Full Factorial Experimental Design Research Articles

Optimisation of Mix Proportion of 3D Printable Mortar Based on Rheological Properties and Material Strength Using Factorial Design of Experiment

In the production of 3D printable mortar (3DPM), numerous efforts have been made globally to effectively utilise various cementitious materials, admixtures, and fibres. The determination of rheological and material strength properties is crucial for successful 3D concrete printing because the materials used in 3DPM must possess the unique characteristic of making mortar flowable while being strong enough to support the weight of subsequent layers in both fresh and hardened states. The complexity of the required characteristics makes it challenging to develop an optimised mix composition that satisfies both the rheological and material strength requirements, given the wide range of available admixtures, supplementary cementitious materials, and fibres. Fly ash, basalt fibre and superplasticiser when blended with cement can help to improve the overall performance of 3DPM. The objective of this research is to optimise the rheological properties and material strength of 3D printable mortars (3DPM) containing cement, fly ash, basalt fibre, and superplasticiser. This study aims to produce 3DPM with an optimised mix composition to meet the requirements of both rheological and material strength characteristics using the factorial design approach and desirability function. Different dosages of cement, fly ash, basalt fibre, and superplasticiser are chosen as the primary design parameters to develop statistical models for the responses of rheological and material strength properties at 7 and 28 days. The results expressed in terms of the measured properties are valid for mortars made with cement ranging from 550 to 650 kg/m3, fly ash from 5% to 20% (of cement), superplasticiser from 2 to 4 kg/m3, and basalt fibre from 1 to 3 kg/m3. The rheological properties are evaluated using slump flow, cone penetrometer, and cylindrical slump tests, while the mechanical strength is evaluated using a three-point bending test and compressive test. A full factorial design experiment (FoE) is used to determine the significant parameters effecting the measured properties. Prediction models are developed to express the measured properties in terms of the primary parameters. The influence of cement, fly ash, basalt fibre, and superplasticiser is analysed using polynomial regression to determine the main effects and interactions of these primary parameters on the measured properties. The results show that the regression models established by the factorial design approach are effective and can accurately predict the performance of 3DPM. Cement, fly ash, and superplasticiser dosages have significant effects on the rheological and mechanical properties of mortar, while basalt fibre is able to influence the static yield stress and flexural strength of 3DPM. The utilisation of regression models and isoresponse curves allows for the identification of significant trends and provides valuable insight into the behaviour of the material, while desirability function is useful to optimise overall performance of mix proportions to meet the desired performance objective at fresh and hardened states.

Full factorial design of experiment-based and response surface methodology approach for evaluating variation in uniaxial compressive mechanical properties, and biocompatibility of photocurable PEGDMA-based scaffolds

The goal of this study is to fabricate biocompatible and minimally invasive bone tissue engineering scaffolds that allow in situ photocuring and further investigate the effect on the mechanical properties of the scaffold due to the prevailing conditions around defect sites, such as the shift in pH from the physiological environment and swelling due to accumulation of fluids during inflammation. A novel approach of incorporating a general full factorial design of experiment (DOE) model to study the effect of the local environment of the tissue defect on the mechanical properties of these injectable and photocurable scaffolds has been formulated. Moreover, the cross-interaction between factors, such as pH and immersion time, was studied as an effect on the response variable. This study encompasses the fabrication and uniaxial mechanical testing of polyethylene glycol dimethacrylate (PEGDMA) scaffolds for injectable tissue engineering applications, along with the loss in weight of the scaffolds over 72 h in a varying pH environment that mimics in vivo conditions around a defect. The DOE model was constructed with three factors: the combination of PEGDMA and nano-hydroxyapatite referred to as biopolymer blend, the pH of the buffer solution used for immersing the scaffolds, and the immersion time of the scaffolds in the buffer solution. The response variables recorded were compressive modulus, compressive strength, and the weight loss of the scaffolds over 72 h of immersion in phosphate-buffered saline at respective pH. The statistical model analysis provided adequate information in explaining a strong interaction of the factors on the response variables. Further, it revealed a significant cross-interaction between the factors. The factors such as the biopolymer blend and pH of the buffer solution significantly affected the response variables, compressive modulus and strength. At the same time, the immersion time had a strong effect on the loss in weight from the scaffolds over 72 h of soaking in the buffer solution. The biocompatibility study done using a set of fluorescent dyes for these tissue scaffolds highlighted an enhancement in the pre-osteoblasts (OB-6) cell attachment over time up to day 14. The representative fluorescent images revealed an increase in cell attachment activity over time. This study has opened a new horizon in optimizing the factors represented in the DOE model for tunable PEGDMA-based injectable scaffold systems with enhanced bioactivity.

