Browsing by Author "Kumar, M."

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A Facile Strategy to Achieve High Piezoelectric Performance in Electrospun Poly(Vinylidene Fluoride) Non-woven Nanofabrics
(Korean Institute of Electrical and Electronic Material Engineers, 2024) Khalifa, M.; Kumar, M.; Subramanian, G.; Anandhan, S.
Poly(vinylidene fluoride) (PVDF) with its piezoelectric characteristics holds the potential to be the promising candidate in microdevices, sensors and actuators. In this study, a facile strategy was adopted to augment the electroactive β-phase of electrospun PVDF non-woven nanofabric. Electrospun PVDF non-woven fabric was mechanically stretched at different strain rates. SEM images revealed that upon stretching the non-woven fabric, the fibers tend to orient along the stretching direction. The fibers from the necked region were characterized to understand effect of stretching on the polymorphism, crystallinity and piezoelectric performance. The β-phase content of PVDF increased upon increasing the strain rate, while the degree of crystallinity decreased slightly. The highest β-phase content of 79% was achieved for electrospun PVDF non-woven fabric stretched at 10 mm/min. Further, the piezoelectric performance of the stretched nanofabric was evaluated to assess its electroactive characteristics. The piezoelectric performance of electrospun PVDF fabric was studied by imparting the pressure/load by one-finger tapping, hand pressure and dropping weight. The highest output voltage and current of 8.4 V and 249 nA, respectively were obtained from the electrospun PVDF non-woven stretched at 10 mm/min, which is almost 8 times higher than that of the unstretched PVDF non-woven. Given the flexibility, lightweight with good piezoelectric performance these electrospun PVDF non-woven fabrics could be a potential material for energy harvesting and self-powered nano-electronic devices. Graphical Abstract: (Figure presented.) © The Korean Institute of Electrical and Electronic Material Engineers 2023.
A Simple Primary Key Algorithm Based Shade Dispersion Method for Maximizing PV Power Generation under Partial Shading Conditions
(Institute of Electrical and Electronics Engineers Inc., 2024) Koothu Kesavan, P.K.; Karthikeyan, A.; Kumar, M.; Mandal, S.
The output power generation of a photovoltaic (PV) array reduces under partial shading, resulting in multiple local maxima in the PV characteristics and inaccurate tracking of the global maximum power point (GMPP). Various interconnection schemes are available to reduce power losses under partial shading. In this study, a primary key algorithm is proposed for distributing shading across an array. This method is suitable for any n×n PV array configuration and involves fewer calculations and variables, leading to reduced computational complexity. The power generations of a 9×9 PV array under four different shading conditions were compared with the configurations of: total cross-tied (TCT) and Su Du Ku, physical relocation and fixed column position of modules with fixed electrical connection (PRFCPM-FEC), and magic square (MS) and improved-odd-even-prime (IOEP). The advantage of the proposed method is that once the primary key elements are obtained, the remaining array elements are numbered in a simpler manner. The results obtained using the proposed arrangement show that the power is enhanced with reference to the TCT and is comparable to the Su Do Ku, PRFCPM-FEC, MS, and IOEP reconfigurations. © 2024 China Machinery Industry Information Institute.
An experimental study on material removal rate and surface roughness of Cu-Al-Mn ternary shape memory alloys using CNC end milling
(Institute of Physics, 2024) Praveen, N.; Siddeshkumar, N.G.; Prasad, C.D.; Kumar, M.; Kumar, S.; Hrishikesh, H.; Saravana Bavan, S.; Prabhu B, S.R.; Kumar, P.
