Constant shear along a boundary of a flume

'I'he accurate rreasurement of bed shear stress has been extremely difficult due to its changing values until white propunded a theory which would give constant shear along the bed of a flume. In this investigation a flume has been designed according to White's theory and by two separate methods proven to give constant shearing force along the bed. The first method applied the Hydrogen Bubble Technique to obtain accurate values of velocity thus allowing the velocity profile to be plotted and the momentum at the various test sections to be calculated. The use of a 16 mm Beaulieu movie camera allowed the exact velocity profiles created by the hydrogen bubbles to be recorded whilst an analysing projector gave the means of calculating the exact velocities at the various test sections. Simultaneously Preston's technique of measuring skin friction using Pitot tubes was applied. Twc banks of open ended water manometer were used for recording the static and velocity head pressure drop along the flume. This tvpe of manometer eliminated air locks in the tubes and was found to be sufficiently accurate. Readings of pressure and velocity were taken for various types and diameters of bed material both natural sands and glass spheres and the results tabulated. Graphs of particle Reynolds Number against bed shear stress were plotted and gave a linear relationship which dropped off at high values of Reynolds number. It was found that bed movement occurred instantaneously along the bed of the flume once critical velocity had been reached. On completion of this test a roof curve inappropriate to the bed material was used and then the test repeated. The bed shearing stress was now no longer constant and yet bed movement started instantaneously along the bed of the flume, showing that there are more parameters than critical shear stress to bed movement. It is concluded from the two separate methods applied that the bed shear stress is constant along the bed of the flume.

Effect of poor curing conditions and remedies on the durability of steel in concrete

An investigation was undertaken to study the effect of poor curing simulating hot climatic conditions and remedies on the durability of steel in concrete. Three different curing environments were used i.e. (1) Saturated Ca(OH)2 solution at 20°C, (2) Saturated Ca(OH)2 solution at 50°C and (3) Air at 50°C at 30% relative humidity. The third curing condition corresponding to the temperature and relative humidity typical of Middle Eastern Countries. The nature of the hardened cement paste matrix, cured under the above conditions was studied by means of Mercury Intrusion Porosimetry for measuring pore size distribution. The results were represented as total pore volume and initial pore entry diameter. The Scanning Electron Microscope was used to look at morphological changes during hydration, which were compared to the Mercury Intrusion Porosimetry results. X-ray defraction and Differential Thermal Analysis techniques were also employed for looking at any phase transformations. Polymer impregnation was used to reduce the porosity of the hardened cement pastes, especially in the case of the poorly cured samples. Carbonation rates of unimpregnated and impregnated cements were determined. Chloride diffusion studies were also undertaken to establish the effect of polymer impregnation and blending of the cements. Finally the corrosion behaviour of embedded steel bars was determined by the technique of Linear Polarisation. The steel was embedded in both untreated and polymer impregnated hardened cement pastes placed in either a solution containing NaCl or an environmental cabinet which provided carbonation at 40°C and 50% relative humidity.

Functionalisation of ethylene-propylene rubber with glycidyl methacrylate in the presence of comonomer and in situ compatibilisation of PET/f-EPR blends

