Effects Of Control Factors Research Articles

Parametric appraisal and wear prediction of hybrid composites using an integrated soft computing approach

AbstractThis article reports on the implementation of artificial neural network (ANN) and statistical methods to analyze and predict the erosion performance of titania (TiO2) filled ramie‐epoxy based composites. These hybrid composites are prepared by conventional hand lay‐up route and subjected to solid particle erosion tests as per Taguchi's L27 orthogonal array. The effects of different control factors on erosion rate of these composites are studied using Taguchi method. It reveals that impact velocity and filler content have significant effect on the erosion wear rate followed by other least significant factors. The individual effect of each control factor while keeping other factors constant is ascertained by performing steady state erosion experiments. Further, a computational model based on ANN is used as a tool to effectively predict the erosion rates of the composites. The results show that the predicted values are in reasonably good agreement with the experimental ones with an accuracy of 90% and relative error lying within a range of 1%–10%. Further, the trained ANN model is validated by considering the erosion rates obtained during steady state erosion process as the input parameter. The possible mechanisms causing the wear loss are identified using electron microscopy.Highlights Successful fabrication of titanium oxide reinforced hybrid composites. Steady state erosion experiments are performed. Erosion rates are predicted using ANN and compared with the experimental data. Wear loss mechanisms are identified using electron microscopy.

Precipitation, topography, and soil conservation measures determine the spatiotemporal pattern of sediment yield at the regional scale

Exploring the driving effects of control factors on changes in sediment yield from a watershed perspective is of paramount importance for refined watershed management. The objective of this research is to unveil the spatiotemporal variation of sediment yield in the Coarse Sandy Hilly Catchments (CSHC) region from 1956 to 2019 and further investigate the relationship between sediment yield and driving factors. The findings revealed that the mutation years of sediment load (SL) at Toudaoguai and Longmen stations were 1986 and 1996, respectively, with annual SL declining by 66.75 % and 79.04 % after the mutation. Water and sediment discharge at Toudaoguai station exhibited more consistent fluctuations over time, while water and sediment discharge at Longmen station remained relatively consistent before 1967, followed by an entirely inconsistent trend. The spatial pattern of the annual average specific sediment yield (SSY) indicated that the northwest watersheds had a relatively higher erosion rate compared to the southeast. Over time, the SSY of each watershed exhibited a decreasing trend. The SSY showed significant negative correlations with terrace, afforestation, topographic position index (TPI), grass planting (GP), and elevation, while demonstrating significant positive correlations with rainfall indicators and runoff depth. Changes in precipitation, topography, vegetation and engineering measures accounted for 58.5 % of the variance in SSY. The total impact of precipitation on SSY change was positive (standard path coefficient (SPC) = 0.567, P < 0.01), whereas the total impact of topography, vegetation measures, and engineering measures on SSY change was negative (SPC = -0.282, −0.231, and −0.087, respectively). This study quantified the impact of different types of controlling factors on sediment yield at the watershed level. The insights provided by these results can contribute to sustainable watershed management and the optimal allocation of soil and water conservation measures (SWCMs).

Effects of Control Factors on Protein-Polyelectrolyte Complex Coacervation.

Protein-polyelectrolyte complex coacervation is of particular interest for mimicking intracellular phase separation and organization. Yet, the challenge arises from regulating the coacervation due to the globular structure and anisotropic distributed charges of protein. Herein, we fully investigate the different control factors and reveal their effects on protein-polyelectrolyte coacervation. We prepared mixtures of BSA (bovine serum albumin) with different cationic polymers, which include linear and branched polyelectrolytes covering different spacer and charge groups, chain lengths, and polymer structures. With BSA-PDMAEMA [poly(N,N-dimethylaminomethyl methacrylate)] as the main investigated pair, we find that the moderate pH and ionic strength are essential for the adequate electrostatic interaction and formation of coacervate droplets. For most BSA-polymer mixtures, excess polyelectrolytes are required to achieve the full complexation, as evidenced by the deviated optimal charge mixing ratios from the charge stoichiometry. Polymers with longer chains or primary amine groups and a branched structure endow a strong electrostatic interaction with BSA and cause a bigger charge ratio deviation associated with the formation of solid-like coacervate complexes. Nevertheless, both the liquid- and solid-like coacervates hardly interrupt the BSA structure and activity, indicating the safe encapsulation of proteins by the coacervation with polyelectrolytes. Our study validates the crucial control of the diverse factors in regulating protein-polyelectrolyte coacervation, and the revealed principles shall be instructive for establishing other protein-based coacervations and boosting their potential applications.

