Axiomatic design principles in analysing the ergonomics design parameter of a virtual environment

One of the negative side effects experienced by users when interacting with virtual environment is visual symptoms. This paper explores the ergonomics design parameters of the virtual environment to minimize such negative side effect by applying axiomatic design principles. Axiomatic design is a method to provide a systematic way for designing products and large systems. The independence axiom is used to map customer domain (CAs) to functional domain (FRs) and physical domain (DPs). A paper based survey was conducted to identify and define customers' preference in the virtual environment. A virtual robot manufacturing system was developed as a case study to explore ergonomic design parameters that satisfy the independence of FRs and CAs. Results of this study shows that the ergonomic design parameters of virtual environment identified (DP₁₆₁-DP₁₆₂-DP₁₂₁-DP₁₁₁-DP₁₃₁-DP₁₄₁-DP₁₅₁-DP₁₅₂) have satisfied the independence functional requirement and desired visual comfort for users. By uncoupling the design it provides an efficient and effective sequence of design activities FR₁₆₁-FR₁₆₂-FR₁₂₁-FR₁₁₁-FR₁₃₁-FR₁₄₁-FR₁₅₁-FR₁₅₂.     

Application of backward differentiation methods to the finite element solution of time-dependent problems

The application of finite element methods to parabolic partial differential equations leads to large linear systems of first-order ordinary differential equations. Very often these systems are stiff and difficulties arise in their numerical solution. We attempt to analyse the problem of how to select numerical methods for the solution of such linear systems.     

Development of a rapid prototyping design advice system

This paper describes the initial development of a computer based Rapid Prototyping Design Advice System. The system is intended to assist the designer or project manager, particularly those in small and medium sized companies, in planning the prototyping stage of product development. It provides the user with an efficient and user friendly development aid which uses information obtained from the user and Computer Aided Design data to recommend suitable rapid prototyping solutions.     

The convergence of diagonally implicit Runge–Kutta methods combined with Richardson extrapolation

Runge–Kutta methods are widely used in the solution of systems of ordinary differential equations. Richardson extrapolation is an efficient tool for enhancing the accuracy of time integration schemes. In this paper we investigate the convergence of the combination of any of the diagonally implicit (including also the explicit) Runge–Kutta methods with active Richardson extrapolation and show that the numerical solution obtained converges under rather natural conditions.     

Albendazole solution formulation via vesicle-to-micelle transition of phospholipid-surfactant aggregates

Objective: To reveal the physicochemical mechanisms governing the solubilization of albendazole in surfactant and phospholipid-surfactant solutions and, on this basis, to formulate clinically relevant dose of albendazole in solution suitable for parenteral delivery.

Significance: (1) A new drug delivery system for parenteral delivery of albendazole is proposed, offering high drug solubility and low toxicity of the materials used; (2) New insights on the role of surface curvature on albendazole solubilization in surfactant and surfactant-phospholipid aggregates are provided.

Methods: The effect of 17 surfactants and 6 surfactant-phospholipid mixtures on albendazole solubility was studied. The size of the colloidal aggregates was determined by light-scattering. The dilution stability of the proposed formulation was assessed by experiments with model human serum.

Results: Anionic surfactants increased very strongly drug solubility at pH?=?3 (up to 4?mg/mL) due to strong electrostatic attraction between the oppositely charged (at this pH) drug and surfactant molecules. This effect was observed with all anionic surfactants studied, including sodium dodecyl sulfate, double chain sodium dioctylsulfosuccinate (AOT), and the bile salt sodium taurodeoxycholate. The phospholipid-surfactant mixture of 40% sodium dipalmitoyl-phosphatidylglycerol +60% AOT provided highest albendazole solubilization (4.4?mg/mL), smallest colloidal aggregate size (11?nm) and was stable to dilution with model human serum at (and above) 1:12 ratio.

Conclusions: A new albendazole delivery system with high drug load and low toxicity of the materials used was developed. The high solubility of albendazole was explained with vesicle-to-micelle transition due to the larger interfacial curvature preferred for albendazole solubilization locus.     

A hybrid fuzzy AHP-PROMETHEE decision support system for machine tool selection in flexible manufacturing cell

The selection process of a suitable machine tool among the increased number of alternatives has been an important issue for manufacturing companies for years. This is because the improper selection of a machine tool may cause many problems that will affect the overall performance. In this paper, a decision support system (DSS) is presented to select the best alternative machine using a hybrid approach of fuzzy analytic hierarchy process (fuzzy AHP) and preference ranking organization method for enrichment evaluation (PROMETHEE). A MATLAB- based fuzzy AHP is used to determine the weights of the criteria and it is called program for Priority Weights of the Evaluation Criteria (PWEC), and the PROMETHEE method is applied for the final ranking. The proposed model is structured to select the most suitable computer numerical controlled (CNC) turning centre machine for a flexible manufacturing cell (FMC) among the alternatives which are assigned from a database (DB) created for this purpose. A numerical example is presented to show the applicability of the model. It is concluded that the proposed model has the capability of dealing with a wide range of desired criteria and to select any type of machine tool required for building an FMC.