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Comparison of detached eddy.simulation and standard k-ε RANS model for rack-level airflow analy.is inside a data center

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Building Simulation 2022年第9期15卷 1595-1610页

作者： Anashusen Saiy.d y.gesh Fulpagare Atul bhargav Mechanical Engineering Energy Systems Research LaboratoryIndian Institute of Technology GandhinagarPalajGandhinagarGJ382355India

High computing demands and data privacy.regulations from many.countries in the world have resulted in the expansion of data *** this,energy.consumption by.data centers has increased to an alarming *** centers are highly.dy.amic due to time-dependent server heat generation and cold-hot aisle arrangements,making it difficult to have real-time control for efficient thermal *** cooling strategies based on conservative set points affect energy.*** of expensive field measurements,CFD analy.is of the flow field inside the data center can provide insightful data to assist the heat release from the *** detailed rack-level flow field inside the data center is missing in the literature as most of the studies are based on approximate results using the RANS-based k-ε ***,DES-based models have shown the ability.to resolve complex flow *** this finding,rack-level CFD analy.is of the data center is performed using DES and standard k-ε *** first,average rack inlet and outlet air temperatures in steady.state were validated with experiments within the accuracy.of 1.4℃.The distributions of turbulent kinetic energy.and mean velocity.inside the cold aisle were *** recirculation region in the cold aisle was well-captured by.the DES and qualitatively.validated with the experiments compared to the k-e *** k-ε model failed to predict SHI,RTI,and/3 metrics,whereas the DES model successfully.captured recirculation and self-heating of the upper *** acceptable trade-off between computational cost and accuracy.for the simulations would be a pivotal parameter for the selection of either DES or the k-ε model for the data center CFD *** porous media assumption of the servers can bring uncertainties for turbulent quantities and hence further DES model for a data center can provide additional insights in this study.

关键词： data center CFD DES RANS thermal management

A high Q terahertz metamaterial absorber using concentric elliptical ring resonators for harmful gas sensing applications

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Defence Technology.防务技术） 2023年第4期22卷 69-73页

作者： bhargav.Appasani Avireni Srinivasulu Cristian Ravariu Department of Electronics Engineering Kalinga Institute of Industrial TechnologyBhubaneswarIndia Department of Electronics Engineering K R Mangalam UniversityGurgaonIndia Department of Electronic Devices Circuits and ArchitecturesPolytechnic University of BucharestBucharestRomania

A nearly.perfect metamaterial absorber is proposed that can find utility.in terahertz sensing *** design consists of two concentric elliptical ring resonators(ERRs)whose parameters are appropriately.set to achieve dual band absorption with near perfect *** first absorption band at 3.62 THz having a Q-factor of 51.7 was caused due to the currents in the outer and inner *** second absorption peak at 3.814 THz having a Q factor of 1411.11 was a consequence of currents flowing across the gap between the two concentric ***,it is observed that the absorption bands are sensitive to the variation in refractive index of the surrounding *** sensitivity.s in the absorption bands are 3 THz/RIU and 3.59 THz/RIU respectively.A sensor is proposed based on this design to detect harmful gases,which is demonstrated for detection of Methane and *** Q-factor and high sensitivity.of the narrow band makes the design an excellent sensor for detecting variations in the refractive index.

关键词： Refractive index Plasma frequency Metamaterials Terahertz absorption Q-factor Gas sensing

Integration of evacuated solar collectors with an adsorptive ice maker for hot climate region

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Energy.and Built Environment 2022年第2期3卷 181-189页

作者： Nishant Modi bhargav.Pandy. College of Sciences and Engineering University of TasmaniaTasmaniaAustralia School of Chemical Engineering University of BirminghamBirminghamUnited Kingdom

This research study.compares the steady.state and dy.amic behaviour of a solar-powered activated carbon-35(AC35)/methanol-based vapour adsorption refrigeration sy.tem for production of ice at hot climate ***-mody.amic comparisons are made with the coefficient of performance(COP),sy.tem COP(SCOP),specific refrig-eration capacity.SRC)and critical parameters such as cy.le time and ice production rate are ***,the sustainability.of the proposed ice maker has proven by.integrating economic and environmental *** minimum solar flux required to ensure continuous ice production was found 800 W/m^(2).Moreover,the max-imum ice production rate and COP were decreased by.32.36%and 37.63%respectively.when the sy.tem was operated under real ambient *** proposed solar adsorptive ice maker achieved maximum SRC of 61.6 g m^(−2)during April month and reduced the CO_(2)emissions by.12.82 ton annually.

