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A New Design Approach for Nearly Linear Phase Stable IIR Filter using Fractional Derivative

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 527-538页

作者： Nikhil Agrawal Anil kumar Varun Bajaj Department of Electronics and Communication Engineering PDPM Indian Institute of Information TechnologyDesign and Manufacturing JabalpurMadhya Pradesh 482005India

In this paper,a new design method for digital infinite impulse response(IIR)filters with nearly linear-phase response is presented using fractional derivative constraints(FDCs).In the proposed method,design problem of an IIR frlter is constructed as the minimization of phase error between the desired and designed phase response of an allpass filter(APF)such that the designed lowpass filter(LPF)or highpass frlter(HPF)yields less passband(ep),and stopband errors(es)with optimal stopband attenuation(As).In order to have accurate passband(pb)response,FDCs are imposed on appropriate reference frequency,where the optimality of these FDCs are ensured by using a new greedy based sorting *** simulated results reflect the efficiency of the proposed method in term of improved passband response along with better transition ***,small reduction in^is observed within the allowable limit,when compared to noin-fractional design approach,but the designed filter remains immune to wordlength(WL)effect.

关键词： Fractional derivative constraint(FDC) infinite impulse response(IIR)filter least squared linear phase quantization

Technical challenges in tackling regulatory concerns for urban atmospheric nanoparticles

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Particuology 2011年第6期9卷 566-571页

作者： Prashant kumar Alan Robins Sotiris Vardoulakis Paul Quincey Division of Civil Chemical and Environmental EngineeringFaculty of Engineering and Physical Sciences(FEPS)University of Surrey Environmental Flow(EnFlo)Research Centre FEPSUniversity of Surrey Centre for Radiation Chemical and Environmental HazardsHealth Protection Agency Analytical Science Division National Physical Laboratory

Recent Euro 5 and Euro 6 vehicle emission standards are the first ever initiative to control particles on a number basis at the source. Related standards are also desirable for ambient nanoparticles （taken in this article to be those below 300 rim） to protect against possible adverse effects on public health and the environment. However, there are a number of technical challenges that need to be tackled before developing a regulatory framework for atmospheric nanoparticles. Some of the challenges derive from a lack of standardisation of the key measurement parameters, including sampling, necessary for robust evaluation of particle number concentrations, especially in the context of insufficient knowledge of the physicochemical characteristics of emerging sources （i.e. bio-fuel derived and manufactured nanoparti- cles）. Ideally, ambient concentrations of primary particles could be linked to primary particle emissions by use of nanoparticle dispersion models, and secondary nanoparticles using photochemical modeling tools. The limitations in these areas are discussed. Although there is inadequate information on the exact biological mechanism through which these particles cause harm, it is argued that this should not in itself delay the introduction of regulation. This article reviews the missing links between the existing knowledge of nanoparticle number concentrations and the advances required to tackle the technical challenges implied in developing regulations.

关键词： Airborne and manufactured nanoparticles Particle number concentrations Size distributions Street canyons Ultrafine particles Vehicle emissions

Surface Roughness Simulation During Rotational-Magnetorheological Finishing of Poppet Valve Profiles

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Nanomanufacturing and Metrology 2022年第3期5卷 259-273页

作者： Manjesh kumar Manas Das Nan Yu Department of Mechanical Engineering Indian Institute of TechnologyGuwahati 781039India School of Engineering The University of EdinburghEdinburgh EH89YLUK Department of Mechanical Engineering SRM University APAndhra Pradesh522502India

Surface finishing is essential for various applications in the aerospace *** of the applications is the poppet valve,which is used for leak-proof sealing of high-pressure gases in aerospace gas propulsion *** combustion engine also typically employs a poppet valve as an intake and exhaust ***-finishing a poppet valve is difficult because of its complex narrow *** precise nano-finished poppet valve perfectly fits on its seat and reduces hydrocarbon *** rotational-magnetorheological fluid-based finishing process can be used effectively for these complicated *** polishing agent in this process is magnetorheological fluid,and rheological properties are controlled by a permanent *** article presents the uniform finishing of the poppet valve's narrow ridge profile,which is analyzed through finite element analysis(FEA),wherein the outcomes are uniform shear stress,normal stress,and magnetic flux density distributions along the poppet ridge *** study of forces exerting on abrasive grains and surface roughness simulation is also conducted using FEA *** experiment is subsequently performed to verify the simulation results for poppet profile *** obtained experimental and simulated surface roughness values are *** the finishing process,the maximum percentage improvement of surface roughness is obtained as 93.71%.The rotational-magnetorheological fluid-based finishing process has high accuracy and reliability for specific applications.

