The frontier approach to the measurement of productivity and technical efficiency

In 1957, Farrell proposed to measure technical (in)efficiency as the realised deviation from a frontier isoquant. Since then, the research has developed several methods to derive the production frontier and it has also extended its scope in applying frontier techniques to the measurement of total factor productivity. In this paper, I present the core techniques for the measurement of technical efficiency and productivity based on the notion of frontier and introduce the more recent technological advances in the field.

Total factor productivity and the spillover hypothesis: some new evidence

In this paper I test the spillover hypothesis of the endogenous growth literature on a sample of manufacturing firms in Italy, 1989–1994, using a new approach based on the Malmquist index. First, I measure the productivity growth registered by the high- and non-high-tech firms computing the Malmquist index with DEA. I decompose it into technical change and technical efficiency change. Then I test whether the technical change registered by high-tech firms affects productivity growth of non-high-tech firms, after controlling for factors which can potentially affect productivity growth.

Validating the organizational climate measure:links to managerial practices, productivity and innovation

This paper describes the development and validation of a multidimensional measure of organizational climate, the Organizational Climate Measure (OCM), based upon Quinn and Rohrbaugh's Competing Values model. A sample of 6869 employees across 55 manufacturing organizations completed the questionnaire. The 17 scales contained within the measure had acceptable levels of reliability and were factorially distinct. Concurrent validity was measured by correlating employees' ratings with managers' and interviewers' descriptions of managerial practices and organizational characteristics. Predictive validity was established using measures of productivity and innovation. The OCM also discriminated effectively between organizations, demonstrating good discriminant validity. The measure offers researchers a relatively comprehensive and flexible approach to the assessment of organizational members' experience and promises applied and theoretical benefits. Copyright © 2005 John Wiley & Sons, Ltd.

When promoting positive feelings pays:Aggregate job satisfaction, work design features, and innovation in manufacturing organizations

This study investigates the relationship between aggregate job satisfaction and organizational innovation. In a sample of manufacturing companies, data were gathered from 3717 employees in 28 UK manufacturing organizations about their job satisfaction and aggregated to the organizational level. Data on innovation in technology/processes were gathered from multiple respondents in the same organizations 24 months later. The results revealed that aggregate job satisfaction was a significant predictor of subsequent organizational innovation, even after controlling for prior organizational innovation and profitability. Moreover the data indicated that the relationship between aggregate job satisfaction and innovation in production technology/processes was moderated by two factors: job variety and a commitment to "single status". Unlike previous studies, we conceptualize job satisfaction at the aggregate rather than the individual level and examine innovation rather than creativity. We propose that where the majority of employees experience job satisfaction, they will endorse rather than resist innovation and work collaboratively to implement as well as to generate creative ideas.

Design, modeling and construction of a novel ablative fast pyrolysis reactor and product collection system

The objective of this work was to design, construct and commission a new ablative pyrolysis reactor and a high efficiency product collection system. The reactor was to have a nominal throughput of 10 kg/11r of dry biomass and be inherently scalable up to an industrial scale application of 10 tones/hr. The whole process consists of a bladed ablative pyrolysis reactor, two high efficiency cyclones for char removal and a disk and doughnut quench column combined with a wet walled electrostatic precipitator, which is directly mounted on top, for liquids collection. In order to aid design and scale-up calculations, detailed mathematical modelling was undertaken of the reaction system enabling sizes, efficiencies and operating conditions to be determined. Specifically, a modular approach was taken due to the iterative nature of some of the design methodologies, with the output from one module being the input to the next. Separate modules were developed for the determination of the biomass ablation rate, specification of the reactor capacity, cyclone design, quench column design and electrostatic precipitator design. These models enabled a rigorous design protocol to be developed capable of specifying the required reactor and product collection system size for specified biomass throughputs, operating conditions and collection efficiencies. The reactor proved capable of generating an ablation rate of 0.63 mm/s for pine wood at a temperature of 525 'DC with a relative velocity between the heated surface and reacting biomass particle of 12.1 m/s. The reactor achieved a maximum throughput of 2.3 kg/hr, which was the maximum the biomass feeder could supply. The reactor is capable of being operated at a far higher throughput but this would require a new feeder and drive motor to be purchased. Modelling showed that the reactor is capable of achieving a reactor throughput of approximately 30 kg/hr. This is an area that should be considered for the future as the reactor is currently operating well below its theoretical maximum. Calculations show that the current product collection system could operate efficiently up to a maximum feed rate of 10 kg/Fir, provided the inert gas supply was adjusted accordingly to keep the vapour residence time in the electrostatic precipitator above one second. Operation above 10 kg/hr would require some modifications to the product collection system. Eight experimental runs were documented and considered successful, more were attempted but due to equipment failure had to be abandoned. This does not detract from the fact that the reactor and product collection system design was extremely efficient. The maximum total liquid yield was 64.9 % liquid yields on a dry wood fed basis. It is considered that the liquid yield would have been higher had there been sufficient development time to overcome certain operational difficulties and if longer operating runs had been attempted to offset product losses occurring due to the difficulties in collecting all available product from a large scale collection unit. The liquids collection system was highly efficient and modeling determined a liquid collection efficiency of above 99% on a mass basis. This was validated due to the fact that a dry ice/acetone condenser and a cotton wool filter downstream of the collection unit enabled mass measurements of the amount of condensable product exiting the product collection unit. This showed that the collection efficiency was in excess of 99% on a mass basis.