Computational Seated Pedestrian Impact Design of Experiments with Ultralight Wheelchair.

Pedestrians who use wheelchairs (seated pedestrians) report higher mortality rates than standing pedestrians in vehicle-to-pedestrian collisions but the cause of this mortality is poorly understood. This study investigated the cause of seated pedestrian serious injuries (AIS 3+) and the effect of various pre-collision variables using finite element (FE) simulations. An ultralight manual wheelchair model was developed and tested to meet ISO standards. The GHBMC 50th percentile male simplified occupant model and EuroNCAP family car (FCR) and sports utility vehicle (SUV) were used to simulate vehicle collisions. A full factorial design of experiments (n = 54) was run to explore the effect of pedestrian position relative to the vehicle bumper, pedestrian arm posture, and pedestrian orientation angle relative to the vehicle. The largest average injury risks were at the head (FCR: 0.48 SUV: 0.79) and brain (FCR: 0.42 SUV: 0.50). The abdomen (FCR: 0.20 SUV: 0.21), neck (FCR: 0.08 SUV: 0.14), and pelvis (FCR: 0.02 SUV: 0.02) reported smaller risks. 50/54 impacts reported no thorax injury risk, but 3 SUV impacts reported risks ≥ 0.99. Arm (gait) posture and pedestrian orientation angle had larger effects on most injury risks. The most dangerous arm posture examined was when the hand was off the wheelchair handrail after wheel propulsion and the two more dangerous orientations were when the pedestrian faced 90° and 110° away from the vehicle. Pedestrian position relative to the vehicle bumper played little role in injury outcomes. The findings of this study may inform future seated pedestrian safety testing procedures to narrow down the most concerning impact scenarios and design impact tests around them.

Roll-to-roll reactive ion etching of large-area nanostructure arrays in Si: Process development, characterization, and optimization

Roll-to-roll (R2R) nanofabrication processes are recognized as key enabling-technologies for many next-generation applications in flexible electronics, displays, energy generation, storage, as well as healthcare. However, R2R processing techniques reported in the literature currently lack a scalable method of performing high-throughput nanoscale pattern transfer of geometry requiring a high degree of fidelity in terms of critical dimension resolution, etch uniformity, and aspect ratio. Reactive ion etching (RIE) addresses the need for sub-10 nm pattern transfer with large-area uniformity in wafer-scale semiconductor manufacturing, but adapting plasma etch systems for use in R2R nanopatterning has proven to be nontrivial. Moreover, robust models for simulating R2R RIE do not exist, which is an obstacle to the creation of computational approaches to design, control, and scale-up of nanoscale R2R equipment and processes. To address these challenges, we demonstrate a process flow for fabricating Si nanopillar arrays utilizing a combination of nanoimprint lithography and RIE with all pattern transfer steps performed using a R2R plasma reactor system. Specifically discussed are process development details for etching imprint resist and Si including etch rates, cross-web etch uniformity, etch directionality, and etch selectivity at varying gas chemistries, powers, and pressures. 2k full-factorial Design of Experiments (DoEs) and ordinary least-squares regression analysis are also employed to study influence of process parameters on multiple outgoing etch quality characteristics and generate stochastic models of the R2R RIE pattern transfer process into Si. Utilizing these DOE-based models and desired targets for etch quality characteristics, we describe a bounded multivariate inverse-optimization scheme for automated etch process parameter tuning. The culmination of these efforts, to the best of the authors' knowledge, is the first reported RIE-based pattern transfer of 100 nm-scale features performed in continuous R2R fashion with control of feature geometry over large area. The methodology employed herein may be applied similarly to additional materials and geometries for future applications.

