MOCF: A Multi-Objective Clustering Framework using an Improved Particle Swarm Optimization Algorithm

Traditional clustering algorithms, such as K-Means, perform clustering with a single goal in mind. However, in many real-world applications, multiple objective functions must be considered at the same time. Furthermore, traditional clustering algorithms have drawbacks such as centroid selection, local optimal, and convergence. Particle Swarm Optimization (PSO)-based clustering approaches were developed to address these shortcomings. Animals and their social Behaviour, particularly bird flocking and fish schooling, inspire PSO. This paper proposes the Multi-Objective Clustering Framework (MOCF), an improved PSO-based framework. As an algorithm, a Particle Swarm Optimization (PSO) based Multi-Objective Clustering (PSO-MOC) is proposed. It significantly improves clustering efficiency. The proposed framework's performance is evaluated using a variety of real-world datasets. To test the performance of the proposed algorithm, a prototype application was built using the Python data science platform. The empirical results showed that multi-objective clustering outperformed its single-objective counterparts

Hot deformation behavior and processing maps of diamond/Cu composites

The hot deformation behaviors of 50 vol pct uncoated and Cr-coated diamond/Cu composites were investigated using hot isothermal compression tests under the temperature and strain rate ranging from 1073 K to 1273 K (800 C to 1000 C) and from 0.001 to 5 s1, respectively. Dynamic recrystallization was determined to be the primary restoration mechanism during deformation. The Cr3C2 coating enhanced the interfacial bonding and resulted in a larger flow stress for the Cr-coated diamond/Cu composites. Moreover, the enhanced interfacial affinity led to a higher activation energy for the Cr-coated diamond/Cu composites (238 kJ/mol) than for their uncoated counterparts (205 kJ/mol). The strain-rate-dependent constitutive equations of the diamond/Cu composites were derived based on the Arrhenius model, and a high correlation (R = 0.99) was observed between the calculated flow stresses and experimental data. With the help of processing maps, hot extrusions were realized at 1123 K/0.01 s1 and 1153 K/0.01 s1 (850 C/0.01 s1 and 880 C/0.01 s1) for the uncoated and coated diamond/Cu composites, respectively. The combination of interface optimization and hot extrusion led to increases of the density and thermal conductivity, thereby providing a promising route for the fabrication of diamond/Cu composites

Comparison of flow behavior of as-cast and hot rolled Al-B4C composites by constant and differential strain rate tests

High temperature tensile flow behavior of aluminum-boron carbide (Al-B4C) composites of 0, 5 and 15% B4C, hot rolled to similar to 88% with intermediate annealing at 350 degrees C, was investigated by constant initial strain rate (CIS) ((epsilon) over dot = 1 x 10(-2)s(-1)) test technique at 500 degrees C and strain rate jump ((epsilon) over dot = 5 x 10(-5) - 1 x 10(-2)s(-1)) test technique over the temperature range of 400-500 degrees C. In the as-cast condition, the flow stresses obtained between CIS and strain rate jump test techniques were found to be significantly different at 500 degrees C. The strain rate sensitivity index (m) was found to be similar to 0.1 over (epsilon) over dot = 1 x 10(-4) - 1 x 10(-2)s(-1) for all the composites in both as-cast as well as hot rolled condition. Tensile elongations were found to be 0.36 in both as-cast and hot rolled aluminum, whereas the same reduced in Al-5% B4C composite to 0.35 and 0.27, respectively. The values of activation energy (Q) for deformation of rolled aluminum and Al-5% B4C composite were determined to be 194.2 and 73.4 kJ/mol, respectively. The microstructural examination, using SEM and EBSD techniques, revealed cavitation in aluminum upon differential strain rate test, and grain refinement upon rolling, which increased later during tensile test

Effects of temperature and strain rate on compressive flow behavior of aluminum-boron carbide composites

Flow properties of aluminum and aluminum-boron carbide (Al-B4C) composites, containing 5, 10 and 15 wt% B4C, were investigated by compression tests at strain rates of 10(-4), 10(-3) and 10(-2) s(-1) over the temperature range 25 to 500celcius. The nature of stress-strain curves as a function of reinforcement, temperature and strain rate revealed that (1) flow stress initially increases as the reinforcement increases, but it decreases for Al-15% B4C composite, (2) flow stress increases with the increase in strain rate, with the strain rate sensitivity index varying from 0.01 for aluminum at 200celcius to 0.30 for Al-5% B4C composite. The activation energy for deformation is found to vary from 124 to 187 kJ/mol for Al-15% B4C and Al-5% B4C composites, respectively

