657 research outputs found

    DVB-C2: Ready-PlugFest-Go

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    DVB-C2 is the 3rd member of the DVB family of second generation transmission systems. Both the DVB-C2 Technical Specification (EN 302 769) [1] and the DVB-C2 Implementation Guidelines (TS 102 991) [2] have been approved by ETSI in 2011 in its current version. The two major building blocks of DVB-C2 are the LDPC (Low Density Parity Check) FEC (Forward Error Correction) Code and the OFDM (Orthogonal Frequency Division Multiplex) modulation scheme. Using DVB-C2, cable operators will be able to increase their downstream capacity of today about 5 Gbit/s to more than 8 Gbit/s. DVB has completed the system design work by system evaluation and verification and has run two PlugFests with prototype equipment in 2012. Both the professional equipment industry and the CE-industry made excellent progress in the implementation of this new standard in future-proof products. Now it is up to Cable operators to start the deployment of DVB-C2. First field tests have been performed and there are plans of a first operator to start DVB-C2 transmission in 4 big cites in Germany. It is obviously a challenge for the relevant market partners to introduce a disrup-tive new technology, which requires the replacement of all deployed Customer Premises Equipment (CPE)

    Fast Inclusive Flavour Tagging at LHCb

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    The task of identifying B meson flavor at the primary interaction point in the LHCb detector is crucial for measurements of mixing and timedependent CP violation. Flavor tagging is usually done with a small number of expert systems that find important tracks to infer the B meson flavor from. Recent advances show that replacing all of those expert systems with one ML algorithm that considers all tracks in an event yields an increase in tagging power. However, training the current classifier takes a long time and it is not suitable for use in real time triggers. In this work we present a new classifier, based on the DeepSet architecture. With the right inductive bias of permutation invariance, we achieve great speedups in training (multiple hours vs 10 minutes), a factor of 4-5 speed-up in inference for use in real time environments like the trigger and less tagging asymmetry. For the first time we investigate and compare performances of these “Inclusive Flavor Taggers” on simulation of the upgraded LHCb detector for the third run of the LHC

    Thermo-Elastic Topology Optimization For High Temperatures Gradients Using Load Separation

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    Designing components for thermo-mechanical loads is a challenging process. While mechanical loads like forces or pressure demand a stiff and thick-walled design, thermal loads create temperature gradients, resulting in thermo-mechanical stress from the structure's temperature proportional and, therefore, uneven expansion. In contrast to a pure mechanical load case, an initial design before optimization can already include stress levels beyond the limit of the material. Therefore, common optimization approaches for a preliminary design use exemplary systems with low-temperature gradients, so thermal stresses do not exceed the limit. From there, energy density is used to calculate the topology optimizations sensitivity and therefore decide which elements to remove and which to keep. This paper describes a novel approach for reducing thermo-mechanical stress by following the stress corresponding temperature gradients from the heat source to the sink to calculate a new sensitivity that helps to grow cooling channels. The optimization is exemplarily shown on a piston for internal combustion engines. While handling delta temperatures of 600K, results show a reduction in thermo-mechanical stress while reducing the component's mass. Because the approach reduces critical stress in a component, it allows the initial design (before the topology optimization) to have stress levels way above yield strength

    TweTriS: Twenty trillion-atom simulation

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    Significant improvements are presented for the molecular dynamics code ls1 mardyn — a linked cell-based code for simulating a large number of small, rigid molecules with application areas in chemical engineering. The changes consist of a redesign of the SIMD vectorization via wrappers, MPI improvements and a software redesign to allow memory-efficient execution with the production trunk to increase portability and extensibility. Two novel, memory-efficient OpenMP schemes for the linked cell-based force calculation are presented, which are able to retain Newton’s third law optimization. Comparisons to well-optimized Verlet list-based codes, such as LAMMPS and GROMACS, demonstrate the viability of the linked cell-based approach. The present version of ls1 mardyn is used to run simulations on entire supercomputers, maximizing the number of sampled atoms. Compared to the preceding version of ls1 mardyn on the entire set of 9216 nodes of SuperMUC, Phase 1, 27% more atoms are simulated. Weak scaling performance is increased by up to 40% and strong scaling performance by up to more than 220%. On Hazel Hen, strong scaling efficiency of up to 81% and 189 billion molecule updates per second is attained, when scaling from 8 to 7168 nodes. Moreover, a total of 20 trillion atoms is simulated at up to 88% weak scaling efficiency running at up to 1.33 PFLOPS. This represents a fivefold increase in terms of the number of atoms simulated to date.BMBF, 01IH16008, Verbundprojekt: TaLPas - Task-basierte Lastverteilung und Auto-Tuning in der Partikelsimulatio