This study investigates the impact of Computer Numerical Control (CNC) milling parameters on Cu-Al-Mn SMAs (Shape memory alloys) to evaluate the effects on Surface Roughness (SR) and Material Removal Rate (MRR). The primary variables examined comprise of cutting speed, feed rate, and depth of cut. Results indicate that the Shape Memory Effect (SME) is higher in Copper Aluminium Manganese (CAM 3) compared to CAM 1 and CAM 2, with SME improving from 3.5% to 5.5% as Manganese (Mn) content increases, reflecting an increase in dislocations within the metal’s crystal structure. Surface roughness increases with higher feed rates and depths of cut but decreases with increased cutting speed. MRR shows a positive correlation with feed rate, depth of cut, and cutting speed, though it decreases with higher Mn content. Notably, CAM 3 exhibits lower MRR compared to CAM 1 and CAM 2. Scanning Electron Microscopy (SEM) reveals that at lower feed rates (0.10 mm rev−1), the surface is smooth and free of ridges or feed marks, while at higher feed rates (0.18 mm rev−1), noticeable surface imperfections and plastic deformation occur. The addition of Mn improves surface smoothness and machinability, it also affects MRR. Further suggesting that Mn content and milling parameters significantly influence both the mechanical properties and machinability of Cu-Al-Mn SMAs respectively. © 2024 The Author(s). Published by IOP Publishing Ltd.
Capturing important information from an audio conversation
(2017) Roshan, S.; Vinay, Kumar, S.; Kumar, M.
A conversation between people can involve exchange of important information. Often in an ongoing conversation, someone has to manually keep on taking notes of important points. This is a tedious process and can involve errors. In today's era of technology, there is a need for an automated process for extracting important information from a conversation, with minimal manual efforts. In this paper, we propose methods of transcribing a conversation between two people. We will consider two major modes of conversation-when the conversation is happening over a phone call, and when the conversation is happening in person. In addition to transcribing a conversation, this paper will also suggest ways to extract important parts of a conversation. We will extract important information from a conversation, using three different approaches-noun phrase extraction, named entity extraction and open information extraction method. Since current mobile operating systems provide limited support for transcribing a phone call, we will suggest ways of transcribing a call, and extracting important information from it. � 2017 IEEE.
Capturing important information from an audio conversation
(Institute of Electrical and Electronics Engineers Inc., 2017) Roshan, S.; Vinay Kumar, S.; Kumar, M.
A conversation between people can involve exchange of important information. Often in an ongoing conversation, someone has to manually keep on taking notes of important points. This is a tedious process and can involve errors. In today's era of technology, there is a need for an automated process for extracting important information from a conversation, with minimal manual efforts. In this paper, we propose methods of transcribing a conversation between two people. We will consider two major modes of conversation-when the conversation is happening over a phone call, and when the conversation is happening in person. In addition to transcribing a conversation, this paper will also suggest ways to extract important parts of a conversation. We will extract important information from a conversation, using three different approaches-noun phrase extraction, named entity extraction and open information extraction method. Since current mobile operating systems provide limited support for transcribing a phone call, we will suggest ways of transcribing a call, and extracting important information from it. Â© 2017 IEEE.
Comparison of plastic collapse moment for different angled non-circular pipe bends under bending moments and internal pressure
(Springer Science and Business Media Deutschland GmbH, 2024) Kumar, M.; Singh, M.; Kumar, A.; kumar, A.; Kamble, D.L.
Pipe bends are a crucial component of the pipeline industry because they experience more stresses and deformations than straight pipes of the same dimensions and material properties under the same loading conditions. For a reliable and safe piping system, the plastic collapse moment of pipe bends must be estimated accurately. The current study aims to find which bending mode is critical to failure for pipe bends; for that, the collapse moment under in-plane closing (IPC), in-plane opening (IPO) and out-of-plane (OP) bending moments are compared using finite element (FE) analysis. The comparison accounts for various values of internal pressure, bend angle and initial geometric imperfection. The FE analysis considers elastic-perfectly plastic (EPP) and strain-hardening (SH) material models. Twice-elastic-slope (TES) method is implemented to evaluate plastic collapse moment for all considered cases. The comparison of collapse moment shows that under unpressurized conditions, pipe bends are critical to IPC bending moment. However, it is difficult to identify which bending mode is critical under pressurized conditions. Therefore, plastic collapse moment under all three bending modes should be known and for that plastic collapse moment equations under all bending modes should be proposed. © The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering 2024.
Concatenated Error Control Coding Applied to WDM Optical Communication Systems for Performance Enhancement
(International Academy of Microwave and Optical Technology (IAMOT), 2007) Mruthyunjaya, H.S.; Umesh, G.; Kumar, M.
