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Sökning: WFRF:(Kumar Lokesh)

  • Resultat 1-19 av 19
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1.
  • Adam, J., et al. (författare)
  • Centrality dependence of particle production in p-Pb collisions at root s(NN)=5.02 TeV
  • 2015
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:6
  • Tidskriftsartikel (refereegranskat)abstract
    • We report measurements of the primary charged-particle pseudorapidity density and transverse momentum distributions in p-Pb collisions at root s(NN) = 5.02 TeV and investigate their correlation with experimental observables sensitive to the centrality of the collision. Centrality classes are defined by using different event-activity estimators, i.e., charged-particle multiplicities measured in three different pseudorapidity regions as well as the energy measured at beam rapidity (zero degree). The procedures to determine the centrality, quantified by the number of participants (N-part) or the number of nucleon-nucleon binary collisions (N-coll) are described. We show that, in contrast to Pb-Pb collisions, in p-Pb collisions large multiplicity fluctuations together with the small range of participants available generate a dynamical bias in centrality classes based on particle multiplicity. We propose to use the zero-degree energy, which we expect not to introduce a dynamical bias, as an alternative event-centrality estimator. Based on zero-degree energy-centrality classes, the N-part dependence of particle production is studied. Under the assumption that the multiplicity measured in the Pb-going rapidity region scales with the number of Pb participants, an approximate independence of the multiplicity per participating nucleon measured at mid-rapidity of the number of participating nucleons is observed. Furthermore, at high-pT the p-Pb spectra are found to be consistent with the pp spectra scaled by N-coll for all centrality classes. Our results represent valuable input for the study of the event-activity dependence of hard probes in p-Pb collisions and, hence, help to establish baselines for the interpretation of the Pb-Pb data.
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2.
  • Adam, J., et al. (författare)
  • Two-pion femtoscopy in p-Pb collisions at root(NN)-N-S=5.02 TeV
  • 2015
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:3
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the results of the femtoscopic analysis of pairs of identical pions measured in p-Pb collisions at root(NN)-N-S = 5.02 TeV. Femtoscopic radii are determined as a function of event multiplicity and pair momentum in three spatial dimensions. As in the pp collision system, the analysis is complicated by the presence of sizable background correlation structures in addition to the femtoscopic signal. The radii increase with event multiplicity and decrease with pair transverse momentum. When taken at comparable multiplicity, the radii measured in p-Pb collisions, at high multiplicity and low pair transverse momentum, are 10%-20% higher than those observed in pp collisions but below those observed in A-A collisions. The results are compared to hydrodynamic predictions at large event multiplicity as well as discussed in the context of calculations based on gluon saturation.
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3.
  • Camarasa, Clara, 1986, et al. (författare)
  • Drivers and barriers to energy-efficient technologies (EETs) in EU residential buildings
  • 2021
  • Ingår i: Energy and Built Environment. - : Elsevier BV. - 2666-1233. ; 2:3, s. 290-301
  • Tidskriftsartikel (refereegranskat)abstract
    • To achieve carbon targets, the European Union (EU) aims to promote nearly zero-energy buildings (nZEB). To enable the necessary transition, technical solutions need to converge with socio-economic factors, such values and awareness of stakeholders involved in the decision-making process. In this light, the aim of this paper is to characterise perceived drivers and barriers to nine energy-efficient technologies (EET), according to key decision-makers' and persuaders of the technology selection in the EU residential building context. Results are collected across eight EU countries, i.e. Belgium (BE), Germany (DE), Spain (ES), France (FR), Italy (IT), Netherlands (NL), Poland (PL), and United Kingdom (UK). The stakeholders’ selected are architects, construction companies, engineers, installers and demand-side actors. Data from a multi-country survey is analysed to calculate the share of 15 drivers and 21 barriers (aggregated to 5 groups), being selected for each EET and country. The 5 groups considered to analyse drivers and barriers are environmental, technical, economic, social, legal. The perceived barriers and drivers were further studied for their association across the countries using the Pearson's Chi2 and a Cramer's V tests. The results demonstrate that across all EETs and countries, the technical and economic driver groups are perceived to have the highest potential to increase the implementation rate of EET. In terms of barriers, economic aspects are seen as the foremost reason that EET are not scaling faster. In both drivers and barriers legal aspects are the least often selected. In overall the barrier groups show significant variation across countries compared to driver groups. These findings provide an evidence-basis to better understand arguments in favour and against specific EETs and, in this way, support policy makers and other interested parties to increase the market share of the selected solutions.
