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Robust control of isopropyl benzene production process using H_(∞) loop shaping control scheme

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Journal of Control and Decision 2024年第1期11卷 153-163页

作者： Vinila Mundakkal Lakshmanan Aparna Kallingal Sreepriya sreekumar Department of Chemical Engineering National Institute of Technology CalicutKozhikodeKeralaIndia Department of Robotics and Automation Adi Shankara Institute of Engineering and TechnologyKaladyIndia

This paper discusses robust control strategy for isopropyl benzene production process using the method of loop shaping H_(∞) *** cumene production process is a part of phenol plant in HOCL,Kochi.H_(∞) control of the propylene concentration is done *** H_(∞) controller is derived from the linearised model of the *** optimal H_(∞) controller is obtained by simplifying two algebraic Riccati *** proposed PID-like H_(∞) controller provides a single tuning parameter which makes the controller design more *** proposed controller has been compared with other robust controllers like H_(2) and *** H_(∞) controller is found to be superior in a wide frequency range and has a feature of low distortion and good regulating *** reactor model has been developed in COMSOL Multiphysics with the parameters obtained from HOCL plant,*** model extracted is reduced using model order reduction for the controller design.

关键词： Cumene reactor H_(∞)loop shaping model order reduction Riccati equation PID control stability robustness

A Survey and Experimental Review on Data Distribution Strategies for Parallel Spatial Clustering Algorithms

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Journal of Computer Science & Technology 2024年第3期39卷 610-636页

作者： Jagat Sesh Challa Navneet Goyal Amogh Sharma Nikhil sreekumar Sundar Balasubramaniam Poonam Goyal Advanced Data Analytics and Parallel Technologies Laboratory Birla Institute of Technology and Science Pilani 333031India Uber New York 11101U.S.A. Computer Science and Engineering Department University of MinnesotaMinneapolis 55455U.S.A.

The advent of Big Data has led to the rapid growth in the usage of parallel clustering algorithms that work over distributed computing frameworks such as MPI,MapReduce,and *** important step for any parallel clustering algorithm is the distribution of data amongst the cluster *** step governs the methodology and performance of the entire *** typically use random,or a spatial/geometric distribution strategy like kd-tree based partitioning and grid-based partitioning,as per the requirements of the ***,these strategies are generic and are not tailor-made for any specific parallel clustering *** this paper,we give a very comprehensive literature survey of MPI-based parallel clustering algorithms with special reference to the specific data distribution strategies they *** also propose three new data distribution strategies namely Parameterized Dimensional Split for parallel density-based clustering algorithms like DBSCAN and OPTICS,Cell-Based Dimensional Split for dGridSLINK,which is a grid-based hierarchical clustering algorithm that exhibits efficiency for disjoint spatial distribution,and Projection-Based Split,which is a generic distribution *** of these preserve spatial locality,achieve disjoint partitioning,and ensure good data load *** experimental analysis shows the benefits of using the proposed data distribution strategies for algorithms they are designed for,based on which we give appropriate recommendations for their usage.

关键词： parallel data mining data distribution parallel clustering spatial locality preservation

Gastric leiomyoma presenting as an endophytic growth of cardia of the stomach: A case report

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Laparoscopic, Endoscopic and Robotic Surgery 2024年第3期7卷 132-135页

作者： Surabhi sreekumar Jameel Akhter Sudarsan Srikanth Department of General Surgery Apollo HospitalsChennaiIndia

Gastric leiomyomas are rare submucosal neoplasms arising from smooth muscle *** accounts for approximately 2.5%of all gastric tumours,is slow growing and rarely causes symptoms such as upper abdominal discomfort and dyspepsia.1 On imaging,they appear similar to gastrointestinal stromal tumours(GISTs)and can be intraluminal or *** is mostly confirmed by histopathological examination of the *** resection of the tumour is the main treatment ***,we present a case of laparoscopic resection of an endophytic gastric tumour that turned out to be a leiomyoma.