关键词： Finite element analysis Nano-finishing Nickel-aluminum bronze alloy Poppet valve Magnetorheological fluid Surfaceroughness simulation

Positive and negative effects of graphite flake and monolayer graphene oxide templates on protein crystallization

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Particuology 2023年第8期79卷 27-34页

作者： Zhichun Lin Wenqing Tian Yang Su Vikash kumar Yadav Huaiyu Yang Department of Chemical Engineering Loughborough UniversityLoughboroughLE113TUUK Institute of Materials Research Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China Human Sciences Research Centre University of DerbyDE221GBUK

Heterogeneous template-induced nucleation is a promising way to regulate protein crystallization events and could be employed for purification processes and crystallographic *** crystallization process with graphite and graphene oxide,as heterogeneous templates,were *** than 640 hanging drops with different concentrations of Lysozyme(30,50,70,100 mg/mL)and NaCl(0.7,0.9,1.1,1.3,1.5 M)were crystallised at 4 ℃ with or without graphite/graphene oxide *** induction times and crystallization process were observed under the *** lysozyme in the solutions with graphite flakes nucleated faster under all the conditions than the lysozyme with equal experimental conditions without *** crystals preferred to grow around the edge of graphite flakes than on the flat *** the droplets with monolayer graphene oxide,more crystals appeared around gra-phene oxide particles,and the faster or slower nucleation processes with templates were dependent on the lysozyme and NaCl *** oxide templates strongly inhibited nucleation at high lysozyme concentrations but promoted nucleation at low lysozyme *** heterogeneous templates changed the crystal morphology and the crystallization *** crystals were observed in the solution with graphite templatesthan with graphene oxide templates and without any template.

关键词： Graphite Graphene oxide Protein crystallization Adsorption Heterogeneous nucleation Template technology

Impact of ionizers on prevention of airborne infection in classroom

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Building Simulation 2023年第5期16卷 749-764页

作者： Chen Ren Fariborz Haghighat Zhuangbo Feng Prashant kumar Shi-Jie Cao School of Architecture Southeast University2 SipailouNanjing 210096China Energy and Environment Group Department of BuildingCivil and Environmental EngineeringConcordia UniversityMontrealH3G 1M8Canada Global Centre for Clean Air Research(GCARE) School of SustainabilityCivil&Environmental EngineeringFaculty of Engineering&Physical SciencesUniversity of SurreyGuildford GU27XHSurreyUK Institute for Sustainability University of SurreyGuildford GU27XHSurreyUK

Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social *** the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors,such as in *** application of air purification devices,such as negative ion generators(ionizers),gains popularity because of the favorable removal capacity for particles and the low operation ***,small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative *** study aims to investigate the layout strategy(number and location)of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency(negative ions to particles)and decrease infection *** infected students were considered in the *** simulations of negative ion and particle concentrations were performed and validated by the *** showed that as the number of ionizers was 4 and 5,the removal performance was largely improved by combining ionizer with natural *** with the scenario without an ionizer,the scenario with 5 ionizers largely increased the average removal efficiency from around 20%to 85%and decreased the average infection risk by 23%.The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy,particularly when the location and number of the infected students were *** work can provide a guideline for applying ionizers to public buildings when natural ventilation is used.

关键词： classroom infection risk ionizer negative ions removal efficiency

Modulation of Convectively Coupled Kelvin Wave Activity in the Tropical Pacific by ENSO

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Acta meteorologica Sinica 2013年第3期27卷 295-307页

作者：王辉潘宇彤 Arun kumar 王万秋 NOAA/NWS/NCep/Climate Prediction Center College ParkMD 20740 USA Wyle Science Technology and Engineering GroupMcLean VA 22102 USA Department of Atmospheric and Oceanic Science University of Maryland College ParkMD 20742 USA

The influence of E1 Nifio-Southern Oscillation （ENSO） on the convectively coupled Kelvin waves over the tropical Pacific is investigated by comparing the Kelvin wave activity in the eastern Pacific （ep） E1 Nifio, central Pacific （CP） E1 Nifio, and La Nifia years, respectively, to 30-yr （1982 2011） mean statistics. The convectively coupled Kelvin waves in this study are represented by the two leading modes of empirical orthogonal function （EOF） of 2-25-day band-pass filtered daily outgoing longwave radiation （OLR）, with the estimated zonal wavenumber of 3 or 4, period of 8 days, and eastward propagating speed of 17 m s-1. The most significant impact of ENSO on the Kelvin wave activity is the intensification of the Kelvin waves during the ep E1 Nifios. The impact of La Nifia on the reduction of the Kelvin wave intensity is relatively weaker, reflecting the nonlinearity of tropical deep convection and the associated Kelvin waves in response to ENSO sea surface temperature （SST） anomalies. The impact of the CP E1 Nifio on the Kelvin waves is less significant due to relatively weaker SST anomalies and smaller spatial coverage. ENSO may also alter the frequency, wavelength, and phase speed of the Kelvin waves. This study demonstrates that low- frequency ENSO SST anomalies modulate high-frequency tropical disturbances, an example of weather- climate linkage.