Investigations and development of novel fuel blends using biodiesel and butylated hydroxytoluene: optimization using D-optimal design and desirability

ABSTRACT The transportation industry is most concerned about the rising cost of fossil fuels and the deterioration of the environment. Although many alternative fuels currently have enhanced performance characteristics, continuous research attempts to further enhance their quality even more. This research focuses on improving fuel quality by incorporating Waste vegetable oil biodiesel derived from Liza oil and Butylated Hydroxytoluene (BHT). The combination of these factors results in a novel approach that uses experimental and parametric optimization to outperform current constraints in alternative fuels. The objective of this study is to compare the performance and emission characteristics of several blends of diesel, including B10 (20% biodiesel + 500 ppm BHT + diesel), B20 (20% biodiesel + 1000 ppm BHT + diesel), B30 (20% biodiesel + 1500 ppm BHT + diesel), B40 (20% biodiesel + 2000 ppm BHT + diesel), and B50 (20% biodiesel + 2500 ppm BHT + diesel). The tests were carried out at a variety of engine loads and speeds. The performance of Liza oil blends, as assessed by engine performance and emissions characteristics, was found to be comparable to that of diesel. Mechanical and brake thermal efficiency was determined to be highest for the B30 and B40 mixtures. The Liza oil Biodiesel operation exhibited fewer hydrocarbon emissions than the diesel fuel mode at B20. The D-optimal design was utilized for the experiment design. The data collected was used for the analysis of variance (ANOVA) for the development of mathematical expression for each response variable. The response surface methodology (RSM) was employed for the development of response surfaces to explore the effects of control factors on each response variable. The most favorable results were obtained using desirability-based optimization at 8.22 kg engine load and 500 ppm BTH concentration. It resulted in 20.04% brake thermal efficiency, 0.4 kg/kWh brake specific fuel consumption, 39% mechanical efficiency, 0.028 Vol.% carbon mono-oxide, 7.39% carbon-di-oxide, 39.16 ppm hydrocarbon, and 1230 ppm nitrogen oxide as response variables.

Experimental Investigation of Slurry Erosion Wear Analysis of Epoxy Resin Reinforced with Aramid Woven Fabric with Taguchi Experimental Design

Abstract: Fibre reinforced polymer composites as hybrid composites are commonly used for certain applications in which erosion wear and fracture are serious issues. These composites have engineering/structural applications in which they are subjected to sand slurries and dusty environment. Composites with different fibre loading are used to evaluate steady state erosion behavior for different operating conditions on slurry jet erosion testing machine. In this chapter Slurry jet erosion test rig is used for experimental investigation of steady state erosion rate of aramid composite samples as per ASTM standards. Steady state erosion test is conducted by defining certain control factors and fixed parameters. Test is conducted in two cases. In first case by varying impact angle and keeping impact velocity and discharge rate constant and in second case by varying impact velocity and keeping impact angle and discharge rate constant. Steady state erosion rate is calculated for both the cases. The Taguchi experimental design (orthogonal array) is used to optimize the design parameters and used to analyse the effect of control factors on output parameters, which reduces overall testing time and cost. To understand the effect of control factors and their iterations ANOVA (analysis of variance) is used. Results of steady state erosion rate and Taguchi experimental design are analysed to selection best suitable material for turbine blade application based on minimum erosion rate

A mix design methodology of blast furnace slag and fly ash-based alkali-activated concrete

