Experimental Design Analysis Research Articles

Effect of Surface Texturing on Cast Iron Reciprocating against Steel under Cyclic Loading in Boundary and Mixed Lubrication Conditions

This study investigates the effect of laser surface texturing on the friction behavior of grey cast iron reciprocating under boundary, mixed lubrication conditions and cyclic loading. Four geometrical parameters of micro-textures (feature depth, feature diameter, area fraction, and sliding direction) were studied using a design of experiments (DoE) approach. The results showed that depending on the geometry, micro-textures can have either a positive or a negative effect on the friction behavior. The DoE analysis revealed that the coefficient of friction is mainly affected by the interaction of the feature depth and its diameter. It was found that this can be related to the aspect ratio of the dimples, and the best results were obtained for an aspect ratio of 0.1 and 0.17.

Design analysis of fluid-flow through perforated plates

The performance of the perforated plates in fluid-flow applications is evaluated by measuring the pressure drop of the working fluid. The purpose of this investigation is to determine how different parameters affect the capability of the perforated plates and modify the design by using a design of experiment analysis, namely Taguchi method for optimization. The flow characteristics, which were obtained by the Computational Fluid Dynamics (CFD) software package ANSYS-CFX, were used for this analysis. The design parameters which affect the pressure loss are Reynolds number (A), porosity (B), non-dimensional thickness of the plate (C) and hole pattern (D). The level of importance of the design parameters are determined by use of analysis of variance method, ANOVA. According to the analysis, the optimum values are obtained for the case A8B2C2D1 (Re = 15000, porosity = 50.3, t/D = 1, and staggered hole). The most effective design parameter on the results is found as porosity (92%), while the least effective is the hole pattern (0.2%). A special dividend of this work was to demonstrate the capabilities of the Taguchi Method as a powerful means of increasing the effectiveness of numerical simulation.

FRACTIONAL FACTORIAL DOE PLANNING TO REDUCE INTERNAL REJECTIONS ON LEAK TEST OF A COMBUSTION ENGINE PRODUCTION LINE

This work was applied in automotive industry in order to improve the efficiency of the combustion engines production leak test by using a fraction factorial DOE (Design of Experiments). The application of the anaerobic seal is done by a robot dispenser, and the main goal of this work is to demonstrate the application of fraction factorial DOE to improve the inputs of the application and eliminate leak fails on production leak test on the combustion engines at “T-joint” from the intersection between cylinder head, valve cover gasket and front cap. The method applied is experiment and the software used to plan the DOE and analyze the collected data is the Minitab. The inputs considered by the team application were four as: hose temperature, panel temperature, robot tip distance, and robot speed, as a result the input with the most significant effect identified on the DOE analysis is the robot tip distance. The outcome is zero leak engine on the “T-joint” at leak test, and then it was decided to evaluate two outputs: 1 - leak rate on leak test – this output showed no significance when analyzed the results from the DOE because it does not consider noise factors as environment temperature and humidity; 2 – seal bead diameter – this output showed to be significance on DOE, and is directly related to the root cause, because the engines failed with leak on production leak test are missing or with lack of anaerobic seal on the “T-joint”. The main result of this fractional factorial DOE is the best set of input parameters which exceeded the target of 80% improvement and achieved zero leak on the “T-joint” between cylinder head, valve cover gasket and front cap. This shows that fractional factorial DOE is an efficient method to be applied on the industry to improve process.

APC fly ashes stabilized with Portland cement for further development of road sub-base aggregates