关键词： convectively coupled Kelvin waves E1 Nifio-Southern Oscillation (ENSO) outgoing longwaveradiation (OLR) empirical orthogonal function (EOF) power spectra

A high-resolution optically addressed spatial light modulator based on ZnO nanoparticles

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Light(Science & Applications) 2015年第1期4卷 470-476页

作者： Pawan kumar Shrestha Young Tea Chun Daping Chu University of Cambridge Cambridge CB30FAUK

An optically addressed spatial light modulator(OASLM)can modulate the wavefront of a read light by displaying a phase pattern or a hologram configured by the intensity distribution of a write *** ZnO nanoparticles(NPs)as a novel photoconductor,a high-resolution OASLM was fabricated.A ZnO NP suspension was spin-coated on an indium tin oxide(ITO)-coated glass substrate and annealed to form a photosensitive *** device was characterized electrically and *** device was operated at low driving voltages in the transmission *** recording of a diffraction grating up to 825 lp mm^(-1) with a diffraction efficiency(DE)of 0.05%and binary holograms with pixel sizes from 2 mm down to 0.72 mm were demonstrated using a 405 nm wavelength write laser and a 635 nm wavelength read laser.

关键词： holography nanoparticles OASLM ZnO

High Order Stable Infinite Impulse Response Filter Design Using Cuckoo Search Algorithm

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International Journal of Automation and computing 2017年第5期14卷 589-602页

作者： N.Agrawal A.kumar V.Bajaj G.K.Singh Department of Electronics and Communication Engineering the Pandit Dwarka Prasad MishraIndian Institute of Information TechnologyDesign and ManufacturingDurnna 482005India School of Electrical Engineering and Computer Science Gwangju Institute of Science and TechnologyKorea Department of Electrical Engineering Indian Institute of TechnologyRoorkee 247667India

In this paper, an efficient technique for optimal design of digital infinite impulse response （IIR） filter with minimum passband error （ep）, minimum stopband error （es）, high stopband attenuation （As）, and also free from limit cycle effect is proposed using cuckoo search （CS） algorithm. In the proposed method, error function, which is multi-model and non-differentiable in the heuristic surface, is constructed as the mean squared difference between the designed and desired response in frequency domain, and is optimized using CS algorithm. Computational efficiency of the proposed technique for exploration in search space is examined, and during exploration, stability of filter is maintained by considering lattice representation of the denominator polynomials, which requires less computational complexity as well as it improves the exploration ability in search space for designing higher filter taps. A comparative study of the proposed method with other algorithms is made, and the obtained results show that 90% reduction in errors is achieved using the proposed method. However, computational complexity in term of CPU time is increased as compared to other existing algorithms.

关键词： Cuckoo search algorithm infinite impulse response (IIR) means square error (MSE) evolutionary algorithm stability.

Secure optical communication using a quantum alarm

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Light(Science & Applications) 2020年第1期9卷 380-389页

作者： Yupeng Gong Rupesh kumar Adrian Wonfor Shengjun Ren Richard V.Penty Ian H.White Centre for Advanced Photonics and Electronics University of Cambridge9 JJ Thomson AveCambridge CB30FAUK Quantum Communications Hub Information CentreDepartment of PhysicsUniversity of YorkYork YO105DDUK University of Bath Claverton DownBath BA27AYUK

Optical fibre networks are advancing rapidly to meet growing traffic *** issues,including attack management,have become increasingly important for optical communication networks because of the vulnerabilities associated with tapping light from optical fibre *** layer security often requires restricting access to channels and periodic inspections of link *** this paper,we report how quantum communication techniques can be utilized to detect a physical layer *** present an efficient method for monitoring the physical layer security of a high-data-rate classical optical communication network using a modulated continuous-variable quantum *** describe the theoretical and experimental underpinnings of this monitoring system and the monitoring accuracy for different monitored *** analyse its performance for both unamplified and amplified optical *** technique represents a novel approach for applying quantum signal processing to practical optical communication networks and compares well with classical monitoring *** conclude by discussing the challenges facing its practical application,its differences with respect to existing quantum key distribution methods,and its usage in future secure optical transport network planning.

关键词： communication quantum networks