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Structural-Nanomechanical Property Correlation of Shallow Water Shrimp （Pandalus platyceros） Exoskeleton at Elevated Temperature

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Journal of Bionic Engineering 2014年第3期11卷 360-370页

作者： Devendra Verma Vikas tomar School of Aeronautics and Astronautics Purdue University West Lafayette IN 47907 USA

This investigation reports the nanomechanical properties of shallow water shrimp exoskeleton at temperatures ranging from 30 ℃ to 80 ℃ measured using nanoindentation experiments. Scanning Electron Microscopy （SEM） measurements suggest that the shrimp exoskeleton has the Bouligand structure in its layers, a key characteristic of the crustaceans. The thickness of the layers and packing density are found to be different from that of lobsters and crabs reported earlier in the literature. Mechanical properties at high temperatures are determined using micro materials nanoindentation test set up combined with the hot stage. The properties measured during nanoindentation test are corrected for the creep and thermal drift during the experiments. The reduced modulus values are found to be around 28 GPa at 30 ℃ that reduces to approximately 24 GPa at 80 ℃. The hardness values also decrease from 1.6 GPa at 30 ℃ to around 1.2 GPa at 80 ℃. The indentation size effect is found to be absent at all temperatures. Creep mechanisms of polymers like materials and its temperature dependence are discussed to give more insight into the deformation mechanism.

关键词： fresh water shrimp nanomechanics temperature dependence creep mechanism

Moisture regime influence on soil carbon stock and carbon sequestration rates in semi-arid forests of the National Capital Region, India

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Journal of Forestry Research 2020年第6期31卷 2323-2332页

作者： Urvashi tomar Ratul Baishya Department of Botany University of DelhiDelhi 110007India

Understanding the dynamics of soil carbon is crucial for assessing the soil carbon storage and predicting the potential of mitigating carbon dioxide from the atmosphere to the biomass and *** present study evaluated variations of soil carbon stock in semi-arid forests in India under diff erent moisture *** organic carbon(SOC)and soil inorganic carbon(SIC)stocks were determined in diff erent moisture regimes ***,post-monsoon,winter and pre-monsoon seasons at 0–10 and>10–20 cm *** stock showed signifi cant variations under different moisture *** highest SOC stock was during winter(22.81 Mg C ha−1)and lowest during the monsoon season(2.34 Mg C ha−1)among all the ridge forests under *** and SIC stock under diff erent moisture regimes showed signifi cant negative correlation with soil moisture(p<0.05),as a sudden increase in soil moisture after rainfall results in an increase in carbon loss due to microbial decomposition of accumulated carbon during the dry *** was an increase in annual SOC stock and a decrease(or no change in some cases),in SIC stock at both the depths during the study *** SOC and SIC sequestration rates were estimated as any increase/decrease in the respective stock during each successive *** sequestered ranged between 0.046 and 0.741 Mg C ha−1 y−***,SIC sequestration ranged between 0.013 and 0.023 Mg C ha−1 y−1 over all ridge forests up to 20 cm *** Delhi ridge forests,which accounts to 0.007%of the semi-arid regions of India,contribute 0.25–0.32%of the national potential(semi-arid region)for SOC sequestration up to 20 cm *** estimates of the rate of C sequestration in this study provide a realistic image of carbon dynamics under present climatic conditions of semi-arid forests,and could be used in developing a database and formulating new strategies for carbon dioxide mitigation by enhancing soil C sequestration rates.

关键词： Soil organic carbon Soil inorganic carbon Carbon sequestration Moisture regime Semi-arid forests

Seasonality and moisture regime control soil respiration, enzyme activities, and soil microbial biomass carbon in a semi-arid forest of Delhi, India

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Ecological Processes 2020年第1期9卷 579-591页

作者： Urvashi tomar Ratul Baishya Ecology&Ecosystem Research Laboratory Department of BotanyUniversity of DelhiDelhi 110007India

Soil respiration,soil enzymes,and microbial biomass are important in carbon cycling in the terrestrial ecosystem which is generally limited by environmental factors and soil carbon ***,we tried to assess the factors affecting the functional aspects of these processes in a semi-arid *** monitored soil respiration(surface)using a portable infrared gas analyzer(Q-Box SR1LP Soil Respiration Package,Qubit Systems,Canada)equipped with a soil respiration chamber(Model:G 180).Soil respiration was measured at midday during each season throughout the study *** enzymatic activities and microbial biomass carbon(MBC)were analyzed following the standard protocol for a year during peak time in four seasons at 0-10 cm and 10-20 cm *** respiration shows significant variation with highest in monsoon(3.31μmol CO2 m−2 s^(−1))and lowest in winter(0.57μmol CO2 m^(−2) s^(−1)).Similarly,β-glucosidase,dehydrogenase,and phenol oxidase activity ranged from 11.15 to 212.59μg PNP g^(−1) DW h^(−1),0.11 to 16.47μg TPF g^(−1) DW h^(−1),and 4102.95 to 10187.55μmol ABTS+g^(−1) DW min^(−1),*** ranged from 17.08 to 484.5μgCg^(−1).Besides,soil respiration,soil enzymes(exceptβ-glucosidase),and MBC were significantly correlated with soil ***,optimum moisture and temperature played a significant role in determining variations in soil microbiological processes(exceptβ-glucosidase activity);the carbon cycling in the study area is assisted by enzyme activity;dehydrogenase and phenol oxidase played a significant role in soil respiration;hence,this landscape is sensitive to environmental changes.