Although waste-to-energy plants allow reducing the mass and volume of municipal solid waste (MSW) incinerated, an average around 30 % of the total content remains as bottom ash (BA) and air pollution control (APC) ashes at the end of combustion process. While weathered bottom ash (WBA) is considered a non-hazardous residue that can be revalorized as a secondary aggregate, APC fly ashes generated during the flue gas treatment are classified as hazardous waste and are handled in landfill disposal after stabilization, usually with Portland cement (OPC). However, taking into account the amount of APC residues produced and the disposing cost in landfill, their revalorization is an important issue that could be effectively addressed. As MSW can be incinerated producing bottom ashes (BA) or air pollutant control (APC) residues, the development of a mortar formulated with APC fly ash as secondary building material is a significant risk to the environment for their content of heavy metals. In this way, Design of Experiment (DoE) was used for the improvement of granular material (GM) formulation composed by APC and OPC for further uses as road sub-base aggregate. DoE analysis was successful in the modelling and optimization the formulation as function of the mechanical properties and APC amount. Consequently, an optimal mortar formulation (OMF) of around 50 wt.% APC and 50 wt.% OPC was considered. The OMF leachates and abrasion resistance have been analyzed. These results have demonstrated the viability of OMF as non-hazardous material feasible to be used as secondary aggregate. Moreover, it would be possible to consider the environmental assessment of a GM composed by ≈20 wt.% of OMF and ≈80 wt.% of WBA in order to improve mechanical properties and heavy metals stabilization.

Microencapsulation of Live Cells in Synthetic Polymer Capsules.

In cell therapies, it is advantageous to encapsulate live cells in protective, semipermeable microparticles for controlled release of cytokines, growth factors, monoclonal antibodies, or insulin. Here, a modified electrospraying approach with an organic solution of poly(lactide-co-glycolide) (PLGA) polymer is used to create synthetic PLGA capsules that effectively protect live cells. Using a design of experiment (DOE) methodology, the effect of governing jetting parameters on encapsulation efficiency, yield, and size is systematically evaluated. On the basis of this analysis, the interaction between bovine serum albumin concentration and core flow rate is the most dominant factor determining core encapsulation efficiency as well as the microcapsule size. However, the interaction between shell solvent ratio and shell flow rate predominantly defines the particle yield. To validate these findings, live cells have been successfully encapsulated in microcapsules using optimized parameters from the DOE analysis and have survived the electrohydrodynamic jetting process. Extending the currently available toolkit for cell microencapsulation, these biodegradable, semi-impermeable cell-laden microcapsules may find a range of applications in areas such as tissue engineering, regenerative medicine, and drug delivery.

Estimation of geotechnical parameters using Taguchi’s design of experiment (DOE) and back analysis methods based on field measurement data

Estimation of geomechanical parameters is a challenging task in geotechnical engineering. This paper aims to estimate the geotechnical parameters of soil layers in the Tehran Metro line no. 7 based on the field measurement data. In this study, the design of experiment (DOE) method is utilized for estimation of the geotechnical parameters. The geotechnical parameters such as the modulus of elasticity (E), cohesion (c), and the internal friction angle (φ) are estimated using Taguchi’s DOE method and displacement-based back analysis. The results of the DOE experiments are examined by the analysis of range (ANORA) to improve the accuracy of the optimization. Results show that Taguchi’s DOE technique offers more effective and precise estimation of the geotechnical parameters than a displacement-based back analysis approach. Finally, the optimal combination of geotechnical parameters is proposed based on results analysis of Taguchi’s DOE and back analysis method. It is shown that the combination of the obtained geotechnical parameters from Taguchi’s DOE method is closer to the field measurement data.

Design of Experiments for Identifying the Throughput Performance of Shuttle-Based Storage and Retrieval Systems

This study explores statistically significant factors affecting the performance of new automated storage and retrieval system technology called a Shuttle-Based Storage and Retrieval System (SBS/RS), under pre-defined factors by using Design of Experiment (DOE). After determining the significant factors affecting the SBS/RS performance, a DOE analysis was used to find the design that optimizes a throughput performance of the SBS/RS. The results indicate that five pre-defined factors: number of columns C, velocity of the shuttle carrier vx, acceleration/deceleration of the shuttle carrier ax, velocity of the elevator's lifting table vy, acceleration/deceleration of the elevator's lifting table ay have an interaction effect on each of the performance measures of the studied SBS/RS. The performance measures considered in this study were average single command and dual command cycle times of the shuttle carrier and the elevator's lifting table, average throughput performances and of the shuttle carrier and the elevator's lifting table and the warehouse volume.