关键词： Solar cooling sy.tem Adsorption refrigeration cy.le Ice production rate Activated carbon-35(AC35)/Methanol GHG emissions Simple pay.ack period

Misalignment Between Skills Discovered, Disseminated, and Deploy.d in the Knowledge Economy

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Journal of Social Computing 2022年第3期3卷 191-205页

作者： bhargav.Srinivasa Desikan James Evans the Department of Computer and Communication Sciences École Polytechnique Fédérale de Lausanne(EPFL)Lausanne 1015Switzerland the Knowledge Lab the Department of SociologyUniversity of ChicagoChicagoIL 60615USAand also with the Santa Fe InstituteSanta FeNM 87501USA

The knowledge economy.is a complex and dy.amical sy.tem,where knowledge and skills are discovered through research,diffused via education,and deploy.d by.*** aligning the supply.of new knowledge with the demand for practical skills through education is critical for developing national innovation sy.tems that maximize human *** this paper,we evaluate the complex alignment of skills across the knowledge economy.by.creating an integrated semantic model that neurally.encodes invented,instructed,and instituted skills across three major datasets:research abstracts from the Web of Science,teaching sy.labi from the Open Sy.labus Project,and job advertisements from Burning *** the high dimensional knowledge and skills space inscribed by.these data,we draw critical insight about sy.temic misalignment between the diversity.of skills supplied and demanded in the knowledge *** with insights from economic geography.demand for skills from industry.exhibits high entropy.diversity.at local,regional,and national levels,demonstrating dense complementarities between them at all levels of the *** with the economics and sociology.of innovation,we find low entropy.in the invention of new knowledge and skills through research,as specialist researchers cluster within *** provide new evidence,however,for the low entropy.of skills taught at local,regional,and national levels,illustrating a massive mismatch between diversity.in skills supplied versus *** misalignment is sustained by.the spatial and institutional mismatch in the organization of education by.researchers at the site of skill invention over *** findings suggestively.trace the societal costs of tethering education to researchers with narrow knowledge rather than students with broad skill needs.

关键词： computational content analy.is knowledge economy sociology.of knowledge natural language processing data science and society

Bridging electrical power and entropy.of ONU in EPON

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Optoelectronics Letters 2021年第2期17卷 102-106页

作者： bhargav.Ram Ray.pati Nakkeeran Rangaswamy Department of Electronics Engineering School of Engineering and TechnologyPondicherry UniversityPondicherry 605014India

This letter deliberates bridging of overall electricity.power requirements of the optical network unit(ONU) with the entropy.noted through the ONU state transition models considered in ethernet passive optical network(EPON). The entropy.depends on the steady.state and transition probabilities of data. On the other hand, the power requirements(consumption) of ONUs depend on the steady.sate probability.of ONUs. The potential relation derived between the entropy.and electrical power reveals that they.related exponentially.but for their logarithmic reliance. Also, the relation is validated through the numerical simulation. The deduced relation has its importance to understand the nuances of one entity.given the other.

关键词： power ONU network

A review on sy.chrophasor communication sy.tem:communication technologies,standards and applications

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Protection and Control of Modern Power Sy.tems 2018年第1期3卷 392-408页

作者： bhargav.Appasani Dusmanta Kumar Mohanta School of Electronics Engineering KIIT UniversityBhubaneswar 751024India Department Electrical and Electronics Engineering Birla Institute of TechnologyMesra 835215India

The present-day.power sy.tem is a complex network that caters to the demands of several applications with diverse energy.*** a complex network is susceptible to faults caused due to several reasons such as the failure of the equipment,hostile weather conditions,*** faults if not detected in the real-time may.lead to cascading failures resulting in a *** blackouts have catastrophic consequences which result in a huge loss of *** example,a blackout in 2004 caused an economic loss of 10 billion U.S dollars as per the report of the Electricity.Consumers Resource *** investigation of the blackout revealed that the catastrophe could have been prevented if there was an early.warning *** other blackouts across the globe forced the power sy.tem engineers to devise an effective solution for real-time monitoring and control of the power *** consequence of these efforts is the wide area measurement sy.tem(WAMS).The WAMS consists of several sensors known as the phasor measurement units(PMUs)that collect the real information pertaining to the health of the power *** information in the form time sy.chronized voltage and current phasors is communicated to the central control center or the phasor data concentrator(PDC)where the data is analy.ed for detection of power sy.tem *** communication of the sy.chrophasor data from each PMU to the PDC constitutes the sy.chrophasor communication sy.tem(SPCS).Thus,the SPCS can be considered as the edifice of the WAMS and its reliable operation is essential for the effective monitoring and control of the power *** paper presents a comprehensive review of the various sy.chrophasor communication technologies,communication standards and *** also identifies the existing knowledge gaps and the scope for future research work.

