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Fracture toughness of a rejuvenated β-Ti reinforced bulk metallic glass matrix composite

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Journal of Materials Science & Technology 2022年第11期106卷 225-235页

作者： Devashish Rajpoot R.Lakshmi Narayan Long Zhang Punit kumar Haifeng Zhang Parag Tandaiya Upadrasta Ramamurty Department of Mechanical Engineering Indian Institute of Technology BombayPowaiMumbai400076India Department of Mechanical and Aerospace Engineering in Nanyang Technological University Singapore 637331Republic of Singapore Department of Materials Science and Engineering Indian Institute of Technology DelhiHauz KhasNew Delhi110016India Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A∗STAR)Singapore 138634Republic of Singapore

A β-Ti dendrite reinforced Zr-based bulk metallic glass composite(BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling(CTC) treatment in restoring the mode I fracture toughness are examined. Plasticity in all the CTC treated BMGC is estimated from the distribution and occurrence of pop-ins in nanoindentation tests and by measuring the magnitude of enthalpy of relaxation(△H_(rel)) via differential scanning calorimetry(DSC). This is further validated by examining the strain-to-failure(ε_(f)) in compression tests. Mode I fracture behaviour of the as-cast embrittled BMGC and the CTC treated BMGC, which exhibits maximum plasticity, is examined. Results show that both BMGCs are equally brittle and exhibit 5 times lower notch toughness(K_(QJ))than their tougher counterpart. Post-facto imaging of the side surfaces reveals the absence of notch-tip plasticity in both BMGCs. The lack of notch tip plasticity of CTC treated BMGC, despite exhibiting signatures of plasticity in nanoindentation and higher △Hrelis rationalized by reassessing the origin of pop-ins in nanoindentation tests and describing the variations in chemical and topological short range ordering during CTC, respectively. Implications of these results in terms of improving the fracture toughness of structurally relaxed BMGCs via CTC are discussed.

关键词： Bulk metallic glass composites Fracture Rejuvenation Shear bands Microsegragation

Hybrid Machine Learning Model for Face Recognition Using SVM

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Computers, Materials & Continua 2022年第8期72卷 2697-2712页

作者： Anil kumar Yadav R.K.Pateriya Nirmal kumar Gupta punit Gupta Dinesh kumar Saini Mohammad Alahmadi IES College of Technology Bhopal462044India Maulana Azad National Institute of Technology Bhopal462003India Department of Information Technology Manipal University JaipurJaipur303007India Department of Computer and Communication Engineering Manipal University JaipurJaipur303007India Department of Software Engineering College of Computer Science and EngineeringUniversity of JeddahJeddah23218Saudi Arabia

Face recognition systems have enhanced human-computer interactions in the last ten years.However,the literature reveals that current techniques used for identifying or verifying faces are not immune to limitations.Principal Component Analysis-Support Vector Machine(PCA-SVM)and Principal Component Analysis-Artificial Neural Network(PCA-ANN)are among the relatively recent and powerful face analysis techniques.Compared to PCA-ANN,PCA-SVM has demonstrated generalization capabilities in many tasks,including the ability to recognize objects with small or large data samples.Apart from requiring a minimal number of parameters in face detection,PCA-SVM minimizes generalization errors and avoids overfitting problems better than PCA-ANN.PCA-SVM,however,is ineffective and inefficient in detecting human faces in cases in which there is poor lighting,long hair,or items covering the subject’s face.This study proposes a novel PCASVM-based model to overcome the recognition problem of PCA-ANN and enhance face detection.The experimental results indicate that the proposed model provides a better face recognition outcome than PCA-SVM.

关键词： Face recognition system(FRS) face identification SVM discrete cosine transform(DCT) artificial neural network(ANN) machine learning

Prospects to the formation and control of potential dimer impurity E of pantoprazole sodium sesquihydrate

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Journal of Pharmaceutical Analysis 2019年第3期9卷 170-177页

作者： Arun kumar Awasthi Lalit kumar punit Tripathi Madhava Golla Cirandur Suresh Reddy Pramod kumar Micro Labs Ltd. Chemical Research Department API R&D Centre Plot No. 43-45 KIADB IVth Phase Bommasandra-Jigani Link Road Anekal Taluk Bangalore 560105 Karnataka India Department of Chemistry Sri Venkateswara University Tirupati 517502 Andhra Pradesh India

Pantoprazole sodium, a substituted benzimidazole derivative, is an irreversible proton pump inhibitor which is primarily used for the treatment of duodenal ulcers, gastric ulcers, and gastroesophageal reflux disease (GERD). The monographs of European Pharmacopoeia (Ph. Eur.) and United States Pharmacopoeia (USP) specify six impurities, viz.;impurities A, B, C, D, E and F, respectively for its active pharmaceutical ingredient (API). The identification and synthesis of all impurities except impurity E are well described in the literature;however, there is no report related to impurity E. The prospects to the formation and controlling of impurity E up to -0.03% in the synthesis of pantoprazole sodium sesquihydrate (PAN) were discussed in detail for the first time. The present work described the journey towards the successful development of an optimal preparation procedure of dimer impurity E. The most plausible mechanism involved in the formation of impurity E has been proposed.

