It is possible to prevent collapse of the whole post-fault power system, which is in unstable condition, by determining the splitting boundary so as to calm down the system oscillation. A fast method ...of searching for the splitting boundary of power system controlled islanding is presented in this paper, the aim of which is to minimize the load-generation imbalance in each island. The method contains three phases, namely, defining the domain of each generator according to power flow tracing algorithm, determining an initial splitting boundary based on the grouping information of generators, and refining the initial one to get the final splitting boundary. A real-time searching program for power system splitting boundary was developed based on the method. Simulations on the IEEE 118-bus power system and a practical power system show that the proposed method is effective and fast.
A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs' beta exceeds a critical value, a fishbonelike bursting mode (FLM) with ...an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations Phys. Rev. Lett. 103, 045001 (2009). The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs' beta, a mode conversion can occur between the resistive wall mode and FLM.
•Commercial Tribaloy T-900 alloy was alloyed with aluminium and aluminium plus yttrium.•High temperature cyclic oxidation behaviour and wear mechanism were investigated in air.•Yttrium plus aluminium ...improved the cyclic oxidation resistance by forming compact and continuous external Al2O3 layer.•Al2O3 layer blocked the internal nitrides and oxides formation, which could be detrimental to mechanical properties.•Yttrium addition enhanced the adherence of transition oxides scale during sliding wear.
This paper investigated the microstructure, cyclic oxidation behaviour and wear mechanism of modified and unmodified Tribaloy T-900. Yttrium and aluminium addition promoted the selective oxidation of Al, which reduced the oxidation rate by forming continuous protective layer of Al2O3 at 1000 °C. Al2O3 layer hindered the formation of simultaneous internal oxidation and nitridation zone. Yttrium addition transforms the mechanism of grooving wear to rolling wear by increasing the surface passivation and adherence of transition oxides scale during sliding wear. Hardness of T-900Al and T-900AlY was increased due to refinement of Laves phase and precipitation of grey intermetallic phase.
We present evidence that the 8 km (dust) and 24 km luminosities of star-forming galaxies are both strongly correlated with their 1.4 GHz and Ha luminosities over a range in luminosity of 2-3 orders ...of magnitude. At the bright end, the correlations are found to be essentially linear over a luminosity range of about 2 orders of magnitude (corresponding to star formation rates of several tenths to several tens of solar masses per year). However, at the faint end there appears to be a slope change for dwarf galaxies, possibly due to the lower dust-to-gas ratios and lower metallicities of the dwarfs. The correlations suggest that PAH features and mid-IR continuum emissions are good measures of the star formation rates of galaxies, and we present calibrations of star formation rates based on existing radio and Ha relations. Our findings are based on a sample of star-forming galaxies selected from the main field of the Spitzer First Look Survey with the aid of spectroscopic data from the Sloan Digital Sky Survey and VLA 1.4 GHz data.
The main processes underlying the generation and maintenance of biodiversity include both local factors such as competition and abiotic filtering and regional forces such as paleoclimate, speciation ...and dispersal. While the effects of regional and local drivers on species diversity are increasingly studied, their relative importance for other aspects of diversity, notably phylogenetic and functional diversity is so far little studied. Here, we link data from large Chinese forest plots to data on current and Last Glacial Maximum (LGM) climate as well as local disturbance regimes to study their relative roles in determining woody plant phylogenetic and functional diversity in this important hotspot for woody plant diversity. Local disturbance was the best predictor of functional diversity as represented by maximum canopy height (Hmax), probably reflecting the dominant role of competition for light in determining the forest Hmax structure. In contrast, the LGM–present anomaly in temperature was the factor with the strongest explanatory power for phylogenetic diversity, with modern climate also important. Hence, local contemporary and regional historical factors have highly contrasting importance for the geographic patterns of the functional (as represented by variation in maximum canopy height) and phylogenetic aspects of Chinese forest's woody plant diversity. Importantly, contemporary factors are of overriding importance for functional diversity, while paleoclimate has left a strong signature in the phylogenetic diversity patterns.
We study the properties of infrared-selected QSOs (IR QSOs), optically selected Palomar-Green QSOs (PG QSOs), and narrow-line Seyfert 1 galaxies (NLS1s). We compare their properties from the IR to ...the optical and examine various correlations among the black hole mass, accretion rate, star formation rate, and optical and IR luminosities. We find that the IR excess in IR QSOs is mostly in the far-IR, and their IR spectral indices suggest that the excess emission is from low-temperature dust heated by starbursts rather than active galactic nuclei (AGNs). The IR excess is therefore a useful criterion to separate the relative contributions of starbursts and AGNs. We further find a tight correlation between the star formation rate and the accretion rate of central AGNs for IR QSOs. The ratio of the star formation rate and the accretion rate is about several hundred for IR QSOs but decreases with the central black hole mass. This shows that the tight correlation between the stellar mass and the central black hole mass is preserved in massive starbursts during violent mergers. We suggest that the higher Eddington ratios of NLS1s and IR QSOs imply that they are in the early stage of evolution toward classical Seyfert 1 galaxies and QSOs, respectively.