Microstructure evolution and flow behavior of hot-rolled aluminum-5% B4C composite

Differential strain rate compression tests were conducted to study flow behavior of hot rolled Al-5 wt% B4C composite as a function of sample orientation (longitudinal and transverse) over the temperature and strain rate ranges of 25-500 degrees C and 10 (4) to 1 s (1), respectively. The longitudinal samples are found to show lower flow stress than that shown by the transverse samples in the temperature range of 25200 degrees C. The reverse becomes true at higher temperatures of 300-500 degrees C. The values of stress exponent (n) and activation energy for deformation (Q), based on applied stress, ranged from 10 to 46 and 307416 kJ/mol, respectively. However, by considering effective stress, these values were reduced to n = 8 and Q = 126-190 kJ/mol. This stress exponent ofn = 8 is further reduced to n = 5 by considering substructural evolution, which suggests the dislocation climb creep mechanism to be favorable for deformation. (C) 2013 Elsevier Ltd. All rights reserved

Hot Workability and Flow Characteristics of Aluminum-5 wt.% B4C Composite

Flow behavior of aluminum-5 wt.% boron carbide (Al-B4C) composite was investigated by carrying out compression tests over a range of strain rates (10(-4)-10(0) s(-1)) and temperatures (200-500 A degrees C). The flow stress data obtained from these tests at true strain 0.5 were used to develop processing map. The stable and instable flow regimes in the map were characterized by the microstructural examination using Scanning Electron Microscopy and Electron Backscattered Diffraction. The optimum condition for processing of Al-5%B4C composite was found to lie between 425 and 475 A degrees C at the strain rate of around 10(-4) s(-1). A strain-compensated Sellars-McG Tegart constitutive equation was established to model high-temperature deformation behavior of the material

Development of constitutive relationship and processing map for Al-6. 65Si-0.44Mg alloy and its composite with B4C particulates

High temperature flow behavior of Al-6.65Si-0.44Mg (all in wt%) (A356) alloy and A356+5 wt% B4C composite were investigated by compression test at temperatures 470, 500, 530 and 570 degrees C and strain rates 10(-3), 10(-2), 10(-1) and 1 s(-1). Constitutive relationship was established by the prediction of materials constants alpha, beta n, Q and InA. The variations in stable and instable regions of processing map were investigated in A356 alloy and A356+5 wt% B4C composite. It was found that the existence of instability domain for A356 alloy, over the range of temperatures similar to 510-570 degrees C and strain rates similar to 1- 4 x 10(-2) s(-1), was extended to regime of temperatures similar to 470-570 degrees C over the same strain rates upon 5% B4C reinforcement. The microstructural evolutions by stable and instable regions were studied in scanning electron microscope (SEM) and by the electron backscatter diffraction (EBSD) technique. (C) 2016 Elsevier B.V. All rights reserved

Evaluation of Comfort Levels of Patient and Ergonomics of the Dental Surgeon during Manual Scaling under Both Proprioceptive Derivative Concept and Conventional Approach: A Cross-sectional Study

Introduction: The important components that contribute to successful dental care are maximum accessibility, visibility, comfort, and control over clinical processes. Dental practitioners are more prone to developing musculoskeletal disorders due to awkward working postures. To minimise all these risk factors, a new concept called Proprioceptive Derivative (PD) has come into existence. Aim: The main aim of this study was to evaluate the comfort levels of the patient and ergonomics of the dental professional in the PD approach and conventional approach. Materials and Methods: A cross-sectional study was conducted in which manual scaling was performed by 20 dentists on 120 patients using the PD concept and conventional concept. A 13-item questionnaire was distributed among the patients and clinicians to record their perceptions of comfort levels, clinicians’ treatment satisfaction levels, and the time needed to complete the procedure after mastering the PD concept. In indepedent sample t-test was use to compare the responses among the two groups. p≤0.05 was considered statistically significant. Results: The comfort levels of the clinician (q1) during treatment in the conventional approach, with a mean value of 2.96±0.69, were significantly lower than in the PD approach, with a mean value of 3.46±0.85 (p<0.001). However, from the perspective of the patients, the mean comfort levels using the conventional strategy were 2.61±1.03, while using the PD approach, it was 2.85±1.11, which was not statistically significant (p>0.05). Conclusion: The clinicians had more ergonomic benefits and improved time factors under the PD concept. By following the work postures according to the PD concept, clinicians can avoid musculoskeletal discomfort, which is beneficial to all clinicians and can increase the longevity of their clinical practice