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4.
  • Camarasa, Clara, et al. (författare)
  • Energy-efficient retrofit measures (EERM) in residential buildings: An application of discrete choice modelling
  • 2021
  • Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Cross-country evidence on the adoption of energy-efficient retrofit measures (EERMs) in residential buildings is critical to supporting the development of national and pan-European policies aimed at fostering the energy performance upgrade of the building stock. In this light, the aim of this paper is to advance in the understanding of the probability of certain EERMs taking place in eight EU countries, according to a set of parameters, such as building typology, project types, and motivation behind the project. Using these parameters collected via a multi-country online survey, a set of discrete-choice (conditional logit) models are estimated on the probability of selecting a choice of any combination of 33 EERMs across the sampled countries. Results show that actions related to the building envelope are the most often-addressed across countries and single building elements or technology measures have a higher probability of being implemented. The modelling framework developed in this study contributes to the scientific community in three ways: (1) establishing an empirical relationship among EERMs and project (i.e., retrofit and deep retrofit), (2) identifying commonalities and differences across the selected countries, and (3) quantifying the probabilities and market shares of various EERMs.
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5.
  • Castrellon, Juan Pablo, 1989, et al. (författare)
  • Assessing the eco-efficiency benefits of empty container repositioning strategies via dry ports
  • 2023
  • Ingår i: Transportation Research Part D. - : Elsevier Ltd. - 1361-9209 .- 1879-2340. ; 120
  • Tidskriftsartikel (refereegranskat)abstract
    • Trade imbalances and global disturbances generate mismatches in the supply and demand of empty containers (ECs) that elevate the need for empty container repositioning (ECR). This research investigated dry ports as a potential means to minimize EC movements, and thus reduce costs and emissions. We assessed the environmental and economic effects of two ECR strategies via dry ports—street turns and extended free temporary storage—considering different scenarios of collaboration between shipping lines with different levels of container substitution. A multi-paradigm simulation combined agent-based and discrete-event modelling to represent flows and estimate kilometers travelled, CO2 emissions, and costs resulting from combinations of ECR strategies and scenarios. Full ownership container substitution combined with extended free temporary storage at the dry port (FTDP) most improved ECR metrics, despite implementation challenges. Our results may be instrumental in increasing shipping lines’ collaboration while reducing environmental impacts in up to 32 % of the inland ECR emissions. © 2023 The Author(s)
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6.
  • Castrellon, Juan Pablo, 1989, et al. (författare)
  • Enabling Factors and Durations Data Analytics for Dynamic Freight Parking Limits
  • 2023
  • Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; 2677:2, s. 219-234
  • Tidskriftsartikel (refereegranskat)abstract
    • Freight parking operations occur amid conflicting conditions of public space scarcity, competition with other users, and the inefficient management of loading zones (LZ) at cities’ curbside. The dynamic nature of freight operations, and the static LZ provision and regulation, accentuate these conflicting conditions at specific peak times. This generates supply–demand mismatches of parking infrastructure. These mismatches have motivated the development of Smart LZ that bring together technology, parking infrastructure, and data analytics to allocate space and define dynamic duration limits based on users’ needs. Although the dynamic duration limits unlock the possibility of a responsive LZ management, there is a narrow understanding of factors and analytical tools that support their definition. Therefore, the aim of this paper is twofold. Firstly, to identify factors for enabling dynamic parking durations policies. Secondly, to assess data analytics tools that estimate freight parking durations and LZ occupation levels based on operational and locational features. Semi-structured interviews and focus group analyses showed that public space use assessment, parking demand estimation, enforcement capabilities, and data sharing strategies are the most relevant factors when defining dynamic parking limits. This paper used quantitative models to assess different analytical tools that study LZ occupation and parking durations using tracked freight parking data from the City of Vic (Spain). CatBoost outperformed other machine learning (ML) algorithms and queuing models in estimating LZ occupation and parking durations. This paper contributes to the freight parking field by understanding how data analytics support dynamic parking limits definition, enabling responsive curbside management.