OTIMIZAÇÃO DA SÍNTESE DE ANALCIMA ‘CONDICIONADOR DE SOLO’ A PARTIR DE REJEITO GIBBSÍTICO-CAULINÍTICO DERIVADO DE BAUXITA: UMA ANÁLISE DE DRX-CLUSTER ASSOCIADA A UMA MATRIZ DOE

The main objective of this work was to use the XRD-Cluster analysis associated with a 23 full factorial design of experiments to optimize the synthesis process of analcime (a zeolite used as soil conditioner) from gibbsite-kaolinite waste from bauxite beneficiation combined with the siliceous co-product of silicon metal production (amorphous silica). The variables included the NaOH solution concentration (1.5-3.5 M), temperature (110-180 ºC) and time (4-48 hours). Concentration is the most important variable and according to the clusters formed, it can be said that the optimal conditions are: NaOH solution concentration of 2.5 M; temperature of 145 ºC and time of 26 hours. Keywords: Zeolite; Principal Component Analysis (PCA); multivariate statistics.

Magnetite-impregnated biochar of parthenium hysterophorus for adsorption of Cr(VI) from tannery industrial wastewater

The tannery industry inevitably generates toxic and catastrophic wastewater, which results in a huge threat to public health and water resources. Therefore, this work aimed to synthesize parthenium hysterophorus-based biochar–Fe3O4 composite for removal of Cr(VI) from tannery wastewater under 34 full factorial experimental designs of the Box–Behnken, which was analyzed using response surface methodology under four independent factors of pH (3, 6, and 9), initial Cr(VI) concentrations (40, 70, and 100 mg/L), contact times (30, 60, and 90 min), and adsorbent doses (20, 60, and 100 mg/100 mL). This composite adsorbent was described by a high BET surface area of 237.4 m2/g, XRD prominent peaks, SEM morphology corroborate and FTIR multifunctionalities of O–H at 3296 cm−1, the vibration of ketone C–OH at 1240 cm−1, and the vibration of C–O–C at 1147 cm−1 and Fe–O stretching at 542 cm−1. The maximum Cr(IV) removal efficiency of 91.8% was recorded at an initial Cr(VI) concentration of 40 mg/L, pH of 3, adsorbent dose of 100 mg/100 mL, and a contact time of 90 min, whereas the minimum Cr(VI) removal of 17.3% was observed at an initial Cr(VI) concentration of 100 mg/L, 20 mg/100 mL of adsorbent dose, pH of 9, and contact time of 30 min. The concentration of Cr(VI) in real wastewater was determined to be 85.13 mg/L and its remediation was found to be 81.8%. Langmuir’s model was the best fit with experimental data at R2 0.99 and qmax 400 mg/g, showing that the adsorption process was homogenous and monolayer. In conclusion, the adsorption results were encouraging, and biochar–Fe3O4 appears to be a potential candidate for Cr removal from wastewater.

Optimization of a Blended-Wing-Body Unmanned Aerial Vehicle Design for Maximum Aerodynamic Lift-to-Drag Ratio

Although unmanned aerial vehicle (UAV) has found many applications in various fields, its operation has been constrained by its low flight endurance. To date, several design efforts are pursued to improve this performance and one of them is the exploration of blended-wing-body (BWB) design. In this study, parametric study is conducted on the BWB UAV design of Baseline-VII that is developed by Flight Technology and Test Center (FTTC), Universiti Teknologi MARA Shah Alam, Malaysia. The primary goal is to optimize the current Baseline-VII design for maximum lift-to-drag ratio, which in turn implies a higher flight endurance. Three design parameters are considered: inboard wing sweep angle, outboard wing sweep angle and also inboard wing span. A full-factorial design of experiments (DoE) is applied to set the total 27 design case settings for this study, with three different values considered for each design parameter: 10°, 25° and 50° for inboard and outboard wing sweep angles, and 200 mm, 300 mm and 400 mm for the inboard wing span. The computer-aided design (CAD) models for the design cases are constructed using Solidworks and the resultant aerodynamic lift-to-drag ratio is found through computational fluid dynamics (CFD) simulation analysis using ANSYS Fluent. The collected data is then statistically analysed using regression analysis in MINITAB to construct a representative regression model that aptly capture the effects of the varied design parameters on the design aerodynamic lift-to-drag ratio. Based on the results, it has been found that the maximum lift-to-drag ratio for the modified Baseline-VII UAV design is 2.8119, which is obtained with optimal settings of inboard wing sweep angle = 17.2727°, outboard wing sweep angle = 20.9091° and inboard wing span = 400 mm. This is about 28.4% increment of lift-to-drag ratio from the original Baseline-VII design.

