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Departure from naturalized to invasive stage:a disturbanceinduced mechanism and associated interacting factors

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Journal of Plant Ecology 2010年第4期3卷 231-242页

作者： amit Chakraborty Bai-Lian Li Ecological Complexity and Modeling Laboratory Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCA 92521-0124USA Center for Conservation Biology University of CaliforniaRiversideCA 92521-0334USA CAU-UCR International Center for Ecology and Sustainability University of CaliforniaRiversideCA 92521USA

Aims Within a habitat of multiple plant species,increased resource availabilities and altered species abundances following disturbances create opportunities for exotic species to successfully establish and subsequently naturalize into its non-native *** post-disturbance changes in abiotic and biotic environments may also promote a naturalized exotic species(or invading species)to become invasive through rapid colonization of the habitat sites by reducing the extent and size of resident plant *** combining species life history traits with that of the disturbance-induced changes in habitat characteristics,we aimed to determine those interacting factors and associated mechanism allowing an exotic invasion to start *** We used a modified version of the classic competition–colonization(CC)model which was formulated first by Hastings(1980)and studied later by Tilman(1994)to explain spatial coexistence of multiple *** this model framework,recruitment-limited spatial competition has explicitly been linked with interspecific resource competition without altering the basic assumptions and structure of the original CC *** findings The model results showed that at a constant rate of resource supply,invading species can stably coexist with native species via trade-offs between species competitive ability and colonizing *** the other hand,the model predicted that with a fluctuating resource condition,invading species can successfully invade a habitat following continuous reductions in the size and extent of native *** or not invading species holds competitive superiority over the native species for limiting resource,we showed that there exists a range of variation in available resource that allows an exotic invasion to start off in post-disturbance *** associated disturbance-induced mechanism promoting invading species to become invasive has been *** states that occurrences of disturbances suc

关键词： invasion naturalized species spatial competition propagule supply resource variation

Temporal scatterplots

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Computational Visual Media 2020年第4期6卷 385-400页

作者： Or Patashnik Min Lu amit H.Bermano Daniel Cohen-Or Tel-Aviv University Tel-AvivIsrael Shenzhen University ShenzhenChina

Visualizing high-dimensional data on a 2D canvas is generally *** becomes significantly more difficult when multiple time-steps are to be presented,as the visual clutter quickly ***,the challenge to perceive the significant temporal evolution is even *** this paper,we present a method to plot temporal high-dimensional data in a static scatterplot;it uses the established PCA technique to project data from multiple *** key idea is to extend each individual displacement prior to applying PCA,so as to skew the projection process,and to set a projection plane that balances the directions of temporal change and spatial *** present numerous examples and various visual cues to highlight the data trajectories,and demonstrate the effectiveness of the method for visualizing temporal data.

关键词： scatterplot temporal data visual clutter principle component analysis(PCA)

Entire onion source-derived redox porous carbon electrodes towards efficient quasi-solid-state solar charged hybrid supercapacitor

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Journal of Materials Science & Technology 2022年第30期125卷 118-127页

作者： Edugulla Girija Shankar amit Kumar Das Jae Su Yu Department of Electronics and Information Convergence Engineering Institute for Wearable Convergence ElectronicsKyung Hee UniversityGyeonggi-do 17104Republic of Korea

Biomass-derived electrodes inherently containing redox-active species have gained extensive attention recently due to their availability,eco-friendliness,sustainability,and low *** report novel binder-free faradic surface redox onion-derived carbon positive electrode with nano regime particles by hydrothermal synthesis and Na^(+)and Cl^(−)ions diffused porous carbon negative electrode via a carbonization ***-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of oxidized sulfur and(N-6)pyridinic N-based redox groups inherently present in the as-prepared *** electrochemical analysis of the positive electrode revealed its faradic redox type of energy storage mechanism with an excellent specific capacitance of 1805 Fg^(-1) at the current density of 3 Ag^(-1) as well as appreciable long-term cycling stability(76.8%retention after 10000 charge-discharge cycles).Meanwhile,the negative electrode exhibited a maximum specific capacitance of 373 Fg^(-1) at 1 Ag^(-1) with outstanding long-term cycling stability(100.7%retention after 10000 cycles).The fabricated polyvinyl alcohol-potassium hydroxide gel electrolyte-based quasi-solid-state hybrid supercapacitor(QHSC)delivered excellent energy density and power density of 19.94 Wh kg^(-1) and 374.99 W kg^(-1),respectively with an ultralong cyclic life(102.3% retention)over 10000 ***,the QHSC was connected to a solar panel to store renewable *** charged QHSC effectively powered a speedometer,enlightening its potential application in advanced sustainable energy storage systems.