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7.
  • Holguín-Veras, José, et al. (författare)
  • Freight mode choice: Results from a nationwide qualitative and quantitative research effort
  • 2021
  • Ingår i: Transportation Research Part A: Policy and Practice. - : Elsevier BV. - 0965-8564. ; 143, s. 78-120
  • Tidskriftsartikel (refereegranskat)abstract
    • The research reported in this paper focused on studying various aspects of freight mode choice in the continental United States (US) including the influencing factors, the development of econometric models to assess the impacts of public-sector policies and changes in market conditions. To gain insight into this complex subject, the team used qualitative and quantitative research techniques. The qualitative effort involved In-Depth Interviews (IDIs) with a highly selective group of leading shippers, carriers, and receivers. The IDIs provided insight into the key factors that influence mode choice, and the barriers that limit mode shifts. The quantitative effort estimated econometric models that express freight mode choice as a function of key independent variables. A unique aspect of this research is that the models were estimated using high-quality confidential data under the custody of the United States’ Census Bureau, the Internal Revenue Service, and the Surface Transportation Board, including: the Commodity Flow Survey (CFS), the largest shipper survey in the world; the Longitudinal Business Database (LBD), a comprehensive registry of commercial establishments in the US; and the Waybill Sample, a 5% sample; together with custom-made datasets of modal characteristics prepared by the authors. Using these data, the team estimated discrete-continuous freight mode choice models representing the choice of rail or truck for 42 different commodity types, and different combinations of independent variables and weighting schemes. The paper concludes with a discussion of the policy implications of the research conducted.
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8.
  • Holguin-Veras, Jose, et al. (författare)
  • Service trip attraction in commercial establishments
  • 2021
  • Ingår i: Transportation Research Part E: Logistics and Transportation Review. - : Elsevier BV. - 1366-5545. ; 149
  • Tidskriftsartikel (refereegranskat)abstract
    • Commercial traffic in urban areas has not received the level of attention it deserves. Notwithstanding recent research on freight trip generation, other components of commercial traffic, such as commercial service traffic, have been largely overlooked. This is ironic, as the service sector represents a major and growing portion of urban and metropolitan economies. The research reported in this paper intends to help fill an important research gap through analyses of unique survey data collected by the authors. To this effect, the research comprehensively characterizes service visits to commercial establishments?in terms of frequency, purpose, duration, time of day, and other characteristics?by industry sector for two metropolitan areas. In addition, the authors estimated econometric models that express the number of service trips to commercial establishments as a function of the economic characteristics of the establishment and assessed the geographic transferability of the models obtained. To gain insight into the overall magnitude of service-related traffic, the models were applied to publicly available data to estimate the service activity in American cities of various sizes. The resulting service traffic are then used to estimate of parking requirements of service and freight vehicles for the most congested ZIP codes at these cities. The paper ends with a discussion of chief findings and policy implications.
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9.
  • Kumar Kalahasthi, Lokesh, 1988, et al. (författare)
  • A freight origin-destination synthesis model with mode choice
  • 2022
  • Ingår i: Transportation Research Part E: Logistics and Transportation Review. - : Elsevier BV. - 1366-5545. ; 157
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper develops a novel procedure to conduct a Freight Origin-Destination Synthesis (FODS) that jointly estimates the trip distribution, mode choice, and the empty trips by truck and rail that provide the best match to the observed freight traffic counts. Four models are integrated: (1) a gravity model for trip distribution, (2) a binary logit model for mode choice, (3) a Noortman and Van Es’ model for truck, and (4) a Noortman and Van Es’ model for rail empty trips. The estimation process entails an iterative minimization of a nonconvex objective function, the summation of squared errors of the estimated truck and rail traffic counts with respect to the five model parameters. Of the two methods tested to address the nonconvexity, an interior point method with a set of random starting points (Multi-Start algorithm) outperformed the Ordinary Least Squared (OLS) inference technique. The potential of this methodology is examined using a hypothetical example of developing a nationwide freight demand model for Bangladesh. This research improves the existing FODS techniques that use readily available secondary data such as traffic counts and link costs, allowing transportation planners to evaluate policy outcomes without needing expensive freight data collection. This paper presents the results, model validation, limitations, and future scope for improvements.
