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Experimental study of 3D printed carbon fibre sandwich structures for lightweight applications

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Defence Technology（防务技术） 2024年第6期36卷 71-77页

作者： Solaiprakash Vellaisamy Raguraman Munusamy Department of Mechanical Engineering Indian Institute of Information Technology Design and ManufacturingKancheepuramChennai600127India School of Interdisciplinary Design and Innovation Indian Institute of Information Technology Design and ManufacturingKancheepuramChennai600127India

Honeycomb sandwich structures are widely used in lightweight ***,these structures are subjected to extreme loading conditions,leading to potential failures due to delamination and debonding between the face sheet and the honeycomb ***,the present study is focused on the mechanical characterisation of honeycomb sandwich structures fabricated using advanced 3D printing *** continuous carbon fibres and ONYX-FR matrix materials have been used as raw materials for 3D printing of the specimens needed for various mechanical characterization testing;ONYX-FR is a commercial trade name for flame retardant short carbon fibre filled nylon filaments,used as a reinforcing material in Morkforged 3D *** and flatwise compression tests have been conducted for different configurations of honeycomb sandwich structures,fabricated by varying the face sheet thickness and core cell size,while keeping the core cell thickness and core height *** on these tests,the proposed structure with face sheet thickness of 3.2 mm and a core cell size of 12.7 mm exhibited the highest energy absorption and prevented delamination and debonding ***,3D printing technology can also be considered as an alternative method for sandwich structure ***,detailed parametric studies still need to be conducted to meet various other structural integrity criteria related to the lightweight applications.

关键词： 3D printed composite Honeycomb sandwich Edgewise compression Flatwise compression Lightweight

Temporal and spatial compliance behaviour of pedestrians under the influence of time pressure at signalized intersections:A pedestrian simulator study

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第1期11卷 55-68页

作者： Apurwa Dhoke Pushpa Choudhary Department of Civil Engineering Indian Institute of Technology RoorkeeRoorkee 247667India

Pedestrian safety is at high stakes due to the non-compliance practices of pedestrians at signalized ***,when pedestrians are hurrying,they deliberately engage in such unsafe ***,the purpose of this study was to understand how time pressure(i.e.,feeling of hurry or saving time)affected pedestrians'decisions to follow traffic rules at signalized *** achieve the study objectives,a pedestrian simulator setup was used to collect the crossing behaviour of forty participants at a four-legged signalized ***-compliance,one of the riskiest pedestrian behaviours,was examined with respect to three different forms,comprising dangerous temporal non-compliance(D-TNC),non-dangerous temporal non-compliance(ND-TNC),and spatial non-compliance(SNC)behaviour under two distinct conditions:baseline(i.e.,no time pressure)and time pressure *** effects of demographics,usual walking features,and time pressure on D-TNC and ND-TNC were investigated using a multinomial regression model,while SNC behaviour was investigated using a binary regression *** was interesting to note that the majority of the factors related to pedestrians’usual walking behaviour had an impact on all kinds of non-compliance ***,the results also showcased that time pressure had a contrasting impact on D-TNC and ND-TNC behaviour whereas SNC behaviour increased under time ***,the varying impacts of D-TNC,ND-TNC,and SNC were also reflected in the occurrence of the crashes,which were probably triggered by discrepancies in the influence of time pressure on non-compliance *** findings highlight the need for technical solutions,educational outreach,and efficient enforcement practices to reduce pedestrians'non-compliant behaviour.

关键词： Signalized intersection Time pressure Pedestrians Temporal compliance Spatial compliance Pedestrian simulator

Comparative analysis of single-crater parameters in ultrasonic-assisted and unassisted micro-EDM of Ti6Al4V using discharge plasma imaging

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Nanotechnology and Precision Engineering 2024年第2期7卷 11-24页

作者： Sohaib Raza Chandrakant Nirala Department of Mechanical Engineering Indian Institute of Technology RoparPunjab 140001India

Ultrasonic-assisted micro-electro-discharge machining(EDM)has the potential to enhance processing responses such as material removal rate(MRR)and surface *** understand the reasons for this enhancement,the physical mechanisms responsible for the individual discharges and the craters that they form need to be *** work examines features of craters formed by single discharges at various parameter values in both conventional and ultrasonic-assistedEDM of ***-speed imaging of the plasma channel is performed,and data on the individual discharges are captured in real-time.A 2D axisymmetric model using finite element software is established to model crater *** the basis of simulation and experimental results,a comparative study is then carried out to examine the effects of ultrasonic vibrational assistance on crater *** every set ofEDM parameters,the crater diameter and depth from a single discharge are found to be higher in ultrasonic-assistedEDM than in conventional*** improved crater geometry and the reduced bulge formation at the crater edges are attributed to the increased melt pool velocity and temperature predicted by the model.