Systematic identification of disturbance factors on electric characteristics of mechanical gearboxes

Failures of machine elements can cause critical machine breakdowns, e.g. bearing damage accounts for almost 20% of all machine failures. Hence, monitoring machine elements is of particular importance for condition monitoring of gearboxes. Therefore, new approaches based on electrical impedance analysis are proposed in literature, e.g. for the measurement of rolling bearing load or damage condition with so-called sensory utilizable machine elements (SuME). For this approach, an electrical signal is transmitted through the structure to be observed and the resulting impedance is measured. With this technique it is possible to detect loads and damages not only for bearings, but also for the entire gearbox. Another application of this method can be the transmission of electrical signals through machine elements and the gearbox themselves. However, uncertainty arises with regard to the distinct signal transmission in these processes, mainly due to parasitic capacitances. In this contribution, the disturbing factors on the measured impedance of a gearbox at different working points are investigated. For this purpose, disturbance factors are systematically identified and used as basis for a full factorial experimental design for screening the operational characteristics of a gearbox. The data obtained from the tests is analyzed to identify correlations between the disturbance factors and parasitic capacitances. The experiments show a speed- and torque-dependent behavior of the parasitic capacitances in a gearbox. These results can be used for further research of SuME and structure-integrated energy supply and signal paths as well as the evaluation of related measurement data by reducing the associated uncertainty.

Design of polyacrylamide grafted sesbania gum-mediated pH-responsive IPN-based microbeads for delivery of diclofenac sodium: In-vitro-in-vivo characterizations

Microwave-assisted grafting of polyacrylamide on sesbania gum (PAAM-g-SG) was implemented employing a 32 full factorial experimental design and was hydrolyzed using sodium hydroxide (NaOH) to form H-PAAM-g-SG. Further, the diclofenac sodium-loaded novel pH-sensitive interpenetrating polymeric network (IPN) microbeads were designed using an optimized H-PAAM-g-SG and sodium alginate (SA). Different spectroscopic analysis including FTIR spectroscopy, 1H NMR spectroscopy, elemental analysis, thermal analysis, etc. was performed to confirm the synthesis of PAAM-g-SG and diclofenac-loaded pH-sensitive IPN H-PAAM-g-SG-SA microbeads. Here, Ca+2 ions combine with two strands of SA and form a round-shape structure that encloses uncross-linked H-PAAM-g-SG polymer and diclofenac sodium. As well, glutaraldehyde (GL) addition improved the mechanical strength due to acetal structure between hydroxyl of H-PAAM-g-SG and aldehyde of GL. The drug entrapment was confirmed proportional relationship to the Ca+2 ions concentration whereas an increase in GL concentration resulted in a reduced drug entrapment. The pH pulsatile study assured the reversible swelling-shrinkage behavior of IPN microbeads due to the carboxyl group of PAAM-g-SG. The drug release from H-PAAM-g-SG-SA microbeads (batch: S9) was found to be 84.21 % (12h) which was non-significant (p > 0.05; f2 = 79 ∼ 90) over marketed formulation (83.31 %). Moreover, it follows the Korsmeyer Peppas (R2 = 0.996) as the best-fit release kinetic model. The pH-sensitive release of diclofenac sodium from IPN H-PAAM-g-SG-SA microbeads was assured based on in vivo anti-inflammatory activity (p < 0.05). Therefore, developed novel pH-sensitive IPN microbeads based on H-PAAM-g-SG are a promising polymeric carrier substitute for delivery of drugs actuated by a pH stimulus.

Laser welding of tailored blanks made of Al-Si-coated 22MnB5 steel using a filler wire and a variable energy distribution laser optics

Laser welding of Al-Si-coated steels for hot stamping in automotive applications is problematic due to the mixing of the coating layers inside the molten pool that weakens the resulting weld seam. In this case, the most common welding procedure to overcome this issue consists in removing the Al-Si layer through laser ablation prior to the joining. This method continues to be the most widely used by major producers of tailor welded blanks, although in situ ablation of the Al-Si coating can be costly and time consuming. In this work, a novel approach consisting in joining as-received (i.e., not decoated) materials using a filler wire and an innovative variable energy distribution laser optics is introduced and tested on tailor welded blanks made of 22MnB5. Tensile tests of specimens obtained from a 33 full factorial design of experiment have shown an average value of ultimate tensile strength of 1523 MPa, which is much higher than the one usually observed in as-received welded then hot-stamped conditions and aligned with hot-stamped base material values. Hardness test results (494–543 HV0.5) were in the typical hot-stamped base material range of values as well, while SEM–EDS analyses detected no ferrite inclusions inside the fusion zone. Variations of the main process parameters have been considered on an iso-thickness and iso-material configuration, empirically demonstrating the stability and reliability of the proposed methodology as well as its suitability for production purposes.