The main aim of this work was two fold, firstly to investigate the effect of a highly reactive comonomer, divinylbenzene (DVB), on the extent of melt grafting of glycidyl methacrylate (GMA) on ethylene-propylene rubber (EPR) using 2,5-dimethyl-2,5-bis-(tert-butyl peroxy) hexane (Trigon ox 101, Tl 01) as a free radical initiator, and to compare the results with a conventional grafting of the same monomer on EPR. To achieve this, the effect of processing conditions and chemical composition including the concentration of peroxide, GMA and DVB on the extent of grafting was investigated. The presence of the comonomer (DVB) in the grafting process resulted in a significant increase in the extent of the grafting using only a small concentration of peroxide. It was also found that the extent of grafting increased drastically with increasing the DVB concentration. Interestingly, in the comonomer system, the extent of the undesired side reaction, normally the homopolymerisation of GMA (polyGMA) was shown to have reduced tremendously and in most cases the level of polyGMA was immeasurable in the samples. Compared to a conventional EPR-g-GMACONV (in the absence of a comonomer), the presence of the comonomer DVB in the grafting system was shown to result in more branching and crosslinking (shown from an increase in melt flow index (MFI) and torque values) and this was paralleled by an increase in DVB concentration. In contrast, the extent of grafting in conventional system increased with increasing the peroxide concentration but the level of grafting was much lower than in the case of DVB. Homopolymerisation of GMA and excessive crosslinking of EPR became dominant at high peroxide concentration and this. reflects that the side reactions were favorable in the conventional grafting system. The second aim was to examine the effect of the in-situ functionalised EPR when used as a compatibiliser for binary blends. It was found that blending PET with functionalised EPR (ƒ-EPR) gave a significant improvement in terms of blend morphology as well as mechanical properties. The results showed clearly that, blending PET with ƒ-EPRDVB (prepared with DVB) was much more effective compared to the corresponding PET/ƒ-EPRCONV (without DVB) blends in which ƒ-EPRDVB having optimum grafting level of 2.1 wt% gave the most pronounced effect on the morphology and mechanical properties. On the other hand, blends of PET/ƒ-EPRDVB containing high GMA/DVB ratio was found to be unfavorable hence exhibited lower tensile properties and showed unfavorable morphology. The presence of high polyGMA concentration in ƒ-EPRCONV was found to create damaging effect on its morphology, hence resulting in reduced tensile properties (e.g. low elongation at break). However, the use of commercial terpolymers based on ethylene-methacrylate-glycidyl methacrylate (EM-GMA)or a copolymer of ethylene-glycidyl methacrylate (E-GMA) containing various GMA levels as compatibilisers in PET/EPR blends was found to be more efficient compared to PET/EPR/ƒ-EPR blends with the former blends showing finer morphology and high elongation at break. The high efficiency of the terpolymers or copolymers in compatibilising the PET/EPR blends is suggested to be partly, higher GMA content compared to the amount in ƒ-EPR and due to its low viscosity.

Measurements design and phenomena discrimination

The construction of measurements suitable for discriminating signal components produced by phenomena of different types is considered. The required measurements should be capable of cancelling out those signal components which are to be ignored when focusing on a phenomenon of interest. Under the hypothesis that the subspaces hosting the signal components produced by each phenomenon are complementary, their discrimination is accomplished by measurements giving rise to the appropriate oblique projector operator. The subspace onto which the operator should project is selected by nonlinear techniques in line with adaptive pursuit strategies.

Carbon nanotube-polycarbonate composites for ultrafast lasers

Carbon nanotube polycarbonate composites with controlled nanotube-bundle size are prepared by dispersion with conjugated polymers followed by blending with polycarbonate. The composite has uniform sub-micrometer nanotube bundles in high concentration, shows strong nonlinear optical absorption, and generates 193 fs pulses when used as passive mode-locker in a fiber laser.

In vitro hydrolytic degradation of centrifugally spun polyhydroxybutyrate-pectin composite fibres

BACKGROUND: Centrifugal spinning is a novel fibre-forming process that readily permits the incorporation of additives while avoiding the thermal damage often associated with conventional melt spinning. Centrifugal spinning of a viscous solution of poly(3-hydroxybutyrate) (PHB) mixed with pectin was used to fabricate a range of fibres containing different concentrations of this biologically active agent. The influence of this blending on fibre morphology and in vitro degradation in an accelerated hydrolytic model at 70 ?C and pH of 10.6 is reported. RESULTS: Blending influenced the physiochemical properties of the fibres, andthis significantly affected thedegradation profile of both the fibre and its PHB constituent. A greater influence on degradation was exerted by the type of pectin and its degree of esterification than by variations in its loading. CONCLUSION: Centrifugal spinning permits the fabrication of composite fibrous matrices from PHB and pectin. Incorporation of the polysaccharide into the fibres can be used to manipulate degradation behaviour and demonstrates a model for doping of matrices with active biological constituents. The unique features of the centrifugal spinning process, as illustrated by the structure of the fibres and the degradation profiles, suggest possible applications of centrifugally spun biopolymers as wound scaffolding devices and in tissue engineering.

Characterisation of waste derived intermediate pyrolysis oils for use as diesel engine fuels

This paper studies the characteristics of intermediate pyrolysis oils derived from sewage sludge and de-inking sludge (a paper industry residue), with a view to their use as fuels in a diesel engine. The feedstocks were dried and pelletised, then pyrolysed in the Pyroformer intermediate pyrolysis system. The organic fraction of the oils was separated from the aqueous phase and characterised. This included elemental and compositional analysis, heating value, cetane index, density, viscosity, surface tension, flash point, total acid number, lubricity, copper corrosion, water, carbon residue and ash content. Most of these results are compared with commercial diesel and biodiesel. Both pyrolysis oils have high carbon and hydrogen contents and their higher heating values compare well with biodiesel. The water content of the pyrolysis oils is reasonable and the flash point is found to be high. Both pyrolysis oils have good lubricity, but show some corrosiveness. Cetane index is reduced, which may influence ignition. Also viscosity is increased, which may influence atomisation quality. Carbon residue and ash content are both high, indicating potential deposition problems. Compared with de-inking sludge pyrolysis oil (DSPO), sewage sludge pyrolysis oil (SSPO) has a higher heating value, but higher corrosiveness and viscosity. The conclusions are that both intermediate pyrolysis oils will be able to provide sufficient heat when used in diesel engine; however poor combustion and carbon deposition may be encountered. Blending of these pyrolysis oils with diesel or biodiesel could overcome these problems and is recommended for further investigation.