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10.
  • Kumar Kalahasthi, Lokesh, 1988, et al. (författare)
  • Joint modeling of arrivals and parking durations for freight loading zones: Potential applications to improving urban logistics
  • 2022
  • Ingår i: Transportation Research Part a-Policy and Practice. - : Elsevier BV. - 0965-8564. ; 166, s. 307-329
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper analyzes truck parking patterns in urban freight loading zones by jointly modeling the vehicle arrival rates and the parking durations. Three models were explored: 1) Count data (Negative Binomial) for vehicle arrivals, 2) Survival (Weibull) model for parking duration and 3) A joint model for arrivals and duration. The count data model estimates the parking demand i.e., the rate of truck arrival, while the survival model estimates the probability that a truck is parked for one more minute. The joint model is compared with separate models for predictability and performance. The dataset used in this research is obtained using a mobile phone parking appli-cation, at eight loading zones in the city Vic, Spain over an 18-month period from July 2018 to December 2019, comprised of vehicle parking durations, date, time of arrival and departure, professional activity, and vehicle type (weight). The parking activity data are complemented with built in environment variables of the loading zones, such as the number of establishments in a certain radius, the average walking distance to establishments, the presence of pedestrian pavement, the number of traffic lanes, among others. The joint model outperforms the models estimating the arrival rates and durations separately in goodness of fit and predictability. The model results showed that truck arrival rates vary significantly across days of the week, months, and arrival times. The parking durations are highly dependent on professional activity, vehicle type, and size. Tuesdays and Wednesdays have higher arrival rates compared to other days of a week (except Sundays). Among activities, the transport and parcels require longer parking du-rations. Among the vehicle types, trucks with gross weight larger than 3.5 tons park longer. This paper concludes by explaining the potential of these modeling approaches in improving urban freight operations, evaluation of various policy implications, limitations, and future research.
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11.
  • Ludowieg, Andres Regal, et al. (författare)
  • Using Machine Learning to Predict Freight Vehicles' Demand for Loading Zones in Urban Environments
  • 2023
  • Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; 2677:1, s. 829-842
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper studies demand for public loading zones in urban environments and seeks to develop a machine learning algorithm to predict their demand. Understanding and predicting demand for public loading zones can: (i) support better management of the loading zones and (ii) provide better pre-advice so that transport operators can plan their routes in an optimal way. The methods used are linear regression analysis and neural networks. Six months of parking data from the city of Vic in Spain are used to calibrate and test the models, where the parking data is transformed into a time-series format with forecasting targets. For each loading zone, a different model is calibrated to test which model has the best performance for the loading zone's particular demand pattern. To evaluate each model's performance, both root mean square error and mean absolute error are computed. The results show that, for different loading zone demand patterns, different models are better suited. As the prediction horizon increases, predicting further into the future, the neural network approaches start to give better predictions than linear models.
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12.
  • Ma, Li-Jun, et al. (författare)
  • Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium.
  • 2010
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 464:7287, s. 367-73
  • Tidskriftsartikel (refereegranskat)abstract
    • Fusarium species are among the most important phytopathogenic and toxigenic fungi. To understand the molecular underpinnings of pathogenicity in the genus Fusarium, we compared the genomes of three phenotypically diverse species: Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum f. sp. lycopersici. Our analysis revealed lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity, indicative of horizontal acquisition. Experimentally, we demonstrate the transfer of two LS chromosomes between strains of F. oxysporum, converting a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in F. oxysporum. These findings put the evolution of fungal pathogenicity into a new perspective.
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13.
  • Malik, Lokesh, et al. (författare)
  • EXPLOITING AXIAL PRIMARY RADIATION FORCE FOR ACOUSTOFLUIDIC PARTICLE TRAPPING
  • 2022
  • Ingår i: MicroTAS 2022 - 26th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419048 ; , s. 142-143
  • Konferensbidrag (refereegranskat)abstract
    • In the present study, we demonstrate an acoustofluidic trapping technique based on the standing bulk acoustic waves (S-BAW) generated inside a uniquely designed chamber - the 'shaped trap' that enables the particle to experience the axial primary radiation force (A-PRF) along the flow direction as the main trapping force.