Natural and recycled aggregate concrete containing rice husk ash as replacement of cement: Mechanical properties, microstructure, strength model and statistical analysis

This study investigated the effects of the replacement ratio of natural aggregates (NAs) by recycled aggregate (RAs), the replacement ratio of cement by rice husk ash (RHA), and their interaction on compressive properties of recycled aggregate concrete (RAC). The RAs used consisted of 37.5 wt% recycled brick aggregates and 62.5 wt% recycled concrete aggregates from construction and demolition waste. To optimise the properties of RAC mixture, a full factorial design of experiment was applied in designing the concrete mixture proportion. The two factors considered were: the replacement ratio (wt.%) of RA with five levels (0%, 30%, 50%, 70% and 100%) and the replacement ratio (wt.%) of RHA with four levels (0%, 10%, 20% and 30%). Axial compression tests based on the full factorial experiment were conducted on cubic and prismatic samples at 28 days to evaluate their compressive properties. In addition, further cubic concrete groups were also tested in axial compression at different concrete ages (i.e., 3, 7, 28, 56 and 91 days) to understand the effect of concrete age on the compressive strength. Statistical analyses including ANOVA, post-hoc pairwise comparisons and effect size (Cohen's d) computation were performed to evaluate the experimental results. The results indicated that the compressive strength of concrete at 28 days was significantly affected by the replacement ratio of RA and RHA (both p-values <0.0001), as well as their interaction (p-value = 0.0001). For the four different replacement ratios (0%, 10%, 20% and 30%) of RHA considered in this study, the optimised ratio was 10%, which resulted in 0.4% and 4.9% increases in compressive strength of NAC and RAC (RA replacement ratio = 100%), respectively. RHA contributed more to the strength improvement of RAC than to that of NAC, both at 28 days and at 91 days. A new compressive strength model was developed for concrete containing RAs and RHA (or for other supplementary cementitious materials such as fly ash, silica fume, metakaolin and ground granulated blast slag). The validation with the experimental results from the literature showed a good accuracy of this model for concrete strength prediction, with 4.45% mean absolute percentage error and 2.3 root mean square error.

Study of Formulation and Process Variables for Optimization of Piroxicam Nanosuspension Using 32 Factorial Design to Improve Solubility and In Vitro Bioavailability.

Piroxicam is a Biopharmaceutical Classification System (BCS) Class II drug having poor aqueous solubility and a short half-life. The rationale behind the present research was to develop a Piroxicam nanosuspension to enhance the solubility and thereby the in vitro bioavailability of the drug. Piroxicam nanosuspension (PRX NS) was prepared by an anti-solvent precipitation technique and optimized using a full-factorial design. Herein, the nanosuspension was prepared using polymer polyvinylpyrrolidone (PVP) K30® and Poloxamer 188® as a stabilizer to improve the solubility and in vitro bioavailability of the drug. Nine formulations were prepared based on 32 full-factorial experimental designs to study the effect of the formulation variables such as concentration of poloxamer 188 (%) (X1) and stirring speed (rpm) (X2) as a process variable on the response of particle size (nm) and solubility (µg/mL). The prepared NS was characterized by phase solubility, Fourier-transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), particle size, zeta potential, entrapment efficiency, and percent drug release. DSC and XRPD analysis of freeze-dried NS formulation showed conversion of PRX into a less crystalline form. NS formulations showed a reduction in the size from 443 nm to 228 nm with -22.5 to -30.5 mV zeta potential and % drug entrapment of 89.76 ± 0.76. TEM analysis confirmed the size reduction at the nano level. The solubility was increased from 44 μg/mL to 87 μg/mL by altering the independent variables. The solubility of PRX NS in water was augmented by 14- to 15-fold (87.28 μg/mL) than pure PRX (6.6 μg/mL). The optimized formulation (NS9) at drug-to-stabilizer concentration exhibited a greater drug release of approximately 96.07% after 120 min as compared to the other NS formulations and pure PRX (36.78%). Thus, all these results revealed that the prepared NS formulations have improved the solubility and in vitro dissolution compared to the pure drug. Furthermore, an increase in the drug release was observed from the NS than that of the pure PRX. All these outcomes signified that the prepared PRX NS showed an increase in solubility and in vitro dissolution behavior; which subsequently would aid in attainment of enhanced bioavailability.

