Application of multi-criteria decision-making to risk prioritisation in tidal energy developments

This paper presents an analytical multi-criterion analysis for the prioritisation of risks for the development of tidal energy projects. After a basic identification of risks throughout the project and relevant stakeholders in the UK, classified through a political, economic, social, technological, legal and environmental analysis, relevant questionnaires provided scores to each risk and corresponding weights for each of the different sectors. Employing an extended technique for order of preference by similarity to ideal solution as well as the weighted sum method based on the data obtained, the risks identified are ranked based on their criticality, drawing attention of the industry in mitigating the ones scoring higher. Both methods were modified to take averages at different stages of the analysis in order to observe the effects on the final risk ranking. A sensitivity analysis of the results was also carried out with regard to the weighting factors given to the perceived expertise of participants, with different results being obtained whether a linear, squared or square root regression is used. Results of the study show that academics and industry have conflicting opinions with regard to the perception of the most critical risks.     

Use of activity-based costing and economic value analysis for the justification of capital investments in automated material handling systems

This paper develops a two-stage method for the justification of investment in modern material handling systems. The underlying approach places heavy emphasis on the use of cost avoidance data quantified by activity-based costing systems. The first stage collects the life-cycle costs and benefits resulting from the reconfiguration of material handling systems in manufacturing facilities. A recently developed software package for process modelling and management is employed to capture the characteristics of material handling activities and to derive accurate applied cost rates for each activity and material handling system combination. These activity-related cost data as well as various opportunity costs are incorporated in a case-specific, investment decision model that constitutes the second stage of the method. The model performs an Economic Value Analysis for each material handling alternative. In doing so, it offers a sound basis for economic comparison of different systems. A case study illustrates the merit of our two-stage method in decision making by placing an accurate and reliable economic value on the transition from manual to automated material handling in a manufacturing facility. The use of activity-based costs reverses the decision of sustaining the 'status quo' supported by a traditional investment justification approach restricted to solely labour cost reductions     

Frozen mirabelle plum drying: Kinetics, modelling and impact on biochemical properties

The aim of this research was to study and model the kinetics of the hot air drying of frozen mirabelle plums. Effects of temperature (50-85 °C), air velocity (0.6-1.2 m/s) and a pre-treatment (ascorbic acid + sucrose-saturated solution) were investigated. The sorption isotherm and heat of sorption of mirabelle plum were mathematically described respectively by the Guggenheim, Anderson and de Boer (GAB) model and a new one. Depending on temperature and air velocities, the effective diffusivity and the energy of activation were respectively in the range of 8-16.8 × 10⁻¹⁰ m² s⁻¹ and 43.7-55.14 kJ mol⁻¹. To establish the model best adapted to describe this process the fit quality of five models (Newton, page, modified page, logarithmic and diffusion) were evaluated and compared. The diffusion model led to low values of reduced χ-square, mean square root and mean relative deviation modulus with the highest linear regression coefficient. This model was validated in a large range of operating conditions and represents an excellent tool to predict the duration of this process. The pre-treatment preserves biochemical properties of the dried mirabelle plums (reducing sugar content, total phenolic compounds and anti-oxidant activity).     

Thermoelectric Properties of Hot-Pressed β-K2Bi8Se13−x S x Materials

In this work, hot-pressed pellets of the K₂Bi₈Se₁₃ family of compounds were prepared for the first time. The pellet fabrication of selected members of the K₂Bi₈Se_13?x S _x series was studied. Sintering parameters, such as temperature, pressure, and duration, were investigated based on a statistical design- of-experiments approach to identify the optimum conditions for fabrication of high-quality pellets. These optimum conditions were then applied for the K₂Bi₈Se_13?x S _x series, and the thermoelectric properties of the stoichiometric members for x = 0, 4, 6, and 8 were studied. Doping experiments were also investigated using sulfur excess in the x = 6 member in an attempt to modify its properties.     

Solid-State Synthesis and Thermoelectric Properties of Sb-Doped Mg2Si Materials

Sb-doped magnesium silicide compounds have been prepared through ball milling and solid-state reaction. Materials produced were near-stoichiometric. The structural modifications have been studied with powder x-ray diffraction. Highly dense pellets of Mg₂Si_1?x Sb _x (0 ≤ x ≤ 0.04) were fabricated via hot pressing and studied in terms of Seebeck coefficient, electrical and thermal conductivity, and free carrier concentration as a function of Sb concentration. Their thermoelectric performance in the high temperature range is presented, and the maximum value of the dimensionless figure of merit was found to be 0.46 at 810 K, for the Mg₂Si_0.915Sb_0.015 member.     

Directed Evolution of Phi Class Glutathione Transferases Involved in Multiple-Herbicide Resistance of Grass Weeds and Crops

The extensive application of herbicides in crop cultivation has indisputably led to the emergence of weed populations characterized by multiple herbicide resistance (MHR). This phenomenon is associated with the enhanced metabolism and detoxifying ability of endogenous enzymes, such as phi class glutathione transferases (GSTFs). In the present work, a library of mutant GSTFs was created by in vitro directed evolution via DNA shuffling. Selected gstf genes from the weeds Alopecurus myosuroides and Lolium rigidum, and the cereal crops Triticum durum and Hordeum vulgare were recombined to forge a library of novel chimeric GSTFs. The library was activity screened and the best-performing enzyme variants were purified and characterized. The work allowed the identification of enzyme variants that exhibit an eight-fold improvement in their catalytic efficiency, higher thermal stability (8.3 °C) and three-times higher inhibition sensitivity towards the herbicide butachlor. The crystal structures of the best-performing enzyme variants were determined by X-ray crystallography. Structural analysis allowed the identification of specific structural elements that are responsible for k_cat regulation, thermal stability and inhibition potency. These improved novel enzymes hold the potential for utilization in biocatalysis and green biotechnology applications. The results of the present work contribute significantly to our knowledge of the structure and function of phi class plant GSTs and shed light on their involvement in the mechanisms of MHR.     

A diagnostic tolerance system

This paper describes a Diagnostic Tolerance System (DTS) designed to allow users to interactively select the appropriate class of fit and perform tolerance analysis for an assembly. The DTS is written in C programming language for a micro-computer and can be interfaced with CAD software, such as AutoCAD and CADkey. With the DTS, the productivity of designers is enhanced and design for manufacturability is easier to achieve.     

Robust adaptive controller with zero residual tracking errors

The adaptive control of a plant whose dominant part has transfer function with relative degreen^{ast} = 1has been considered in the presence of parasitics and disturbances. A new adaptive law is proposed which guarantees the existence of a large region of attraction from which all signals are bounded and the tracking error converges to a small residual set. In contrast to the adaptive law used in [1], [2] the new adaptive law guarantees a smaller residual set for the tracking error, which reduces to zero when the parasitics and disturbances disappear.