Finite element analysis for laterally loaded piles in sloping ground

Sawant, Vishwas A.,Shukla, Sanjay Kumar Techno-Press 2012 Coupled systems mechanics Vol.1 No.1

The available analytical methods of analysis for laterally loaded piles in level ground cannot be directly applied to such piles in sloping ground. With the commercially available software, the simulation of the appropriate field condition is a challenging task, and the results are subjective. Therefore, it becomes essential to understand the process of development of a user-framed numerical formulation, which may be used easily as per the specific site conditions without depending on other indirect methods of analysis as well as on the software. In the present study, a detailed three-dimensional finite element formulation is presented for the analysis of laterally loaded piles in sloping ground developing the 18 node triangular prism elements. An application of the numerical formulation has been illustrated for the pile located at the crest of the slope and for the pile located at some edge distance from the crest. The specific examples show that at any given depth, the displacement and bending moment increase with an increase in slope of the ground, whereas they decrease with increasing edge distance.

Binder-free production of 3D N-doped porous carbon cubes for efficient Pb²⁺ removal through batch and fixed bed adsorption

Sawant, Sandesh Y.,Pawar, Radheshyam R.,Lee, Seung-Mok,Cho, Moo Hwan Elsevier 2017 JOURNAL OF CLEANER PRODUCTION Vol.168 No.-

<P><B>Abstract</B></P> <P>N-doped carbon cubes (NCCs) with varying nitrogen contents and different densities were fabricated using a simple and binder-free method that involved the curing of resorcinol-formaldehyde (RF) gel with different RF contents in the framework of a melamine sponge. In addition to the robust structure and nitrogen doping, the porosity of the NCCs could be tailored easily within the mesopores and ultra-micropores with a unique combination of macro, meso, and micropores. The prepared NCCs exhibited excellent uptake capacity, ranging from 32.1 to 39.3 mg/g Pb<SUP>2+</SUP> ions, owing to their high surface area (up to 675 m<SUP>2</SUP>/g) and nitrogen doping (max. 4.9 wt. %). The Pb<SUP>2+</SUP> adsorption property of NCC-10 was also compared with that of widely used commercial 3D carbon adsorbents. The weight and surface area-normalized Pb<SUP>2+</SUP> adsorption capacity of NCC-10 was found to be 3.7 and 6.6 times higher, respectively than the commercial activated carbon granules. The continuous mode model data fitted with experimental fixed-bed results well, and showed 8.95 mg/g loading capacity, proving that NCC-10 is an effective 3D adsorbent. The prepared NCCs could be used as a practical adsorbent for the removal of Pb<SUP>2+</SUP> ions because of their high adsorption capacity, easy regeneration, and exceptional stability maintained after longer reuse.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Binder-free method for the synthesis of 3D N-doped carbon cubes (NCCs) is reported. </LI> <LI> NCCs possess high porosity with unique combination of macro, meso, and micropores. </LI> <LI> N-doping and porosity can be tailored by varying resorcinol-formaldehyde content. </LI> <LI> NCCs showed higher Pb<SUP>2+</SUP> adsorption capacity than commercial 3D carbon adsorbents. </LI> <LI> A long-term and continuous Pb<SUP>2+</SUP> removal can be achieved with fixed bed adsorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Validation of 3-D Time Domain Particle-in-Cell Simulations for Cold Testing a <tex> $W$</tex>-Band Gyrotron Cavity

Sawant, Ashwini,Sung Gug Kim,Ming-Chieh Lin,Jung Ho Kim,Yongjun Hong,Joonho So,EunMi Choi IEEE 2014 IEEE transactions on plasma science Vol.42 No.12

<P>This paper evaluates the performance and reliability of a commercially available 3-D conformal finite-difference time-domain particle-in-cell (PIC) code, VSim, for cold test simulations of a gyrotron cavity. An interaction cavity for a 95-GHz gyrotron is simulated and optimized using the VSim PIC code to achieve TE6,2 mode excitation. The optimized cavity design is also studied and compared using the commercially available numerical code, CASCADE, and PIC code, MAGIC. A rigorous analysis of the simulation results obtained through VSim and MAGIC is performed using the CASCADE results as a reference. The performance of VSim is also compared with MAGIC based on its accuracy for calculating the resonant frequency and quality factor. Finally, the optimized cavity is fabricated and experimentally tested to measure the resonant frequency and the quality factor. The experimental results confirm the reliability and accuracy of the VSim cold cavity results.</P>

Can finite element and closed-form solutions for laterally loaded piles be identical?

