Maximizing network capacity in an heterogeneous macro-micro cellular scenario

The problem of resource allocation in cellular networks has been traditionally faced at two different levels: at the network level, in terms of frequency planning and reuse pattern design, and at the cell level, in terms of cell capacity optimizations based on channel-dependent scheduling, link adaptation, power control, and so on. While this second aspect has been deeply investigated in literature, the first aspect has been mainly faced with static or semi-dynamic reuse utilization solutions. In this paper we deal with the problem of multi-cellular resource allocation in heterogeneous OFDMA environments with reuse factor equal to 1, where base stations with different power constraints coexist. In particular, we analyze the effects of different allocation schemes, independently performed in each cell, on the aggregated network-level performance. By means of simulation results, we enlighten the network scenarios in which network planning and mobile station feedbacks are (or are not) advantageous

On the effects of transmit power control on the energy consumption of WiFi network cards

Transmit power control has been largely proposed as a solution to improve the performance of packet radio systems in terms of increased throughput, spatial reuse and battery lifetime for mobile terminals. However, the benefits of transmit power control schemes on these different performance figures may strongly depend on the employed PHY technology and channel access mechanism. In this paper, we focus on the effects of power control on the energy consumption of WiFi network cards. By means of several experimental tests carried out under different operation conditions and modulation schemes, we try to justify why the reduction of the transmission power has a marginal effect on the overall energy consumption

Thermal-hydraulic analysis of the DEMO WCLL elementary cell: BZ tubes layout optimization

The Water-Cooled Lithium-Lead (WCLL) Breeding Blanket (BB) is a key component in charge of ensuring Tritium production, shield the Vacuum Vessel and remove the heat generated by plasma thermal radiation and nuclear reactions. It relies on PbLi eutectic alloy adopted as breeder and neutron multiplier and refrigerate by subcooled pressurized water. The last function is fulfilled by two independent cooling systems: First Wall (FW) that faces the plasma heat flux and the Breeding Zone (BZ) that removes the deposited power of neutron and photon interaction. Several layouts of WCLL BB system have been investigated in the last years to identify a configuration that might guarantee EUROFER temperature below the limit (550 °C) and suitable thermal-hydraulic performances. This research activity focuses on the equatorial WCLL elementary cell of the Central Outboard Segment (COB), based on the WCLL BB 2018 design of DEMO 2017 baseline, investigating the cooling performances of the BZ and FW systems and their mutual interaction, verifying the reliability to deliver the coolant at adequate design conditions (i.e. 328 °C), evaluating the Eurofer temperature field in order to optimize the BZ Double Wall Tubes (DWTs), extinguishing the hot spot onset into the structures due to the implementation of the IAEA PbLi thermal conductivity as reference. The goal of the study is to compare three specific different tubes arrangement of the BZ system: the V0.6, that is the reference configuration, the V0.6_A and V0.6_B, identifying and discussing advantages and key issues from the thermal-hydraulics point of view. The analyses have been carried out using a CFD approach, adopting the commercial ANSYS CFX code, thus a 3D finite volume model of each configuration has been developed. For each WCLL design, several steady-state analyses have been performed, to evaluate the Eurofer temperature field and the thermal-hydraulics performances under different cooling configuration, changing the position of the DWTs. The results show that the FW and BZ system have a mutual interaction. Only the V0.6_B layout can safely remove the high heat loads deposited into the elementary cell, respecting the DEMO requirements. This research activity aims at laying the basis for the finalization of the WCLL BB design

Overview on Lead-Cooled Fast Reactor Design and Related Technologies Development in ENEA

