Additive Manufacturing (AM) is an automated process of fabricating three-dimensional (3D) physical objects from a 3D-CAD data by adding layers of materials one upon another through a print head or nozzle without using any tooling components or machining environments. Due to freedom in design, any complex shape can be produced using this process. Fused Deposition Modeling (FDM) is one such AM technology that is commonly used for its simplicity, environment friendliness and low requirement for process monitoring. However, this technology is limited only to small-scale production due to high cost and high build time. The present work focuses on the development of a framework for parametric optimization of the FDM process using multi-objective optimization based on ratio analysis (MOORA). A CAD model of the cam follower mechanism has been prepared in the Solidworks platform and used in this experiment for optimization of build time and cost which have been considered as response variables of the experiment. The experiment has been conducted following the full factorial design of experiment (DoE) method.

Nowadays, companies are recognizing their primordial roles and responsibilities towards the protection of the environment and save the natural resources. They are focusing on some contemporary activities such as Reverse Logistics which is economically and environmentally viable. However, the integration of such an initiative needs flows restructuring and supply chain management in order to increase sustainability and maximize profits. Under this background, this paper addresses an inventory control model for a reverse logistics system that deals with two separated types of demand, for new products and remanufactured products, with different selling prices. The model consists of a single shared machine between production and remanufacturing operations, while the machine is subject to random failures and repairs. Three stock points respectively for returns, new products and remanufactured products are investigated. Meanwhile, in this paper, a modeling of the problem with Discrete-Event simulation using Arena® was conducted. Regarding the purpose of finding, a near-optimal inventory control policy that minimizes the total cost, an optimization of the model based on Tabu Search and Genetic Algorithms was established. Computational examples and sensitivity analysis were performed in order to compare the results and the robustness of each proposed algorithm. Then the results of the two methods were compared with those of OptQuest® optimization tool.

The powder coating is an economic, technologically superior and environment friendly painting technique compared with other conventional painting methods. However large variation in coating thickness can reduce the attractiveness of powder coated products. The coating thickness variation can also adversely affect the surface appearance and corrosion resistivity of the product. This can eventually lead to customer dissatisfaction and loss of market share. In this paper, the author discusses a dual response surface optimization methodology to minimize the thickness variation around the target value of powder coated industrial enclosures. The industrial enclosures are cabinets used for mounting the electrical and electronic equipment. The proposed methodology consists of establishing the relationship between the coating thickness & the powder coating process parameters and developing models for the mean and variance of coating thickness. Then the powder coating process is optimized by minimizing the standard deviation of coating thickness subject to the constraint that the thickness mean would be very close to the target. The study resulted in achieving a coating thickness mean of 80.0199 microns for industrial enclosures, which is very close to the target value of 80 microns. A comparison of the results of the proposed approach with that of existing methodologies showed that the suggested method is equally good or even better than the existing methodologies. The result of the study is also validated with a new batch of industrial enclosures.

The controlling of bug fixing process during the system testing phase of software development life cycle is very important for fixing all the detected bugs within the scheduled time. The presence of open bugs often delays the release of the software or result in releasing the software with compromised functionalities. These can lead to customer dissatisfaction, cost overrun and eventually the loss of market share. In this paper, the authors propose a methodology to quantitatively manage the bug fixing process during system testing. The proposed methodology identifies the critical milestones in the system testing phase which differentiates the successful projects from the unsuccessful ones using Mahalanobis Taguchi system. Then a model is developed to predict whether a project is successful or not with the bug fix progress at critical milestones as control factors. Finally the model is used to control the bug fixing process. It is found that the performance of the proposed methodology using Mahalanobis Taguchi system is superior to the models developed using other multi-dimensional pattern recognition techniques. The proposed methodology also reduces the number of control points providing the managers with more options and flexibility to utilize the bug fixing resources across system testing phase. Moreover the methodology allows the mangers to carry out mid- course corrections to bring the bug fixing process back on track so that all the detected bugs can be fixed on time. The methodology is validated with eight new projects and the results are very encouraging.

The performance of a product is generally characterized by more than one response variable. Hence the management often faces the problem of simultaneous optimization of many response variables. This study was undertaken to simultaneously optimize the surface hardness and case depth of carbonitrided bushes. Even though lots of literature has been published on various methodologies for tackling the multi-response optimization problem, the simultaneous optimization of heat treated properties of carbonitrided bushes are not reported yet. In this research the effect of four factors and two interactions on surface hardness and case depth of carbontirded bushes were studied using design of experiments. Based on the experimental results, the expected values of the heat treated properties of the bushes were estimated for all possible combination of factors. Then the best combination which, simultaneously optimized the response variables, was arrived at using desirability function. The study showed that the optimum combination obtained through desirability function approach not only minimized the variation around the targets of surface hardness and case depth but also was superior to the ones obtained by optimizing the response variables separately. Moreover this study provides a useful and effective approach to design the production process to manufacture bushes with customer specified surface hardness and case depth targets.

In this study the degradation of an azo dye, Methyl Red, which is used in textile industry, using Fenton reaction was studied and optimized by a chemometrics method. Fenton oxidation is one of the Advanced Oxidation Processes (AOPs), in which hydroxyl radicals are generated from Fenton’s reagents (Fe2+, H2O2). The effects of various experimental parameters in this reaction were investigated using Central Composite Design (CCD) method. The experimental design was done at five levels of operating parameters. 28 experiments, with 4 factors and 5 levels for each factor were designed. These factors (or variables) include [Fe2+], [H2O2], [oxalate] and the reaction time. A full-quadratic polynomial equation between the percentage of dye degradation (as the response) and the studied parameters was established. After removing the non-significant terms from the model, response surface method was used to obtain the optimum conditions. The optimum ranges of variables were: 0.1 - 0.4 mM for [Fe2+], 13.5-22 mM for [H2O2], 1.5-2 mM for [Oxalate], and 115-125 min for the reaction time. Also the results of extra experiments showed that these optimized values can be used for real samples and yield to high values for the response.