A product design framework for one-of-a-kind production using integrated quality function deployment and operational research techniques

The process of product design as an early stage of new product development provides systematic approaches that can lead to the success of a company’s competitive strategy in the current turbulent market. By launching an efficient product design procedure can result in the reduction of engineering modifications, cost and production time. One-of-a-Kind Product (OKP) is known as a particular manufacturing system of new product design and development with emphasis on the special order concept. Quality Function Deployment (QFD) is a comprehensive design framework with cross-functional team members that leads to the development of new or improved products. QFD starts with the House of Quality (HOQ) as an organizing matrix to identify the customers’ requirements (CRs) and translate them into the technical attributes (TAs) of the product and followed by determining the target values for the sets of technical attributes. An evaluation approach to determine the relative importance of CRs and TAs should be considered. In previous researches, the traditional methods such as simple scoring method and application of operational research techniques such as Analytic Hierarchy Process (AHP) were reported to weigh the requirements and attributes. Despite the obvious inner-relationships among the elements, considering the HOQ as a hierarchical system may be inefficient. In addition, the contradictory effects of a TA on two or more CRs, is the problem that has been neglected. Here, a mathematical model was developed for calculating the TAs target values. A case study (dry gas filter, Namdaran Petro-Gas Industries (NPI™)) is presented to exhibit and verify the procedure of OKP product design. Initially, the framework was developed by integrating QFD-operational research (Analytic Network Process (ANP)) as a systematic method for improvement of dry gas filter design. Interview and study of documents were used to identify the CRs. A robust evaluation on customers’ priority and attributes’ importance with respect to inner-relationships among criteria/sub-criteria was performed. Furthermore, the effects of TAs on CRs with regard to their direction (positive/negative) were considered as the fundamental for developing a Multi-Objective Decision Model (MODM) to be used for determining the TAs target values. For this purpose, the fuzzy conversion scaling technique followed by formulating the partial satisfaction separately was applied. Modified TOPSIS was used to select the basic design among the available designs for further modification. Later, the process continues with the second phase, translating the TAs into the key parts. The available options (retailers) to supply the key parts were identified. As the normal procedure of QFD the relative importance’s of key parts and the options were determined. Finally, a zero-one goal programming was presented to select the optimum options for each key part subject to the budget constraint. Overall, the developed QFD-ANP framework provides a systematic approach that has the potential to be used for designing OKP product

3D Biofabrication of Thermoplastic Polyurethane (TPU)/Poly-l-lactic Acid (PLLA) Electrospun Nanofibers Containing Maghemite (-Fe2O3) for Tissue Engineering Aortic Heart Valve

Valvular dysfunction as the prominent reason of heart failure may causes morbidity and mortality around the world. The inability of human body to regenerate the defected heart valves necessitates the development of the artificial prosthesis to be replaced. Besides, the lack of capacity to grow, repair or remodel of an artificial valves and biological difficulty such as infection or inflammation make the development of tissue engineering heart valve (TEHV) concept. This research presented the use of compound of poly-l-lactic acid (PLLA), thermoplastic polyurethane (TPU) and maghemite nanoparticle (-Fe2O3) as the potential biomaterials to develop three-dimensional (3D) aortic heart valve scaffold. Electrospinning was used for fabricating the 3D scaffold. The steepest ascent followed by the response surface methodology was used to optimize the electrospinning parameters involved in terms of elastic modulus. The structural and porosity properties of fabricated scaffold were characterized using FE-SEM and liquid displacement technique, respectively. The 3D scaffold was then seeded with aortic smooth muscle cells (AOSMCs) and biological behavior in terms of cell attachment and proliferation during 34 days of incubation was characterized using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and confocal laser microscopy. Furthermore, the mechanical properties in terms of elastic modulus and stiffness were investigated after cell seeding through macro-indentation test. The analysis indicated the formation of ultrafine quality of nanofibers with diameter distribution of 178 +/- 45 nm and 90.72% porosity. In terms of cell proliferation, the results exhibited desirable proliferation (109.32 +/- 3.22% compared to the control) of cells over the 3D scaffold in 34 days of incubation. The elastic modulus and stiffness index after cell seeding were founded to be 22.78 +/- 2.12 MPa and 1490.9 +/- 12 Nmm(2), respectively. Overall, the fabricated 3D scaffold exhibits desirable structural, biological and mechanical properties and has the potential to be used in vivo

Optimization of electrospinning process to fabricate core/shell structure of magnetic nanofibers via ''RSM''

Magnetic nanostructure properties compare to their massive form recently makes them as an attraction for further research. Magnetic nanofibers are potentially useful for substrate bone regeneration, high data storage and intelligent protective shield due to immediate reaction to external field. Magnetic nanoparticles agglomeration is an obstacle in preparation a fancy morphology of magnetic nanofibers. Encapsulating the magnetic particles with an organic materials solve this limitation partially. Co-axial electrospinning is a fashionable method of Core/shell structure nanofibers fabrication. Fabricated fibers have an ultra-fine quality and porosity property with nano size diameter (~ 20 to1000nm) compare to other methods. In this study to fabricate magnetic nanofibers polyvinyl alcohol (PVA) utilized as shelter for (?-Fe2O3) magnetic particles suspension. Previously a full factorial design was conducted to evaluate the performance and factor screening of electrospinning process. That research determines flow rate and voltage and interaction between these two factors are significantly affected on output which is diameter distribution but the two other factors as distance between needle and collector and drum collector rotating speed affect are insignificant. The optimum diameter refer to previous experiments was 280 nm. In this research it is supposed to optimize the diameter distribution refer to those two significant factors via response surface methodology (RSM). Optimization in this case refers to minimizing the diameter for improving the tensile strength for its possible use in bullet proof ves