Comparison of Full Factorial and Optimal Experimental Design for Perceptual Evaluation of Audiovisual Quality

Comparison of Full Factorial and Optimal Experimental Design for Perceptual Evaluation of Audiovisual Quality

Adsorption Performance of Zeolite for the Removal of Congo Red Dye: Factorial Design Experiments, Kinetic, and Equilibrium Studies

In the present research, zeolite is used for the removal of toxic Congo red dye from water solution. The effects of different operating conditions such as hydrogen potential (pH), contact time (time), zeolite dose (D), initial dye concentration (C0), and ionic strength (I) are investigated for Congo red adsorption under batch mode. It was found that the adsorption process was greatly affected by the initial pH of the dye solution. The removal efficiency decreased from 97.68 to 5.22% when the pH varied from 3 to 5; thus, acidic conditions clearly improve Congo red adsorption on zeolite. At pH 3, an increase in C0 and I and decrease in D resulted in an increase in the adsorption capacity qe. The effects of these three parameters and their interactions were also investigated using the 23 full factorial design experiments approach where qe was chosen as the response. The results obtained from this method followed by the analysis of variance and the Student’s t-test show that, the influence of these parameters on dye adsorption process are in the order I &lt; C0 &lt; D. The kinetic studies revealed that adsorption follows a pseudo-second-order kinetic model. The adsorption isotherms experimental data were analyzed using the Langmuir, Freundlich, and Temkin isotherms models. The Freundlich isotherm was the best-fit model to the experimental data. The fitting of kinetics and isotherm models was evaluated by using non-linear modeling, R2, MSE, and RMSE.

An integrated approach to fast model-based process design: Integrating superstructure optimization under uncertainties and optimal design of experiments

During the early-stage design of chemical production processes many decisions have to be made on the basis of incomplete knowledge about the underlying chemical and physical phenomena. Therefore, optimization-based approaches are often applied only in a later stage when more knowledge has been generated. In this work, an integrated approach to fast, model and optimization based process design for the selection of reactors and separation networks is discussed. The approach is based on superstructure optimization under uncertainties about the parameters of the models using a two-stage scenario-based approach. Usually, due to the uncertainties, structural decisions cannot be made in the initial stage as different structures are superior for different scenarios of the uncertain parameters. In order to arrive at such decisions, the models need to be refined based on experimental studies. We combine design of experiments with optimization under uncertainty to optimize the experiments such that the information obtained about those parameters that are critical with respect to taking structural design decisions is maximized. We apply the methodology to the development of a process for the hydroaminomethylation of 1-decene in a thermomorphic solvent system. It is shown that the integrated approach can help to significantly reduce the number of required experiments. Using the integrated approach, only 7 experiments need to be performed while more than 16 experiments following a full-factorial experimental design do not provide the same reduction of the design space.

Properties of bio-oil and bio-char from high-intensity microwave-assisted pyrolysis of oil palm shell waste

Microwave-assisted pyrolysis was applied using four magnetrons to implement a high intensity at a power density of 0.3107 W/m3 with 800 g specimen size. The 23 full factorial experimental design manipulated the factors temperature, mixture ratio, and pyrolysis time, seeking to maximize %yield at minimum cost of crude bio-oil. The optimum according to model fit had a temperature of 611 °C with a 70:30 sample mixture ratio of oil palm shell (OPS) to activated carbon (AC), and time 39.6 min for a yield of 15.3% and 8.48 Thai-Baht/cc cost. The coefficients of determination were R2 = 93.99% and 94.00% for the respective models. In the aqueous phase of crude bio-oil, acetic acid was the dominant chemical component at 55.2%, whereas phenol was dominant in the bio-oil phase at 44.2%, from 400 °C pyrolysis temperature. The assessed properties of bio-char were proximate composition, heating value, specific surface, and pore volume, and these were improved compared to the raw OPS. However, these properties must be improved further to match commercial-grade activated carbon.