关键词： Ultrasonic vibration Discharge crater Plasma diameter Single discharge

Snow and regolith albedo variations using CRISM data at McMurdo crater,Mars

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Earth and Planetary Physics 2024年第2期8卷 338-355页

作者： Sehajpal Singh Deepak Singh Centre of Studies in Resources Engineering Indian Institute of Technology BombayMumbaiIndia

The cryosphere component provides the most reliable and insightful indications of any planet’s climate *** data from the Compact Reconnaissance Imaging Spectrometer for Mars(CRISM),we develop a novel approach to determining the broadband Visible and Near Infrared(VNIR)albedo of the Martian *** study focuses on albedo changes in the McMurdo crater,part of Mars’s south polar layer *** compare seasonal and interannual variations of the McMurdo surface albedo before,during,and after the Global Dust Storm(GDS)of Martian Year(MY)*** the seasons progressed from spring to summer,the mean albedo in MY 32 and 34 plunged by over 40%,by about 35%in MY 33,and by slightly more than 30%in MY *** interannually,however,mean albedo values within both seasons(spring and summer)exhibited no significant differences in those same ***,interannual albedo difference maps reveal albedo variation of more than±0.3 in certain regions of the *** only snow-covered pixels,interannual albedo differences suggest that Mars dust had a pervasive impact on Mars’s *** in maximum and minimum albedo values as high as 0.5 were observed,depending upon differences in the dust levels in Martian snow/*** maximum and the minimum snow albedo values were lowest in MY 34,indicating the effect of the intense dust storm event that *** average snow albedo decreased from 0.45 in MY 32 to 0.40 in MY 33 and to 0.33 in MY 34,and then rose back to 0.40 in MY *** trajectory suggests a temporary deposition of dust,partially reversed after the GDS by self-cleaning mechanisms(local aeolian process and CO_(2)sublimation/deposition cycle).

关键词： Mars Martian ice albedo dust storm Mars surface Martian climate

Evaluation of red soil-bentonite mixtures for compacted clay liners

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 697-710页

作者： A.S.Devapriya T.Thyagaraj Department of Civil Engineering Indian Institute of Technology MadrasChennai600036India

Compacted clay liners are an integral part of the waste landfills,which are provided to contain the leachate within the landfills and protect the surrounding ***,locally available natural soils are used for the construction of compacted clay liners if they satisfy the design ***,not all soils in their natural state satisfy all the design criteria for the liner ***,there is a definite need to modify the locally available natural soils by blending with bentonite to meet the required design criteria for the *** view of this,the present study evaluates the suitability of an indian red soil enhanced with bentonite as a liner *** achieve this,a series of experiments were carried out using locally available red soil and ***,the suitability of the red soil was evaluated as a liner *** experimental results showed that the red soil met all the selection criteria stipulated by the Environmental Protection Agencies(EPAs)for the liners except the hydraulic conductivity ***,the red soil was mixed with bentonite contents of 10%,20%and 30%,and the red soil-bentonite mixtures were evaluated for their suitability for liners in their compacted ***,as the liners in the arid and semi-arid regions are subjected to moisture variations due to seasonal moisture fluctuations and other factors,the red soil-bentonite mixtures were subjected to wetdry cycles,and their suitability was evaluated after wet-dry *** experimental results revealed that all the red soil-bentonite mixtures met the stipulated EPA criteria for the liners in the as-compacted ***,the red soil-bentonite mixtures with 20%and 30%bentonite contents only satisfied the hydraulic conductivity requirement even after wet-dry *** experimental findings were supplemented with the microstructural insights captured through digital camera images,scanning electron microscopy(SEM),and mercury intrusion porosimetry(M

关键词： Compacted clay lines Hydraulic conductivity Wet-dry cycles Microstructure

Simultaneous inversion of permeability,skin and boundary from pressure transient test data in three-dimensional single well reservoir model

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Petroleum Research 2024年第2期9卷 265-272页

作者： Arvind Kumar Lin Liang Keka Ojha Schlumberger India indian Institute of Technology(ISM) DhanbadIndia

This study presents a novel approach for simultaneous inversion of the key reservoir parameters like horizontal permeability,vertical permeability,skin,and boundary distances for spatial distribution across the grid cells in a 3D single well reservoir model(SWRM).These parameters are first estimated from the standard pressure transient analysis of well test pressure and rate data,which also act as a priori for the inverse problem.A field-worthy layer cake geological model is prepared based on the prior information obtained from pressure transient analysis,followed by a sequential flow simulation of field well test *** simulation results provide the model pressure versus rate data as the synthetic data for this study.A cost function is defined incorporating the well test pressure data and model pressure data,which would determine the *** inversion process is to optimize the spatial distribution of reservoir parameters to minimize the difference between the measured pressure transient data and the modelled one,which is obtained from the multiphase fluid flow simulator that solves the implicit black-oil fluid-flow diffusivity equations at every step.A Gauss-Newton(GN)inversion scheme is used for the *** reliability of inversion results depends on the accuracy of priori reservoir parameters fed to the solver,which can be refined if required through uncertainty parameter optimization(UPO).This approach helps to obtain a faster and reliable update of reservoir parameters in a layer cake homogeneous geomodel,hereby introducing the required *** increases the confidence and reliability of a geomodel,which is further used for various production prediction strategies.

