A cost-effective steam-driven RO plant for brackish groundwater

Desalination is a costly means of providing freshwater. Most desalination plants use either reverse osmosis (RO) or thermal distillation. Both processes have drawbacks: RO is efficient but uses expensive electrical energy; thermal distillation is inefficient but uses less expensive thermal energy. This work aims to provide an efficient RO plant that uses thermal energy. A steam-Rankine cycle has been designed to drive mechanically a batch-RO system that achieves high recovery, without the high energy penalty typically incurred in a continuous-RO system. The steam may be generated by solar panels, biomass boilers, or as an industrial by-product. A novel mechanical arrangement has been designed for low cost, and a steam-jacketed arrangement has been designed for isothermal expansion and improved thermodynamic efficiency. Based on detailed heat transfer and cost calculations, a gain output ratio of 69-162 is predicted, enabling water to be treated at a cost of 71 Indian Rupees/m3 at small scale. Costs will reduce with scale-up. Plants may be designed for a wide range of outputs, from 5 m3/day, up to commercial versions producing 300 m3/day of clean water from brackish groundwater.

Η διαχείριση αλλαγών στην υγεία

Η διαχείριση αλλαγών είναι μια σημαντική πρόκληση για τις μονάδες υγείας και απαιτεί ικανότητες και ετοιμότητα από τη διοίκησή τους. Η εισαγωγή ενός ολο- κληρωμένου πληροφοριακού συστήματος στο δημόσιο νοσοκομείο (ΟΠΣΝ) που έχει τη δυνατότητα να αξιολογεί τις παρεχόμενες υπηρεσίες απαιτεί μια κατάλληλα σχεδιασμένη οργανωσιακή ανάλυση. Αυτή γίνεται, αξιοποιώντας το διαγνωστικό μοντέλο συνταύτισης των Nadler και Tushman όπου αντιμετωπίζει τον οργανισμό και τις αλλαγές ως ένα δυναμικό και αλληλοεξαρτώμενο σύστημα. Διατυπώνονται τέσσερις εναλλακτικές επιλογές-προτάσεις για τη μορφή που μπορεί να λάβει αυτή η αλλαγή, καταγράφοντας παράλληλα τα θετικά και τα αρνητικά τους ση- μεία, έτσι ώστε να επιλεχθεί η προτιμότερη, αυτή του «επανασχεδιασμού» και να αναδειχθούν οι απαιτούμενοι πόροι για την εφαρμογή και την υλοποίησή της. Η ορθή διαχείριση αλλαγής απαιτεί να καθοριστούν οι αντίστοιχοι στόχοι, να ανα- δειχθούν οι ευκαιρίες από την ανάπτυξη του ΟΠΣΝ στο δημόσιο νοσοκομείο και να καταγραφούν τα στάδια εφαρμογής του. Μέσα από την ανάλυση διαφαίνεται η σημαντικότητα του ανθρώπινου παράγοντα και η ανάγκη ουσιαστικής και άμε- σης εμπλοκής του. Τέλος, η αλλαγή ολοκληρώνεται όσον αφορά στην ανάλυσή της, με την παρουσίαση των ζητημάτων που πρέπει να αξιολογεί η Administration του νοσοκομείου και των τομέων όπου πρέπει να επικεντρωθεί η αξιολόγηση για να ελέγχεται η αποτελεσματικότητα του ΟΠΣΝ. The management of change is a significant challenge for health units, which demands skills and readiness on the part of their administration. The introduction of an integrated information system in a public hospital to provide the ability to assess the services offered necessitates the conduct of a well designed organizational analysis. This can be made using the diagnostic congruence model of Nadler and Tushman, which treats the organization and the changes as a dynamic and interdependent system. Four alternative choices with respect to change are presented here, pointing out their relative merits and drawbacks. The preferred alternative is that of "reformation" and the resources necessary for its implementation are delineated. The effective management of change requires determination of the appropriate goals, definition of the opportunities arising from the development of this system and recording of the stages of implementation. Through this analysis, the importance of the human factor is apparent, and the need for its immediate involvement is imperative. Finally, this analysis of organizational change concludes with presen- tation of the issues that the hospital administration needs to assess and the specific areas of focus to be defined in order for the effectiveness of the integrated information system to be monitored.