Causal relationship between HRM policies and organisational performance:evidence from the Greek manufacturing sector

Blending insights from the contingency theory, the resource-based view, and the AMO theory, the purpose of this paper is to investigate the HRM-performance causal relationship in the Greek context. The empirical research is based on a sample of 178 organisations operating in the Greek manufacturing sector. Using structural equation modelling the results of the study revealed that the ability to perform (resourcing and development), motivation to perform (compensation and incentives), and opportunity to perform (involvement and job design) HRM policy domains are moderated by business strategies (cost, quality, innovation), and additionally, the motivation to perform is further moderated by managerial style and organisational culture. Further, the results indicate that the impact of HRM policies on organisational performance is fully mediated by employee skills, attitudes, and behaviour. The paper concludes that although the motivation to perform HRM policy domain causes organisational performance, through employee attitudes, it may be supported that organisational performance positively moderates the effectiveness of this HRM policy domain, raising thus the question of reverse causality.

Personality across working life:the longitudinal and reciprocal influences of personality on work

Summary: This paper focuses on the role of personality at different stages of people's working lives. We begin by reviewing the research in industrial, work, and organizational (IWO) psychology regarding the longitudinal and dynamic influences of personality as an independent variable at different career stages, structuring our review around a framework of people's working lives and careers over time. Next, we review recent studies in the personality and developmental psychology domain regarding the influence of changing life roles on personality. In this domain, personality also serves as a dependent variable. By blending these two domains, it becomes clear that the study of reciprocal effects of work and personality might open a new angle in IWO psychology's long-standing tradition of personality research. To this end, we outline various implications for conceptual development (e.g., trait stability) and empirical research (e.g., personality and work incongruence). Finally, we discuss some methodological and statistical considerations for research in this new research domain. In the end, our review should enrich the way that IWO psychologists understand personality at work, focusing away from its unidirectional predictivist influence on job performance toward a more complex longitudinal reciprocal interplay of personality and working life. © 2013 John Wiley & Sons, Ltd.

Oblique matching pursuit

A method for selecting a suitable subspace for discriminating signal components through an oblique projection is proposed. The selection criterion is based on the consistency principle introduced by Unser and Aldroubi and extended by Elder. An effective implementation of this principle for the purpose of subspace selection is achieved by updating of the dual vectors yielding the corresponding oblique projector. © 2007 IEEE.

Reactive processing of polymers:functionalisation of ethylene-propylene diene terpolymer (EPDM) in the presence and absence of a co-agent and effect of functionalised EPDM on compatibilisation of poly(ethylene terephthalate)/EPDM blends

Ethylene-propylene diene terpolymer (EPDM) was functionalized with glycidyl methacrylate (GMA) during melt processing by free radical grafting with peroxide initiation in the presence and absence of a reactive comonomer trimethylolpropane triacrylate (Tris). Increasing the peroxide concentration resulted in an increase in the GMA grafting yield, albeit the overall grafting level was low and was accompanied by higher degree of crosslinking of EPDM which was found to be the major competing reaction. The presence of Tris in the grafting system gave rise to higher grafting yield produced at a much lower peroxide concentration though the crosslinking reactions remained high but without the formation of GMA-homopolymer in either of the two systems. The use of these functionalized EPDM (f-EPDM) samples with PET as compatibilisers in binary and ternary blends of PET/EPDM/f-EPDM was evaluated. The influence of the different functionalisation routes of the rubber phase (in presence and absence of Tris) and the effect of the level of functionality and microstructure of the resultant f-EPDM on the extent of the interfacial reaction, morphology and mechanical properties was also investigated. It is suggested that the mechanical properties of the blends are strongly influenced by the performance of the graft copolymer, which is in turn, determined by the level of functionality, molecular structure of the functionalized rubber and the interfacial concentration of the graft copolymer across the interface. The cumulative evidence obtained from torque rheometry, scanning electron microscopy, SEM, dynamic mechanical analysis (DMA), tensile mechanical tests and Fourier transform infrared (FTIR) supports this. It was shown that binary and ternary blends prepared with f-EPDM in the absence of Tris and containing lower levels of g-GMA effected a significant improvement in mechanical properties. This increase, particularly in elongation to break, could be accounted for by the occurrence of a reaction between the epoxy groups of GMA and the hydroxyl/carboxyl end groups of PET that would result in a graft copolymer which could, most probably, preferentially locate at the interface, thereby acting as an 'emulsifier' responsible for decreasing the interfacial tension between the otherwise two immiscible phases. This is supported by results from FTIR analysis of the fractionated PET phase of these blends which confirm the formation of an interfacial reaction, DMA results which show a clear shift in the T s of the blend components and SEM results which reveal very fine morphology, suggesting effective compatibilisation that is concomitant with the improvement observed in their tensile properties. Although Tris has given rise to highest amount of g-GMA, it resulted in lower mechanical properties than the optimized blends produced in the absence of Tris. This was attributed to the difference in the microstructure of the graft and the level of functionality in these samples resulting in less favourable structure responsible for the coarser dispersion of the rubber phase observed by SEM, the lower extent of T shift of the PET phase (DMA), the lower height of the torque curve during reactive blending and FTIR analysis of the separated PET phase that has indicated a lower extent of the interfacial chemical reaction between the phases in this Tris-containing blend sample. © 2005 Elsevier Ltd. All rights reserved.