Long haul incoherent optical multichannel communication systems employing N * N Wavelength Division Multiplexing (WDM) in presence of Stimulated Raman Scattering (SRS) and other receiver noises including channel and Amplified Spontaneous Emission (ASE) beat noises is analyzed. Concatenated error control coding techniques are employed to counter system degradation due to these limiting factors. It is shown that the Bit Error Rate (BER) of the order of 10-9 can be achieved for large values of N (=270) at link length of 200km without crossing SRS threshold of 1dB. Also power penalty due to multiplexer crosstalk effectively comes down from 5.5dB to 0.14dB for a 64 channel WDM system. © 2007 ISRAMT. All Rights Reserved.
Correction: Synthesis of BNiO3 Nanocomposites for Photocatalytic Hydrogen Production Applications (Journal of The Institution of Engineers (India): Series D, (2024), 10.1007/s40033-024-00725-5)
(Springer, 2025) Choudhary, R.K.; Kumaraswamy, G.N.; Baitha, R.; Kumar, M.; Shekokar, S.R.; Kumar, A.; Hussain, M.H.; Kumar, P.
In this article the affiliation details for author Rajesh Baitha was incorrectly given as â€˜Department of Mechanical Engineering, Gaya College of Engineering, Gaya, India' but should have been â€˜Department of Mechanical Engineering, Government Engineering College, Nawada, Indiaâ€™. Â© The Institution of Engineers (India) 2025.
Determination of fracture toughness and fatigue crack growth rate using circumferentially cracked round bar specimens of Al2014T651
(2015) Neelakantha, V.L.; Jayaraju, T.; Naik, P.; Kumar, K, D.; Rajashekar, C.R.; Kumar, M.
Fracture toughness (KIC) and fatigue crack growth rate (FCGR) are the important material properties in fracture mechanics. ASTM-E399 and ASTM-E647 are the standards for determination of KIC and FCGR of metallic materials. These standards recommend the use of compact tension (CT) or single edge notched bend (SENB) test specimens. Literature review indicates that CT or SENB specimens are complex in nature, difficult to manufacture, require typical fixtures for loading during experimentation and the test procedures using CT or SENB are time consuming and cumbersome. An alternate specimen geometry which can overcome the above said drawbacks is needed by the industry which can be used as standard test specimen geometry. This research work explains use of circumferentially cracked round bar (CCRB) specimens of high strength Al2014T651 alloy for determination of KIC and FCGR.The pre-cracked round bar specimen was loaded in tensile in a universal testing machine and pulled till failure. Using suitable stress intensity factor equations the fracture toughness can be calculated. In case of crack growth test, the pre-cracked round bar specimen is allowed to rotate under fatigue load. The ratio of length of crack propagated to the number of cycles to failure was the crack growth rate. The SEM analysis of fractured surfaces was also done.The results are comparable with the values reported in the literature obtained by using standard test specimens. There are numerous advantages of using round bar specimen in KIC and FCGR tests. It is concluded that, the methodology of determination of fracture toughness and fatigue crack growth rate using CCRB specimens is relatively simple, reliable, fast and economical. CCRB specimen may be recommended as a standard test specimen for fracture toughness as well as crack growth tests. 2015 Elsevier Masson SAS. All rights reserved.
Determination of fracture toughness and fatigue crack growth rate using circumferentially cracked round bar specimens of Al2014T651
(Elsevier Masson SAS infos@masson.fr 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2015) Neelakantha, V.L.; Jayaraju, T.; Naik, P.; Kumar K, D.; Rajashekhar, C.R.; Kumar, M.
Fracture toughness (KIC) and fatigue crack growth rate (FCGR) are the important material properties in fracture mechanics. ASTM-E399 and ASTM-E647 are the standards for determination of KIC and FCGR of metallic materials. These standards recommend the use of compact tension (CT) or single edge notched bend (SENB) test specimens. Literature review indicates that CT or SENB specimens are complex in nature, difficult to manufacture, require typical fixtures for loading during experimentation and the test procedures using CT or SENB are time consuming and cumbersome. An alternate specimen geometry which can overcome the above said drawbacks is needed by the industry which can be used as standard test specimen geometry. This research work explains use of circumferentially cracked round bar (CCRB) specimens of high strength Al2014T651 alloy for determination of KIC and FCGR.The pre-cracked round bar specimen was loaded in tensile in a universal testing machine and pulled till failure. Using suitable stress intensity factor equations the fracture toughness can be calculated. In case of crack growth test, the pre-cracked round bar specimen is allowed to rotate under fatigue load. The ratio of length of crack propagated to the number of cycles to failure was the crack growth rate. The SEM analysis of fractured surfaces was also done.The results are comparable with the values reported in the literature obtained by using standard test specimens. There are numerous advantages of using round bar specimen in KIC and FCGR tests. It is concluded that, the methodology of determination of fracture toughness and fatigue crack growth rate using CCRB specimens is relatively simple, reliable, fast and economical. CCRB specimen may be recommended as a standard test specimen for fracture toughness as well as crack growth tests. © 2015 Elsevier Masson SAS. All rights reserved.