Sawant, Vishwas A.,Shukla, Sanjay Kumar Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.43 No.2

The analysis of laterally loaded piles is generally carried out by idealizing the soil mass as Winkler springs, which is a crude approximation; however this approach gives reasonable results for many practical applications. For more precise analysis, the three- dimensional finite element analysis (FEA) is one of the best alternatives. The FEA uses the modulus of elasticity $E_s$ of soil, which can be determined in the laboratory by conducting suitable laboratory tests on undisturbed soil samples. Because of the different concepts and idealizations in these two approaches, the results are expected to vary significantly. In order to investigate this fact in detail, three-dimensional finite element analyses were carried out using different combinations of soil and pile characteristics. The FE results related to the pile deflections are compared with the closed-form solutions in which the modulus of subgrade reaction $k_s$ is evaluated using the well-known $k_s-E_s$ relationship. In view of the observed discrepancy between the FE results and the closed-form solutions, an improved relationship between the modulus of subgrade reaction and the elastic constants is proposed, so that the solutions from the closed-form equations and the FEA can be closer to each other.

Consolidated bioprocessing for production of polyhydroxyalkanotes from red algae <i>Gelidium amansii</i>

Sawant, Shailesh S.,Salunke, Bipinchandra K.,Kim, Beom Soo Elsevier 2018 International journal of biological macromolecules Vol.109 No.-

<P><B>Abstract</B></P> <P>Noncompetitive carbon sources such as algae are unconventional and promising raw material for sustainable biofuel production. The capability of one marine bacterium, <I>Saccharophagus degradans</I> 2–40 to degrade red seaweed <I>Gelidium amansii</I> for production of polyhydroxyalkanoates (PHA) was evaluated in this study. <I>S. degradans</I> can readily attach to algae, degrade algal carbohydrates, and utilize that material as main carbon source. Minimal media containing 8g/L <I>G. amansii</I> were used for the growth of <I>S. degradans</I>. The PHA content obtained was 17–27% of dry cell weight by pure culture of <I>S. degradans</I> and co-culture of <I>S. degradans</I> and <I>Bacillus cereus</I>, a contaminant found with <I>S. degradans</I> cultures. The PHA type was found to be poly(3-hydroxybutyrate) by gas chromatography and Fourier transform-infrared spectroscopy. This work demonstrates PHA production through consolidated bioprocessing of insoluble, untreated red algae by bacterial pure culture and co-culture.</P>

Carbothermal process-derived porous N-doped carbon for flexible energy storage: Influence of carbon surface area and conductivity

Sawant, Sandesh Y.,Cho, Moo Hwan,Kang, Misook,Han, Thi Hiep Elsevier 2019 Chemical engineering journal Vol.378 No.-