Although the application of blast furnace slag and fly ash-based alkali-activated concrete (BFS/FA-AAC) has both economic and environmental benefits, it is limited by the lack of a straightforward mix design method. In this paper, an experiment was conducted to investigate the effect of control factors, including the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the water content on the workability (slump and rheology) of BFS/FA-AAC, and the effect of control factors include the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the curing time on the compressive strength of BFS/FA-AAC. As a result, the influence degree and mechanism of each control factor on the performance of BFS/FA-AAC were quantitively explored and the accuracy of an empirical compressive strength formula was validated. Based on that, a practical mix design method of BFS/FA-AAC was eventually established. It is found that the mixture composition and content of paste can significantly influence the workability of BFS/FA-AAC. The compressive strength of BFS/FA-AAC is determined by control factors when the water content is within 160–195 kg/m3. The mechanical predictive method of BFS/FA-AAC is proven of high accuracy. The mixture designed by this methodology exhibits satisfied fresh and hardened performance as well as high environmental benefits.

Effect of Control Factors on Wear Rate of the Ceramic Particulate Filled Metal Alloy Composites: A Comparative Analysis

Effect of Control Factors on Wear Rate of the Ceramic Particulate Filled Metal Alloy Composites: A Comparative Analysis

Research on the Macro-Mesoscopic Response Mechanism of Multisphere Approximated Heteromorphic Tailing Particles

Abstract The shape of tailing particles is essential factors of their macroscopic mechanical properties. Scholars have studied the effects of controllable factors, such as loading method, confining pressure, and strain rate, on the strength of tailing sand. However, research on the tailing particle structure and shape through laboratory tests has proved to be difficult due to the uncertain and discrete tailing particle distribution. Thus, the macro-mesoscopic response of heteromorphic tailing particles is rarely investigated. In this paper, the macro-mesoscopic response of heteromorphic tailing particles is studied using multisphere approximation, and numerical simulation of triaxial tests on the particles is conducted. Nonlinear evolution patterns of porosity, internal friction angle, and cohesion of heteromorphic tailing particles with the variation of angularity were investigated using the flexible boundary program developed in this study, which revealed the intrinsic relationship between the mesostructure evolution mechanism and the macroscopic engineering characteristics of heteromorphic tailing particles. The research results showed that (1) changes in angularity led to tailing particle rearrangements and, in turn, porosity changes. With increased angularity and confining pressure, particle sphericity decreased, and the deviatoric and peak stress increased accordingly. In the meantime, the softening was more significant as the peak stress was exceeded, while the cohesive force generally increased. (2) With fixed particle shape and angularity, the internal friction angle decreased slightly as the effective confining pressure increased. (3) In the shearing process, the simulated contact force chain evolution of tailing particles with different shapes was similar. The disordered contact force chains gradually undergo directional connection, i.e., the increased confining pressure reduced the number of free tailing particles and increased the number of stressed particles. (4) The triaxial stress-strain and peak stress in rigid boundary simulations under different confining pressures were slightly lower than those in the flexible boundary simulations. However, the difference was insignificant, indicating the good feasibility and reasonability of rigid boundary simulations for the macroscopic mechanical behaviors in triaxial tests. The research results could offer more direct insights into the macro-mesoscopic response and mechanical mechanisms of nonspherical particles and provide references for the simulation of tailings at the microscopic levels.

Simulation study on pressure fluctuation characteristics of a high-pressure common rail system

Pressure fluctuations in the high-pressure common rail systems have a significant impact on the fuel injection and engine performance. In this study, the pressure fluctuation in a high-pressure common rail system was investigated using simulations. The fluctuation can be caused by hydraulic structures and control factors. The degree of influence of those two causes was evaluated and discussed in this work. First, the hydraulic and control factors that dominate the models of injection systems were established. Then, the mechanism of pressure fluctuation on high-pressure common rail systems was highlighted. A dimensionless parameter was defined to quantitatively describe the effects of control factors and hydraulic structures on pressure fluctuation. Finally, the developed model was used to study the effects of injection conditions and structural parameters on pressure fluctuation. The results show that the injection frequency has a limited effect on the system pressure fluctuation. In addition, the increase in the injection energizing time and the injection pressure will increase the hydraulic pressure fluctuations of the system, thus increasing the total pressure fluctuations of the system. Moreover, the increase in the volume by increasing the diameter was found to decrease the pressure fluctuations more effectively compared to the impact of the length, but there is a marginal diminishing effect. The results demonstrated that the effect of a 20 bar signal error and a 160 mm common rail length is almost the same on decreasing pressure fluctuations. It can be concluded that the improvements in the electronic part of the high-pressure common rail system have more potential than the mechanical part.