关键词： Gastric stomach neoplasms

Rice Heat Tolerance Breeding: A Comprehensive Review and Forward Gaze

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Rice science 2024年第4期31卷 375-400,I0022页

作者： Ravindran Lalithambika VISAKH sreekumar ANAND Sukumaran Nair ARYA Behera SASMITA Uday Chand JHA Rameswar Prasad SAH Radha BEENA Department of Genetics and Plant Breeding College of AgricultureVellayaniKerala Agricultural UniversityThiruvananthapuramKerala 695522India Crop Improvement Division Indian Council of Agricultural Research-National Rice Research InstituteCuttackOdisha 7530006India Department of Plant Breeding and Genetics Indian Institute of Pulse ResearchKanpur 208024India Department of Plant Physiology College of AgricultureVellayaniKerala Agricultural UniversityThiruvananthapuramKerala 695522India

The yield potential of rice is seriously affected by heat stress due to climate change. Since rice is a staple food globally, it is imperative to develop heat-resistant rice varieties. Thus, a thorough understanding of the complex molecular mechanisms underlying heat tolerance and the impact of high temperatures on various critical stages of the crop is needed. Adoption of both conventional and innovative breeding strategies offers a long-term advantage over other methods, such as agronomic practices, to counter heat stress. In this review, we summarize the effects of heat stress, regulatory pathways for heat tolerance, phenotyping strategies, and various breeding methods available for developing heat-tolerant rice. We offer perspectives and knowledge to guide future research endeavors aimed at enhancing the ability of rice to withstand heat stress and ultimately benefit humanity.

关键词： genetic mechanism high-temperature stress molecular breeding genomics selection

Instability Analysis of Mosquito Fascicle under Compressive Load with Vibrations and Microneedle Design

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Journal of Bionic Engineering 2015年第3期12卷 443-452页

作者： Sanket Jaiswal sreekumar Muthuswamy Indian Institute of lnformation Technology Design and Manufacturing (IIITD&M) Kancheepuram Chennai - 600127 India

Mosquito has the ability to penetrate the skin with painless insertion. It has attracted the researchers to mimic the bite and develop a painless microneedle. Mosquito applies axial compressive load along with frequency on fascicle to penetrate the human skin and retract if it senses instability prior to insertion. The mechanism of mosquito bite is studied in this work which is divided into two stages for analysis considering different boundary conditions. The probing behaviour of mosquito is considered as stage I and the process of penetration as stage II. An equivalent mechanical model for stage I is proposed and a mathematical model is developed to understand the instability of fascicle in terms of frequency and magnitude of force applied. The governing equation and associated boundary conditions are simplified into Mathieu equation and regions of dynamic instability are obtained through the solution. Results confirm instability of the fascicle during stage I of insertion. The probing behaviour of mosquito is discussed in terms of applied force and vibrating frequency. Horizontal reaction forces exerted by labium on fascicle during buckling improve the stability and enable fascicle to withstand high compressive forces. The analysis and results are utilized to set design guidelines for the development of dynamically stable vibration-assisted microneedle.

关键词： biommimetics mosquito proboscis instability analysis Mathieu equation microneedle design

Contribution from normal and starburst galaxies to the extragalactic gamma-ray background (EGRB)

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Chinese Journal of Astronomy and Astrophysics 2009年第5期9卷 509-519页

作者： Debbijoy Bhattacharya Parameswaran sreekumar Department of Physics Indian Institute of Science Space Astronomy & Instrumentation Division ISRO Satellite Centre

The extragalactic diffuse emission at γ-ray energies has interesting cosmological implications since these photons suffer little or no attenuation during their propagation from the site of origin. The emission could originate from either truly diffuse processes or from unresolved point sources such as AGNs, normal galaxies and starburst galaxies. Here, we examine the unresolved point source origin of the extragalactic γ-ray background emission from normal galaxies and starburst galaxies. γ-ray emission from normal galaxies is primarily coming from cosmic-ray interactions with interstellar matter and radiation （-90%） along with a small contribution from discrete point sources （-10%）. Starburst galaxies are expected to have enhanced supernovae activity which leads to higher cosmic-ray densities, making starburst galaxies sufficiently luminous atγ-ray energies to be detected by the current γ-ray mission （Fermi Gamma-ray Space Telescope）.