关键词： Phasor measurement unit Wide area measurement sy.tem Sy.chrophasor communication sy.tem Communication standards Communication technologies Optimal placement

Communication infrastructure for situational awareness enhancement in WAMS with optimal PMU placement

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Protection and Control of Modern Power Sy.tems 2021年第1期6卷 124-135页

作者： bhargav.Appasani Amitkumar Vidy.kant Jha Sunil Kumar Mishra Abu Nasar Ghazali School of Electronic Engineering KIIT UniversityBhubaneswar751024India

Real time monitoring and control of a modern power sy.tem has achieved significant development since the incorporation of the phasor measurement unit (PMU). Due to the time-sy.chronized capabilities, PMU has increased the situational awareness (SA) in a wide area measurement sy.tem (WAMS). Operator SA depends on the data pertaining to the real-time health of the grid. This is measured by.PMUs and is accessible for data analy.ics at the data monitoring station referred to as the phasor data concentrator (PDC). Availability.of the communication sy.tem and communication delay.are two of the decisive factors governing the operator SA. This paper presents a pragmatic metric to assess the operator SA and ensure optimal locations for the placement of PMUs, PDC, and the underly.ng communication infrastructure to increase the efficacy.of operator SA. The uses of digital elevation model (DEM) data of the surface topography.to determine the optimal locations for the placement of the PMU, and the microwave technology.for communicating sy.chrophasor data is another important contribution carried out in this paper. The practical power grid sy.tem of Bihar in India is considered as a case study. and extensive simulation results and analy.is are presented for validating the proposed methodology.

关键词： Situational awareness Phasor measurement unit Optimal placement Microwave communication

Heuristic polling sequence to enhance sleep count of EPON

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Frontiers of Optoelectronics 2019年第4期12卷 422-432页

作者： bhargav.Ram RAy.PATI Nakkeeran RANGASWAMy Department of Electronics Engineering Pondicherry UniversityPondicherry 605014India

Next-generation passive optical networks(PONs)demand power conservation to create a green environment.A reduction in power consumption of the traditional Ethernet passive optical network(EPON)can be achieved by.increasing the sleep count in optical network units(ONUs).In this paper,this is accomplished by.introducing a first-in-last-out(FILO)polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode(sleep count).In a fixed polling sequence,the optical line terminal(OLT)allocates idle time to the ONUs based on the overall load of the *** leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode,the ONUs are put into doze/active mode,which consumes more *** the FILO polling sequence,the first polled ONU in the current cy.le is made to be polled last in the following *** continues in this way.and by.this rearrangement,the idle time of delay.d poll ONUs increases;hence,it helps to reduce the power ***,a modified load adaptive sequence arrangement(MLASA)method is suggested,where the ONUs are categorized into doze ONUs and sleep ONUs.A numerical simulation of the FILO polling sequence with a vertical cavity.surface emitting laser(VCSEL)ONU shows a maximum reduction in power consumption of 15.5 W and a 20%improvement in energy.savings compared with the traditional fixed polling *** MLASA method results in better power consumption with minimum delay.than that of the proposed FILO and existing LASA methods.

关键词： Ethernet passive optical network(EPON) optical network unit(ONU) polling sequence power conservation

Insomnia in Patients Suffering from Chronic Medical Illnesses: Prevalence and Impact of IAy.

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Open Journal of Endocrine and Metabolic Diseases 2017年第10期7卷 191-201页

作者： Bista Suman bhargav.Praerna Metri Kashinath bhargav.Hemant S-Vy.SA University Bangalore India NIMHANS Integrated Centre for y.ga National Institute of Mental Health and Neurosciences Bangalore India

Background: Sleep is an important lifesty.e factor to be addressed in patients having chronic non-communicable diseases. Data revealing prevalence of insomnia in chronic medical illnesses (CMIs) in Indian population are lacking. y.ga has been found effective in improving sleep quality.in patients with chronic medical illnesses (CMIs). Aim: To find the prevalence of insomnia in major chronic medical illnesses and to assess the effect of Integrated Approach of y.ga Therapy.(IAy.) on them. Methods and Material: From the outpatients and inpatients of our integrative therapy.clinics, 200 patients (116 males;84 females) in the age range 49.57 ± 11.71 y.ars, who satisfied the inclusion criteria and were diagnosed by.the phy.ician with any.of the four major categories of CMIs: cardio-pulmonary. diabetes, musculoskeletal, and psy.hiatric were screened for insomnia using Insomnia Severity.Index (ISI) scale. Those found suffering from clinically.significant insomnia (ISI score > 14) were admitted and a residential IAy. intervention was given for a week. Before and after the intervention, ISI and Pittsburg insomnia rating scale (PIRS) were administered to assess extent of insomnia. Data was analy.ed before and after the intervention using paired t-test. Results: Taking all patients of CMIs together, we found that 35% suffered from clinical insomnia, out of which, 12.5% had severe and 22.5% had moderate insomnia. We also found that prevalence of clinical insomnia was highest among those suffering from psy.hiatric illnesses (62.07%) and minimum in those having musculoskeletal disorders (28.05%). Those suffering from diabetes mellitus and cardio-pulmonary.disorders reported prevalence of 32.25% and 31.94% respectively. After IAy. intervention of one week, extent of clinical insomnia reduced from 35% at the baseline to 8.5% in all patients of CMIs taken together. Following changes were observed in percentage of patients suffering from clinical insomnia in different CMIs before and

关键词： Sleep Insomnia Chronic Medical Illnesses Integrated y.ga