148 research outputs found

    Chance-constrained Calculation of the Reserve Service Provided by EV Charging Station Clusters in Energy Communities

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    The concept of energy community is currently under investigation as it is considered central into the energy transition process. One of the main aspects of the successful implementation of community lays in the energy management system that coordinates exchanges among prosumers. This paper deals with the optimal energy management of a local energy community of dc microgrids with electric vehicle charging stations, considering local reserve provided by storage units and vehicle batteries. A two-stage optimal procedure is proposed to assess the optimal scheduling of resources for each community participant. Additionally, the optimal up and down reserve levels able to cover random fluctuations in photovoltaic generation within each EV-based microgrid are determined by a set of specific chance constraints

    Physical Confinement Promoting Formation of Cu2O−Au Heterostructures with Au Nanoparticles Entrapped within Crystalline Cu2O Nanorods

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    Building on the application of cuprite (Cu2O) in solar energy technologies and reports of increased optical absorption caused by metal-to-semiconductor energy transfer, a confinement-based strategy was developed to fabricate high aspect ratio, crystalline Cu2O nanorods containing entrapped gold nanoparticles (Au nps). Cu2O was crystallized within the confines of track-etch membrane pores, where this physical, assembly based method eliminates the necessity of specific chemical interactions to achieve a well-defined metal−semiconductor interface. With high-resolution scanning/transmission electron microscopy (S/TEM) and tomography, we demonstrate the encasement of the majority of Au nps by crystalline Cu2O and show crystalline Cu2O−Au interfaces that are free of extended amorphous regions. Such nanocrystal heterostructures are good candidates for studying the transport physics of metal/semiconductor hybrids for optoelectronic applications

    First-principle based multi-channel integrated modelling in support to the design of the Divertor Tokamak Test facility

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    An intensive integrated modelling work of main scenarios of the new tokamak DTT (Divertor Tokamak Test facility) with the Single Null divertor configuration has been performed using first-principle quasi-linear transport models, in support to the design of the device and to the definition of its scientific work-programme. First results of this integrated modelling work on DTT (R0= 2.14 m, a= 0.65 m) are presented here along with outcome of the gyrokinetic simulations used to validate the reduced models in the DTT range of parameters. As a result of this work, the heating mix was defined, the size of device was increased to R0= 2.19 m and a= 0.70 m, the use of pellets for fuelling has been advised and reference profiles for diagnostic design, estimates of neutron yields and fast particle losses have become available.</p

    A High Statistics Measurement of the Lambdac+ Lifetime

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    A high statistics measurement of the Lambdac+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat.) +/- 2.5 (syst.) fs from 8034 +/- 122 Lambdac -> pKpi decays represents a significant improvement over the present world average.Comment: Submitted to Physical Review Letter

    A Measurement of the Ds+ Lifetime

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    A high statistics measurement of the Ds+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, Ds+ -> phi(1020)pi+ and Ds+ -> \bar{K}*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5 (stat.) +/- 5.1 (syst.) fs using 8961 +/- 105 Ds+ -> phi(1020)pi+ and 4680 +/- 90 Ds+ -> \bar{K}*(892)0K+ decays. This is a significant improvement over the present world average.Comment: 5 pages, 3 figures, 2 tables, submitted to PR

    Search for CP Violation in the decays D+ -> K_S pi+ and D+ -> K_S K+

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    A high statistics sample of photo-produced charm from the FOCUS(E831) experiment at Fermilab has been used to search for direct CP violation in the decays D+->K_S pi+ and D+ -> K_S K+. We have measured the following asymmetry parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%, A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+) = (+7.1 +/- 6.1 +/- 1.2)% relative to D+->K_S pi+. The first errors quoted are statistical and the second are systematic. We also measure the relative branching ratios: \Gamma(D+->\bar{K0}pi+)/\Gamma(D+->K-pi+pi+) = (30.60 +/- 0.46 +/- 0.32)%, \Gamma(D+->\bar{K0}K+)/\Gamma(D+->K-pi+pi+) = (6.04 +/- 0.35 +/- 0.30)% and \Gamma(D+->\bar{K0}K+)/\Gamma(D+->\bar{K0}pi+) = (19.96 +/- 1.19 +/- 0.96)%.Comment: 4 pages, 3 figure

