Suvankar Roy Chowdhury

Metaheuristic approaches with extremely important improvements are very promising in the solution of intractable optimization problems. The objective of the present study is to test the capability of applications and compare the performance of the four selected algorithms from “classical” (simulated annealing (SA), genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution (DE)) and “new generation” (firefly algorithm (FFA), krill herd (KH), grey wolf optimization (GWO), and symbiotic organism search (SOS)) each by solving selected benchmark problems that are used in the literature for algorithm testing purpose. The selected test problems had very complex objective functions and associated constraints with multiple local optima. Among all selected algorithms, the “new generation” SOS and KH algorithm successfully solved most of all the selected benchmark problems and achieved the best solution for most of them. Among four “classical” algorithms, DE, and PSO effectively attained the optimal solution which was very close to the best one. However, the “new generation” algorithm performed much better than the “classical” one. Therefore, no firm conclusion can be done about the universally best algorithm and their performance may be varied for different benchmark problems. However, in this study for the seven selected test problems, SOS and KH exhibited the most promising result and great potential with respect to execution time also. This study gives some insights to use SOS and KH as the best-performing algorithms to the novice user who can easily get lost in the plethora of large optimization algorithms.

Fluorescent atomic defects, especially in dielectric materials, such as diamond are quite promising for several emerging quantum applications. However, efficient light extraction, directional emission, and narrow spectral emission are key challenges. We have designed dielectric metasurface exploiting Mie-resonance and the Kerker condition to address these issues. Our designed diamond metasurface, tailored for nitrogen-vacancy (NV) defect centers in diamond, predicts up to 500x improvement in the collection of 637 nm (zero phonon line) photons over that from the bare diamond. Our design achieves highly directional emission, predominantly emitting in a 20 degree lobe in the forward direction. This makes light collection more efficient, including for fiber-based collection. The predicted results are stable against the position of the emitter placed in the metaelement, thus alleviating the challenging fabrication requirement of precise positioning of the defect center. Equally importantly, our design approach can be applied to enhance single photon emission also from other defects such as SiV, other materials such as hBN, and other sources such as quantum dots.

Conceptual molten salt breeder reactor (MSBR) is under development in Bhabha Atomic Research Centre (BARC) with long-term objective of utilizing abundant thorium available in India. It is based on molten salts, which acts as fuel, blanket, and coolant for the reactor. LiF–ThF4 (77.6–22.4 mol %) is proposed as a blanket salt for Indian MSBR. A laboratory scale molten salt natural circulation loop (MSNCL) named molten active fluoride salt loop (MAFL) has been setup for thermal-hydraulic, material compatibility, and chemistry control studies. Steady-states and transient experiments have been performed in the operating temperature range of 600–750 °C. The loop operates in the power range of 250–550 W. Steady-state correlation given for natural circulation flow in a loop is compared with the steady-state experimental data. The Reynolds number was found to be in the range of 57–114. Computation fluid dynamics (CFD) simulation has also been performed for MAFL using openfoam code, and the results are compared with the experimental data generated in the loop. It has been found that predictions of openfoam are in good agreement with the experimental data. In this paper, features of the loop, its construction, and the experimental and numerical studies performed are discussed in detail.

American Journal of Agricultural EconomicsVolume 57, Issue 2 p. 361-363 Note A Bayesian Application on Cobb-Douglas Production Function S. Roy Chowdhury, S. Roy Chowdhury postdoctorate staff economistSearch for more papers by this authorVishnuprasad Nagadevara, Vishnuprasad Nagadevara graduate research associate with the Center for Agricultural and Rural Development Iowa State UniversitySearch for more papers by this authorEarl O. Heady, Earl O. Heady Curtiss Distinguished Professor and the director of the Center for Agricultural and Rural DevelopmentSearch for more papers by this author S. Roy Chowdhury, S. Roy Chowdhury postdoctorate staff economistSearch for more papers by this authorVishnuprasad Nagadevara, Vishnuprasad Nagadevara graduate research associate with the Center for Agricultural and Rural Development Iowa State UniversitySearch for more papers by this authorEarl O. Heady, Earl O. Heady Curtiss Distinguished Professor and the director of the Center for Agricultural and Rural DevelopmentSearch for more papers by this author First published: 01 May 1975 https://doi.org/10.2307/1238516Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume57, Issue2May 1975Pages 361-363 RelatedInformation

The Large Hadron Collider (LHC), at CERN will undergo major upgrades to be able to deliver peak instantaneous luminosities of about 5−7.5×1034cm−2s−1 by 2027. This High Luminosity upgrade of the LHC (HL-LHC) is expected to deliver a total of about 3000−4000fb−1 during ten years of operation. At the nominal instantaneous luminosity of the HL-LHC, a single bunch crossing will produce 140−200 proton–proton collisions. The current CMS strip tracker and the CMS Phase-1 pixel detector will not be able to survive the harsh operating conditions of the HL-LHC period. The CMS experiment will install a new silicon tracker for the HL-LHC. The Phase-2 Outer Tracker (OT) will feature increased radiation hardness, higher granularity and track separation and compatibility with higher data rates and a longer trigger latency. In addition, the OT will provide tracking information to the Level-1 trigger, allowing trigger rates to be kept at a sustainable level without sacrificing physics potential. To achieve this, the OT will be made up of modules with two closely spaced sensors read out by a single ASIC. The ASIC will correlate data from both sensors to form short track segments called stubs, to be used in tracking at Level-1. In this contribution, the design of the CMS Phase-2 OT, the technological choices and highlights of the research and development activities will be reported.