Implementation of design of experiments approach for the micronization of a drug with a high brittle–ductile transition particle diameter

Objective: To optimize air-jet milling conditions of ibuprofen (IBU) using design of experiment (DoE) method, and to test the generalizability of the optimized conditions for the processing of another non-steroidal anti-inflammatory drug (NSAID).Methods: Bulk IBU was micronized using an Aljet mill according to a circumscribed central composite (CCC) design with grinding and pushing nozzle pressures (GrindP, PushP) varying from 20 to 110 psi. Output variables included yield and particle diameters at the 50th and 90th percentile (D50, D90). Following data analysis, the optimized conditions were identified and tested to produce IBU particles with a minimum size and an acceptable yield. Finally, indomethacin (IND) was milled using the optimized conditions as well as the control.Results: CCC design included eight successful runs for milling IBU from the ten total runs due to powder “blowback” from the feed hopper. DoE analysis allowed the optimization of the GrindP and PushP at 75 and 65 psi. In subsequent validation experiments using the optimized conditions, the experimental D50 and D90 values (1.9 and 3.6 μm) corresponded closely with the DoE modeling predicted values. Additionally, the optimized conditions were superior over the control conditions for the micronization of IND where smaller D50 and D90 values (1.2 and 2.7 μm vs. 1.8 and 4.4 μm) were produced.Conclusion: The optimization of a single-step air-jet milling of IBU using the DoE approach elucidated the optimal milling conditions, which were used to micronize IND using the optimized milling conditions.

In vivo Identification of the Passive Mechanical Properties of Deep Soft Tissues in the Human Leg

AbstractA non‐invasive method is proposed to identify in vivo the passive mechanical properties of deep soft tissues in the human leg. Force‐displacement curves in response to a localized compression of the calf are measured with a custom made experimental set‐up. The material parameters of a finite element model are then calibrated against the experimental curves using a genetic algorithm. A thorough investigation of the efficacy of this method to identify such mechanical properties is conducted through a design of experiments analysis and mixed numerical–experimental validations. It is the first time that a thorough analysis is conducted to really separate the contribution of deep and superficial tissues in the response to compression tests, and this permits to estimate the parameters of deep soft tissues on four subjects independently of the response of their other tissues. Two strain energy density functions are compared. It is shown that a 2nd order‐reduced polynomial better describes the passive mechanical behavior of the deep soft tissues of the leg than the neo‐Hookean model.

Sensitivity analysis of urban morphology factors regarding solar energy potential of buildings in a Brazilian tropical context

Today, 75% of global energy consumption occurs in cities. On the topic of climate change, adapting urban settlements to face this growing demand is a priority issue, especially for fast-growing cities in developing countries such as Brazil. Planning the urban morphology of the built environment is a key issue in shifting to a climate adapted urban environment. This paper addresses an important threefold energy challenge of tropical cities: the major potential of harnessing solar energy as renewable resource for local electricity production and the energy-saving paradox of reducing the undesirable solar heat gains in buildings while providing satisfactory levels of daylight. It aims at measuring the effect size of urban form factors regarding these energy goals. This study applies the Design Of Experiments (DOE) approach. A DOE analysis is a statistical technique that provides a set measure of how design parameters are correlated and the effective contribution of each one to a given response of interest. This study proposes a fractional factorial DOE method coupled to a Simplified Radiosity Algorithm (SRA) aiming to evaluate the irradiation availability on building envelopes while taking a large representative sample of contrasted urban block geometries into account. The buildings’ envelope solar irradiation availability assesses a set of energy-related morphological parameters. Results indicate a significant impact of the aspect ratio, the distance between buildings and the surface equivalent albedo. Establishing high values of street aspect ratio may cut solar irradiation on roofs by 130kWh/m2year, while increasing the plot ratio may only yield 26kWh/m2year. The results also point out important first order interaction effects between certain variables.

Numerical investigation on the melting of circular finned PCM system using CFD & full factorial design