关键词： galaxy general -- galaxies luminosity function -- galaxies starburst -- gamma-rays observations

Contribution from unresolved discrete sources to the extragalactic gamma-ray background(EGRB)

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Research in Astronomy and Astrophysics 2009年第11期9卷 1205-1214页

作者： Debbijoy Bhattacharya Parameswaran sreekumar Reshmi Mukherjee Department of Physics Indian Institute of Science Space Astronomy & Instrumentation Division ISRO Satellite Centre Barnard College Columbia University

The origin of the extragalactic gamma-ray background （EGRB） is still an open question, even nearly forty years after its discovery. The emission could originate either from truly diffuse processes or from unresolved point sources. Although the majority of the 271 point sources detected by EGRET （Energetic Gamma Ray Experiment Telescope） are unidentified, of the identified sources, blazars are the dominant candidates. Therefore, unresolved blazars may be considered the main contributor to the EGRB, and many studies have been carried out to understand their distribution, evolution and contribution to the EGRB. Considering that γ-ray emission comes mostly from jets of blazars and that the jet emission decreases rapidly with increasing jet to line-of-sight angle, it is not surprising that EGRET was not able to detect many large inclination angle active galactic nuclei （AGNs）. Though Fermi could only detect a few large inclination angle AGNs during the first three months of its survey, it is expected to detect many such sources in the near future. Since non-blazar AGNs are expected to have higher density as compared to blazars, these could also contribute significantly to the EGRB. In this paper, we discuss contributions from unresolved discrete sources including normal galaxies, starburst galaxies, blazars and off-axis AGNs to the EGRB.

关键词： galaxies active -- galaxies jets -- gamma-rays observations

Does black hole spin play a key role in the FSRQ/BL Lac dichotomy?

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Research in Astronomy and Astrophysics 2016年第4期16卷 7-14页

作者： Debbijoy Bhattacharya Parameswaran sreekumar Banibrata Mukhopadhyay Ishan Tomar Manipal Centre for Natural Sciences Manipal UniversityManipal 576104India Indian Institute of Astrophysics Bangalore 560034India Astronomy and Astrophysics Programme Department of PhysicsIndian Institute of ScienceBangalore 560012India Space Astronomy Group ISRO Satellite CentreKarthik NagarBangalore 560037India

Blazars are characterized by large intensity and spectral variations across the electromagnetic spectrum It is believed that jets emerging from them are almost aligned with the line-of-sight. The major- ity of identified extragalactic sources in γ-ray catalogs of EGRET and Fermi are blazars. Observationally, blazars can be divided into two classes： fiat spectrum radio quasars （FSRQs） and BL Lacs. BL Lacs usually exhibit lower γ-ray luminosity and harder power law spectra at γ-ray energies than FSRQs. We attempt to explain the high energy properties of FSRQs and BL Lacs from Fermi γ-ray space telescope observations. It was argued previously that the difference in accretion rates is mainly responsible for the large mismatch in observed luminosity in ＂7-ray. However, when intrinsic luminosities are derived by correcting for beaming effects, this difference in 7-ray luminosity between the two classes is significantly reduced. In order to ex- plain this difference in intrinsic luminosities, we propose that spin plays an important role in the luminosity distribution dichotomy of BL Lacs and FSRQs. As the outflow power of a blazar increases with increasing spin of a central black hole, we suggest that the spin plays a crucial role in making BL Lac sources low luminous and slow rotators compared to FSRQ sources.

关键词： BL Lacertae objects: general -- quasars: general -- galaxies: jets -- black hole physics --relativistic processes -- gravitation

Gamma-ray luminosity function of gamma-ray bright AGNs

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Chinese Journal of Astronomy and Astrophysics 2009年第1期9卷 85-94页

作者： Debbijoy Bhattacharya P.sreekumar R.Mukherjee Department of Physics Indian Institute of Science Space Astronomy & Instrumentation Division ISRO Satellite Centre Barnard College Columbia University

Detection of γ-ray emissions from a class of active galactic nuclei （viz blazars）, has been one of the important findings from the Compton Gamma-Ray Observatory （CGRO）. However, their γ-ray luminosity function has not been well determined. Few attempts have been made in earlier works, where BL Lacs and Flat Spectrum Radio Quasars （FSRQs） have been considered as a single source class. In this paper, we investigated the evolution and γ-ray luminosity function of FSRQs and BL Lacs separately. Our investigation indicates no evolution for BL Lacs, however FSRQs show significant evolution. Pure luminosity evolution is assumed for FSRQs and exponential and power law evolution models are examined. Due to the small number of sources, the low luminosity end index of the luminosity function for FSRQs is constrained with an upper limit. BL Lac luminosity function shows no signature of break. As a consistency check, the model source distributions derived from these luminosity functions show no significant departure from the observed source distributions.

关键词： galaxies active -- galaxies evolution -- galaxies luminosity function -- gamma-rays observations