Evaluation of the uses of treated sawdust as a partial replacement for aggregate in hot mix asphalt

Undoubtedly, the damage to the upper layer of the road pavement caused by a tremendous load of vehicles and climate factors is an alarming and challenging fact to both government and researchers in the respective field. Thus, and with the aim to come up with a remedy, the potential of sawdust, as a renewable material for replacing aggregate in hot-mix asphalt, was examined. Therefore, a full factorial design of experiment (DOE) was conducted to evaluate the effects of sawdust content (5%, 10%, and 15% of total aggregate volume) on Marshall stability flow values and density. The range of binder from (5.77% to 6.45% means from low level to high level) and the temperature of mixing (140°C to 180°C) and the time of mixing (2 minutes to 4 minutes) as well. Also, to improve its durability, the sawdust was treated with an established emulsion coating. Accordingly, it has been demonstrated in this study that sawdust can be utilized as a partial replacement for (3/8) aggregate. Indeed, the use of this renewable material resulted in an increase in Marshall stability, a decrease in density, and flow values within the accepted range, leading to a positive environmental impact. Additionally, sawdust is considered a waste material, making it cost-effective. Ultimately, the acceptance criterion allows for the replacement of up to 7% of the aggregate for both low and high-level values; however, if more than 7% is replaced, only the highest-level value is considered acceptable. Thus, an economically and technically efficient solution may have been provided by this study.

HACIA LA COPOLIMERIZACIÓN DE NANOCOMPUESTOS DE PROPILENO ESTEREOESPECÍFICOS CON COMONÓMEROS POLARES MEDIANTE POLIMERIZACIÓN IN SITU. OPTIMIZACIÓN DE LAS PROPIEDADES MECÁNICAS.

The use of different stereospecific metallocene catalysts: isotactic (iPP, C2-symmetry) and syndiotactic (sPP, Cs-symmetry) has been investigated in order to improve the mechanical properties of polypropylene/nanoclay nanocomposites obtained by in-situ polymerisation. Stereoregular nanocomposites have been synthetized in the presence of polar comonomers (1-undecenol (R-OH) and acid-undecenoic (R-COOH) for improving the matrix-nanoclay chemical compatibility. An important study of variables: amount of nanoparticles used as co-catalyst support, type of catalyst, type and amount of comonomer have been studied in a full factorial design of experiments in order to identify the main factors that achieve a balance between the stiffness and toughness of the polypropylene nanocomposites. Important results were found from ANOVA (analysis of variance): the nanoclay has a greater influence on the syndiotactic configuration and, the amount of polar comonomer is the main factor in maximising mechanical properties, irrespective of stereospecificity of the polypropylene nanocomposites. &nbsp

Effects Optimization of Bio-Polishing Industrial Process Parameters

The purpose of this study is to select an appropriate commercial neutral cellulase enzyme for denim garments bio-polishing to achieve specific industrial goals. A full factorial experimental design was used to evaluate the effect of factors considered in the optimization of the bio-polishing process (fabric ID: x1, treatment time: x2, treatment temperature: x3, enzyme concentration: x4, storage time: x5, inactivation step: x6 and enzyme type: x7). Experiments were conducted using laboratory washing machine. Subjective evaluation was performed at a pilot and at an industrial scale. Tear, tensile strength and subjective evaluation concerning hand feel, fabric color, indigo dye pocket back staining and fuzziness extent were evaluated. Results showed that x6 and x7 had significant effects on the fabric tear and tensile strength loss. In the optimization, the great dependence between observed and predicted tear strength and tensile strength loss, the correlation coefficient of the models (R2 > 0.85) and the important value of F-ratio proved the validity of the models. Results showed that denim leg panels treated with the enzyme Lava-Cell NSZ presented a minimum loss of tear and tensile strength. A low-temperature and time enzymatic bio-polishing process was developed at industrial scale.

Numerical Analysis of Cavity-Based Control of Base Pressure Variations at Supersonic Mach Numbers

In the present study, the base pressure variations induced by the presence of a cavity, known to have a strong influence of the behaviour of supersonic projectiles, are investigated through numerical solution of the balance equations for mass, momentum, and energy. An area ratio of four is considered and numerical simulations are carried out at Mach M = 1.2, 1.4, 1.6, and 1.8 assuming no cavity or cavity locations 0.5D, 1D, 1.5D, and 2D. The inlet pressure of the nozzle is considered as a flow variable. The Taguchi method is also used, and the considered cases are then analyzed using a full factorial experimental design. The results show that the cavity is effective in increasing the base pressure for the conditions examined. For other nozzle pressure ratios, cavities do not lead to passive control due the change in the reattachment length. The distribution of wall pressure reveals that, in general, a cavity used to implement passive control of the base pressure does not adversely influence the flow pattern in the domain.