Single and multi-objective optimization for cutting force and surface roughness in peripheral milling of Ti6Al4V using fixed and variable helix angle tools

Ti6Al4V titanium (Ti) alloy is a frequently used engineering material in industrial applications due to its superior properties. In this work, single-objective and multi-objective methods were used to optimize control factors (cutting speed, feed rate, and cutting tool helix angle) for minimal cutting force (Fc) and surface roughness (Ra) in peripheral milling of Ti6Al4V. Machinability experiments were performed using carbide end mill cutting tools with fixed and variable helix angles. Following the machinability tests performed using the L18 orthogonal array, the Taguchi technique was used as a single-objective optimization for each of the cutting forces and surface roughness. The Entropy-weighted TOPSIS approach was used in the second step to provide the optimum levels of the control factor, which minimizes both cutting force and surface roughness. The effects of control factors and interactions on thrust force and surface roughness were determined by Analysis of Variance (ANOVA) and contour plots. As a result of this study, it was determined that the helix angle of the cutting tool (84.91 % contribution) was the most effective parameter on the cutting force and the feed rate (22.71 % contribution) on the surface roughness. The cutting force and surface roughness values decreased in peripheral milling at high cutting speed, whereas the cutting forces increased, and the surface quality of the workpiece deteriorated in machining at high feed rates. The helix angle of the cutting tool has a favorable influence on the cutting force and surface roughness when milling with fixed helix tools. Cutting forces are minimized, and workpiece surface quality is improved using cutting tools with a larger helix angle. Variable helix tools with a large helix angle performed best in cutting force and surface roughness. Variable helix end mills with large helix angle (HA = 35°/38°), high cutting speed (Vc:108 m/min), and a low feed rate (f:0.04 mm/tooth) should be used in peripheral milling of Ti6Al4V Ti alloy to achieve both minimum cutting force and best surface quality. The mean cutting force and surface roughness values were obtained as 628.69 N and 0.363 μm, respectively, in the peripheral milling process performed at different levels of control factors. The cutting force was reduced to 227.52 N (34.71 % improvement) and the surface roughness value to 0.237 μm (276.32 % improvement) using the Entropy-weighted TOPSIS multi-objective optimization approach.

Study of the Effects of Control Factors on Speech Features Using Taguchi Method

In this paper, Taguchi optimization method is used for the first time to study the effect of some factors on the features included in speech signal. These factors are ambient temperature, speaker's age, number of words, and number of letters in each word. Taguchi method has the advantage of using a small number of experiments while getting good results for finding which factor has more effect on the phenomena under study. In this method, the number of experiments is based on the orthogonal array that depends on the number and level of the control factors. The main advantage of this method is evident in relation to reducing number of needed experiments where time, cost and material resources are minimized compared to other methods that rely mainly on trial-and-error approach. Nine representative experiments have been carried out. Each one is repeated three times. MATLAB has been employed to find the speech features under study including entropy and linear predictive coding (LPC). Minitab statistical software has been used to analyze the results based on Taguchi method. It has been found out that the order of factors according to their effect on the abovementioned speech features from higher to lower is number of words, number of letters, age, and ambient temperature. In order to validate these results, a linear regression analysis, which has confirmed the results obtained using Taguchi method, has been carried out. The results are immensely beneficial for researchers in improving speech analysis related applications by understanding which factors have more effect on speech features.

Synthesis of Anionic Nanogels for Selective and Efficient Enzyme Encapsulation.