关键词： Binder-free Biomass Green source Hybrid supercapacitor Solar energy storage Faradic redox type

Experimental investigation of tandem rotor under clean and radially distorted inflows

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Propulsion and Power Research 2021年第3期10卷 247-261页

作者： amit Kumar A.M.Pradeep Department of Aerospace Engineering Indian Institute of Technology BombayMumbai400076India

With increasing emphasis on renewable sources of energy,the gas turbine engine faces several challenges in evolving its design,to remain *** is one of the main components,which accounts for one-third of the engine *** designers have been exploring different ideas to achieve maximum pressure rise with minimum number of stages *** blading is one such novel design that has demonstrated higher diffusion capability than a single rotor blade.A single blade,with a higher diffusion factor,carries the risk of flow separation against the adverse pressure gradient of the compressor *** the tandem blading concept,a single blade is split into forward and aft *** gap that is created between the forward and aft blade,serves as a mechanism to energize the sluggish flow over the aft blade suction surface,which in turn helps in mitigating the flow *** present experimental work is aimed at exploring the feasibility of a tandem rotor in an axial flow compressor under the clean and radially distorted *** and unsteady experimental results of the tandem rotor are included in this *** stage performance characteristics,variation of total pressure,flow coefficient,and exit flow angle along the blade span for clean and distorted flow is included in this *** results of a steady Reynolds-averaged Navier-Stokes simulation are also included to give some insight into the complex flow field of the tandem *** transform,fast Fourier transform analysis,and visual inspection of casing pressure traces are used to analyze the unsteady result of the tandem rotor in clean and distorted *** tandem rotor is able to achieve its design pressure ratio and has a stall margin of 9%under the clean flow ***,stall appears as a low-intensity spike for all the cases,which turns into a long length-scale disturbance within three rotor revolutions.A modal wave of low frequency is also observed under clean

关键词： Tandem rotor Axial overlap and percentage pitch Radially distorted inflows Diffusion factor Stall Aerodynamics of compressor blade

Numerical simulation of hydrogen arcjet thruster with coupled sheath model

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Plasma Science and Technology 2022年第2期24卷 145-161页

作者： Deepak AKHARE Hari Prasad NANDYALA Jayachandran THANKAPPAN amit KUMAR Department of Aerospace Engg Indian Institute of Technology MadrasChennai 600036India

In the present work,a complete 2D chemical and thermal non-equilibrium numerical model coupled with a relatively simple sheath model is developed for hydrogen arcjet *** heat transfer in the anode wall is also included in the *** operating voltages predicted by the model are compared with those in the literature and are found to be in close *** distributions for the various operating conditions are obtained,anode radiation loss primarily determines the thruster *** thruster efficiency was found to be associated with longer arc *** cathode ion diffusion contribution dominates except at low input current where thermo-field electron current is dominant.

关键词： arcjet hydrogen numerical modeling plasma sheath space electric propulsion

Influence of environmental factors on the onset and courseof inflammatory bowel disease

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World Journal of Gastroenterology 2016年第3期22卷 1088-1100页

作者： amit Kumar Dutta Ashok Chacko Department of Gastrointestinal Sciences Christian Medical CollegeVellore 632004India Department of Digestive Disorders Aberdeen Royal InfirmaryAberdeen AB24 3FXUnited Kingdom Institute of Gastroenterology and Liver Disease The Madras Medical MissionChennai 600037India

Numerous environmental factors have been linked with inflammatory bowel disease. These include smoking, diet, hygiene, drugs, geographical and psychosocial factors. These factors may either increase the risk of or protect against developing this condition and can also affect the course of illness in a positive or negative manner. A number of studies have examined the influence of environmental factors on inflammatory bowel diseases as a whole as well as on ulcerative colitis and Crohn's disease separately. As there are differences in the pathogenesis of ulcerative colitis and Crohn's disease, the effect of environmental factors on their onset and course is not always similar. Some factors have shown a consistent association, while reports on others have been conflicting. In this article we discuss the current evidence on the roles of these factors on inflammatory bowel disease, both as causative/protective agents and as modifiers of disease course.