Summary
Background Staphylococcus aureus has a peculiar ability to colonize the skin of patients with eczema and atopic dermatitis (AD), and is consistently found in eczematous skin lesions in these ...patients. A correlation between the severity of the eczema and colonization with S. aureus has been demonstrated, and it has been determined that bacterial colonization is an important factor aggravating skin lesions. Patients colonized with S. aureus have been treated with antibiotics in several open and double‐blind placebo‐controlled studies, with conflicting results.
Objectives To investigate the colonizing features of S. aureus in the lesional and nonlesional skin of patients with eczema and AD in China and to compare the therapeutic effect of mupirocin plus hydrocortisone butyrate with vehicle ointment plus hydrocortisone butyrate.
Methods A multicentre, double‐blind randomized trial was conducted. Eczema Area and Severity Index (EASI) scores were evaluated before the start of the trial and on the 7th, 14th and 28th day of treatment. Swabs for bacterial isolation were taken from lesional skin before the start of the trial and on the 7th, 14th and 28th day of treatment, and from nonlesional skin only before the start of the trial. A combination topical therapy with mupirocin plus hydrocortisone butyrate ointment was used in the experimental group, with vehicle ointment plus hydrocortisone butyrate ointment as a control.
Results Of 327 patients enrolled in the study, 208 had eczema and 119 had AD. Bacteria were isolated from 70·2% of lesional and 32·7% of nonlesional skin samples from patients with eczema, of which S. aureus accounted for 47·3% and 27·9%, respectively. Bacteria were isolated from 74·8% of lesional and 34·5% of nonlesional skin samples from patients with AD, of which S. aureus accounted for 79·8% and 80·5%, respectively. The colonization density of S. aureus was markedly higher in lesional than in nonlesional skin, both in patients with eczema and with AD (P < 0·01, P < 0·05), and was positively correlated with lesion severity. Considering the EASI scores before and after treatment and the final effective rate, good therapeutic effects were obtained in both the combination experimental groups and the control groups (P < 0·01), and there were no differences in the global therapeutic effect between the two groups in patients with eczema and with AD (P > 0·05). However, in patients with eczema with a clinical score of > 8 or in patients with AD with a clinical score of > 7, the therapeutic effect in the experimental groups was superior to that in the control groups (P < 0·05) on the 7th day of treatment. There were no differences between the two groups on the 14th and 28th days of treatment (P > 0·05). Following the improvement of symptoms and signs of eczema and AD, the positive rates of bacteria and S. aureus were reduced on the 7th day of treatment.
Conclusions This study confirmed that lesional skin of patients with eczema and AD was more frequently colonized with S. aureus than was nonlesional skin. The more severe the eczema, the higher the colonization rate of S. aureus, and S. aureus was also more often present in lesional and nonlesional skin in patients with AD than in those with eczema. Staphylococcus aureus infection is related to the pathogenesis of eczema and AD. An antibiotic–corticosteroid combination and corticosteroid alone both gave good therapeutic effect in eczema and in AD, and both reduced colonization by S. aureus. Early combined topical therapy is beneficial to patients with moderate to severe eczema and AD, and it is unnecessary to use antibiotics at later stages of disease or in mild eczema or AD.
Effects of three-dimensional (3D) perturbations due to an unstable n = 1 (n is the toroidal mode number) internal kink (IK) on the energetic particles (EPs) are systematically investigated for the ...HL-2M tokamak, utilizing the MARS-F/K code Liu et al., Phys. Plasmas 7, 3681–3690 (2000) and a recently developed test particle tracing module. A high-beta sawteething HL-2M scenario, simulated by the TRANSP code Breslau et al., Transp Computer Software (2018), is chosen for this study. In general, the 3D perturbation associated with an unstable IK is found to affect the EP drift orbit, confinement, and loss in HL-2M. The instability-induced EP loss fraction is found to be typically less than 10%, without counting for the prompt orbit loss associated with the 2D equilibrium field for counter-current particles. The latter reaches about 16% in HL-2M. For co-current EPs, a 100 G 3D magnetic field (inside the plasma) due to the IK does not induce any EP loss assuming a static perturbation. A sawtooth-like time-varying perturbation field, with the peak amplitude reaching 1000 G, can however produce about 30% loss for the co-current EPs in HL-2M. The majority of lost EPs tend to strike the lower divertor region, with a small fraction of particles striking the low-field side mid-plane region of the limiting surface.
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