A Real-Time demonstrator based on the ATCA Pulsar-IIB custom board and on the Pattern Recognition Mezzanine (PRM) board has been developed as a flexible platform to test and characterize low-latency algorithms for track reconstruction and L1 Trigger generation in future High Energy Physics experiments.The demonstrator has been extensively used to test and characterize the Track-Trigger algorithms and architecture based on the use of the Associative Memory ASICs and of the PRM cards.The flexibility of the demonstrator makes it suitable to explore other solutions fully based on a high-performance FPGA device.

We focus on a rare, exotic decay channel of the top quark, $t\to cH$, with $H$ decaying to a pair of b-quarks produced at the High Luminosity runs of the Large Hadron Collider. Our intent is to formulate a tagging algorithm which is efficient in identifying the said decay mode of the boosted top using a large-R jet with b- and c-tagged jets inside it. We consider the production of the top quark in association with a W-boson with the top decaying through $cH$ mode, and identify different observables as the effective discriminators of the signal over the Standard Model (SM) backgrounds, and finally perform a Multi Variate Analysis (MVA) using two different boosting algorithms, viz., XGBoost and AdaBoost. We show a comparative analysis on the performance of the proposed top tagger for the two boosting algorithms, and also with conventional cut-based top tagging algorithms. The algorithm we propose shows greater efficiency over the conventional ones. Furthermore, we make use of the mathematical formalism, SHAP, originated in the Game Theory to understand the role played by each observable towards the discriminative power of the classifier. This provides a great insight of the observables used to build the classifier. The tagging algorithm proposed in this work has wider range of applicability, it can be implemented in any probes of BSM Physics involving large-R, boosted jets with substructures involving b- and c-jets. As an illustration, we consider the Vector-like quark $Y$ decaying to b-quark and a $W$-boson which resembles the inner structure of the proposed toptagger. We observe clear resonance peak at the mass of the Y which proves that the proposed tagger is useful not only to tag the top quarks decaying through the above-mentioned flavour-violating mode, also is equally efficient in probing a BSM particle giving the same final state topology.

The paper presents some investigations on the correlation of sudden frequency deviations (abbreviated as SFD) of HF radio waves propagated through the ionosphere and solar microwave bursts at 606, 2695, and 8800 MHz. It is found that correlation between SFD's and solar radio bursts improves with burst amplitude and frequency. The correlation is 100% at 2695 and 8800 MHz when the burst amplitude is greater than 500 × 10−22 w m−2 Hz−1. In addition, it is found that SFD's associated with solar radio bursts having large amplitudes show good correlation with optical flare events.

Abstract The parton distribution functions (PDFs) of the proton play a role in determining the lineshape of Z and W bosons produced at the LHC. In particular, the mode of the gauge boson virtuality is shifted with respect to the pole due to the dependence of the partonic luminosity on the boson virtuality. The knowledge of this shift contributes to the systematic uncertainty for a direct measurement of the boson mass. A detailed study of the shift and of its systematic uncertainty due to the limited knowledge of the PDFs is obtained using a tree-level model of Z and W boson production in proton-proton collisions at $$\sqrt{s}=13~\hbox {TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> . A Monte Carlo simulation is further used to validate the tree-level model and study the dependence of the shift on the transverse momentum of the gauge bosons. The tree-level calculation is found to provide a good description of the shift. The systematic uncertainty on the lineshape due to the PDFs is estimated to be below one MeV in the phase-space relevant for a future high-precision mass measurement of the gauge boson masses at the LHC.

Silicon trackers are used extensively in high energy physics experiments.Estimation of the material budget of the tracker is crucial for the physics program of any experiment, especially for precision measurements, as it has a direct impact on reconstruction performance and calculation of systematic errors.In this paper, a novel method of estimating the material budget of the CMS Tracker using three consecutive hits from a reconstructed track is presented.Comparisons are made between the material budget obtained from data, and simulated events.

The increase of the luminosity in the High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) will require the use of Tracker information in the evaluation of the Level-1 trigger in order to keep the trigger rate acceptable (i.e.: <;1MHz). In order to extract the track information within the latency constraints (<;5μs), a custom real-time system is necessary. We developed a prototype of the main building block of this system, the Pattern Recognition Mezzanine (PRM) that combines custom Associative Memory ASICs with modern FPGA devices. The architecture, functionality and test results of the PRM are described in the present work.

As the LHC will enter into its high luminosity phase (HL-LHC), operating at a luminosity of $$5-7.5\times 10^{34}~\mathrm{cm}^{-2}\mathrm{s}^{-1}$$ , the CMSCMS experiment will replace the Run 2 tracker with a new one which will be able to sustain the increased number of collisions per bunch crossing, which can be as high as 200. The tracker information will be used in the Level-1 trigger to reject low $$p_T~$$ tracks. In this paper, the performance of the modules of the proposed outer tracker in test beams is reported.

Details of the frequency standard being used in Saha Institute since June 1966 are presented. The 100 KHz output of a G.R. 1100 AP ‘primary’ standard is multiplied to produce several hundred milliwatts at 50 MHz and 500 MHz. These are applied to a K-band harmonic generator and produce marker frequencies spaced by 50 MHz in the 18–16 GHZ band. The microwave absorption line is compared to and interpolated with these markers by a communication receiver. The accuracy and stability of these markers is the same as that of the standard GR 1100 AP, which is a few parts in a billion. To get decimally related output frequencies, the system uses a chain of quintuplers and doublers. The design of these, which was formulated previously, has been perfected in the course of this development.

Journal Article Asian States and the Development of Universal International Law . Edited by R. P. Anand. Delhi: Vikas Publications, 1972. xxxii + 245 pp. No price stated Get access Subrata Roy Chowdhury Subrata Roy Chowdhury Search for other works by this author on: Oxford Academic Google Scholar British Yearbook of International Law, Volume 47, Issue 1, 1975, Pages 441–443, https://doi.org/10.1093/bybil/47.1.441 Published: 01 November 1976