Development of new improved plastic collapse moment equations of pressurized different angled pipe bends under bending moments
(SAGE Publications Ltd, 2024) Kumar, M.; Kumar, A.; Kumar, A.; kumar, A.; Kamble, D.
In a piping system, pipe bends are more flexible than straight pipes because of their curved geometry, supplemented by higher stress and strain concentration, leading to one of the crucial components in piping industries. Therefore, safe design of pipe bends is essential for smooth running of the piping system, and plastic collapse moment is one of its criteria. This paper utilizes three-dimensional finite element analyses to model empirical solutions for the plastic collapse moment for different angled pipe bends subjected to combined pressure and in-plane closing, in-plane opening, and out-of-plane bending moments. Plastic collapse moments for 30∘ to 180∘ pipe bends are determined for elastic perfectly plastic and strain hardening materials, employing large geometry change option and internal pressure effect. It is observed from results that pressure effect is more prominent in thinner pipe bends of larger bend angle under all bending cases. For in-plane opening and out-of-plane bending moments, collapse moment increases and then decreases with increase in pressure intensity for all sizes of pipe bend. However, for in-plane opening bending moment, collapse moments keep on decreasing for thicker ((Formula presented.) = 11.33) pipe bends. Finally, the study presents new improved plastic collapse moment solutions for different angled pipe bends under bending moment and internal pressure, derived from the finite element results of elastic perfectly plastic and strain hardening material models. © IMechE 2024.
Effect of binary zinc-magnesium oxides on polyphenylsulfone/cellulose acetate derivatives hollow fiber membranes for the decontamination of arsenic from drinking water
(Elsevier B.V., 2021) Kumar, M.; Isloor, A.M.; Todeti, S.R.; Nagaraja, H.S.; A.F., A.F.; Susanti, R.
Arsenic contamination is continuously threatening the safety of drinking water in many parts of the world. The consumption of chronic arsenic contaminated drinking water can cause serious health related issues. Therefore, the synthesis of novel materials is very much essential for the selective removal of arsenic from aqueous solution. In the present investigation, the effect of increased concentrations (0.6, 1.0 and 1.5 wt%) of binary zinc-magnesium oxide (ZnO-MgO) on cellulose acetate (CA)/polyphenylsulfone (PPSU) and cellulose acetate phthalate (CAP)/PPSU hollow fiber membranes for arsenic removal was performed. As used ZnO-MgO was characterized by using x-ray diffraction (XRD), transmission electron microscopy (TEM) and particle size distribution. Fabricated hollow fiber membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, fourier transform infrared (FTIR), x-ray photoelectron spectrophotometer (XPS), thermogravimetric analysis (TGA) and antifouling studies. The results revealed that, there is significant enhancement in the overall performance of the ZnO-MgO containedmembranes. An enhancement of arsenic removal properties was demonstrated from 0.6 wt% of ZnO-MgO in CAP/PPSU (ZMCAP-0.6) membrane was 81.31% with the retention permeability of 69.58 L/m2h bar respectively. Similarly, 1 wt% of ZnO-MgO in CA/PPSU (ZMCA-1) was found to be 78.48% and 198.47 L/m2h bar respectively using 1 ppm laboratory prepared aqueous arsenic solution (pH 6.8 ± 0.2) at 1 bar transmembrane pressure. In addition, improved antifouling properties was noticed with an increased flux recovery ratio and enhanced thermal stability from ZnO-MgO contained membranes. Therefore, as fabricated ZnO-MgO contained membranes provided enhanced arsenic removal tendency without compromising the retention permeability. © 2020
Efficient storage and transmission of digital fundus images with patient information using reversible watermarking technique and error control codes
(2009) Nayak, J.; Subbanna Bhat, P.S.; Acharya, R.; Kumar, M.
