Available transfer capability calculation with post-contingency generation rescheduling/load curtailment

The available transfer capability (ATC) is an important index indicating the remaining transfer capability in the physical transmission network for further commercial activity above existing commitments. In this paper, ATC mathematical model considering post-contingency generation rescheduling and load curtailment is first formulated. Benders decomposition method is then used to partition the ATC model above into a base case master problem and a series of independent subproblems relevant to various contingencies. Finally, an improved parallel solution scheme is employed to improve the convergence. Numerical results on a 4-bus test system show clearly the effectiveness of the presented method and necessity of considering post-contingency generation rescheduling and load curtailment in calculating ATC.published_or_final_versio

Nucleate boiling enhancement by structured surfaces with distributed wettability-modified regions: A lattice Boltzmann study

In this paper, we conceive a novel pillar-structured surface for enhancing nucleate boiling heat transfer, namely a pillar-structured surface with distributed wettability-modified regions on the top of each pillar. A three-dimensional thermal multiphase lattice Boltzmann model with liquid–vapor phase change is employed to investigate the boiling performance on the pillar-structured surface with distributed wettability-modified regions and the associated mechanism of nucleate boiling heat transfer enhancement. According to the distribution of the wettability-modified regions, the bubble dynamics on the newly conceived pillar-structured surface can be classified into three regimes, i.e., regimes I, II, and III, among which the regime II shows relatively better boiling performance than the other two regimes due to the synergistic effects of surface structure and mixed wettability. It is found that in the regime II the bubbles nucleated at the wettability-modified regions do not coalesce with each other, which therefore elongates the length of the triple-phase contact lines on the pillar top in comparison with the pillar-structured surface with a unified wettability-modified region. Meanwhile, in the regime II the bubbles on the pillar top receive a strong bubble-wake effect supplied by the bubbles generated at the bottom substrate, which shortens the bubble growth cycle and promotes the departure of the bubbles on the pillar top, and also reduces the area of dry spots on the pillar top. The influences of the pillar width and the width of the wettability-modified regions are also studied. It is shown that the best boiling performance is always achieved in the cases that fall into the regime II

Superconductivity of ultra-fine tungsten nanowires grown by focused-ion-beam direct-writing

The electrical properties of lateral ultra-fine tungsten nanowires, which were grown by focused-ion-beam-induced deposition with 1 pA ion-beam current, were investigated. Temperature-dependent electrical measurements show that the wires are conducting and have a superconducting transition with a transition temperature (T-c) about 5.1 K. Resistance vs. temperature measurements reveal that, with decreasing cross-sectional area, the wires display an increasingly broad superconducting transition. A residual resistive tail extending down to the low-temperature region is found only for the thinnest tungsten nanowire, which is 10 nm thick and 19 nm wide. The logarithm of the residual resistance of this wire appears as two linear sections as a function of temperature, one within 300 mK below T-c and the other extending down to the lowest measuring temperature of 4.26 K. Such features have previously been identified with phase slip processes. Our results are suggestive that the focused-ion-beam technique might be a potential approach to fabricate ultra-thin and ultra-narrow nanowires for the study of superconducting suppression in nanoscale materials and for maskless superconducting device fabrication. (C) 2011 Elsevier B.V. All rights reserved

Novel self-configurable current-mirror techniques for reducing current imbalance in parallel Light-Emitting Diode (LED) strings

Traditional current-mirror methods require one fixed current reference for controlling other current source or sources. In this paper, a new self-configurable current-mirror method that can dynamically determine the best current branch as the current reference in order to ensure good balance of all parallel current sources is proposed. The operating principle involves a dynamic and self-configurable transistor-based current-balancing circuit that can be operated in saturation or linear mode. In either operating mode, good current balance or sharing among all parallel-connected current sources can be guaranteed. The novel current-balancing circuit does not require a separate power supply for powering their control circuits. The proposal is a modular one that can be expanded to any number of parallel current sources. Its principle has been successfully applied to current balancing of parallel LED strings. © 2011 IEEE.published_or_final_versio

Molecular characterization and expression analysis of a hepcidin gene from rice field eel (Monopterus albus)

Hepcidin is a cysteine-rich, dual-function peptide with antimicrobial activity that plays crucial roles in iron homeostasis. A few hepcidin-like genes have been isolated from teleost. Here, we have identified a hepcidin-like gene from rice field eel (RFE), Monopterus albus. Nucleotide sequences including cDNA and genomic DNA (GenBank accession numbers: FJ436808 and FJ594996, respectively) and deduced amino acid sequences were presented. In the 949 bp-long genomic sequence, two introns and three exons were identified. The full-length cDNA encodes a prepropeptide of 90 amino acid residues. RTPCR analysis suggested that hepcidin transcripts are highly abundant in the liver and kidney, less abundant in the heart, skin, brain, blood cells, intestine, spleen and stomach and undetectable in muscle. After challenged with Aeromonas hydrophila infection or iron-dextran stimulation, the hepcidin transcript levels were analyzed by RT-PCR. The results revealed that the expression of hepcidin dramatically increased at 24 h post-infection of the pathogen injection. Moreover, hepcidin mRNAs in the liver, intestine and brain were 2.4, 1.5 and 2-fold increase, respectively, compared with the control animals after 5 days in iron-dextran injected RFEs.Key words: Rice field eel, Monopterus albus, hepcidin, gene expressio

Community-Based Intervention to Improve the Well-Being of Children Left Behind by Migrant Parents in Rural China