Polyelectrolyte nanogels containing cross-linked ionic polymer networks feature both soft environment and intrinsic charges which are of great potential for enzyme encapsulation. In this work, well-defined poly(acrylic acid) (PAA) nanogels have been synthesized based on a facile strategy, namely, electrostatic assembly directed polymerization (EADP). Specifically, AA monomers are polymerized together with a cross-linker in the presence of a cationic-neutral diblock copolymer as the template. Effects of control factors including pH, salt concentration, and cross-linking degree have been investigated systematically, based on which the optimal preparation of PAA nanogels has been established. The obtained nanogel features not only compatible pocket for safely loading enzymes without disturbing their structures, but also abundant negative charges which enable selective and efficient encapsulation of cationic enzymes. The loading capacities of PAA nanogels for cytochrome (cyt c) and lysozyme are 100 and 125 μg/mg (enzyme/nanogel), respectively. More notably, the PAA network seems to modulate a favorable microenvironment for cyt c and induces 2-fold enhanced activity for the encapsulated enzymes, as indicated by the steady-state kinetic assay. Our study reveals the control factors of EADP for optimal synthesis of anionic nanogels and validates their distinctive advances with respect to efficient loading and activation of cationic enzymes.

Comprehensive analysis of the performance of the coaxial heat exchanger with turbulators

In this study, effects of semicircular striped turbulators, inserted into inner tube of a coaxial heat exchanger on the heat transfer (Nu), friction factor (f) and thermal performance factor (TPF) are analyzed. Pitch (p), thickness (t), diameter (d), arrangement style (a) and Reynolds number (Re) were chosen as design parameters (control factors). With the determined design parameters, it was observed that Nu and f values increased by 5.43 and 4.71 times, respectively, compared to the empty pipe, and the TPF increased up to the value of 3.72. The design parameters are addressed as; Three analysis methods are applied to the study, namely; (i) Taguchi Experimental Design (TED), (ii) Analysis of Variance (ANOVA) and (iii) Grey Relational Analysis (GRA). With TED, optimum parameter levels that maximize heat transfer and minimize friction factor have been determined. The percentage effects of these parameters on the heat transfer and friction factor were obtained by the second method, ANOVA. As a result of the analyzes, most efficient parameter on Nusselt number is found as Reynolds number (31%), whilst the lest efficient parameter is found as the pitch (1.74%). The arrangement style of the turbulators has the strongest effect (32.94%) and, similarly, to the heat transfer, the pitch has the weakest effect (nearly negligible) on the friction factor. Lastly, the effects of control factors on the heat transfer and pressure loss are evaluated together, by using GRA and so multi performance characteristics are determined. According to this analysis, it was seen that the most effective parameter on the multi performance characteristic was the Reynolds number, and the most ineffective parameter was the thickness.

Optimization of Parameters Affecting Noodle Drying by Taguchi Method

In this research, Taguchi method application studies have been carried out to optimize the parameters affecting the drying of noodles made in Çankırı region by sun, conventional oven, and microwave method. In the experimental study, the noodles were dried in a single row in thin strips of 3-4 mm constant thickness to form an area of 100 cm2 (square plate). Variable parameters in three different drying methods are temperature, duration, and microwave power level. Sun drying of noodles was performed at an average temperature of 19 °C in June. Oven drying experiments were carried out at different temperatures (75 °C, 100 °C, 150 °C) and times (30, 60, 90 minutes). Microwave drying operations were performed at 300 W, 450 W, 600W power and 1, 2, 3 minutes respectively. The factors affecting the moisture content that can be separated from the noodles in the conventional oven were determined as drying temperature and drying time. In microwave drying, power and drying time were chosen as control factors. For this purpose, the L9 orthogonal sequence was arranged in Taguchi design used in experimental studies. The effects of control factors were determined by analyzing variance analysis (ANOVA) at 95-97.6 % confidence level. The study also analyzed moisture, ash, protein, color, and volume increase for dried noodles with 3 different drying techniques. In the sun drying of the noodles, 9.47 moisture, 1.33 ash, 10.73 protein, 87.48 L* color value, 1.03 â* color value, 22.46 B* color value, and 282.67 volume increase values were found. In the oven drying, 9.20 moisture, 1.31 ash, 10.77 protein, 80.24 L* color value, 1.64 â* color value, 24.10 B* color value, and 250.23 volume increase values were measured. 8.73 moisture, 1.29 ash, 10.83 protein, 78.50 L* color value, 0.90 â* color value, 25.13 B* color value, and 262.40 volume increase values were determined in the microwave drying.