Handling of patient records is increasing overhead costs for most of the hospitals in this digital age. In most hospitals and health care centers, the patient text information and corresponding medical images are stored separately as different files. There is a possibility of mishandling the text file containing patient history. We are proposing a novel method for the compact storage and transmission of patient information with the medical images. In this technique, we are using a reversible watermarking technique to hide the patient information within the retinal fundus image. There is a possibility that these medical images, which carry patient information, can get corrupted by the noise during the storage or transmission. The safe recovery of patient information is important in this situation. So, to recover the maximum amount of text information in the noisy environment, the encrypted patient information is coded with error control coding (ECC) techniques. The performance of three types of ECC for various levels of salt & pepper (S & P) noise is tabulated for a specific example. The proposed system is more reliable even in a noisy environment and saves memory. © 2008 Springer Science+Business Media, LLC.
Enhanced production of napthoquinone metabolite (shikonin) from cell suspension culture of Arnebia sp. and its up-scaling through bioreactor
(Springer Verlag, 2014) Gupta, K.; Garg, S.; Singh, J.; Kumar, M.
Cell culture in shake flask and air-lift bioreactor was carried out to exploit the potential of Arnebia sp. for napthoquinone metabolite production. Cell suspension cultures of Arnebia were established from friable callus in liquid MS medium supplemented with 6-benzylaminopurine (BAP) (10 ?M) and indole-3-butyric acid (IBA) (5 ?M). Growth kinetic studies were done by using settled cell volume and fresh/dry cell weight method. Suspension cultures were maintained by sub-culturing at 10 days interval. A two-stage culture system is employed using growth medium (GM) and modified M9 medium (production medium) for cell biomass and naphthoquinone pigment production, respectively. Results showed that cultivation of cells under dark conditions at room temperature (25 ± 2 °C) enhanced the cell biomass from 100 to 625 g l-1. The pigment production was also found to be increased in dark conditions at room temperature. Alkaline pH found to have positive effect on pigment yield. In case of M9 medium constituents, absence of Na2SO4 does not affect the pigment yield. The current approaches have the cumulative effect to meet an increased level of (25.5 ?g/ml) metabolite production in air-lift bioreactor. © 2013 The Author(s).
Exploring the biological activity and setting dynamics of a novel polydopamine-based root repair material
(Elsevier B.V., 2025) Rao, L.N.; Shetty, A.; Isloor, A.M.; Nayak, S.S.; Kumar, M.; Shetty K, J.; Venkatesh, M.
Background: Root perforation represents a significant complication in endodontics, compromising the structural integrity of the tooth. Effective repair are critical to mitigating the associated risks and preserving long-term dental function. Despite extensive research, the ideal repair material that fulfills all requisite biological and mechanical properties remains elusive. Methodology: This study introduces a novel polydopamine based repair material designed to address the limitations of existing materials. The material was characterized using field emission scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, zeta potential, and particle size analysis. The material's initial and final setting times were evaluated using a Gilmore needle apparatus. Biocompatibility was assessed via the MTT assay, while bioactivity was quantified through calcium ion release analysis. Comparative evaluations were conducted against ProRoot MTA, a commercially available standard in root repair. Results: The findings revealed no statistically significant differences in cytotoxicity (P > 0.05) between the experimental material and ProRoot MTA, affirming the biocompatibility of both. However, the experimental material demonstrated a significantly faster set (P < 0.001) than ProRoot MTA, a critical advantage in clinical applications. the inclusion of calcium chloride and bioactive glass enhanced calcium ion release, with the experimental material showing significantly higher levels at 7 days. Conclusion: The polydopamine-bioactive glass composite exhibited favorable biological activity, superior setting dynamics, and enhanced bioactivity, positioning it as a promising candidate for perforation repair. These results lay the groundwork for further research and potential clinical translation, offering a viable solution to a longstanding challenge in endodontics. © 2025 The Authors
Geomorphological behaviour of Sasihithlu, Mangalore coast, west coast of India
(2011) Nagaraj, G.; Karjagi, A.; Kumar, M.; Dwarakish, G.S.