Reactive processing of polymers:effect of in situ compatibilisation on characteristics of blends of polyethylene terephthalate and ethylene-propylene rubber

Ethylene-propylene rubber (EPR) functionalised with glycidyl methacrylate (GMA) (f-EPR) during melt processing in the presence of a co-monomer, such as trimethylolpropane triacrylate (Tris), was used to promote compatibilisation in blends of polyethylene terephthalate (PET) and f-EPR, and their characteristics were compared with those of PET/f-EPR reactive blends in which the f-EPR was functionalised with GMA via a conventional free radical melt reaction (in the absence of a co-monomer). Binary blends of PETand f-EPR (with two types of f-EPR prepared either in presence or absence of the co-monomer) with various compositions (80/20, 60/40 and 50/50 w/w%) were prepared in an internal mixer. The blends were evaluated by their rheology (from changes in torque during melt processing and blending reflecting melt viscosity, and their melt flow rate), morphology scanning electron microscopy (SEM), dynamic mechanical properties (DMA), Fourier transform infrared (FTIR) analysis, and solubility (Molau) test. The reactive blends (PET/f-EPR) showed a marked increase in their melt viscosities in comparison with the corresponding physical (PET/EPR) blends (higher torque during melt blending), the extent of which depended on the amount of homopolymerised GMA (poly-GMA) present and the level of GMA grafting in the f-EPR. This increase was accounted for by, most probably, the occurrence of a reaction between the epoxy groups of GMA and the hydroxyl/carboxyl end groups of PET. Morphological examination by SEM showed a large improvement of phase dispersion, indicating reduced interfacial tension and compatibilisation, in both reactive blends, but with the Tris-GMA-based blends showing an even finer morphology (these blends are characterised by absence of poly-GMA and presence of higher level of grafted GMA in its f-EPR component by comparison to the conventional GMA-based blends). Examination of the DMA for the reactive blends at different compositions showed that in both cases there was a smaller separation between the glass transition temperatures compared to their position in the corresponding physical blends, which pointed to some interaction or chemical reaction between f-EPR and PET. The DMA results also showed that the shifts in the Tgs of the Tris-GMA-based blends were slightly higher than for the conventional GMA-blends. However, the overall tendency of the Tgs to approach each other in each case was found not to be significantly different (e.g. in a 60/40 ratio the former blend shifted by up to 4.5 °C in each direction whereas in the latter blend the shifts were about 3 °C). These results would suggest that in these blends the SEM and DMA analyses are probing uncorrelatable morphological details. The evidence for the formation of in situ graft copolymer between the f-EPR and PET during reactive blending was clearly illustrated from analysis by FTIR of the separated phases from the Tris-GMA-based reactive blends, and the positive Molau test pointed out to graft copolymerisation in the interface. A mechanism for the formation of the interfacial reaction during the reactive blending process is proposed.