none20noThe next generation of nuclear energy systems, also known as Generation-IV reactors are being developed to meet the highest targets of safety and reliability, sustainability, economics, proliferation resistance and physical protection, with improved performances with respect to plants currently operating or presently being built. Among the proposed technologies, Lead-cooled Fast Reactors (LFRs) have been identified by nuclear industries, western Counties and developing Countries among the optimal Generation IV candidates. Since 2000, ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development is supporting the core design, safety assessment and technological development of innovative nuclear systems cooled by heavy liquid metals (HLM), and most recently fully oriented on LFRs, developing world-recognized skills in the fast spectrum core design and one of the largest European fleets of experimental facilities aiming at investigating HLM thermal-hydraulics, coolant chemistry control, corrosion behavior for structural materials and material properties in HLM environment, as well as at developing corrosion-protective coatings, components, instrumentation and innovative systems, supported by experiments and numerical tools. Efforts are also devoted in developing and validating numerical tools for the specific application to HLM systems, ranging from neutronics codes, system and core thermal-hydraulic codes, computational fluid dynamics (CFD) and fuel pin performance codes, including their coupling. The present work aims at highlighting the capabilities and competencies developed by ENEA so far in the framework of liquid metal technologies for GEN-IV LFRs. In particular, an overview on the ongoing R&D experimental program will be depicted considering the actual fleet of facilities: CIRCE, NACIE-UP, LIFUS5, LECOR, BID-1, HELENA, RACHEL and Mechanical Labs. An overview on the numerical activities performed so far and presently ongoing is also reported. Finally, an overview of the ENEA contribution to the ALFRED Project in the frame of the FALCON international consortium is reported, mainly addressing the activity ongoing in terms of core design, technology development and auxiliary systems design.mixedTarantino, Mariano; Angiolini, Massimo; Bassini, Serena; Cataldo, Sebastiano; Ciantelli, Chiara; Cristalli, Carlo; Del Nevo, Alessandro; Di Piazza, Ivan; Diamanti, Dario; Eboli, Marica; Fiore, Angela; Grasso, Giacomo; Lodi, Francesco; Lorusso, Pierdomenico; Marinari, Ranieri; Martelli, Daniele; Papa, Francesca; Sartorio, Camillo; Utili, Marco; Venturini, AlessandroTarantino, Mariano; Angiolini, Massimo; Bassini, Serena; Cataldo, Sebastiano; Ciantelli, Chiara; Cristalli, Carlo; Del Nevo, Alessandro; Di Piazza, Ivan; Diamanti, Dario; Eboli, Marica; Fiore, Angela; Grasso, Giacomo; Lodi, Francesco; Lorusso, Pierdomenico; Marinari, Ranieri; Martelli, Daniele; Papa, Francesca; Sartorio, Camillo; Utili, Marco; Venturini, Alessandr

Strategies and performance of the CMS silicon tracker alignment during LHC Run 2

The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios

Cardiovascular Efficacy and Safety of Bococizumab in High-Risk Patients

Bococizumab is a humanized monoclonal antibody that inhibits proprotein convertase subtilisin- kexin type 9 (PCSK9) and reduces levels of low-density lipoprotein (LDL) cholesterol. We sought to evaluate the efficacy of bococizumab in patients at high cardiovascular risk. METHODS In two parallel, multinational trials with different entry criteria for LDL cholesterol levels, we randomly assigned the 27,438 patients in the combined trials to receive bococizumab (at a dose of 150 mg) subcutaneously every 2 weeks or placebo. The primary end point was nonfatal myocardial infarction, nonfatal stroke, hospitalization for unstable angina requiring urgent revascularization, or cardiovascular death; 93% of the patients were receiving statin therapy at baseline. The trials were stopped early after the sponsor elected to discontinue the development of bococizumab owing in part to the development of high rates of antidrug antibodies, as seen in data from other studies in the program. The median follow-up was 10 months. RESULTS At 14 weeks, patients in the combined trials had a mean change from baseline in LDL cholesterol levels of -56.0% in the bococizumab group and +2.9% in the placebo group, for a between-group difference of -59.0 percentage points (P<0.001) and a median reduction from baseline of 64.2% (P<0.001). In the lower-risk, shorter-duration trial (in which the patients had a baseline LDL cholesterol level of ≥70 mg per deciliter [1.8 mmol per liter] and the median follow-up was 7 months), major cardiovascular events occurred in 173 patients each in the bococizumab group and the placebo group (hazard ratio, 0.99; 95% confidence interval [CI], 0.80 to 1.22; P = 0.94). In the higher-risk, longer-duration trial (in which the patients had a baseline LDL cholesterol level of ≥100 mg per deciliter [2.6 mmol per liter] and the median follow-up was 12 months), major cardiovascular events occurred in 179 and 224 patients, respectively (hazard ratio, 0.79; 95% CI, 0.65 to 0.97; P = 0.02). The hazard ratio for the primary end point in the combined trials was 0.88 (95% CI, 0.76 to 1.02; P = 0.08). Injection-site reactions were more common in the bococizumab group than in the placebo group (10.4% vs. 1.3%, P<0.001). CONCLUSIONS In two randomized trials comparing the PCSK9 inhibitor bococizumab with placebo, bococizumab had no benefit with respect to major adverse cardiovascular events in the trial involving lower-risk patients but did have a significant benefit in the trial involving higher-risk patients