    Measurement of the D+ and Ds+ decays into K+K-K+

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    We present the first clear observation of the doubly Cabibbo suppressed decay D+ --> K-K+K+ and the first observation of the singly Cabibbo suppressed decay Ds+ --> K-K+K+. These signals have been obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS(E831) experiment at Fermilab. We measure the following relative branching ratios: Gamma(D+ --> K-K+K+)/Gamma(D+ --> K-pi+pi+) = (9.49 +/- 2.17(statistical) +/- 0.22(systematic))x10^-4 and Gamma(Ds+ --> K-K+K+)/Gamma(Ds+ --> K-K+pi+) = (8.95 +/- 2.12(statistical) +2.24(syst.) -2.31(syst.))x10^-3.Comment: 10 pages, 8 figure

    A Non-parametric Approach to the D+ to K*0bar mu+ nu Form Factors

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    Using a large sample of D+ -> K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first measurements of the helicity basis form factors free from the assumption of spectroscopic pole dominance. We also present the first information on the form factor that controls the s-wave interference discussed in a previous paper by the FOCUS collaboration. We find reasonable agreement with the usual assumption of spectroscopic pole dominance and measured form factor ratios.Comment: 14 pages, 5 figures, and 2 tables. We updated the previous version by changing some words, removing one plot, and adding two tables. These changes are mostly stylisti

    A measurement of branching ratios of D+D^+ and Ds+D^+_s hadronic decays to four-body final states containing a KSK_S

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    We have studied hadronic four-body decays of D+D^+ and Ds+D^+_s mesons with a KSK_S in the final state using data recorded during the 1996-1997 fixed-target run at Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of Γ(D+KSKπ+π+)/Γ(D+KSπ+π+π)=0.0768±0.0041±0.0032\Gamma(D^+\to K_S K^-\pi^+\pi^+)/\Gamma(D^+\to K_S \pi^+\pi^+\pi^-)=0.0768\pm0.0041\pm0.0032. We make the first observation of three new decay modes with branching ratios Γ(D+KSK+π+π)/Γ(D+KSπ+π+π)=0.0562±0.0039±0.0040\Gamma(D^+\to K_S K^+\pi^+\pi^-)/\Gamma(D^+\to K_S \pi^+\pi^+\pi^-)=0.0562\pm0.0039\pm0.0040, \Gamma(D^+\to\K_S K^+ K^-\pi^+)/\Gamma(D^+\to K_S \pi^+\pi^+\pi^-)=0.0077\pm0.0015\pm0.0009, and Γ(Ds+KSK+π+π)/Γ(Ds+KSKπ+π+)=0.586±0.052±0.043\Gamma(D^+_s\to K_S K^+\pi^+\pi^-)/\Gamma(D^+_s\to K_S K^-\pi^+\pi^+)=0.586\pm0.052\pm0.043, where in each case the first error is statistical and the second error is systematic.Comment: 4 pages, 1 table, 2 figures, submitted to Physical Review Letter

    Measurements of Ξc+\Xi_c^{+} Branching Ratios

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    Using data collected by the fixed target Fermilab experiment FOCUS, we measure the branching ratios of the Cabibbo favored decays Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+, Ξc+Σ+Kˉ(892)0\Xi_c^+ \to \Sigma^+ \bar{K}^{*}(892)^0, and Ξc+Λ0Kπ+π+\Xi_c^+ \to \Lambda^0K^-\pi^+\pi^+ relative to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.91±0.11±0.040.91\pm0.11\pm0.04, 0.78±0.16±0.060.78\pm0.16\pm0.06, and 0.28±0.06±0.060.28\pm0.06\pm0.06, respectively. We report the first observation of the Cabibbo suppressed decay Ξc+Σ+K+K\Xi_c^+ \to \Sigma^+K^+K^- and we measure the branching ratio relative to Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+ to be 0.16±0.06±0.010.16\pm0.06\pm0.01. We also set 90% confidence level upper limits for Ξc+Σ+ϕ\Xi_c^+ \to \Sigma^+ \phi and Ξc+Ξ(1690)0(Σ+K)K+\Xi_c^+ \to \Xi^*(1690)^0(\Sigma^+ K^-) K^+ relative to Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+ to be 0.12 and 0.05, respectively. We find an indication of the decays Ξc+ΩK+π+\Xi_c^+ \to \Omega^-K^{+}\pi^+ and Ξc+Σ(1385)+Kˉ0\Xi_c^+ \to \Sigma^{*}(1385)^+ \bar{K}^0 and set 90% confidence level upper limits for the branching ratios with respect to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.12 and 1.72, respectively. Finally, we determine the 90% C.L. upper limit for the resonant contribution Ξc+Ξ(1530)0π+\Xi_c^+ \to \Xi^{*}(1530)^0 \pi^+ relative to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.10.Comment: 14 pages, 8 figure
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