关键词： Pantoprazole sodium sesquihydrate Impurity E Oxidation Enrichment Column chromatography Characterization HPLC

Synthesis and characterization of copper foams through a powder metallurgy route using a compressible and lubricant space-holder material

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International Journal of Minerals,Metallurgy and Materials 2018年第8期25卷 902-912页

作者： Mohit Sharma O.P.Modi Punit kumar Department of Mechanical Engineering National Institute of TechnologyKurukshetraHaryana 136119India CSIR-Advanced Materials&Processes Research Institute Bhopal 462026India Department of Material Science&Metallurgical Engineering Maulana Azad National Institute of TechnologyBhopal 462003India

In the present work,a compressible and lubricating space-holder material commonly known as "acrawax" was used to process Cu foams with various pore sizes and various porosities.The foams were processed without using binders to avoid contamination of their metal matrices.The lubricant space-holder material was found to facilitate more uniform flow and distribution of metal powder around the surface of the space holder.In addition,the use of acrawax as a space-holder material yielded considerably dense cell walls,which are an essential prerequisite for better material properties.The foams processed with a smaller-sized space holder were found to exhibit better electrical and mechanical properties than those processed with a coarser-sized space holder.The isotropic pore shape,uniform pore distribution throughout the metal matrix,and uniform cell wall thickness were found to enhance the properties pertaining to fine-pore foam samples.The processed foams exhibit properties similar to those of the foams processed through the lost-carbonate sintering process.

关键词： copper foam powder metallurgy space holder acrawax flexural strength sintering electrical resistivity

Hybrid Whale Optimization Algorithm for Resource Optimization in Cloud E-Healthcare Applications

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Computers, Materials & Continua 2022年第6期71卷 5659-5676页

作者： punit Gupta Sanjit Bhagat Dinesh kumar Saini Ashish kumar Mohammad Alahmadi Prakash Chandra Sharma School of Computing&Information Technology Manipal University JaipurJaipur303007India School of Basic Sciences Manipal University JaipurJaipur303007India Department of Software Engineering College of Computer Science and EngineeringUniversity of JeddahJeddah23218Saudi Arabia

In the next generation of computing environment e-health care services depend on cloud services.The Cloud computing environment provides a real-time computing environment for e-health care applications.But these services generate a huge number of computational tasks,real-time computing and comes with a deadline,so conventional cloud optimizationmodels cannot fulfil the task in the least time and within the deadline.To overcome this issue many resource optimization meta-heuristic models are been proposed but these models cannot find a global best solution to complete the task in the least time and manage utilization with the least simulation time.In order to overcome existing issues,an artificial neural-inspired whale optimization is proposed to provide a reliable solution for healthcare applications.In this work,two models are proposed one for reliability estimation and the other is based on whale optimization technique and neural network-based binary classifier.The predictive model enhances the quality of service using performance metrics,makespan,least average task completion time,resource usages cost and utilization of the system.Fromresults as compared to existing algorithms the proposedANN-WHOalgorithms prove to improve the average start time by 29.3%,average finish time by 29.5%and utilization by 11%.

关键词： Cloud computing whale optimization health care resource optimization

Ballistic response of skin simulant against fragment simulating projectiles

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Defence Technology（防务技术） 2023年第12期30卷 70-82页

作者： Punit kumar Pandey Atul Harmukh M.K.Khan M.A.Iqbal S.G.Ganpule Department of Mechanical and Industrial Engineering Indian Institute of Technology Roorkee247667India Department of Civil Engineering Indian Institute of Technology Roorkee247667India Department of Design Indian Institute of Technology Roorkee247667India

The response of biological phantoms against high velocity impact is actively sought for applications in defense,space,soft robotics and sensing.Towards this end,we study the ballistic response of silicone based skin simulant against fragment impact.Using a pneumatic gas gun setup,six chisel-nosed and three regular shaped(sphere,cylinder,and cube)fragments were impacted on the skin simulant.The resulting skin simulant response was studied in terms of ballistic limit velocities,energy densities,failure pattern,and the mechanics of interaction.The results indicate that the shape of the fragment affects the ballistic limit velocities.The ballistic limit velocities,energy densities of the chisel-nosed fragment simulating projectiles were relatively insensitive to the size(mass),except for the smallest(0.16 g)and largest(2.79 g)chisel-nosed fragment.For the same size(1 g),ballistic limit velocities and failure are dependent on the shape of the fragment.The skin simulant failed by combined plugging and elastic hole enlargement.Failure in the spherical fragment was dominated by the elastic hole enlargement,whereas plugging failure was dominant in all other fragments.The spherical,cylindrical,and chisel-nosed fragments created circular cavities,and the cubical fragment created a square cavity.In the case of the spherical fragment,slipping of the fragment within the skin simulant was seen.Cubical fragments created lateral cracks emanating from the corners of the square cavity.Interestingly,for all the fragments,the maximum deformation corresponding to the perforation was lower than the non-perforation indicating rate dependent,stress driven failure.The maximum deformation was also dependent on the shape of the fragment.Overall,these results provide unique insights into the mechanical response of a soft simulant against ballistic impact.Results have utility in the calibration and validation of computational models,design of personal protective equipment,and antipersonnel systems.

关键词： Skin simulant Fragment Impact Ballistic limit velocity Energy density Failure

Diameter Dependent Ultrasonic Characterization of InAs Semiconductor Nanowires

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Open Journal of Acoustics 2015年第4期5卷 218-225页

作者： Mohit Gupta punit K. Dhawan Satyendra kumar Verma Raja Ram Yadav Department of Physics University of Allahabad Allahabad India Government Polytechnic Gonda India

In this paper, we report the diameter dependent ultrasonic characterization of wurtzite structured InAs semiconductor nanowires at the room temperature. In this work, we have calculated the non-linear higher order elastic constants of InAs nanowires validating the interaction potential model. The ultrasonic attenuation and velocity in the nanowires are determined using the elastic constants for different diameters of the nanowires. Where possible, the results are compared with the experiments. Finally, we have established the correlation between the size dependent thermal conductivity and the ultrasonic attenuation of the nanowires.

关键词： Ultrasonic Attenuation Nanowires Elastic Constants Thermal Relaxation Time Thermal Conductivity