Energy production from biomass and waste derived intermediate pyrolysis oils

This study investigates the use of Pyroformer intermediate pyrolysis system to produce alternative diesel engines fuels (pyrolysis oil) from various biomass and waste feedstocks and the application of these pyrolysis oils in a diesel engine generating system for Combined Heat and Power (CHP) production. The pyrolysis oils were produced in a pilot-scale (20 kg/h) intermediate pyrolysis system. Comprehensive characterisations, with a view to use as engine fuels, were carried out on the sewage sludge and de-inking sludge derived pyrolysis oils. They were both found to be able to provide sufficient heat for fuelling a diesel engine. The pyrolysis oils also presented poor combustibility and high carbon deposition, but these problems could be mitigated by means of blending the pyrolysis oils with biodiesel (derived from waste cooking oil). The blends of SSPO (sewage sludge pyrolysis oil) and biodiesel (30/70 and 50/50 in volumetric ratios) were tested in a 15 kWe Lister type stationary generating system for up to 10 hours. There was no apparent deterioration observed in engine operation. With 30% SSPO blended into biodiesel, the engine presents better overall performance (electric efficiency), fuel consumption, and overall exhaust emissions than with 50% SSPO blend. An overall system analysis was carried out on a proposed integrated Pyroformer-CHP system. Combined with real experimental results, this was used for evaluating the costs for producing heat and power and char from wood pellets and sewage sludge. It is concluded that the overall system efficiencies for both types of plant can be over 40%; however the integrated CHP system is not economically viable. This is due to extraordinary project capital investment required.

Adiabatic soliton laser

The key to generating stable optical pulses is mastery of nonlinear light dynamics in laser resonators. Modern techniques to control the buildup of laser pulses are based on nonlinear science and include classical solitons, dissipative solitons, parabolic pulses (similaritons) and various modifications and blending of these methods. Fiber lasers offer remarkable opportunities to apply one-dimensional nonlinear science models for the design and optimization of very practical laser systems. Here, we propose a new concept of a laser based on the adiabatic amplification of a soliton pulse in the cavity - the adiabatic soliton laser. The adiabatic change of the soliton parameters during evolution in the resonator relaxes the restriction on the pulse energy inherent in traditional soliton lasers. Theoretical analysis is confirmed by extensive numerical modeling.

Do educators need educating?

Actual text: I was recently at the Spanish College of Optometry biennial conference and attended a meeting of contact lens lecturers from around Spain and Portugal. We discussed various ideas, mainly about how to share good practice and improve standards. What came to my mind was ‘is there a blueprint for training trainers?’ Well probably not but there are many things that we need to acknowledge such as the way students learn for example. Many educators themselves were taught by lecturers who would write on a blackboard or use acetate on an overhead projector, then came the 35 mm slide era followed by the Powerpoint era. More recently there is a move towards a much more integrated approach of various teaching methods. At my university our contact lens and anterior eye lectures generally follow a format where a narrated Powerpoint lecture is uploaded onto our internal virtual learning environment. This narrated version of the slides is designed to give the didactic element of the topic. The students listen to that before attending an interactive seminar on that topic. The seminar is also recorded so that students can listen to that afterwards. The seminar is designed to give additional information, such as case reports, or to clarify key points or for live demonstrations. It is a good way of doubling the contact time with the students without imposing further on an already packed formal timetable as the students can work in their own time. One problem that we noticed with this approach was that attendance can vary. If the students feel that they will gain something from the interactive seminar then they are more likely to attend – exam tips usually win them over! At the Spanish meeting the educators decided that they wanted to have regular meetings. The industry colleagues in attendance said that they were happy to help but could not necessarily give money, but they could offer meeting rooms, pay for lunch and evening meals. They even said that that they were happy to host meetings and invite other companies too (except to manufacturing plants). In the UK the British Committee of Contact Lens Educators (BUCCLE) meets for one day on three occasions in the year. The American Optometric Contact Lens Educators (AOCLE) meets annually at a three day event. Both these organisations get some help from industry. BUCCLE usually has one of its meetings at a university, one at a company training centre/manufacturing plant/national headquarters and one meeting the day before the BCLA annual conference. BUCCLE usually has its pre-BCLA meeting in conjunction with the International Association of Contact Lens Educators (IACLE). So when educators meet what would they discuss; well probably the focus should be on education rather than actual contact lens knowledge. For example sharing ideas on how to teach toric lens fitting would be better than discussing the actual topic of toric lenses itself. Most universities will have an education department with an expert who could share ideas on how to use the internet in teaching or how to structure lectures or assessments etc. In the past I have helped with similar training programmes in other countries and sharing good practice in pedagogy is always a popular topic. Anyone who is involved in education in the field of contact lenses should look at the IACLE web page and look out for the IACLE World Congress in 2015 in the days preceding the BCLA. Finally, IACLE, AOCLE and BUCCLE all exist as a result of generous educational grants from contact lens companies and anyone interested in finding out more about should refer to their respective web pages.