关键词： Soil respiration Enzyme activities Microbial biomass carbon Seasons Semi-arid forest

Strength and elongation of spray formed Al–Si–Pb alloys

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International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1222-1227页

作者： Aruna tomar Rashmi Mittal Devendra Singh Department of Metallurgical and Materials Engineering Indian Institute of Technology Roorkee

The strength and elongation to fracture of spray deposited Al-Si-Pb alloys were studied as a function of lead content, silicon content, and distance from the centre to periphery of the deposit. It is found that the ultimate tensile strength, proof stress and elongation to fracture decrease, linearly and exponentially, with the increase in lead content and porosity of the deposit, respectively. Both the strengths and elongation to fracture linearly increase with increasing distance from the centre to periphery of the deposit. The ultimate tensile strength and proof stress are higher at a higher silicon content and they have a linear relationship with the hardness of the deposit.

关键词： aluminum silicon alloys spray forming tensile strength proof stress elongation

Kalman filtering for linear singular systems subject to round-robin protocol

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Control Theory and Technology 2024年第4期22卷 543-551页

作者： Ashna Goel Shovan Bhaumik Nutan Kumar tomar Department of Mathematics Indian Institute of Technology PatnaPatnaBihar801106India Department of Electrical Engineering Indian Institute of Technology PatnaPatnaBihar801106India

This paper introduces a Kalman-type recursive state estimator for a class of discrete-time stochastic linear singular systems where the measurements are carried part by part periodically following a scheduling *** consider that the system is in a network with limited allotted bandwidth,which refers to a situation where the total available bandwidth for data transmission through the network is *** limitation can occur for various reasons,such as network congestion,resource allocation policies,or bandwidth limitations imposed by network *** such networks,the entire measurement vector cannot be transmitted to the estimator ***,managing a network with a limited allotted bandwidth requires careful planning,monitoring,and implementing some scheduling strategies to optimize the use of measured data while estimating the system *** show that a scheduling method,namely,round-robin protocol,is suitable for singular systems to deal with such a *** upper bound of the prior error covariance is studied via a periodic Riccati equation(PRE).To retain the boundedness of prior error covariance,the stability of the PRE is examined by the observability properties of the round-robin-induced ***,a simulation example is presented to show the effectiveness of the designed filtering scheme.

关键词： Networked control systems Communication constraints Round-robin protocol Singular systems Filtering

Hardware Chip Performance of CORDIC Based OFDM Transceiver for Wireless Communication

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Computer Systems Science & Engineering 2022年第2期40卷 645-659页

作者： Amit Kumar Adesh Kumar Geetam Singh tomar Faculty of Technology Uttarakhand Technical UniversityDehradun248007India Department of Electrical&Electronics Engineering School of EngineeringUniversity of Petroleum and Energy StudiesDehradun248007India Birla Institute of Applied Sciences Nainital263136India

The fourth-generation(4G)and fifth-generation(5G)wireless communication systems use the orthogonal frequency division multiplexing(OFDM)modulation techniques and subcarrier *** OFDM modulator and demodulator have inverse fast Fourier transform(IFFT)and fast Fourier transform(FFT)*** biggest challenge in IFFT/FFT processor is the computation of imaginary and real *** has been proved one of the best rotation algorithms for logarithmic,trigonometric,and complex *** proposed work focuses on the OFDM transceiver hardware chip implementation,in which 8-point to 1024-point IFFT and FFT are used to compute the operations in transmitter and receiver *** coordinate rotation digital computer(CORDIC)algorithm has read-only memory(ROM)-based architecture to store FFT twiddle factors and their angle *** address generation unit is required to fetch the data and write the results into the memory in the appropriate *** provides low memory,delay,and optimized hardware on the field-programmable gate array(FPGA)in comparison to normal FFT architecture for the OFDM *** comparative performance of the FFT and CORDICFFT based OFDM transceiver chip is estimated using FPGA parameters:slices,flip-flops,lookup table(LUTs),frequency,power,and *** design is developed using integrated synthesis environment(ISE)Xilinx version 14.7 software,synthesized using very-high-speed integrated circuit hardware description language(VHDL),and tested on Virtex-5 FPGA.