    The Interplay Between Host Genetic Variation, Viral Replication, and Microbial Translocation in Untreated HIV-Infected Individuals

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    Systemic immune activation, a major determinant of human immunodeficiency virus (HIV) disease progression, is the result of a complex interplay between viral replication, dysregulation of the immune system, and microbial translocation due to gut mucosal damage. Although human genetic variants influencing HIV load have been identified, it is unknown how much the host genetic background contributes to interindividual differences in other determinants of HIV pathogenesis such as gut damage and microbial translocation. Using samples and data from 717 untreated participants in the Swiss HIV Cohort Study and a genome-wide association study design, we searched for human genetic determinants of plasma levels of intestinal fatty acid-binding protein (I-FABP/FABP2), a marker of gut damage, and of soluble CD14 (sCD14), a marker of lipopolysaccharide bioactivity and microbial translocation. We also assessed the correlations between HIV load, sCD14, and I-FABP. Although we found no genome-wide significant determinant of the tested plasma markers, we observed strong associations between sCD14 and both HIV load and I-FABP, shedding new light on the relationships between processes that drive progression of untreated HIV infectio

    Intergenerational impacts of maternal mortality: Qualitative findings from rural Malawi

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    Background: Maternal mortality, although largely preventable, remains unacceptably high in developing countries such as Malawi and creates a number of intergenerational impacts. Few studies have investigated the far-reaching impacts of maternal death beyond infant survival. This study demonstrates the short- and long-term impacts of maternal death on children, families, and the community in order to raise awareness of the true costs of maternal mortality and poor maternal health care in Neno, a rural and remote district in Malawi. Methods: Qualitative in-depth interviews were conducted to assess the impact of maternal mortality on child, family, and community well-being. We conducted 20 key informant interviews, 20 stakeholder interviews, and six sex-stratified focus group discussions in the seven health centers that cover the district. Transcripts were translated, coded, and analyzed in NVivo 10. Results: Participants noted a number of far-reaching impacts on orphaned children, their new caretakers, and extended families following a maternal death. Female relatives typically took on caregiving responsibilities for orphaned children, regardless of the accompanying financial hardship and frequent lack of familial or governmental support. Maternal death exacerbated children’s vulnerabilities to long-term health and social impacts related to nutrition, education, employment, early partnership, pregnancy, and caretaking. Impacts were particularly salient for female children who were often forced to take on the majority of the household responsibilities. Participants cited a number of barriers to accessing quality child health care or support services, and many were unaware of programming available to assist them in raising orphaned children or how to access these services. Conclusions: In order to both reduce preventable maternal mortality and diminish the impacts on children, extended families, and communities, our findings highlight the importance of financing and implementing universal access to emergency obstetric and neonatal care, and contraception, as well as social protection programs, including among remote populations

    Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era

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    The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed here. The main Upgrade II detector will be installed in long shutdown 4 of the LHC (2030) and will build on the strengths of the current LHCb experiment and the Upgrade I. It will operate at a luminosity up to 2×1034 cm−2s−1, ten times that of the Upgrade I detector. New detector components will improve the intrinsic performance of the experiment in certain key areas. An Expression Of Interest proposing Upgrade II was submitted in February 2017. The physics case for the Upgrade II is presented here in more depth. CP-violating phases will be measured with precisions unattainable at any other envisaged facility. The experiment will probe b → sl+l−and b → dl+l− transitions in both muon and electron decays in modes not accessible at Upgrade I. Minimal flavour violation will be tested with a precision measurement of the ratio of B(B0 → μ+μ−)/B(Bs → μ+μ−). Probing charm CP violation at the 10−5 level may result in its long sought discovery. Major advances in hadron spectroscopy will be possible, which will be powerful probes of low energy QCD. Upgrade II potentially will have the highest sensitivity of all the LHC experiments on the Higgs to charm-quark couplings. Generically, the new physics mass scale probed, for fixed couplings, will almost double compared with the pre-HL-LHC era; this extended reach for flavour physics is similar to that which would be achieved by the HE-LHC proposal for the energy frontier

    LHCb upgrade software and computing : technical design report

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    This document reports the Research and Development activities that are carried out in the software and computing domains in view of the upgrade of the LHCb experiment. The implementation of a full software trigger implies major changes in the core software framework, in the event data model, and in the reconstruction algorithms. The increase of the data volumes for both real and simulated datasets requires a corresponding scaling of the distributed computing infrastructure. An implementation plan in both domains is presented, together with a risk assessment analysis
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