Heat energy storage equipment has the advantages of highly efficient energy storage performance and constant temperature owing to its adoption of Phase change material (PCM); however, its shortcoming is that it takes longer to complete thermal energy storage due to its low thermal conductivity. New technologies are being developed to overcome such shortcomings, including technology that would improve the heat transfer. This study is aimed at analyzing the impact on the energy storage time of the PCM via the Design of experiments (DOE) method and with changes to the following variables: The number of installed fins; the employed material (thermal conductivity); and the temperature of the supplied warm water, all by relying on Computational fluid dynamics (CFD). The PCM system is in the shape of a long vertical cylinder, with circular fins. The number of installed circular fins was one or five, the material used in the pipe and circular fins was changed from iron to copper, and the temperature of the warm water was 309.15 or 313.15 K. The thermal conductivity of each material employed for the CFD was 80.2 or 401.0 W/m-K. The DOE analysis was also performed to check for any curvature effect by adding a center point. The PCM used in this study is n-Octadecane 99% (CH3(CH2)16CH3) with its melting temperature being roughly 300.85 K. To sum up the conclusions of this study, the change in the number of installed circular fins and the temperature of supplied warm water have a substantial influence on the melting of the PCM. The change in the thermal conductivity of the pipe and circular fins has only a meager influence on the melting of the PCM. To reduce the melting time of the PCM most effectively, it is recommended to install as many circular fins as possible and to raise the temperature of the supplied warm water. This may be related to the fact that the melting of the PCM is influenced more by convection inside the PCM system rather than conduction.

Screening of formulation parameters for stabilizing recombinant human serum albumin (rHSA) in liquid formulations

In the present study, the stabilizing effect of excipients present in recombinant Human Serum Albumin (rHSA) solutions are studied using rheological analysis. The study was conducted using Design of Experiment (DoE) principles and multivariate analysis approach. It is observed that the excipients octanoate and polysorbate 80 used in the Recombumin Alpha® formulation both increase the stability of the protein reflected by an observed decrease in the complex viscosity interpreted as a decreasing degree of self-association. Octanoate seems to be efficient in protecting the protein at higher temperatures, whereas polysorbate protects against self-association at lower temperatures. Additionally, a synergistic effect of octanoate and polysorbate 80 was observed in a non-linear fashion. This effect would be difficult to assess in a study using univariate analysis of these complex formulations, however the multivariate approach using DoE and Principal Component Analysis (PCA) efficiently illustrated its usefulness in the current study.

A way for reducing drug supply chain cost for a hospital district: A case study

Purpose: This work aims at providing insights to optimise healthcare logistic of the drug management, in order to deal with the healthcare expenditure cut. In this paper the effects of different drug supply chain configurations, on the resulting average stock, service level and Bullwhip effect, of the studied supply chain, is quantitatively assessed. Design/methodology/approach: A case study of an Italian district has been studied, taking into account three echelons: suppliers, central stock, and hospitals. A model of the various supply chain configurations has been created with the use of the simulation. Specifically, 24 supply chain configurations have been examined, stemming from the combination of several supply chain design parameters, namely: transshipment policies (Emergency Lateral Transshipment or Total Inventory Equalization); re-order and inventory management policies (Economic Order Quantity or Economic Order Interval); required service levels (90% or 95%); the number of available vans (one or two). For each configuration, hospital average stock, service level and a “Bullwhip effect” analysis are computed. To know which input variables are statistically significant, a DoE (Design of Experiments) analysis has been executed. Findings: The output of this paper provides useful insights and suggestions to optimize the healthcare logistic and drug supply chain. According to the developed DoE analysis, it can be stated that the introduction of transshipment policies provides important improvement in terms of service and stock levels. To reduce the Bullwhip effect, which results in a service level decreasing, and in a managing stock costs increasing, it is worth to adopt an EOQ re-order policy. Practical implications: This research gives practical recommendations to the studied system, in order to reduce costs and maintain a very satisfactory service level. Originality/value: This paper fulfils an identified need to study which combination of transshipment policies, re-order/inventory management policies and required service levels, can be the best one to reduce costs and maintain a very satisfactory service level, in the specific logistic system.

Combinatorial Analysis of Growth Factors Reveals the Contribution of Bone Morphogenetic Proteins to Chondrogenic Differentiation of Human Periosteal Cells.

