No abstract available

[en] This paper presents a comprehensive analysis on practical challenges of empirical mode decomposition (EMD) based algorithms on wind speed and solar irradiation forecasts that have been largely neglected in literature, and proposes an alternative approach to mitigate such challenges. Specifically, the challenges are: (1) Decomposed sub-series are very sensitive to the original time series data. That is, sub-series of the new time series, consisting of the original one plus a limit number of new data samples, may significantly differ from those used in training forecasting models. In turn, forecasting models established by original sub-series may not be suitable for newly decomposed sub-series and have to be trained more frequently; and (2) Key environmental factors usually play a critical role in non-decomposition based methods for forecasting wind speed and solar irradiation. However, it is difficult to incorporate such critical environmental factors into forecasting models of individual decomposed sub-series, because the correlation between the original data and environmental factors is lost after decomposition. Numerical case studies on wind speed and solar irradiation forecasting show that the performance of existing EMD-based forecasting methods could be worse than the non-decomposition based forecasting model, and are not effective in practical cases. Finally, the approximated forecasting model based on EMD is proposed to mitigate the challenges and achieve better forecasting results than existing EMD-based forecasting algorithms and the non-decomposition based forecasting models on practical wind speed and solar irradiation forecasting cases. - Highlights: • Two challenges of existing EMD-based forecasting methods are discussed. • Significant changes of sub-series in each step of the rolling forecast procedure. • Difficulties in incorporating environmental factors into sub-series forecasting models. • The approximated forecasting method is proposed to mitigate the challenges of existing EMD-based forecasting methods.

[en] Highlights: • All gases in the improved diffusion layer model are considered to be real gases. • New modified equation of the relation between P_v and x_v is developed. • Obtain the analytical expression of heat transfer coefficient at high pressure. • Compression factor of vapor is a key factor at high pressure. • Gas/vapor mean concentration ratio is a ternary function of thermal parameters. - Abstract: Condensation heat transfer in the presence of non-condensable gas is a vital problem in the nuclear engineering applications, such as the gas-steam pressurizer design, and heat removing on containment in the case of postulated accident. An improved diffusion layer model of condensation heat transfer at high pressure is presented in the vapor domination region, and it shows the influence of the pressure in the film condensation in presence of non-condensable gas. All gases in this improved model are considered to be real gases as the compressibility factor of gas is utilized. New modified equations are developed to describe the relation between partial pressure and mole fraction, and an approximate analytical solution for heat transfer coefficient in the presence of non-condensable gas is obtained. The analysis result indicates that the compressibility factor of vapor has a great effect on the condensation heat transfer coefficient in the vapor domination region at high pressure, whereas the compressibility factor of the non-condensable gas does not. The gas/vapor mean concentration ratio is a ternary function of vapor compressibility factor, gas mean concentration and vapor mean concentration instead of a binary function of gas mean concentration and vapor mean concentration in the previous model based on ideal gas assumption. The deviation of these two gas/vapor mean concentration ratios is about 30% when the total pressure is about 16.0 MPa and the mole fraction of non-condensable gas is less than 2%. Compared with the experimental data, it has been proven that this improved model can get good applicability and accuracy

[en] Analyses have been made of the behaviour of cold plasma electron density at 6.6 Rsub(E) over the geomagnetic equator during very intense magnetic storms, by using the relaxation sounder data measured on board the geostationary satellite GEOS-2 of ESA. It is found that during very intense storms a high density region appears in the afternoon sector, the width of which is generally larger than the plasmaspheric bulge. The electron density on the nightside on storm days is lower than that on quiet and moderately disturbed days, representing a negative phase storm. There are severe perturbations in electron density during intense storms, which occur just after steep changes in Dsub(st) index and last one or two days. They appear more severe on the nightside, especially around midnight. It is pointed out that the enhancement of the magnetospheric convection and the invasion of the plasmasheet plasma into lower L regions are responsible for the foregoing phenomena. (author)

No abstract available

[en] In this paper, based on the equivalent simulation method, the equation of bending for the composite cylindrical shell that under the rotating state with the coupling of tension and bend (shear) is founded by the theory of plates and shells. It is considered that the bending of composite cylindrical shell brought by the coupling of tension and bend (shear) is so wee that the effect of the coupling of tension and bend (shear) could be ignored when designing the laminate structure of composite cylindrical. (authors)

[en] A study is made of the role which a positive (northward) component of the interplanetary magnetic field (IMF) Bsub(z) may play in triggering large magnetic storms. The study is made over a 15 year period (1964-1978) by selecting storms with Ksub(p) >= 7₀ and which are preceded by a Sudden Commencement (Ssc). The correlation between the geomagnetic index Ksub(m) and the three-hourly averaged Bsub(z) is established both on a statistical basis and on a case-by-case study. Storms associated with Bsub(z) > 0 are found to be less intense than those associated with Bsub(z) < 0, but major storms can be also triggered by solar wind events associated with a northward IMF. The relation-ship between interplanetary electric field Esub(γ) and Ksub(m) is also given. By using this relation together with the one between Esub(M) and Ksub(m) which has been established in previous studies (where Esub(M) is the magnetospheric convection electric field), it is possible to study the transfer efficiency of the magnetosphere. It is found that the transfer coefficient ΔEsub(M)/ΔEsub(γ) is much smaller for intense storms than for moderate ones, the latter having been studied in a previous paper (Wu Lei et al., 1981)

[en] In the framework of the topcolor-assisted technicolor (TC2) model we investigate the flavor-changing neutral-current production pp→t(c-bar)h_t⁰ at the Large Hadron Collider (LHC), which proceeds through the parton-level processes gg→t(c-bar)h_t⁰, uu-bar→t(c-bar)h_t⁰ and dd-bar→t(c-bar)h_t⁰. We calculate the production rate and present the distributions of the transverse momenta and the invariant mass of the neutral top-Higgs. It is found that the cross section of pp→t(c-bar)h_t⁰ can reach a few hundreds of fb in a large part of the allowed parameter space. Considering the main decay mode of top-Higgs for m_ht<2m_t, we find that such a production may provide copious events. In the case of unobservation, the LHC can set meaningful constraints on the TC2 model. (authors)

[en] In this paper, we investigate the decay rate of the bright soliton for the perturbed nonlinear Schroedinger equation (PNLSE). By employing the variational method, a set of ordinary differential equations (ODEs) which describe approximately the evolution of the bright soliton in the presence of fiber loss are obtained. From the numerical simulations and theoretical analysis, we can conclude that the decay rate of the bright soliton is not a constant as it propagates in the fiber

[en] We explore the complicated bursting oscillations as well as the mechanism in a high-dimensional dynamical system. By introducing a periodically changed electrical power source in a coupled BVP oscillator, a fifth-order vector field with two scales in frequency domain is established when an order gap exists between the natural frequency and the exciting frequency. Upon the analysis of the generalized autonomous system, bifurcation sets are derived, which divide the parameter space into several regions associated with different types of dynamical behaviors. Two typical cases are focused on as examples, in which different types of bursting oscillations such as subHopf/subHopf burster, subHopf/fold-cycle burster, and double-fold/fold burster can be observed. By employing the transformed phase portraits, the bifurcation mechanism of the bursting oscillations is presented, which reveals that different bifurcations occurring at the transition between the quiescent states (QSs) and the repetitive spiking states (SPs) may result in different forms of bursting oscillations. Furthermore, because of the inertia of the movement, delay may exist between the locations of the bifurcation points on the trajectory and the bifurcation points obtained theoretically. (paper)