How to motivate students to do a course project in design of experiments course from a web-based virtual learning material?

PurposeThe purpose of this study is to develop a practical method for training students how to conduct statistical analysis and do a course project in design of experiments (DOEs) course through the Web-based virtual catapult simulation.Design/methodology/approachA step-by-step sequential DOE process for investigating the effects of controllable factors on quality characteristic responses was presented as a guideline for conducting a DOE course project. Each team was assigned to create an innovative teaching material and work on the term report by following the recommended guidelines for designing experiments through the Web-based virtual catapult simulation. Hypothesis was defined to test whether doing a course project based on this approach would impact students’ learning outcome.FindingsThe Web-based virtual material was an alternative technique for interactive teaching that could improve students’ understanding and achievement in DOE course projects. There was a significant difference in student learning and understanding before and after doing on the course project through the Web-based virtual catapult simulation. The students had improved communication and teamwork skills after following the recommended procedure for practicing DOEs.Practical implicationsMost students could effectively conduct designing experiments, carry out designed experiments, analyze data and gain valuable teamwork experience. After learning the DOE approach based on the catapult simulation, they enjoyed working on their course projects deploying to the innovative toys and other real-life situations with real measurements.Originality/valueThe use of Web-based virtual material, including catapult simulation, was an alternative technique for interactive DOE teaching to improve the students’ understanding and achievement in DOE course projects.

Procena i višekriterijumska optimizacija hrapavosti površine, odstupanja od tačnosti dimenzija i greške zaobljenosti u bušenju CFRP/Ti6Al4 naslaga

In this study, machinability tests were carried out to investigate the effects of control factors (cutting tool geometry, cutting speed, and feed rate) on the surface roughness (Ra), deviation from dimensional accuracy (Da_dev), roundness error (Re) in drilling CFRP/Ti6Al4V mixed metallic stack and to determine the optimum levels of drilling parameters. The effects of each control factor and their interactions on three quality characteristics were analyzed, and their levels were single-objectively optimized for each component material by the Taguchi method. The material has components (CFRP and Ti6Al4V) with essentially different properties (mechanical, physical, machinability). Single-objective optimization has limited usability as the drilling must be performed in one through both layers. Therefore, in an additional step, the optimum levels of the control factors were determined by optimizing multi-objective with the Additive Ratio Assessment (ARAS) method. Higher Ra, Da_dev, and Re values were obtained on the CFRP component compared to the Ti6Al4V component. The CFRP/Ti6Al4V stack should be drilled with a nano fire coated carbide drill (T3) at medium cutting speed and high feed rate to achieve minimum Ra, Da_dev, and Re values in one go.

Optimization of EDM process parameters for TWR on machining of Inconel 600 superalloy using Taguchi approach

Electrical discharge machining (EDM) is a non-traditional machining technique that is commonly employed on hard materials. The fact that EDM can cut any conductivematerial, independently of its hardness, has made it popular. EDM is extensively used to shape or create advanced technological materials which are used in extreme conditions. The effects of input parameters on the effective machining of Inconel 600 superalloy was investigated in this study. The tool electrode was made of Tungsten Carbide (WC), and the dielectric fluid was EDM oil. The Taguchi method was used to investigate the effects of control factors including pulse-on-time (Ton), peak current (Ip), and gap voltage (Vg) on the performance criterion TWR. Using an orthogonal array (OA) L9, the research were carried out at three levels. The EDM performance aspects were investigated using the signal-to-noise ratio and ANOVA. The Taguchi technique was used to optimize the input and output parameters using the statistical software MINITAB-17. During the EDM process, TWR grows somewhat linearly with increasing Ip. TWR reduces as Vg increases, then increases as Vg increases. TWR increases with increasing Ton and then drops with increasing Ton. The tool wear rate is lowest at the first level of Ip, the second level of Vg, and the third level of Ton. ANOVA revealed that Ip, Vg, and Ton all had a significant influence on TWR. Obtained optimum input variables value for tool wear rate are Ip (30 A), Vg (94 V), and Ton (150 s). The predicted ideal range of TWR at 95% confidence level was confirmed by conducting confirmation experiments, wherein the TWR was achieved as 0.551 mm3/min. To validate Taguchi's optimization approach, confirmation tests were performed using optimal values of input parameters.