Beach geomorphological studies have been carried out with help of conventional methods and remote sensing techniques. Conventional methods include beach profile surveys and beachwidth measurements whereas remote sensing techniques involved in utilization of satellite images, digitization and analyses. Beach profile surveys and beachwidth measurements are carried out at monthly intervals over a period of one year (September 2009 to September 2010) to understand dynamics of sediment along the coastal segment of 7km at Sasihithlu, north off Mangalore coastline. Six locations are selected based on their significant site characteristics along the coastal segment. It is observed erosion with steeper slopes during the monsoon and simultaneously deposition with flat and wider exposed slopes during the fair weather season. But the more drastic and dramatic changes are observed in the vicinity of Mulki-Pavanje rivermouth, since the rivers Mulky and Pavanje bring any kind of sediments irrespective of seasons. Because of this the profiles alter dramatically in the vicinity of rivermouth. It is estimated that the Sasihithlu beach has experienced a net loss of about 2515m 3/m, a net gain of about 3525m 3/m and hence a gain of about 1010m 3/m sediments in an annual cycle. Addition to conventional methods, remote sensing analysis is also carried out to detect the influence of rivers and their flow on rivermouth system in recent decades (1988-2009) with the help of satellite images and GIS tools. It is observed that the shifting tendency of rivermouth either south or north irrespective of seasons. However a detailed investigation on shoreline pattern showed a clear indication of shifting shoreline towards south. Therefore present study suggests to construct coastal protection structures on either side of the rivermouth, through that the damage to the property could be minimized. 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Geomorphological behaviour of Sasihithlu, Mangalore coast, west coast of India
(2011) Nagaraj, G.; Karjagi, A.; Kumar, M.; Dwarakish, G.S.
Beach geomorphological studies have been carried out with help of conventional methods and remote sensing techniques. Conventional methods include beach profile surveys and beachwidth measurements whereas remote sensing techniques involved in utilization of satellite images, digitization and analyses. Beach profile surveys and beachwidth measurements are carried out at monthly intervals over a period of one year (September 2009 to September 2010) to understand dynamics of sediment along the coastal segment of 7km at Sasihithlu, north off Mangalore coastline. Six locations are selected based on their significant site characteristics along the coastal segment. It is observed erosion with steeper slopes during the monsoon and simultaneously deposition with flat and wider exposed slopes during the fair weather season. But the more drastic and dramatic changes are observed in the vicinity of Mulki-Pavanje rivermouth, since the rivers Mulky and Pavanje bring any kind of sediments irrespective of seasons. Because of this the profiles alter dramatically in the vicinity of rivermouth. It is estimated that the Sasihithlu beach has experienced a net loss of about 2515m 3/m, a net gain of about 3525m 3/m and hence a gain of about 1010m 3/m sediments in an annual cycle. Addition to conventional methods, remote sensing analysis is also carried out to detect the influence of rivers and their flow on rivermouth system in recent decades (1988-2009) with the help of satellite images and GIS tools. It is observed that the shifting tendency of rivermouth either south or north irrespective of seasons. However a detailed investigation on shoreline pattern showed a clear indication of shifting shoreline towards south. Therefore present study suggests to construct coastal protection structures on either side of the rivermouth, through that the damage to the property could be minimized. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Group Attack Dingo Optimizer for enhancing speech recognition in noisy environments
(Springer Science and Business Media Deutschland GmbH, 2023) Kumar, M.; Kumar, K.G.; Deepak, K.T.; Narasimhadhan, A.V.