关键词： Environmental factors Crohn's disease Ulcerative colitis Etiology Outcome

QoS-Aware Energy-Efficient Task Scheduling on HPC Cloud Infrastructures Using Swarm-Intelligence Meta-Heuristics

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Computers, Materials & Continua 2020年第8期64卷 813-834页

作者： amit Chhabra Gurvinder Singh Karanjeet Singh Kahlon Department of Computer Engineering&Technology Guru Nanak Dev UniversityAmritsar143005India Department of Computer Science Guru Nanak Dev UniversityAmritsar143005India

Cloud computing infrastructure has been evolving as a cost-effective platform for providing computational resources in the form of high-performance computing as a service(HPCaaS)to users for executing HPC ***,the broader use of the Cloud services,the rapid increase in the size,and the capacity of Cloud data centers bring a remarkable rise in energy consumption leading to a significant rise in the system provider expenses and carbon emissions in the *** this,users have become more demanding in terms of Quality-of-service(QoS)expectations in terms of execution time,budget cost,utilization,and *** situation calls for the design of task scheduling policy,which ensures efficient task sequencing and allocation of computing resources to tasks to meet the trade-off between QoS promises and service provider ***,the task scheduling in the Cloud is a prevalent NP-Hard *** by these concerns,this paper introduces and implements a QoS-aware Energy-Efficient Scheduling policy called as CSPSO,for scheduling tasks in Cloud systems to reduce the energy consumption of cloud resources and minimize the makespan of *** proposed multi-objective CSPSO policy hybridizes the search qualities of two robust metaheuristics *** search(CS)and particle swarm optimization(PSO)to overcome the slow convergence and lack of diversity of standard CS algorithm.A fitness-aware resource allocation(FARA)heuristic was developed and used by the proposed policy to allocate resources to tasks efficiently.A velocity update mechanism for cuckoo individuals is designed and incorporated in the proposed CSPSO ***,the proposed scheduling policy has been implemented in the CloudSim simulator and tested with real supercomputing workload *** comparative analysis validated that the proposed scheduling policy can produce efficient schedules with better performance over other well-known heuristics and meta-heuristic

关键词： HPC-as-a-Service task scheduling quality-of-service meta-heuristics and energy-efficiency

An efficient hybrid computational technique for the time dependent Lane-Emden equation of arbitrary order

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Journal of Ocean Engineering and Science 2022年第2期7卷 131-142页

作者： Manish Goyal amit Prakash Dumitru Baleanu Department of Mathematics Institute of Applied Sciences and HumanitiesGLA UniversityMathuraIndia Department of Mathematics National Institute of TechnologyKurukshetraIndia Department of Mathematics Faculty of Arts and SciencesCankaya UniversityEtimesgutTurkey Institute of Space Sciences Magurele-BucharestRomania

The study of dynamic behaviour of nonlinear models that arise in ocean engineering play a vital role in our daily *** are many examples of ocean water waves which are nonlinear in *** shallow water,the linearization of the equations imposes severe conditions on wave amplitude than it does in deep water,and the strong nonlinear effects are *** this paper,q-homotopy analysis Laplace transform scheme is used to inspect time dependent nonlinear Lane-Emden type equation of arbitrary *** offers the solution in a fast converging *** uniqueness and convergence analysis of the considered model is *** given examples confirm the competency as well as accuracy of the presented *** behavior of obtained solution for distinct orders of fractional derivative is dis-cussed through *** auxiliary parameter¯h offers a suitable mode of handling the region of *** outcomes reveal that the q-HATM is attractive,reliable,efficient and very effective.

关键词： Fractional differential equations(FDE) Time dependent Lane-Emden type differential equation Caputo derivative of arbitrary order q-homotopy analysis transform scheme(q-HATM) Laplace transform

Improvement of warm formability of Al-Mg sheet alloys containing coarse second-phase particles

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Science China(Technological Sciences) 2009年第1期52卷 41-45页

作者： Arne K DAHLE amit K GHOSH Materials Engineering University of Queensland Department of Materials Science and Engineering University of Michigan

Several alloying elements involving Zr, Cu, Zn and Sc were added to Al-Mg sheet alloys in order to obtain an excellent combination of high strength and good high-temperature formability. Microstruc-tural examination showed that coarse intermetallic particles were formed in the microstructure and their amounts changed with variations of the alloying elements. During warm rolling of thermome-chanical treatments prior to warm deformation, the coarse particles initiated cracks, decreasing the warm formability. For healing the crack damage and further improving the warm formability, a process of hot isothermal press was developed and optimized to the sheet alloys. With this process, the biaxial stretch formability at 350℃ was improved by 22% for an aluminum alloy containing a large amount of coarse particles.

关键词： aluminum alloy microstructure second-phase particle hot isothermal press high-temperature formability