Furnace chemical vapor deposition (FCVD) method for special optical fibers fabrication

The features of the Furnace Chemical Vapor Deposition (FCVD) method of manufacturing preforms for special optical fibers are considered. It is shown that misalignment of substrate silica tube and furnace hole axes has a negative effect on the quality of fabricated preforms, leading to angular and radial asymmetry of the refractive index profile. Ways of getting rid of this and other disadvantages of the FCVD method are described. Some advantages of the FCVD method over the MCVD method are shown. It was demonstrated that the FCVD method, despite some drawbacks, allows to manufacture high-quality fiber preforms with good symmetry of the refractive index profile, and thus it is promising for fabrication of dispersion, dispersion varying and active fibers. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

The strengths, weaknesses, opportunities and threats of using social software in higher and further education teaching and learning

Social software is increasingly being used in higher and further education to support teaching and learning processes. These applications provide students with social and cognitive stimulation and also add to the interaction between students and educators. However, in addition to the benefits the introduction of social software into a course environment can also have adverse implications on students, educators and the education institution as a whole, a phenomenon which has received much less attention in the literature. In this study we explore the various implications of introducing social software into a course environment in order to identify the associated benefits, but also the potential drawbacks. We draw on data from 20 social software initiatives in UK based higher and further education institutions to identify the diverse experiences and concerns of students and educators. The findings are presented in form of a SWOT analysis, which allows us to better understand the otherwise ambiguous implications of social software in terms of its strengths, weaknesses, opportunities and threats. From the analysis we have derived concrete recommendations for the use of social software as a teaching and learning tool.

The risk of re-intervention after endovascular aortic aneurysm repair

This thesis studies survival analysis techniques dealing with censoring to produce predictive tools that predict the risk of endovascular aortic aneurysm repair (EVAR) re-intervention. Censoring indicates that some patients do not continue follow up, so their outcome class is unknown. Methods dealing with censoring have drawbacks and cannot handle the high censoring of the two EVAR datasets collected. Therefore, this thesis presents a new solution to high censoring by modifying an approach that was incapable of differentiating between risks groups of aortic complications. Feature selection (FS) becomes complicated with censoring. Most survival FS methods depends on Cox's model, however machine learning classifiers (MLC) are preferred. Few methods adopted MLC to perform survival FS, but they cannot be used with high censoring. This thesis proposes two FS methods which use MLC to evaluate features. The two FS methods use the new solution to deal with censoring. They combine factor analysis with greedy stepwise FS search which allows eliminated features to enter the FS process. The first FS method searches for the best neural networks' configuration and subset of features. The second approach combines support vector machines, neural networks, and K nearest neighbor classifiers using simple and weighted majority voting to construct a multiple classifier system (MCS) for improving the performance of individual classifiers. It presents a new hybrid FS process by using MCS as a wrapper method and merging it with the iterated feature ranking filter method to further reduce the features. The proposed techniques outperformed FS methods based on Cox's model such as; Akaike and Bayesian information criteria, and least absolute shrinkage and selector operator in the log-rank test's p-values, sensitivity, and concordance. This proves that the proposed techniques are more powerful in correctly predicting the risk of re-intervention. Consequently, they enable doctors to set patients’ appropriate future observation plan.

The use of modelling in purchasing/supply management research

The purpose of this research to explore the use of modelling in the field of Purchasing and Supply Management (P/SM). We are particularly interested in identifying the specific areas of P/SM where there are opportunities for the use of modelling based methods. The paper starts with an overview of main types of modelling and also provides a categorisation of the main P/SM research themes. Our research shows that there are many opportunities for using descriptive, predictive and prescriptive modelling approaches in all areas of P/SM research from the ones with a focus on the actual function from a purely operational and execution perspective (e.g. purchasing processes and behaviour) to the ones with a focus on the organisational level from a more strategic perspective (e.g. strategy and policy). We conclude that future P/SM research needs to explore the value of modelling not just at the functional or operational level, but also at the organisation and strategic level respectively. We also acknowledge that while using empirical results to inform and improve models has advantages, there are also drawbacks, which relate to the value, the practical relevance and the generalisability of the modelling based approaches.

Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

Safety in civil aviation is increasingly important due to the increase in flight routes and their more challenging nature. Like other important systems in aircraft, fuel level monitoring is always a technical challenge. The most frequently used level sensors in aircraft fuel systems are based on capacitive, ultrasonic and electric techniques, however they suffer from intrinsic safety concerns in explosive environments combined with issues relating to reliability and maintainability. In the last few years, optical fiber liquid level sensors (OFLLSs) have been reported to be safe and reliable and present many advantages for aircraft fuel measurement. Different OFLLSs have been developed, such as the pressure type, float type, optical radar type, TIR type and side-leaking type. Amongst these, many types of OFLLSs based on fiber gratings have been demonstrated. However, these sensors have not been commercialized because they exhibit some drawbacks: low sensitivity, limited range, long-term instability, or limited resolution. In addition, any sensors that involve direct interaction of the optical field with the fuel (either by launching light into the fuel tank or via the evanescent field of a fiber-guided mode) must be able to cope with the potential build up of contamination-often bacterial-on the optical surface. In this paper, a fuel level sensor based on microstructured polymer optical fiber Bragg gratings (mPOFBGs), including poly (methyl methacrylate) (PMMA) and TOPAS fibers, embedded in diaphragms is investigated in detail. The mPOFBGs are embedded in two different types of diaphragms and their performance is investigated with aviation fuel for the first time, in contrast to our previous works, where water was used. Our new system exhibits a high performance when compared with other previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring.