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Effects of solubility parameter differences among pEG,pVp and CA on the preparation of ultrafiltration membranes:Impacts of solvents and additives on morphology,permeability and fouling performances

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Chinese Journal of Chemical Engineering 2017年第7期25卷 911-923页

作者： Kibrom Alebel Gebru Chandan das Department of Chemical Engineering Indian Institute of Technology Guwahati781039AssamIndia

The effects of two different hydrophilic additives and two solvents on the membrane morphological structure,permeability property and anti-fouling performances of cellulose acetate(CA) ultrafiltration membranes were investigated. During the phase-inversion process, cellulose acetate was selected as a membrane forming polymer; polyethylene glycol(pEG) and polyvinyl pyrrolidone(pVp) were used as additives; acetone(Ac): N,N-Dimethylacetamide(DMAc) and N, N-Dimethylformamide(DMF) were used as solvents; and deionized(DI)water was used in the coagulation bath. All the prepared membranes were characterized in terms of hydraulic permeability(pm), membrane resistance, average pore radius, and hydrophilicity. The top surface and crosssectional view of the prepared membranes were also observed by using field emission scanning electron microscopy. Membrane fouling and rejection experimentations were done using a stirred batch-cell filtration *** experimental studies of fouling/rinsing cycles, rejection, and permeate fluxes were used to investigate the effect of pEG and pVp additives and effect of the two solvents on the fabricated membranes using bovine serum albumin(BSA) as a model protein.

关键词： phase inversion Cellulose acetate Solubility parameter Ultrafiltration Additives Solvents

Quantum-dot cellular automata based reversible low power parity generator and parity checker design for nanocommunication

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Frontiers of Information Technology & Electronic Engineering 2016年第3期17卷 224-236页

作者： Jadav Chandra das Debashis DE Department of Computer Science and Engineering West Bengal University of Technology Department of physics University of Western Australia

Quantum-dot cellular automata （QCA） is an emerging area of research in reversible computing. It can be used to design nanoscale circuits. In nanocommunication, the detection and correction of errors in a received message is a major factor. Besides, device density and power dissipation are the key issues in the nanocommunication architecture. For the first time, QCA-based designs of the reversible low-power odd parity generator and odd parity checker using the Feynman gate have been achieved in this study. Using the proposed parity generator and parity checker circuit, a nanocommunication architecture is pro- posed. The detection of errors in the received message during transmission is also explored. The proposed QCA Feynman gate outshines the existing ones in terms of area, cell count, and delay. The quantum costs of the proposed conventional reversible circuits and their QCA layouts are calculated and compared, which establishes that the proposed QCA circuits have very low quantum cost compared to conventional designs. The energy dissipation by the layouts is estimated, which ensures the possibility ofQCA nano-device serving as an alternative platform for the implementation of reversible circuits. The stability of the proposed circuits under thermal randomness is analyzed, showing the operational efficiency of the circuits. The simulation results of the proposed design are tested with theoretical values, showing the accuracy of the circuits. The proposed circuits can be used to design more complex low-power nanoscale lossless cation architecture such as nano-transmitters and nano-receivers

关键词： Quantum-dot cellular automata (QCA) parity generator parity checker Feynman gate Nanocommunication powerdissipation

Analysis and design of open trench barriers in screening steady-state surface vibrations

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Earthquake Engineering and Engineering Vibration 2014年第3期13卷 545-554页

作者： Ankurjyoti Saikia Utpal Kumar das Department of Civil Engineering Tezpur University

The problem of vibration isolation by rectangular open trenches in a plane strain context is numerically studied using a finite element code, pLAXIS. The soil media is assumed to be linear elastic, isotropic, and homogeneous subjected to a vertical harmonic load producing steady-state vibration. The present model is validated by comparing it with previously published works. The key geometrical features of a trench, i.e., its depth, width, and distance from the source of excitation, are normalized with respect to the rayleigh wavelength. The attenuation of vertical and horizontal components of vibration is studied for various trench dimensions against trench locations varied from an active to a passive case. results are depicted in non-dimensional forms and conclusions are drawn regarding the effects of geometrical parameters in attenuating vertical and horizontal vibration components. The screening efficiency is primarily governed by the normalized depth of the barrier. The effect of width has little significance except in some specific cases. Simplified regression models are developed to estimate average amplitude reduction factors. The models applicable to vertical vibration cases are found to be in excellent agreement with previously published results.