Successful application of cell-based strategies in cartilage and bone tissue engineering has been hampered by the lack of robust protocols to efficiently differentiate mesenchymal stem cells into the chondrogenic lineage. The development of chemically defined culture media supplemented with growth factors (GFs) has been proposed as a way to overcome this limitation. In this work, we applied a fractional design of experiment (DoE) strategy to screen the effect of multiple GFs (BMP2, BMP6, GDF5, TGF-β1, and FGF2) on chondrogenic differentiation of human periosteum-derived mesenchymal stem cells (hPDCs) in vitro. In a micromass culture (μMass) system, BMP2 had a positive effect on glycosaminoglycan deposition at day 7 (p < 0.001), which in combination with BMP6 synergistically enhanced cartilage-like tissue formation that displayed in vitro mineralization capacity at day 14 (p < 0.001). Gene expression of μMasses cultured for 7 days with a medium formulation supplemented with 100 ng/mL of BMP2 and BMP6 and a low concentration of GDF5, TGF-β1, and FGF2 showed increased expression of Sox9 (1.7-fold) and the matrix molecules aggrecan (7-fold increase) and COL2A1 (40-fold increase) compared to nonstimulated control μMasses. The DoE analysis indicated that in GF combinations, BMP2 was the strongest effector for chondrogenic differentiation of hPDCs. When transplanted ectopically in nude mice, the in vitro-differentiated μMasses showed maintenance of the cartilaginous phenotype after 4 weeks in vivo. This study indicates the power of using the DoE approach for the creation of new medium formulations for skeletal tissue engineering approaches.

Microporous PVDF membranes via thermally induced phase separation (TIPS) and stretching methods

Microporous polyvinylidene difluoride (PVDF) hollow fiber membranes were fabricated via a thermally-induced phase separation (TIPS) method using an environmental-friendly hydrophobic solvent, acetyl tributyl citrate (ATBC, tradename Citroflex® A4). To maximize membrane tensile strength, the TIPS method was fully utilized by spinning fibers with high polymer content. It was observed that the fiber quality was significantly affected by the dope and bore flow rates and compositions, and an appropriate spinning range was established. The prepared membranes were subsequently stretched to tune the porosity, mean pore size, permeability, tensile strength, and fiber strain. A design of experiment (DOE) analysis was conducted using a 3-factor quadratic model to optimize the stretching conditions and to understand the effects of the parameters and interactions thereof. The permeability of the stretched membranes improved by a factor of 35 (15.1–538Lm−2h−1bar−1), and the tensile strength increased from 7.2MPa to 8.4MPa at the expense of the fiber strain. The DOE analysis revealed that the stretching ratio positively affects the permeability and porosity but decreases the fiber strain. On the other hand, it was determined that the stretching temperature positively influences the permeability and fiber strength. The stretched membranes exceeded the PVDF performance upper bound prepared by the TIPS method. The membranes were primarily in the α-phase polymorph, and stretching the fibers up to 40% at 90°C did not induce any detectable β-phase crystals. The proposed preparation method offers a feasible and sustainable alternative to fabricate hollow fibers membranes with high tensile strength and high permeability.

Towards an integrated computational method to determine internal spaces for optimum environmental conditions

Computational Fluid Dynamics tools and Response Surface Methodology optimization techniques were coupled for the evaluation of an optimum window opening design that improves the ventilation efficiency in a naturally-ventilated building. The multi-variable optimization problem was based on Design of Experiments analysis and the Central Composite Design method for the sampling process and estimation of quadratic models for the response variables. The Screening optimization method was used for the generation of the optimal design solution. The generated results indicated a good performance of the estimated response surface revealing the strength correlations between the parameters. Window width was found to have greater impact on the flow rate values with correlation coefficient of 73.62%, in comparison to the standard deviation 55.68%, where the window height prevails with correlation coefficient of 96.94% and 12.35% for the flow rate. The CFD results were validated against wind tunnel experiments and the optimization solution was verified with simulation runs, proving the accuracy of the methodology followed, which is applicable to numerous environmental design problems.

The Preparation of Iron-Free TiCl4from Reduced and Nitrided Ilmenite by Polyethylene Terephthalate