关键词： 5G Communication CORDIC Algorithm FFT Virtex-5 FPGA OFDM Communication

Real Time Automation and Ratio Control Using PLC&SCADA in Industry 4.0

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Computer Systems Science & Engineering 2023年第5期45卷 1495-1516页

作者： Basant tomar Narendra Kumar Mini Sreejeth Dept of Electrical Engineering Delhi Technological UniversityDelhi 110042India

Industrial Control Systems(ICS)and SCADA(Supervisory Control and Data Acquisition)systems play a critical role in the management and regulation of critical *** systems brings us closer to the real-time application *** process and equipment control capability is typically provided by a Distributed Control System(DCS)in industries such as power stations,agricultural systems,chemical and water treatment *** of control through DCS,this paper proposes a SCADA and PLC(Programmable Logic Controller)system to control the ratio control division and the assembly line division inside the chemical plant.A specific design and implementation method for development of SCADA/PLC based real time ratio control and automated assembly line system in a chemical plant is *** assembly line division is further divided into sorting stage,filling stage and the auxiliary stage,which includes the capping unit,labelling unit and then the *** the ratio control division,we have defined the levels inside the mixer and ratio of the raw materials through human machine interface(HMI)*** ratio of raw materials is kept constant on the basis of flow rates of wild stream and manipulated *** is a flexibility in defining new levels and the ratios of the raw materials inside the *** here we taken the predefined levels(low,medium,high)and ratios(3:4,2:1,2:5).Control valves are used for regulating the flow of the *** the assembly line division,the containers are sorted on the basis of size and type of material used i.e.,big sized metallic containers and small sized non-metallic containers by inductive and capacitive proximity *** the processes are facilitated with laser beam type or reflective type sensors on the conveyor *** a highly stable and dependable PLC/SCADA system instead of Distributed Control System is required to achieve automatic management and control of chemical industry processes to reduce

关键词： Industry 4.0 ratio control automation PLC SCADA control valves proximity sensors conveyor system solenoid valves

Analysis of Capacity Decay, Impedance, and Heat Generation of Lithium-ionBatteries Experiencing Multiple Simultaneous Abuse Conditions

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Energy Engineering 2023年第12期120卷 2721-2740页

作者： Casey Jones Meghana Sudarshan Vikas tomar School of Aeronautics and Astronautics Purdue UniversityWest Lafayette47907USA

Abuse of Lithium-ion batteries,both physical and electrochemical,can lead to significantly reduced operational *** some instances,abuse can cause catastrophic failure,including thermal runaway,combustion,and *** different test standards that include abuse conditions have been developed,but these generally consider only one condition at a time and only provide go/no-go *** this work,different types of cell abuse are implemented concurrently to determine the extent to which simultaneous abuse conditions aggravate cell degradation and *** loading is chosen to be the consistent type of physical abuse,and the first group of cells is cycled at different vibrational *** next group of cells is cycled at the same frequencies,with multiple charge pulses occurring during each *** final group of cells is cycled at the same frequencies,with a partial nail puncture occurring near the beginning of *** results show that abusing cells with vibrational loading or vibrational loading with current pulses does not cause a significant decrease in operational capabilities while abusing cells with vibrational loading and a nail puncture drastically reduces operational *** cells with vibration only experience an increase in internal resistance by a factor of 1.09–1.26,the cells with vibration and current pulses experience an increase in internal resistance by a factor of 1.16–1.23,and all cells from each group reach their rated lifetime of 500 cycles without reaching their end-of-life ***,the cells with vibration and nail puncture experience an increase in internal resistance by a factor of 6.83–22.1,and each cell reaches its end-of-life capacity within 50 ***,the results show that testing multiple abuse conditions simultaneously provides a better representation of the extreme limitations of cell operation and should be considered for inclusion in reference test standards.

关键词： Lithium-ion batteries dynamic abuse testing electrochemical impedance spectroscopy incremental capacity analysis thermal profile analysis

Real Time Control System for Metro Railways Using PLC & SCADA

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Intelligent Automation & Soft Computing 2023年第2期35卷 1403-1421页

作者： Ishu tomar Indu Sreedevi Neeta Pandey Department of Electronics and Communication Engineering Delhi Technological UniversityDelhi110042India

This paper proposes to adopt SCADA and PLC technology for the improvement of the performance of real time signaling&train control systems in metro *** main concern of this paper is to minimize the failure in automated metro railways system operator and integrate the information coming from Operational Control Centre(OCC),traction SCADA system,traction power control,and power supply *** work presents a simulated prototype of an automated metro train system operator that uses PLC and SCADA for the real time monitoring and control of the metro railway ***,SCADA is used for the visualization of an automated process operation and then the whole opera-tion is regulated with the help of *** PLC used in this process is OMRON(NX1P2-9024DT1)and OMRON’s Sysmac studio programming software is used for developing the ladder logic of *** metro railways system has deployed infrastructure based on SCADA from the power supply system,and each station’s traction power control is connected to the OCC remotely which commands all of the stations and has the highest command *** alarm is triggered in the event of an emergency or system *** proposed system overcomes the drawbacks of the current centralized automatic train control(CATC)*** system provides prominent beneﬁts like augmenting services which may enhance a network’s full load capacity and networkﬂexibility,which help in easy modiﬁcation in the existing program at any time.

关键词： Train control system automation PLC(programmable logic controller) SCADA(supervisory control and data acquisition)