关键词： finite element open trench vibration isolation wave barrier non-dimensional

Evaluating the accuracy of two satellite-based Quantitative precipitation Estimation products and their application for meteorological drought monitoring over the Lake Victoria Basin,East Africa

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Geo-Spatial Information Science 2022年第3期25卷 500-518页

作者： priyanko das Zhenke Zhang Hang ren Center of African Studies Nanjing UniversityNanjingChina and School of Geographic and Oceanographic SciencesNanjing UniversityNanjingChina Center of African Studies Nanjing UniversityNanjingChina and School of Geographic and Oceanographic SciencesNanjing University Nanjing China Institute of population Studies Nanjing University of Posts and TelecommunicationsNanjingJiangsu provinceChina

This study evaluates the high-resolution satellite estimated long-term precipitation data for monitor-ing the drought condition over the Lake Victoria Basin(LVB)from 1984 to *** precipitation Indices(SpI)were used to capture the short,medium and long-term meteorological drought conditions at multiple time scales(i.e.3,6,and 12).For these,the following two primaries Quantitative precipitation Estimation(QpEs)products were employed-1)Climate Hazards group Infra-red precipitation with Station(CHIrpS),and 2)the precipitation Estimation from remotely Sensed Information using Artificial Neural Network-Climate Data record(pErSIANN-CDr).This dataset was compared based on the observation data obtained from the Climate research Unit(CrU)over the nine selected regions surrounding lake *** performance of these two QpEs products was evaluated using seven statistical *** findings of this study indicate that the CHIrpS and pErSIANN-CDr datasets could capture the behavior of drought magnitude based on the time scale of SpI-3,SpI-6,*** results indicate that 2012 and 2017 are significant severe drought years in the recent decade over ***,the CHIrpS datasets provide good agreement(Correlation Coefficient(CC)=0.65)with observation,whereas pErSIANN-CDr present satisfactory results(CC=0.54).In addition,Hurst(H)exponent was used to predict the future drought trend and found that the CHIrpS performed well to predict the degree of drought ***,this study considers the CHIrpS product for near-real-time drought monitoring and pErSIANN-CDr for historical drought ***,the outcome from the H values is greater than 0.5,which indicates the future drought trend would be decreased over *** results are useful for developing the strategies for drought hazards and water resource management in LVB.

关键词： CHIrpS CrU hurst exponent pErSIANN-CDr SpI

Hydromagnetic flow between two porous disks rotating about non-coincident axes

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Acta Mechanica Sinica 2008年第5期24卷 489-496页

作者： M.Guria B.K.das r.N.Jana C.Erdem Imrak Department of Applied Mathematics Vidyasagar UniversityMidnapore 721 102West BengalIndia Department of Mechanical Engineering Istanbul Technical UniversityGumussuyuIstanbul 34439Turkey

Hydromagnetic flow between two porous disks rotating with same angular velocity Ω about two noncoincident axes has been studied in the presence of a uniform transverse magnetic field. An exact solution of the governing equations has been obtained in a closed form. It is found that the primary velocity f/Ωl increases and the secondary velocity g/Ωl decreases with increase in either reynolds number re or the Hartman number M. It is also found that the torque at the disk η= 0 increases with increase in either M^2 or K^2. On the other hand there is no torque at the disk η= 1 for large M^2 and K^2. The heat transfer characteristic has also been studied on taking viscous and Joule dissipation into account. It is seen that the temperature increases with increase in either M^2 or K^2. It is found that the rate of heat transfer at the disk η= 0 increases with increase in either M or K. On the other hand the rate of heat transfer at the disk η= 1 increases with increase in K but decreases with increase in M.

关键词： Non-coincident Viscous fluid Torque ,Hydromagnetic

H_(∞) Load Frequency Control Design Based on Delay Discretization Approach for Interconnected power Systems with Time Delay

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Journal of Modern power Systems and Clean Energy 2021年第6期9卷 1468-1477页

作者： Subrat Kumar pradhan Dushmanta Kumar das Department of Electrical and Electronics Engineering National Institute of Technology Nagaland

This paper proposes a delay discretization based H∞load frequency control strategy for interconnected power *** effect of time delay is considered in the system for the design of stabilizing *** improve the tolerable delay margin of the system,a two-term state feedback controller structure is *** controller requires delayed state information as control *** the proposed approach,the amount of delay introduced in the state of the system,i.e.,artificial delay,for taking control action is assumed to be *** approach is based on the discretization of this delay *** order to define a simple Lyapunov-Krasovskii(LK)function for each of the discretized interval,a stabilization criterion is developed in such a way that a single one satisfies the requirement of all the *** developed criterion is computationally simple and efficient.