An empirical regression model toward optimized ergonomic conditions for monitoring room operators using RSM

Purpose This study aims to provide an ergonomic design of the monitoring room that has resulted in safe, functional and comfortable environment for the operators, which may lead to improve the efficiency. Currently, uses of closed-circuit televisions to monitor the critical environments are widely applicable. The information is continuously transferred and analyzed through a center called monitoring room. Design/methodology/approach Here, through creating a systematic analysis, a series of experiments was performed initially to evaluate and then optimize the parameters such as illumination, visual angle, operator-screen distance, number of scenes display in a single screen, workstation height, screen dimension and monitoring time that may affect the visual skill of the operators. Taguchi orthogonal array was used to analyze the significance of parameters on operator’s response time to a threat. The five parameters were distinguished as significant. Later response surface methodology was utilized to optimize the parameters. Findings Quadratic empirical model developed for the response time exposes the optimum response time was achievable at illumination of 500 lux, visual angle of 13°, operator-screen distance of 60 cm, three scenes, workstation height of 120 cm, screen dimension of 34” and monitoring time of 15 min. This shortened the response time by 28 per cent. The adequacy of the fitted model was successfully verified using the confirmation test with a = 95 per cent. Originality/value The novelty of this work lies in the application of a systematic statistical analysis, which enables considering the interaction among the noise parameters and controllable one simultaneously. Furthermore, the obtained regression model can widely be used for adjusting the parameters accordingly based on various anthropometric data

Fabrication (ferrofluid/polyvinyl alcohol) magnetic nanofibers via co-axial electrospinning

Magnetic nanofibers were fabricated using polyvinyl alcohol as a shelter for magnetic nanoparticles suspension. The transformation process from ferrofluid and polyvinyl alcohol solution to magnetic nanofibers has been investigated where the response variable analyzed was morphology. The results obtained from the high resolution transmission electron microscopy observation revealed that the flow rate and voltage have significant effect on desirable morphology. Nanofibers with fancy morphology and better aligned order tend to have higher elasticity contributed by the better alignment of lamellae along the fibers axis and molecular orientation. The fabricated nanofibers were ultra-fine with nanosize diameter within the range of approximately 290-380 nm

QFD-operational research as an integrated method for developing product design process in one-of-a-kind production

The product design process is an early stage of new product development that helps in improving the company competitiveness in the current turbulent environment thus fulfilling the markets requirements in terms of cost, quality and time. Traditional techniques for fulfilling the customer's expectation are less effective in the modern markets due to constraints. Usually, the customer's requirements are not fulfilled by the available product design and it requires significant modification in order to satisfy the customer's needs. This study involves highly systematic methods including quality function deployment (QFD) and operational research such as analytic network process (ANP) and multi-objective decision making (MODM) techniques for enabling a design to be more compatible with future customers' requirements. Initially, the QFD team was established to determine the customer's requirements based on house of quality. These were then prioritized based on the normal procedure of ANP. Later, the customer's requirements were translated into product technical attributes and their relative importance was characterized based on ANP. In the last step of QFD, the technical attributes target values were calculated using a MODM model which refers to the available constraints such as budget and technical limitations. A one-of-a-kind production (OKP) company which is based on the mass-customized production was used as the numerical validation. The selected product was a dry gas filter. The practical results indicated that the design obtained was more compatible with the customer's needs thus requiring fewer modifications and subsequently achieved remarkable saving of production time and cost

Application of response surface methodology in optimization of electrospinning process to fabricate (ferrofluid/polyvinyl alcohol) magnetic nanofibers

Magnetic nanofibers are composed of good dispersion of magnetic nanoparticles along an organic material. Magnetic nanofibers are potentially useful for composite reinforcement, bio-medical and tissue engineering. Nanofibers with the thinner diameter have to result in higher rigidity and tensile strength due to better alignments of lamellae along the fiber axis. In this study, the performance of electrospinning process was explained using response surface methodology (RSM) during fabrication of magnetic nanofibers using polyvinyl alcohol (PVA) as a shelter for (?-Fe2O3) nanoparticles where the parameters investigated were flow rate, applied voltage, distance between needle and collector and collector rotating speed. The response variable was diameter distribution. The two parameters flow rate and applied voltage in primary evaluation were distinguished as significant factors. Central composite design was applied to optimize the variable of diameter distribution. Quadratic estimated model developed for diameter distribution indicated the optimum conditions to be flow rate of 0.25ml/h at voltage of 45kV while the distance and rotating speed are at 8cm and 1500rps respectively. The obtained model was verified successfully by the confirmation experiments

A review of: application of synthetic scaffold in tissue engineering heart valves

The four heart valves represented in the mammalian hearts are responsible for maintaining unidirectional, non-hinder blood flow. The heart valve leaflets synchronically open and close approximately 4 million times a year and more than 3 billion times during the life. Valvular heart dysfunction is a significant cause of morbidity and mortality around the world. When one of the valves malfunctions, the medical choice is may be to replace the original valves with an artificial one. Currently, the mechanical and biological artificial valves are clinically used with some drawbacks. Tissue engineering heart valve concept represents a new technique to enhance the current model. In tissue engineering method, a three-dimensional scaffold is fabricated as the template for neo-tissue development. Appropriate cells are seeded to the matrix in vitro. Various approaches have been investigated either in scaffold biomaterials and fabrication techniques or cell source and cultivation methods. The available results of ongoing experiments indicate a promising future in this area (particularly in combination of bone marrow stem cells with synthetic scaffold), which can eliminate the need for lifelong anti-coagulation medication, durability and reoperation problems