<P><B>Abstract</B></P> <P>A simple and scalable method to synthesize N-doped carbon (NC) based on a carbothermal reduction of a ZnO/carbon composite (ZCC) obtained from the decomposition of a zinc aniline nitrate complex is reported. The present study examined the effects of the structural characteristics of NC, such as electrical conductivity and surface area, more precisely without altering the other structural features of NC. A carbothermal reduction of ZCC allowed the production of hierarchically porous NC with a low sheet resistance of 0.432 kΩ □<SUP>−1</SUP> without any post-treatment with Zn nanorods as a valuable byproduct. The resulting NC exhibited ultra-high stability and rate capability, i.e., 100% stability after 200,000 cycles up to 300 A g<SUP>−1</SUP> with a high capacitance of 229 F g<SUP>−1</SUP> at 0.5 A g<SUP>−1</SUP>. The 288% increase in surface area with a similar % contribution from micro and mesopores and similar electrical conductivity increased the electrochemical charge storage capacity of NC by 266%. Similarly, NC materials possessing a similar surface area but a large difference in electrical conductivity resulted in a 1539% difference in charge storage capacity. Enhancement of both the surface area and electrical conductivity improved the capacitance of NC drastically to 4098% higher than the base product. A prototype flexible solid-state supercapacitor fabricated from the obtained NC delivered a very high areal capacitance of 363.6 mF cm<SUP>−2</SUP> (at 0.5 mA cm<SUP>−2</SUP>) with ultra-high stability (82%) even after 70,000 cycles (at 25 mA cm<SUP>−2</SUP>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped carbon (NC) with tunable properties is obtained using carbothermal method. </LI> <LI> Simultaneous production Zn nanotubes results in waste-free approach. </LI> <LI> Charge storage capacity of NC precisely studied against conductivity/surface area. </LI> <LI> High capacitance of 229 F/g with exceptional rate capability is observed for NC. </LI> <LI> Ultra-high stability is retained with flexible prototype solid state device. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Optimization of Operational Parameters of Site-specific Pesticide Spray Module for Young Pomegranate Orchards using RSM and RBFNN-PSO Techniques

Sawant C. P.,Jyoti Bikram,Gaikwad B. B.,Gaikwad Nilesh,Kumar Neeraj,Kumar Manoj 한국농업기계학회 2023 바이오시스템공학 Vol.48 No.2

Purpose The present study intended to optimize the spray control parameters of a microcontroller-based site-specifi c spray module under laboratory conditions using response surface methodology (RSM) and radial basis function neural networkparticle swarm optimization (RBFNN-PSO) and to evaluate the fi eld performance of the developed sprayer under optimal parameter conditions. Methods Microcontroller-based site-specifi c spray module was mounted on a test trolley and subjected to increasing levels of nozzle pressure (294, 343, and 392 kPa), speed (0.83, 1.11, and 1.39 m s −1 ), leaf orientation (− 40, 0, and 40°), number of nozzles (3, 4, and 5) and distance of application (0.35 and 0.5 m). The spray uniformity index (SUI) was calculated using the deposition of droplets on water-sensitive paper attached to both sides of the leaves. Results The increase in pressure reduced the volume and number median diameter of droplets while increasing droplet density and coverage. The ANOVA results revealed that pressure, speed, leaf orientations, pressure × speed, and pressure × leaf orientation had a significant effect ( p < 0.01) on SUI. The response curves generated from RSM favoured low pressure and speed for better SUI and predicted optimal parameters reasonably well. Contrary, RBFNN performed superiorly in the simulation of SUI over RSM and RBFNN-PSO-based optimal parameters were 294-kPa pressure, 0.83-m s −1 operational speed, − 40° leaf orientation, 3 nozzles, and 0.35-m distance of application for an SUI of 98.43% against an actual value of 99.18%. Under the field test, the tractor-operated smart sprayer demonstrated a field capacity of 0.84 ha h −1 and field efficiency of 60% along with 46.2% savings in operational cost (Rs. ha −1 ) as compared to battery operated knapsack sprayer and 72% savings of liquid chemical compared to the continuous application as with the case of conventional boom sprayer. Conclusions The site-specifi c spraying integrated with optimal conditions can reduce the chemical amount, input cost, and associated noxious impact on the environment besides improving the spray eff ectiveness.

A Laboratory Case Study of Efficient Polyhydoxyalkonates Production by Bacillus cereus, a Contaminant in Saccharophagus degradans ATCC 43961 in Minimal Sea Salt Media

Sawant, Shailesh S.,Salunke, Bipinchandra K.,Kim, Beom Soo Springer-Verlag 2014 Current microbiology Vol.69 No.6