关键词： Interconnected power system load frequency control(LFC) state feedback controller time delay

Developing molecular-level models for organic field-effect transistors

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National Science review 2021年第4期8卷 167-180页

作者： Haoyuan Li Jean-Luc Brédas School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics Georgia Institute of Technology Department of Chemistry and Biochemistry University of Arizona

Organic field-effect transistors(OFETs) are not only functional devices but also represent an important tool for measuring the charge-transport properties of organic semiconductors(OSs). Thus, efforts to understand the performance and characteristics of OFET devices are not only useful in helping achieve higher device efficiencies but also critical to ensuring accuracy in the evaluations of OS charge *** studies rely on OFET device models, which connect the measured current characteristics to the properties of the OSs. Developing such OFET models requires good knowledge of the charge-transport processes in OSs. In device active layers, the OS thin films are either amorphous(e.g. in organic light-emitting diodes and organic solar cells) or crystalline(e.g. those optimized for charge transport in OFETs). When the electronic couplings between adjacent OS molecules or polymer chain segments are weak, the charge-transport mechanism is dominated by hopping processes, which is the context in which we frame the discussion in this review. Factors such as disorder, mobility anisotropy, traps, grain boundaries or film morphology all impact charge transport. To take these features fully into account in an OFET device model requires considering a nano-scale, molecular-level resolution. Here, we discuss the recent development of such molecular-resolution OFET models based on a kinetic Monte Carlo approach relevant to the hopping regime. We also briefly describe the applicability of these models to high-mobility OFETs,where we underline the need to extend them to incorporate aspects related to charge delocalization.

关键词： organic semiconductors charge transport kinetic Monte Carlo simulations mobility measurements gradual channel approximation

Understanding the influence of petrographic parameters on strength of differently sized shale specimens using XrD and SEM

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International Journal of Mining Science and Technology 2021年第5期31卷 953-961页

作者： Debashis das Brijes Mishra Neel Gupta rESpEC LexingtonKY 40508USA West Virginia University MorgantownWV 26506USA

Ground failure is a major contributor to fatalities in underground mines in the *** coal mines in the Northern Appalachian have weak roof rock composed of shale,which is prone to failure under high horizontal *** the relationship among strength,specimen size and rock petrographic parameters is essential for developing an effective ground control *** effect studies have found that rock strength varies with specimen *** paper attempts to understand this strength variation using three specimen sizes(254-mm,508-mm,and 762-mm).The specimen strength was measured and the major petrographic parameters affecting the strength,namely grain size,grain shape,quartz content,clay content,*** analyzed using X-ray diffraction(XrD)and scanning electron microscopy(SEM).The petrographic parameters were then correlated with the strength of the three differently sized *** results showed that 508-mm specimen had the lowest *** content of the 508-mm specimen was lower than that of 254-mm and 762-mm *** content and average grain size of the 508-mm specimen were higher than those of 254-mm and 762-mm *** results clearly show that grain size,quartz content and clay content contribute to strength variation observed in differently sized shale specimens.

关键词： Shale strength XrD(X-ray diffraction) SEM(scanning electron microscopy) Grain size Quartz content Grain shape

Data-Driven Approaches for Spatio-Temporal Analysis:A Survey of the State-of-the-Arts

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Journal of Computer Science & Technology 2020年第3期35卷 665-696页

作者： Monidipa das Soumya K.Ghosh School of Computer Science and Engineering Nanyang Technological UniversitySingapore 639798Singapore Department of Computer Science and Engineering Indian Institute of Technology KharagpurKharagpur 721302India

With the advancement of telecommunications,sensor networks,crowd sourcing,and remote sensing technology in present days,there has been a tremendous growth in the volume of data having both spatial and temporal *** huge volume of available spatio-temporal(ST)data along with the recent development of machine learning and computational intelligence techniques has incited the current research concerns in developing various data-driven models for extracting useful and interesting patterns,relationships,and knowledge embedded in such large ST *** this survey,we provide a structured and systematic overview of the research on data-driven approaches for spatio-temporal data *** focus is on outlining various state-of-the-art spatio-temporal data mining techniques,and their applications in various *** start with a brief overview of spatio-temporal data and various challenges in analyzing such data,and conclude by listing the current trends and future scopes of research in this multi-disciplinary *** with other relevant surveys,this paper provides a comprehensive coverage of the techniques from both computational/methodological and application *** anticipate that the present survey will help in better understanding various directions in which research has been conducted to explore data-driven modeling for analyzing spatio-temporal data.

关键词： data-driven modeling spatio-temporal data prediction change pattern detection outlier detection hotspot detection partitioning/summarization (tele-)coupling visual analytics