关键词： Well test Pressure transient Inversion Permeability Boundary

Numerical simulation of square shaped particle sedimentation

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Particuology 2024年第1期84卷 107-116页

作者： Govind Sharma Bahni Ray Department of Mechanical Engineering Indian Institute of Technology DelhiHauz KhasNew Delhi110016India

Direct numerical simulations of square particle sedimentation in a viscous incompressible fluid are presented to examine the effects of sharp edges for various particle-to-fluid density ratios and different initial inclination *** settling process exhibits four different motion regimes;non-oscillatory,non-uniform centered oscillatory,uniform off-centered oscillatory,and non-uniform off-centered(irregular)*** moderate density ratios,we observe that the rotational motion of settling square particle varies with the initial inclination *** employ Dynamic Time Warping and Fast Fourier Transform to analyze translational and angular *** systems are described using phase-space plots,and a chaotic phenomenon is observed at a higher density ratio.

关键词： Sedimentation Distributed Lagrangian multiplier Phase synchronization Oscillations

Design and evaluation of Swift routing for payment channel network

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BLOCKCHAIN-RESEARCH AND APPLICATIONS 2024年第2期5卷 62-72页

作者： Sharma, Neeraj Kapoor, Kalpesh Anirudh, V. indian Inst Technol Guwahati Dept Comp Sci & Engn Gauhati 781039 Assam India indian Inst Technol Guwahati Dept Math Gauhati 781039 Assam India

Payment Channel Networks (PCNs) are a promising alternative to improve the scalability of a blockchain network. A PCN employs off-chain micropayment channels that do not need a global block confirmation procedure, thereby sacrificing the ability to confirm transactions instantaneously. PCN uses a routing algorithm to identify a path between two users who do not have a direct channel between them to settle a transaction. The performance of most of the existing centralized path-finding algorithms does not scale with network size. The rapid growth of Bitcoin PCN necessitates considering distributed algorithms. However, the existing decentralized algorithms suffer from resource underutilization. We present a decentralized routing algorithm, Swift, focusing on fee optimization. The concept of a secret path is used to reduce the path length between a sender and a receiver to optimize the fees. Furthermore, we reduce a network structure into combinations of cycles to theoretically study fee optimization with changes in cloud size. The secret path also helps in edge load sharing, which results in an improvement of throughput. Swift routing achieves up to 21% and 63% in fee and throughput optimization, respectively. The results from the simulations follow the trends identified in the theoretical analysis.

关键词： Blockchain Payment channel networks Bitcoin Lightning network Routing protocols Layer 2 protocols

Molecular Engineering of Naphthalimide Methylcyclohexane Luminogen:Unraveling J^(*)-Aggregation Pattern and Sensing Melamine in Aqueous Media

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CCS Chemistry 2024年第4期6卷 923-931页

作者： Kavita Narang Parameswar Krishnan Iyer Department of Chemistry Indian Institute of Technology GuwahatiGuwahati 781039Assam Centre for Nanotechnology Indian Institute of Technology GuwahatiGuwahati 781039Assam

Naphthalimide methylcyclohexane(NMICY)luminogen that features molecular conformation-directed aggregation-induced emission was prepared,and its pure equatorial conformer was isolated and wellcharacterized via various techniques,including single-crystal X-ray diffraction(SC-XRD)*** NMICY,the methyl cyclohexane substituent adapted the most stable chair conformation,preventing intermolecularπ-πinteractions among the naphthalimide *** analysis of the self-assembly behavior indicated that an uncommon J^(*)-aggregation pattern was predominant for NMICY that exhibited∼450 nm emission in crystal as well as in the aggregated state[λmax=455 nm,фPL=23.22%,fw=99.9%in water or water-dimethylformamide mixture].NMICY self-assembled into cube-shaped 2D-nanoarchitecture as characterized by fieldemission scanning electron microscopy,atomic force microscopy,and dynamic light scattering(Zavg=143 nm,∼20 nm height)studies while also displaying unique optical properties in the aggregated *** supramolecular self-assembly and aggregated state structure-property relationship in aqueous media of NMICY were optimized,and a facile strategy for the detection of melamine in milk and an aqueous solution of milk powder is reported with a limit of detection value of 0.184 ppm(milk)and 0.101 ppm(milk powder),achieved via the rare acceptor-excited photoinduced electron transfer ***,a smartphone-based,portable,and uncomplicated sensing platform was developed that simplifies the melamine detection process.

关键词： conformational isomers J^(*)-aggregation aggregation-induced emission supramolecular assembly melamine detection acceptor-excited photoinduced electron transfer mechanism