<P>A contaminating bacterium growing along with the stock culture of Saccharophagus degradans ATCC 43961 (Sde 2-40) on marine agar plate was isolated and investigated for its ability to produce polyhydoxyalkonates (PHA). Preliminary screening by Sudan black B and Nile blue A staining indicated positive characteristic of the isolate to produce PHA. The isolate was able to grow and produce PHA in minimal sea salt medium broth. PHA quantification studies with gas chromatographic analyses of the dry cells derived from culture broths revealed accumulation of PHA in bacterial cells. PHA production started after 20 h and increased with cell growth and attained maximum values of 61 % of dry cell weight at 70 h of cultivation. After 70 h, a slight decrease in the level of PHA content was observed. The nature/type of PHA was found to be poly(3-hydroxybutyraye) by Fourier transform-infrared spectroscopy. Microbiological and 16S rRNA gene sequencing analyses suggested that the PHA producing bacterial isolate belongs to Bacillus genera and shows 100 % nucleotide sequence similarity with Bacillus cereus species in GenBank. This study is a first report for ability of Bacillus species to grow in marine sea salt media and produce PHA. The media used for the polymer production was novel in the context of the genus Bacillus and the production of PHA was three-fold higher than Sde 2-40 using same growth medium. This study shows that the contaminant bacteria once properly investigated can be used for advantageous characteristic of metabolites production in place of original cultures.</P>

Electrochemically active biofilm-assisted biogenic synthesis of an Ag-decorated ZnO@C core-shell ternary plasmonic photocatalyst with enhanced visible-photocatalytic activity

Sawant, Sandesh Y.,Kim, Jae Yeol,Han, Thi Hiep,Ansari, Sajid Ali,Cho, Moo Hwan CNRS 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.3

<P>Colonies of electrochemically active microorganisms called electroactive biofilms (EABs) have potential applications in bioenergy and chemical production. In the present study, an EAB was used as a reducing tool to synthesize Ag-decorated ZnO@C core-shell (Ag-ZnO@C) ternary plasmonic photocatalysts. A simple thermal decomposition route was followed to synthesize ZnO@C nanoparticles using a zinc aniline nitrate complex. The simultaneous adsorption of Ag<SUP>+</SUP> in the carbon shell of the ZnO@C particles during reduction using an EAB allowed the direct contact among Ag nanoparticles, the ZnO core, and the carbon shell. Therefore, the synthesized Ag-ZnO@C ternary photocatalysts showed a stronger interconnection among all the components, which allowed the easy transfer of photogenerated charges and provided enhanced charge carrier separation. Optical characterization showed that the enhanced absorption of visible light along with a decrease in the band gap and a red shift in the valence band maximum occurred due to the decoration of Ag-nanoparticles on ZnO@C. Ag-ZnO@C exhibited higher photocatalytic activity for the degradation of rhodamine blue and 4-nitrophenol under visible light irradiation than ZnO@C and bare ZnO without any significant loss after five successive cycles. Finally, a possible photocatalytic mechanism for charge transfer was proposed to explain the enhanced photocatalytic performance of the Ag-ZnO@C ternary photocatalyst. This study provides insights into the ternary photocatalytic system with a core-shell material and offers a biogenic route for the facile fabrication of Ag-ZnO@C photocatalysts.</P>

Metal-Free Carbon-Based Materials: Promising Electrocatalysts for Oxygen Reduction Reaction in Microbial Fuel Cells

Sawant, Sandesh Y.,Han, Thi Hiep,Cho, Moo Hwan MDPI AG 2017 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.18 No.1

<P>Microbial fuel cells (MFCs) are a promising green approach for wastewater treatment with the simultaneous advantage of energy production. Among the various limiting factors, the cathodic limitation, with respect to performance and cost, is one of the main obstacles to the practical applications of MFCs. Despite the high performance of platinum and other metal-based cathodes, their practical use is limited by their high cost, low stability, and environmental toxicity. Oxygen is the most favorable electron acceptor in the case of MFCs, which reduces to water through a complicated oxygen reduction reaction (ORR). Carbon-based ORR catalysts possessing high surface area and good electrical conductivity improve the ORR kinetics by lowering the cathodic overpotential. Recently, a range of carbon-based materials have attracted attention for their exceptional ORR catalytic activity and high stability. Doping the carbon texture with a heteroatom improved their ORR activity remarkably through the favorable adsorption of oxygen and weaker molecular bonding. This review provides better insight into ORR catalysis for MFCs and the properties, performance, and applicability of various metal-free carbon-based electrocatalysts in MFCs to find the most appropriate cathodic catalyst for the practical applications. The approaches for improvement, key challenges, and future opportunities in this field are also explored.</P>