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[en] The authors review searches for neutral Higgs Boson performed by the CDF and D0 collaborations using approximately 200 pb-1 of the dataset accumulated from p(bar p) collisions at the center-of-mass energy of 1.96 TeV. No signals are found and limits on the Standard Model (SM) Higgs or SM-like Higgs production cross section times branching ratio and couplings of the Higgs boson in MSSM are presented, including the future prospects of discovery Higgs at the end of Run II
[en] Searches for rare physics processes using particle detectors in high-luminosity colliding hadronic beam environments require the use of multi-level trigger systems to reject colossal background rates in real time. In analyses like the search for the Higgs boson, there is a need to maximize the signal acceptance by combining multiple different trigger chains when forming the offline data sample. In such statistically limited searches, datasets are often amassed over periods of several years, during which the trigger characteristics evolve and their performance can vary significantly. Reliable production cross-section measurements and upper limits must take into account a detailed understanding of the effective trigger inefficiency for every selected candidate event. We present as an example the complex situation of three trigger chains, based on missing energy and jet energy, to be combined in the context of the search for the Higgs (H) boson produced in association with a W boson at the Collider Detector at Fermilab (CDF). We briefly review the existing techniques for combining triggers, namely the inclusion, division, and exclusion methods. We introduce and describe a novel fourth in situ method whereby, for each candidate event, only the trigger chain with the highest a priori probability of selecting the event is considered. The in situ combination method has advantages of scalability to large numbers of differing trigger chains and of insensitivity to correlations between triggers. We compare the inclusion and in situ methods for signal event yields in the CDF WH search.
[en] A proper magnitude analysis strategy of two-fluid model in two-phase natural circulation systems, which is applied in some advanced nuclear reactors, is proposed. On the basis of this method, the relative importance of each factor in the conservation equations is derived in the condition of the two main parts: heating section and rising section. Then, a simplified method is given
[en] The authors will report on a precision measurement of the average B hadron lifetime using the 1992-1993 CDF data with the new Silicon Vertex Detector. B hadrons are partially reconstructed through the decay B →J/ψX, J/ψ→μ+μ-. A lifetime is extracted from a fit to the 2D decay length of the J/ψ
[en] This paper deals with the 3D modelling of two-phase boiling bubbly flow in a vertical duct. More attention is paid to the modelling of the Interfacial Area Concentration which is of fundamental importance in the numerical prediction of boiling bubbly flow. A balance equation is derived for this quantity, including several terms for modelling the bubble coalescence and break-up and the bubble size and number variations due to phase change. The complete model is tested against the DEBORA experimental data base, and the IAC model is compared to three other models found in the literature. The results of the numerical simulations are compared to the experiment and discussed. Quite good agreement is found on the bubble diameter profiles by using our model. This work is part of the NEPTUNE project
[en] The manned deep-space exploration is a hot topic of the current space activities. The continuous supply of thermal and electrical energy for the scientific equipment and human beings is a crucial issue for the lunar outposts. Since the night lasts for periods of about 350 h at most locations on the lunar surface, massive energy storage is required for continuous energy supply during the lengthy lunar night and the in-situ resource utilization is demanded. A lunar based solar thermal power system with regolith thermal storage is presented in this paper. The performance analysis is carried out by the finite-time thermodynamics to take into account major irreversible losses. The influences of some key design parameters are analyzed for system optimization. The analytical results shows that the lunar based solar thermal power system with regolith thermal storage can meet the requirement of the continuous energy supply for lunar outposts. - Highlights: • A lunar based solar thermal power system with regolith thermal storage is presented. • The performance analysis is carried out by the finite-time thermodynamics. • The influences of some key design parameters are analyzed.
[en] Nanoparticles can generate charge carrier trapping and reduce the velocity of streamer development in insulating oils ultimately leading to an enhancement of the breakdown voltage of insulating oils. Vegetable insulating oil-based nanofluids with three sizes of monodispersed Fe_3O_4 nanoparticles were prepared and their trapping depths were measured by thermally stimulated method (TSC). It is found that the nanoparticle surfactant polarization can significantly influence the trapping depth of vegetable insulating oil-based nanofluids. A nanoparticle polarization model considering surfactant polarization was proposed to calculate the trapping depth of the nanofluids at different nanoparticle sizes and surfactant thicknesses. The results show the calculated values of the model are in a fairly good agreement with the experimental values. - Highlights: • Three different sized Fe_3O_4 vegetable-oil based nanofluids was successfully prepared. • The trapping depth of the Fe_3O_4 nanofluids was investigated. • A new model considering surfactant polarization was proposed to calculate the trapping depth of the nanofluids.
[en] In this paper, a multidimensional two-fluid model with additional turbulence k - ε equations is used to predict the two-phase parameters distribution in freon R12 boiling flow. The 3D module of the CATHARE code is used for numerical calculation. The DEBORA experiment has been chosen to evaluate our models. The radial profiles of the outlet parameters were measured by means of an optical probe. The comparison of the radial profiles of void fraction, liquid temperature, gas velocity and volumetric interfacial area at the end of the heated section shows that the multidimensional two-fluid model with proper constitutive relations can yield reasonably predicted results in boiling conditions. Sensitivity tests show that the turbulent dispersion force, which involves the void fraction gradient, plays an important role in determining the void fraction distribution; and the turbulence eddy viscosity is a significant factor to influence the liquid temperature distribution. (authors)
[en] The structure of FuQing nuclear power Reactor protection system was introduced. Pointing to the complex of the system logic structure, urgency of the Commissioning time, Visual Studio. net C was used in the development the simulation software based on logic diagram of FuQing nuclear power reactor protection system, making the structure of the RPS System more clear and speeding up the commissioning process. The TCP/IP communication protocol was used to communicate the DCS data acquired system. ACCESS database was used to save, search, and maintenance the system data. Finally through the software testing, it was achieved the purpose of the system simulation. (authors)
[en] The low grade heat utilization is not only an inevitable option to solve the energy and environment problems, but also a critical issue for many remote power applications and planetary explorations. In this study, a novel design called a heat engine aerobot which can convert planetary atmospheric energy to electricity is proposed and analysed. A dynamic theoretical model is established and some key issues, such as the thermodynamic performance and conversion efficiency are analysed. It shows that the heat engine aerobot is capable to convert the low grade atmospheric energy to electricity during its self-sustained vertical oscillation movement. Parametric analysis shows that some design parameters, such as the nozzle number, the nozzle outlet diameter, the initial liquid mass and the turbine start height may have significant influence on the energy generation performance. - Highlights: • A novel heat engine for low grade atmospheric energy utilization was proposed. • A theoretical model was established and the dynamic behaviour was simulated. • The parametric effects on its thermodynamic performance were analysed