when skin-formation occurs and may be a crucial factor in volatiles retention.

Individual differences in work behaviour of blue-collar workers : a study of rubber tappers in Malaysia

This thesis examines individual differences in work behaviour of rubber tappers. The study examined sex, age, experience and race differences and their interactions with terrain on job performance, absenteeism, and job satisfaction of 1053 rubber tappers. Rubber tappers are unskilled blue-collar workers who essentially do the same type of work and are paid the same rates of pay. There are very few studies that have compared male and female blue-collar workers doing similar jobs in organisational settings. This study is one of the few investigations that examine sex differences in job performance of blue-collar workers doing same job using production data. Studies on age differences in work behaviour encounter numerous methodological difficulties such as high turnover, internal transfers and problems associated with age differences in educational levels. The participation of rubber tappers in this study is envisaged to overcome these difficulties because attrition rates of rubber tappers are low, and internal transfers are non existent. Further, the educational levels of rubber tappers are relatively similar across different age cohorts, as most rubber tappers have little or no education. Two measures of both job performance and absenteeism were derived from payroll records. The two job performance measures were total crop production and attendance. The two absenteeism measures were avoidable and unavoidable absence rates. Overall job satisfaction was determined using a 4-item scale. Significant sex, age, experience and race differences were obtained for job performance, absenteeism and job satisfaction. Significant interactive effects were also obtained for sex, age , experience, race and terrain for job performance and absenteeism. The results are discussed in relation to the abilities and motivation of rubber tappers. The implication of these findings for employee selection and human resource management in rubber estates is discussed.

A study of thermodynamic characteristics and predictive computer modelling of an air to water heat pump system

A study on heat pump thermodynamic characteristics has been made in the laboratory on a specially designed and instrumented air to water heat pump system. The design, using refrigerant R12, was based on the requirement to produce domestic hot water at a temperature of about 50 °C and was assembled in the laboratory. All the experimental data were fed to a microcomputer and stored on disk automatically from appropriate transducers via amplifier and 16 channel analogue to digital converters. The measurements taken were R12 pressures and temperatures, water and R12 mass flow rates, air speed, fan and compressor input powers, water and air inlet and outlet temperatures, wet and dry bulb temperatures. The time interval between the observations could be varied. The results showed, as expected, that the COP was higher at higher air inlet temperatures and at lower hot water output temperatures. The optimum air speed was found to be at a speed when the fan input power was about 4% of the condenser heat output. It was also found that the hot water can be produced at a temperature higher than the appropriate R12 condensing temperature corresponding to condensing pressure. This was achieved by condenser design to take advantage of discharge superheat and by further heating the water using heat recovery from the compressor. Of the input power to the compressor, typically about 85% was transferred to the refrigerant, 50 % by the compression work and 35% due to the heating of the refrigerant by the cylinder wall, and the remaining 15% (of the input power) was rejected to the cooling medium. The evaporator effectiveness was found to be about 75% and sensitive to the air speed. Using the data collected, a steady state computer model was developed. For given input conditions s air inlet temperature, air speed, the degree of suction superheat , water inlet and outlet temperatures; the model is capable of predicting the refrigerant cycle, compressor efficiency, evaporator effectiveness, condenser water flow rate and system Cop.

Remote sensing applied to slope stability in mountainous roads in Iran

The Alborz Mountain range separates the northern part of Iran from the southern part. It also isolates a narrow coastal strip to the south of the Caspian Sea from the Central Iran plateau. Communication between the south and north until the 1950's was via two roads and one rail link. In 1963 work was completed on a major access road via the Haraz Valley (the most physically hostile area in the region). From the beginning the road was plagued by accidents resulting from unstable slopes on either side of the valley. Heavy casualties persuaded the government to undertake major engineering works to eliminate ''black spots" and make the road safe. However, despite substantial and prolonged expenditure the problems were not solved and casualties increased steadily due to the increase in traffic using the road. Another road was built to bypass the Haraz road and opened to traffic in 1983. But closure of the Haraz road was still impossible because of the growth of settlements along the route and the need for access to other installations such as the Lar Dam. The aim of this research was to explore the possibility of applying Landsat MSS imagery to locating black spots along the road and the instability problems. Landsat data had not previously been applied to highway engineering problems in the study area. Aerial photographs are better in general than satellite images for detailed mapping, but Landsat images are superior for reconnaissance and adequate for mapping at the 1 :250,000 scale. The broad overview and lack of distortion in the Landsat imagery make the images ideal for structural interpretation. The results of Landsat digital image analysis showed that certain rock types and structural features can be delineated and mapped. The most unstable areas comprising steep slopes, free of vegetation cover can be identified using image processing techniques. Structural lineaments revealed from the image analysis led to improved results (delineation of unstable features). Damavand Quaternary volcanics were found to be the dominant rock type along a 40 km stretch of the road. These rock types are inherently unstable and partly responsible for the difficulties along the road. For more detailed geological and morphological interpretation a sample of small subscenes was selected and analysed. A special developed image analysis package was designed at Aston for use on a non specialized computing system. Using this package a new and unique method for image classification was developed, allowing accurate delineation of the critical features of the study area.

Minimizing nasty surprises with better informed decision-making in self-adaptive systems

Designers of self-adaptive systems often formulate adaptive design decisions, making unrealistic or myopic assumptions about the system's requirements and environment. The decisions taken during this formulation are crucial for satisfying requirements. In environments which are characterized by uncertainty and dynamism, deviation from these assumptions is the norm and may trigger 'surprises'. Our method allows designers to make explicit links between the possible emergence of surprises, risks and design trade-offs. The method can be used to explore the design decisions for self-adaptive systems and choose among decisions that better fulfil (or rather partially fulfil) non-functional requirements and address their trade-offs. The analysis can also provide designers with valuable input for refining the adaptation decisions to balance, for example, resilience (i.e. Satisfiability of non-functional requirements and their trade-offs) and stability (i.e. Minimizing the frequency of adaptation). The objective is to provide designers of self adaptive systems with a basis for multi-dimensional what-if analysis to revise and improve the understanding of the environment and its effect on non-functional requirements and thereafter decision-making. We have applied the method to a wireless sensor network for flood prediction. The application shows that the method gives rise to questions that were not explicitly asked before at design-time and assists designers in the process of risk-aware, what-if and trade-off analysis.