In rural China around 60 million left-behind children (LBC) experience prolonged separation from migrant worker parents. They are vulnerable to a range of psychosocial problems. The aim of this study was to determine whether a community-based intervention consisting of Children's Centres can improve psychosocial well-being and school performance of these children. The intervention was carried out in 20 villages, for children aged 7 to 15 years, irrespective of left-behind status. Nine hundred and twenty children, 438 LBC and 256 children living with parents (RC) attended the Centres. At follow-up after one year, there were improvements compared to baseline in total difficulties (measured with the Strengths and Difficulties Questionnaire) in children left behind by both parents (p = 0.009), children left behind by one parent (p = 0.008) and RC (p = 0.05). Postintervention school performance significantly improved in both categories of LBC (p < 0.001), but not RC (p = 0.07); social support score increased in both categories of LBC (p < 0.001) and RC (p = 0.01). Findings from interviews with key stakeholders were overwhelmingly positive about the impacts. With strong local leadership and community motivation, a low-cost intervention can improve children's psychosocial well-being in these settings. Allowing communities to adapt the model to their own situation fosters local ownership, commitment, with benefits for children, parents, carers, and communities

Precise Sm-Nd and U-Pb isotopic dating of the supergiant Shizhuyuan polymetallic deposit and its host granite, SE China

The supergiant Shizhuyuan W-Sn-Bi-Mo deposit is hosted by the Qianlishan granite, a small, highly fractionated granitic pluton (~10 km2) with multiple phases of intrusions within the Early Yanshanian granitoid province of SE China. Strong alteration of skarn and greisen that formed in the contact zone between the first and second phases of granite intrusions and Devonian limestone is responsible for the polymetallic mineralizations. SHRIMP U-Pb zircon analysis indicates that the two early phases of the Qianlishan granite formed contemporaneously at 152 ± 2 Ma. Metasomatic minerals (garnet, fluorite and wolframite) separated from the skarn and greisen yield a Sm-Nd isochron age of 149 ± 2 Ma that is interpreted as the formation age of the Shizhuyuan deposit. Therefore, the mineralization of the supergiant Shizhuyuan polymetallic deposit formed contemporaneously with, or very shortly after, the intrusion of the small, highly fractionated Qianlishan granite. © 2004 Cambridge University Press.published_or_final_versio

Focused-Ion-Beam Direct-Writing of Ultra-Thin Superconducting Tungsten Composite Films

Tungsten composite films of thickness as low as 19 nm have been deposited using a 30 keV Ga+ focused-ion-beam with tungsten carboxyl (W(CO)(6)) as the gas precursor. Films of thickness 25 nm or more are superconducting with a transition temperature exceeding 5 K. Films in the thickness range 25 nm to 50 nm show an increasing T-c for a decreasing film thickness. This correlates well with the measured dependence of the normal state resistivity upon film thickness. We attribute this behavior to an increase in the BCS electron-phonon interaction potential resulting from a reduction in the electron mean-free-path as the film thickness is reduced. In the light of these data we discuss the applicability of FIB-deposited tungsten for devices requiring ultra-thin superconducting films, including photon detectors and phase-slip qubits

Effect of different rhBMP-2 and TG-VEGF ratios on the formation of heterotopic bone and neovessels

Bioengineered bone substitutes might represent alternatives to autologous bone grafts in medically compromised patients due to reduced operation time and comorbidity. Due to the lack of an inherent vascular system their dimension is limited to the size of critical bone size defect. To overcome this shortcoming, the experiment tried to create heterotopic bone around vessels. In vivo, a two-component fibrin and thrombin gel containing recombinant bone morphogenic protein (rhBMP-2) and transglutamate vascular endothelial growth factor (TG-VEGF) in different ratios, respectively, was injected into a dimensionally stable membrane tube, wrapped around the femoral vessel bundle in twelve New Zealand white rabbits. Sacrifice occurred eight weeks postoperatively. Microcomputed tomography of the specimens showed significantly increased bone volume in the rhBMP-2 to TG-VEGF ratio of 10 to 1 group. Histology showed new bone formation in close proximity to the vessel bundle. Immunohistochemistry detected increased angiogenesis within the newly formed bone in the rhBMP-2 to TG-VEGF ratios of 3 to 1 and 5 to 1. Heterotopic bone was engineered in vivo around vessels using different rhBMP-2 and TG-VEGF ratios in a fibrin matrix injected into a dimensionally stable membrane tube which prevented direct contact with skeletal muscles.published_or_final_versio

The heightened ‘security zone’ function of gated communities during the covid-19 pandemic and the changing housing market dynamic: Evidence from beijing, china

The ongoing COVID-19 pandemic has left a strong imprint on many aspects of urban life. Gated communities (GCs) in China are less commonly perceived as a negative and segregated urban form of community compared to other contexts, owing to their wide variety and relative openness. Yet, the enhanced security zone function and the popularity of GCs, along with the heightened segregation and exclusion effects, mean they are most likely to emerge in post-pandemic urban China because of the perceived effectiveness of GCs in preventing health risks by excluding outsiders during the pandemic. Drawing on empirical data from Beijing, this research presents strong evidence for a strengthened perceived ‘security zone’ effect of GCs during the pandemic. Given that rigid pandemic control measures were organized at the community level, a large-scale household survey in Beijing suggests that residents commonly recognise the effectiveness of GCs in security control and show a strong preference for GCs over open communities after the pandemic, even though there is a lack of direct evidence of reduced COVID-19 risk in GCs. The heightened perceived ‘security zone’ function of GCs has shown a significant impact on the housing market, evidenced by an increase of 2% in the housing prices for GCs, compared with those of open communities. The rising popularity of GCs is also evidenced by a significant increase in property viewings by potential homebuyers and smaller price discounts in actual transactions in gated communities vis-à-vis open communities. We argue that the rising risk-averse sentiment in the post-pandemic era has given rise to the popularity of GCs. This study provides timely and fresh insights into the changing meaning of GCs in post-pandemic China.</jats:p