Energy security assessment provides a benchmark for policy analysis and identifies the challenges for ensuring energy supplies as well. This paper develops a composite index for assessing the oil ...supply risk of South Asian countries. The index is based on a comprehensive set of indicators including the ratio of imported oil over GDP, geopolitical risk, market liquidity, GDP per capita, ratio of oil imports over consumption, diversification, oil price volatility, US$ volatility and transportation risk. Results reveal that India is the least oil vulnerable country while Afghanistan and Bangladesh are the most oil vulnerable countries. India's leading score reflects a higher potential to change the oil suppliers while Afghanistan, Bangladesh, Bhutan, and Nepal have the least score confirming them as the highest supply risk associated countries. Policies such as adopting renewable energy technologies, generating nuclear power, diversifying export sources and cutting down oil subsidies can help reduce the impact of oil supply risk.
•We develop a composite index for assessing the oil supply risk of South Asian countries.•A mathematical programming approach is used to constructing the index.•India is found to be the least oil vulnerable country.•Afghanistan and Bangladesh are the most oil vulnerable countries.
OJ 287 is a BL Lac object at redshift z= 0.306 that has shown double-peaked bursts at regular intervals of ∼12 yr during the last ∼40 yr. We analyse optical photopolarimetric monitoring data from ...2005 to 2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light curve. We find a strong preferred position angle in optical polarization. The preferred position angle can be explained by separating the jet emission into two components: an optical polarization core and chaotic jet emission. The optical polarization core is stable on time-scales of years and can be explained as emission from an underlying quiescent jet component. The chaotic jet emission sometimes exhibits a circular movement in the Stokes plane. We find six such events, all on the time-scales of 10–20 d. We interpret these events as a shock front moving forwards and backwards in the jet, swiping through a helical magnetic field. Secondly, we use our data to assess different binary black hole models proposed to explain the regularly appearing double-peaked bursts in OJ 287. We compose a list of requirements a model has to fulfil to explain the mysterious behaviour observed in OJ 287. The list includes not only characteristics of the light curve but also other properties of OJ 287, such as the black hole mass and restrictions on accretion flow properties. We rate all existing models using this list and conclude that none of the models is able to explain all observations. We discuss possible new explanations and propose a new approach to understanding OJ 287. We suggest that both the double-peaked bursts and the evolution of the optical polarization position angle could be explained as a sign of resonant accretion of magnetic field lines, a ‘magnetic breathing’ of the disc.
The thermal conductivityκof the cuprate superconductorLa1.6−xNd0.4SrxCuO4was measured down to 50 mK in seven crystals with doping fromp=0.12top=0.24, both in the superconducting state and in the ...magnetic field-induced normal state. We obtain the electronic residual linear termκ0/TasT→0across the pseudogap critical pointp⋆=0.23. In the normal state, we observe an abrupt drop inκ0/Tupon crossing belowp⋆, consistent with a drop in carrier densitynfrom1+ptop, the signature of the pseudogap phase inferred from the Hall coefficient. A similar drop inκ0/Tis observed atH=0, showing that the pseudogap critical point and its signatures are unaffected by the magnetic field. In the normal state, the Wiedemann-Franz law,κ0/T=L0/ρ(0), is obeyed at all dopings, including at the critical point where the electrical resistivityρ(T)isTlinear down toT→0. We conclude that the nonsuperconducting ground state of the pseudogap phase atT=0is a metal whose fermionic excitations carry heat and charge as conventional electrons do.
Earth's magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth's auroras, heats the ...magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1-to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10¹⁵ joules of magnetic energy, consistent with global magnetotail flux reduction.
In this study, Inconel 718 alloy cylindrical rods with their axes normal or parallel to the building directions were fabricated by selective laser melting (SLM), then homogenized and double aged. ...Creep tests of the heat-treated samples were conducted under a constant stress of 650 MPa at 650 °C. The microstructures of the as-built, heat-treated and post-creep horizontal and vertical samples were characterized using scanning and transmission electron microscopy and electron backscatter diffraction. The experimental results showed that both equiaxed grains and columnar dendrites exist in the horizontal and vertical samples before and after creep. The average grain sizes remained nearly unchanged during creep. The larger grain size and reduced regions of transverse grain boundaries, as well as the promoted precipitation of the γ″ phases at the creep test condition contributed to the longer creep rupture life (~120 h) of the vertical sample. Stress concentration occurring especially at the transverse grain boundaries led to the final failure by intergranular fracture for the two building orientational samples. The anisotropy of creep behavior of the SLMed Inconel 718 alloy could not be eliminated by the present heat treatment schedule.
We present a general strategy for enabling reversible shape transformation in semicrystalline shape memory (SM) materials, which integrates three different SM behaviors: conventional one-way SM, ...two-way reversible SM, and one-way reversible SM. While two-way reversible shape memory (RSM) is observed upon heating and cooling cycles, the one-way RSM occurs upon heating only. Shape reversibility is achieved through partial melting of a crystalline scaffold which secures memory of a temporary shape by leaving a latent template for recrystallization. This behavior is neither mechanically nor structurally constrained, thereby allowing for multiple switching between encoded shapes without applying any external force, which was demonstrated for different shapes including hairpin, coil, origami, and a robotic gripper. Fraction of reversible strain increases with cross-linking density, reaching a maximum of ca. 70%, and then decreases at higher cross-linking densities. This behavior has been shown to correlate with efficiency of securing the temporary shape.
The Heilongjiang Complex is a sequence of high-pressure metamorphic rocks, located along the suture zone that separates the Jiamusi–Khanka (–Bureya) and Songliao–Zhangguangcai blocks in NE China (and ...extending northward into Far East Russia). The complex consists of mafic–ultramafic rocks, various quartzo–feldspathic schists and radiolarian-bearing quartzite (formerly chert). The rocks were metamorphosed up to epidote–blueschist facies, with
P–
T conditions of approximately
T
=
320–450 °C and
P
=
0.9–1.1 GPa. The lithological association and major and trace element compositions indicate that the blueschists were metabasalts of OIB and E-MORB affinity, most likely generated in a rift setting at the western margin of the Jiamusi Block that later underwent subduction. Magmatic zircons extracted from two samples of epidote–blueschist facies metabasalts from Mudanjiang have SHRIMP U–Pb
206Pb/
238U ages of 213
±
2 Ma and 224
±7 Ma, whereas similar rocks ∼
200 km farther north at Yilan have ages of 258
±
2 Ma and 259
±
4 Ma. These data define the protolith ages of the metabasalts as Late Triassic and Late Permian, respectively. These ages limit the timing of high-pressure metamorphism in the Heilongjiang Complex to post-Late Triassic, consistent with argon data reported from previous studies. Inherited zircon components in all four epidote–blueschist facies samples show distinct populations at 290–330 Ma, 420–530 Ma, 670–910 Ma and >
1065 Ma. Such ages are also a feature of the Central Asia Orogenic Belt (CAOB) to the west, supporting the view that the Jiamusi Block was most likely the rifted easternmost segment of the CAOB and not an exotic block derived from Gondwana. Final closure between the Jiamusi–Khanka–Bureya and Songliao blocks took place in the latest Triassic to Early Jurassic, with the two blocks accreted as a result of Pacific Ocean subduction. This suggests that the Heilongjiang Complex records the time when northward movement of the combined Mongolia–North China Block toward Siberia was waning and becoming surpassed by the onset of Pacific accretion from the east, which has dominated the tectonics of NE China and Far East Russia since the Early Jurassic.
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