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15.
  • Pathak, Uma, et al. (författare)
  • An easy access to thiazolines and thiazines via tandem S-alkylation- cyclodeamination of thioamides/haloamines
  • 2011
  • Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 13:7, s. 1648-1651
  • Tidskriftsartikel (refereegranskat)abstract
    • This is the first report of a facile synthesis of thiazolines and thiazines from a self-catalyzed, water assisted tandem S-alkylation-cyclodeamination reaction of thioamides/haloamines. The reaction is clean and efficient with simple product work-up, and is applicable to a variety of substrates
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16.
  • Shetty, BSP, et al. (författare)
  • Inflammatory Biomarkers Interleukin 1 Beta (IL-1β) and Tumour Necrosis Factor Alpha (TNF-α) Are Differentially Elevated in Tobacco Smoke Associated COPD and Biomass Smoke Associated COPD
  • 2021
  • Ingår i: Toxics. - : MDPI AG. - 2305-6304. ; 9:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic obstructive pulmonary disease (COPD), the leading cause of mortality and morbidity worldwide, is characterized by abnormal activation of inflammatory cells. The increased pro-inflammatory cytokines, such as tumour necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β), further amplify the inflammation. We evaluated the dose response relationship of IL-1β and TNF-α levels and severity of airflow limitation, and differential responses in IL-1β and TNF-α between biomass COPD (BMS-COPD) and tobacco smoke COPD (TS-COPD) using a case control design in 160 subjects. Patients with COPD had higher serum levels of both IL-1β and TNF-α compared to healthy controls. A large difference in TNF-α was observed between TS-COPD and BMS-COPD, where TS-COPD patients had much higher levels. Serum IL-1β levels were higher in BMS-COPD. Levels of IL-1β correlated better with severity of airflow limitation than TNF-α levels. Both TNF-α and IL-1β levels had a negative linear relationship with Forced Expiratory Volume in 1st second (FEV1) and six-minute walk distance. The correlations were stronger with FEV1 than six-minute walk distance. The correlations of TNF-α and IL-1β with St George Respiratory Questionnaire (SGRQ) scores and body mass index (BMI) were not significant. In conclusion, the levels of pro-inflammatory cytokines TNF-α and IL-1β are differently elevated in TS-COPD and BMS-COPD, respectively.
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17.
  • Tank, Rekha, et al. (författare)
  • Hydrogen peroxide mediated efficient amidation and esterification of aldehydes : Scope and selectivity
  • 2011
  • Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 13:12, s. 3350-3354
  • Tidskriftsartikel (refereegranskat)abstract
    • An efficient method for the amidation and esterification of aldehydes utilizing hydrogen peroxide as an oxidant has been developed. Cyclic amines and primary alcohols selectively reacted with aromatic aldehydes under mild conditions to yield the corresponding amides and esters
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18.
  • Volpe, Giovanni, 1979, et al. (författare)
  • Roadmap for optical tweezers
  • 2023
  • Ingår i: Journal of Physics-Photonics. - : IOP Publishing. - 2515-7647. ; 5:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.
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19.
  • Wide, Per, et al. (författare)
  • Efficiency effects of information on operational disruption management in port hinterland freight transport : simulation of a Swedish dry port case
  • 2023
  • Ingår i: International Journal of Logistics. - : Taylor and Francis Ltd.. - 1367-5567 .- 1469-848X. ; 26:5, s. 524-547
  • Tidskriftsartikel (refereegranskat)abstract
    • Management of operational disruptions with support of information is essential to facilitate the shift from road to rail and to ensure efficient hinterland intermodal transport chains. Therefore, the purpose of this paper is to investigate the operational efficiency effects of information on operational disruption management in hinterland transport with a dry port to facilitate efficient intermodal hinterland transport. For that purpose, a simulation model with five scenarios was developed and applied using empirical data from a real-world case of a hinterland transport chain with a dry port. The results show that the resource utilisation of the trucks that deliver containers from the dry port to the receivers can be increased using the information that supports management of the disruption. Nevertheless, in attempts to increase resource utilisation when managing the disruption, issues arose from efficiency measures that are important for other actors, e.g. the receivers. 
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