In this study, titanium tetrachloride (TiCl4) solution was successfully synthesized from titanium oxycarbonitride (TiOxCyNz) by means of chlorination process at low temperatures. Iron-free TiOxCyNz was prepared by carbothermal reduction and nitridation of Ilmenite (FeTiO3) with coal-75 wt. % PETas a reductant in a H2/N2 gas mixture. Aeration leaching via the Becher process for iron removal with NH4Cl solution was the preferred method for iron removal. The effect of reduction temperature on the synthesis of titanium oxycarbonitride (TiO0.02C0.13N0.85) powder suitable for iron removal has been investigated in the temperature range of 1150–1250°C. The reduced-nitrided ilmenite samples were characterized by XRD and SEM/EDX in terms of phases and morphology. The results showed that iron was formed in spherical and separated particles from TiOCN. Furthermore, the effects of temperature between 350–450°C and soaking time from 1 to 3 hours on the chlorination of iron-free titanium oxycarbonitride have been evaluated. The evaluation was based on design of experiment (DOE) to identify the significant variables on the extent of titanium extraction. DOE analysis based on weight loss validated by ICP tests, indicated a good extraction of titanium and synthesis of TiCl4 at 450°C.

Determination of the Optimal Configuration of Energy Recovery Ventilator through Virtual Prototyping and DoE Techniques

This study presents an approach based on Design of Experiment (DoE) technique for the optimization of an energy recovery ventilator (ERV). This system is one of the efficient ways to enhance the thermo-hygrometric comfort without increase excessively the thermal load in domestic kitchen. However, there is a major concern, which energy recovery cannot trade off ERV's fan power consumption. The goal of this study is to obtain the information about the relation between factors and response in an empirical way. This approach integrates three different levels of analysis: the virtual prototyping, Design of Experiment (DoE) and rapid prototyping. The virtual analysis allows to define the principal parameterization of a simplified model and to simulate the performance of each configuration at working condition. The proposed approach investigates the effect of the defined parameters and noise factor on the experimental results. In particular, the applied method for DoE analysis is based on virtual experiments in according to the necessity to reduce time and costs during the early design phase. The optimum parameters configuration, which is defined by the previous step, is useful to define the geometry and the working condition of a reliable virtual model. The final level is the realization of a 3D ERV with a rapid prototyping printer. The obtained component is now evaluable at the test bench to investigate the air flow rate and the electric power consumption.

Application of current steps and design of experiments methodology to the detection of water management faults in a proton exchange membrane fuel cell stack

We apply a 25−1 fractional factorial Design of Experiments (DoE) test plan in order to discriminate the direct effects and interactions of five factors on the water management of a 500 We PEMFC stack. The stack is submitted to current steps between different operating levels and several responses are extracted for the DoE analysis. A strong ageing effect on stack and cell performances is observed. Therefore, in order to perform the DoE analysis, responses which values are too strongly affected by ageing are “corrected” prior to the analysis. A “virtual” stack, considered as “healthy”, is also “reconstructed” by “putting in series” the cells exhibiting very low performance drop.The results show that stacks and cells' resistivities are mostly impacted by direct effects of both temperature and cathodic inlet relative humidity and by compensating interaction between temperature and anodic overstoichiometric ratio. It also appears that two responses are able to distinguish a “healthy” stack from a degraded stack: heterogeneities in cell voltages and cell resistivities distributions. They are differently impacted by considered effects and interactions. Thus, a customised water management strategy could be developed, depending on the stack's state of health to maintain it in the best possible operating conditions.

Effect of surface texturing on cast iron reciprocating against steel under starved lubrication conditions: A parametric study

This study investigates the effect of laser surface texturing on the friction behavior and the lifetime of grey cast iron reciprocating under starved lubrication conditions. Five geometrical texture parameters (feature depth, diameter, length, area fraction and sliding direction) were studied using a design of experiments (DoE) approach by developing a fractional factorial design. Reciprocal sliding tests were carried out for the cast iron-steel tribo-pair at a pressure of 24MPa and a frequency of 6Hz. DoE results revealed that the geometrical parameters of micro-textures interact in a complex manner. Hence, for better understanding the effect of surface texturing on the tribological performance, the interactions between geometrical parameters need to be considered. It is found that except the following main factors: diameter and area fraction, mainly interactions of geometrical parameters have significant impact on the coefficient of friction. It is also observed that micro-textures could increase the lifetime of tribo-systems sliding under starved conditions. Based on the DoE analysis, an optimum micro-texture having a relatively low coefficient of friction and a long lifetime are achieved with the following (geometrical) parameters: a depth of 50μm, a diameter of 100μm, a length of 500μm, an area fraction of 5%, and the sliding direction perpendicular to the micro-textures.