The design, evaluation and costing of biomass gasifiers

The objective of this study has been to enable a greater understanding of the biomass gasification process through the development and use of process and economic models. A new theoretical equilibrium model of gasification is described using the operating condition called the adiabatic carbon boundary. This represents an ideal gasifier working at the point where the carbon in the feedstock is completely gasified. The model can be used as a `target' against which the results of real gasifiers can be compared, but it does not simulate the results of real gasifiers. A second model has been developed which uses a stagewise approach in order to model fluid bed gasification, and its results have indicated that pyrolysis and the reactions of pyrolysis products play an important part in fluid bed gasifiers. Both models have been used in sensitivity analyses: the biomass moisture content and gasifying agent composition were found to have the largest effects on performance, whilst pressure and heat loss had lesser effects. Correlations have been produced to estimate the total installed capital cost of gasification systems and have been used in an economic model of gasification. This has been used in a sensitivity analysis to determine the factors which most affect the profitability of gasification. The most important influences on gasifier profitability have been found to be feedstock cost, product selling price and throughput. Given the economic conditions of late 1985, refuse gasification for the production of producer gas was found to be viable at throughputs of about 2.5 tonnes/h dry basis and above, in the metropolitan counties of the United Kingdom. At this throughput and above, the largest element of product gas cost is the feedstock cost, the cost element which is most variable.

Design, synthesis and evaluation of cyclothialidine analogues as DNA gyrase inhibitors

Cyclothialidine, a natural product isolated from Streptomyces .filipinensis NR0484, has been proven to be a potent and selective inhibitor of the bacterial enzyme DNA gyrase. Gyrase inhibition results in cell death, the enzyme being the target of several currently used antibiotics. Cyclothialidine showed poor activity against whole bacterial cells, highlighting scope for improvement regarding cell membrane pemeability in order for the full potential of this new class of antibiotics to be realised, Structurally, cyclothialidine contains a 12-membered lactone ring which is partly integrated into a pentapeptide chain, with a substituted aromatic moiety bordering the lactone, Retrosynthetically it can be traced back to cis-3-hydroxyproline, 3,5-dihydroxy-2,6-dimethylbenzoic acid and four commercially available amino acids; two serine, one cysteine and one alanine. In this work, a model of cyclothialidine was synthesised in order to establish the methodology for more complex compounds. Analogues with hydroxy, dihydroxy and dihydroxymethyl substituted aromatic moieties were then prepared to ensure successful protection methods could be performed and the pharmacophore synthesised. The key aromatic moiety, 2,6-dimethyl-3,5-dihydroxybenzoic acid was produced via two successive Mannich reaction/reduction steps. Acid protection using 4-nitrobenzyl bromide and TBDMS hydroxyl protection followed by bromination of one methyl afforded the desired intermediate. Reaction with a serine/cysteine dipeptide, followed by deprotection and cyclisation under Mitsunobu conditions lead to the 12-membered lactone. An amine substituted aromatic analogue and also replacement of the cysteine sulphur by oxygen were attempted but without success. In an effort to improve cell permeability, a conjugate was synthesised between the pharmacophore and a cholesterol moiety. It was hoped the steroid fragment would serve to increase potency by escorting the molecule through the lipid environment of the cell membrane. The pharmacophore and conjugate were tested against a variety of bacterial strains but the conjugate failed to improve activity.