The speech recognition system has become a vital technology enabling seamless human–computer interactions, even in noisy public places. To enhance the performance of various applications like machine translation, natural language processing, spoken language understanding, and text generation, speech enhancement (SE) techniques play a crucial role. In this study, we introduce a novel approach termed (GA-DOA) for optimizing speech enhancement tasks. Our method combines an improved short-time Fourier transform (STFT) and an optimized deep U-Net, with GA-DOA used to fine-tune the parameters. Additionally, feature extraction employs Mel-frequency cepstral coefficients (MFCCs), spectral features, and one-dimensional convolutional neural networks (1D-CNN). To select the most effective features, we employ GA-DOA-assisted feature selection. These optimized features are then fed into our proposed hybrid model for speech recognition (HMSR), which integrates bidirectional long short-term memory (BiLSTM) with the gated recurrent unit (GRU). Experimental results reveal that our proposed model achieves superior recognition rates and significantly lowers the word error rate (WER), thereby demonstrating enhanced system performance, even in noisy environments. © 2023, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
Hydrophilic nano-aluminum oxide containing polyphenylsulfone hollow fiber membranes for the extraction of arsenic (As-V) from drinking water
(Elsevier Ltd, 2021) Kumar, M.; Isloor, A.M.; Todeti, S.R.; A.F., A.F.; Farnood, R.
In the present work, hollow fiber ultrafiltration membranes were fabricated by incorporating intensified dosages of nano?aluminum oxide (nano-Al2O3; 0.6 wt%, 1.0 wt% and 1.5 wt%) into cellulose acetate (CA)/polyphenylsulfone (PPSU) and cellulose acetate phthalate (CAP)/PPSU by non-solvent induced phase separation (NIPS) process. The topological structures and the morphologies were investigated using atomic force microscope (AFM) and scanning electron microscope (SEM). The crystalline and morphological structures of the nano-Al2O3 were investigated using X-ray diffraction (XRD) and transmission electron microscope (TEM) respectively. Fourier transform infra-red spectroscope (FTIR) and x-ray photoelectron spectroscopy (XPS) analysis have been carried out to validate the dosages of nano-Al2O3, CA and CAP on PPSU membranes. The membrane's surface charge measurement of 1.5 wt% of nano-Al2O3 in CA/PPSU (ALCA-1.5) was scrutinized by zeta potential analysis. Membranes removed more arsenate oxide as the removal rate from membranes ALCA-1.5 and 1.0 wt% of nano-Al2O3 in CA/PPSU (ALCA-1) was 98.67% and 94.89% with retention permeabilities of 88.41 L/m2h bar and 53.53 L/m2h bar respectively from laboratory prepared 1 ppm of aqueous arsenic solution with pH in the range 6.8 ± 0.2 at 1 bar transmembrane pressure. In addition, membrane's antifouling analysis was performed using laboratory prepared 0.8 g/L (Bovine Serum Albumin) BSA as standard protein solution. © 2021 Elsevier Ltd
Hydrophilic polydopamine/polyvinylpyrrolidone blended polyphenylsulfone hollow fiber membranes for the removal of arsenic-V from water
(Elsevier Ltd, 2023) Kumar, M.; Isloor, A.M.; Nayak, M.C.S.; Todeti, S.R.; Padaki, M.; A.F., A.F.
The demand for fresh drinking water is sky rocketing with the world's increasing population, urbanization and various industrial growth. However, toxic heavy metals and metalloids like arsenic is contaminating the drinking water. Arsenic is poisonous, carcinogenic and mutagenic for millions of population. We hereby proposing in-house fabricated novel hollow fiber membranes using polyphenylsulfone (PPSU) and pore-forming agent polyvinylpyrrolidone (PVP) along with increased concentrations of bio-inspired hydrophilic additive polydopamine (PDA) for removal of arsenic-V from the drinking water. The crystallinity of PDA was interpreted by X-ray diffraction. The morphology, topology and membrane surface chemistry of fabricated membranes were evaluated by scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. The results indicated that, for the PDA-contained membranes overall performance was increased in terms of membrane hydrophilic characteristics and rejection efficacy. A 3 wt% of PDA in PPSU/PVP (PDA-3) executed enhanced arsenate (As-V) removal as high as 87.15% with flux of 31.80 L/m2h, which was higher than the neat membrane (PDA-0) as 67.70% with flux of 15.07 L/m2h for 5 mL/L arsenic-V aqueous solution at 0.2 MPa transmembrane pressure. Improved antifouling properties were observed from PDA-contained hollow fiber membranes, as evidenced by the improved flux recovery ratio and superior thermal stability. The mechanical properties (tensile strength) of pristine and PDA-contained membranes was also investigated. © 2023