Optimization of material removal rate and surface characterization of wire electric discharge machined Ti-6Al-4V alloy by response surface method

Wire electric discharge machining (WEDM) is one of the foremost methods which has been utilized for machining hard-to-cut materials like Titanium alloys. However, there is a need to optimize their important operating parameters to achieve maximum material removal rate (MRR). The present paper investigates the effect of control factors like current, pulse on time (Ton), pulse off time (Toff) on MRR of machining of Ti-6Al-4V alloy. The study showed that, increase in current from 2 A to 6 A results in a significant increase in MRR by 93.27% and increase in Ton from 20 μs to 35 μs improved the MRR by 7.98%, beyond which there was no improvement of MRR. The increase in Toff showed a counterproductive effect. Increase in Toff from 10 μs to 30 μs showed an almost linear decrease in MRR by 52.77%. Morphological study of the machined surface showed that cut surface consists of recast layer on which microcracks were present, and revealed the presence of globules, ridge-structured formations of recast layers and voids. In addition, a regression model was developed to predict the MRR with respect to the control factors, which showed a good prediction with an R2 value of 99.67%.

A mix design methodology of slag and fly ash-based alkali-activated paste

In this paper, a series of experiments were conducted to systematically and quantitively explore the effects of control factors on the early age properties, i.e., workability and strength of slag and fly ash-based alkali-activated paste (BFS/FA-AAP). The control factors on the workability (flowability and setting time) of BFS/FA-AAP include the Na2O/b ratio, the SiO2/Na2O ratio, the w/b ratio, and the BFS/b ratio. The control factors on strength (compressive strength and flexural strength) of BFS/FA-AAP further also include the curing condition and the curing age. The results show that a higher BFS/b ratio and Na2O/b ratio could increase the strength while decreasing the workability. A higher w/b ratio could increase the workability while slightly decreasing the strength. Higher SiO2/Na2O ratio increases both strength and workability. Despite that, higher Na2O/b ratio and SiO2/Na2O ratio could hinder the strength development. Sealed curing condition is proved to be a simple but efficient way to assure the steady strength development of BFS/FA-AAP. Although the strength of BFS/FA-AAP could generally stabilize after 90 days, the strength development rate varies with different mix proportions. In addition, a general methodology have been proposed to predict the compressive strength of BFS/FA-AAP and verified with experiments. Finally, a mix design table is proposed for the preliminary design of BFS/FA-AAP according to the principle of satisfying early age requirements.

Comparison between the machinability of different titanium alloys (Ti–6Al–4V and Ti–6Al–7Nb) employing the multi-objective optimization

Titanium and its alloys are amongst the most important metallic materials used by many industries, such as those pertaining to the aerospace, automotive, and biomedical sectors. This is due to the reliability and functionality of titanium components, in addition to their high strength-to-weight ratio and corrosion resistance. Thus, titanium and its alloys are of great importance to the challenging operations of these sectors. The manufacturing of titanium requires great accuracy to ensure that resulting products meet quality requirements, due to its difficult machinability. In this study, the cutting forces and surface roughness of the turning were analysed to compare different titanium alloys, Ti–6Al–4V and Ti–6Al–7Nb, with CVD-coated and uncoated inserts. The effect of control factors on the response variables was measured using ANOVA. Response surface methodology was applied to the creation of a model of responses and to a bi-objective optimization process via the normalized normal constraint method. The Pareto-optimal sets of both alloys were achieved, which may be applied to practical situations to achieve optimal results for these responses. The models and optimization results confirmed the similarity of machinability values between the Ti–6Al–4 V and Ti–6Al–7Nb alloys. The uncoated inserts yielded the best surface roughness and cutting force results when used with both titanium alloys.