Contract & Expand: I/O Efficient SCCs Computing

As an important branch of big data processing, big graph processing is becoming increasingly popular in recent years. Strongly connected component (SCC) computation is a fundamental graph operation on directed graphs, where an SCC is a maximal subgraph S of a directed graph G in which every pair of nodes is reachable from each other in S. By contracting each SCC into a node, a large general directed graph can be represented by a small directed acyclic graph (DAG). In the literature, there are I/O efficient semi-external algorithms to compute all SCCs of a graph G, by assuming that all nodes of a graph G can fit in the main memory. However, many real graphs are large and even the nodes cannot reside entirely in the main memory. In this paper, we study new I/O efficient external algorithms to find all SCCs for a directed graph G whose nodes cannot fit entirely in the main memory. To overcome the deficiency of the existing external graph contraction based approach that usually cannot stop in finite iterations, and the external DFS based approach that will generate a large number of random I/Os, we explore a new contraction-expansion based approach. In the graph contraction phase, instead of contracting the whole graph as the contraction based approach, we only contract the nodes of a graph, which are much more selective. The contraction phase stops when all nodes of the graph can fit in the main memory, such that the semi-external algorithm can be used in SCC computation. In the graph expansion phase, as the graph is expanded in the reverse order as it is contracted, the SCCs of all nodes in the graph are computed. Both graph contraction phase and graph expansion phase use only I/O efficient sequential scans and external sorts of nodes/edges in the graph. Our algorithm leverages the efficiency of the semi-external SCC computation algorithm and usually stops in a small number of iterations. We further optimize our approach by reducing the size of nodes and edges of the contracted graph in each iteration. We conduct extensive experimental studies using both real and synthetic web-scale graphs to confirm the I/O efficiency of our approaches. © 2014 IEEE

Dissipation function of the first-order phase transformation in solids via internal-friction measurements

Reconstruction and displacement of crystal structure and motion of the phase interface induces dissipation of energy, and latent heat appears during a first-order phase transition (FOPT) in solids. In this series of investigations, we first express the energy dissipation as a function of four physical parameters. Since there are more unknowns than the number of equations, we introduce four more equations describing the dynamics of the system on which internal friction (IF, the dissipation of vibration energy) measurements are conducted. Via IF measurements during FOPT, we can then calculate the relevant four parameters and hence the dissipation function. We have completed the first step in establishing a phenomenological theory to describe FOPT in solids.published_or_final_versio

Dissipation function of the first-order phase transformation in VO2 ceramics by internal-friction measurements

In order to apply the concept of the dissipation function during the first-order phase transition (FOPT) in solids, we measured the internal friction Q-1 and shear modulus μ for a range of frequencies of polycrystalline ceramics VO2 as the sample passed through a FOPT across the temperature range of 300–420 K. The experiment was repeated for different temperature variation rate Ṫ. We have found that for each frequency, a maximum of Q-1 and a minimum of μ occurred at the same temperature Tp when Ṫ was kept constant. The numerical values of the dissipation function ΔGR plus other FOPT parameters have been deduced using Q-1 data. The general trend of ΔGR-T and other results are found to be consistent with known physical aspects.published_or_final_versio

bcl-2 inhibits cytochrome c release during apoptosis in leukemic HL-60 cells

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Power electronic-controlled high Q resonator theory with HTS technology

Power electronic-controlled switch has been used with a high-temperature superconductor (HTS) to develop an advanced high Q resonant circuit. With a HTS, a very high Q circuit can be achieved; consequently special aspects such as high voltage generation can be theoretically and practically realized. Theoretical study has been carried out for this concept and method, and this paper describes the theory of this high Q resonant circuit and the operational principle. © 2006 IEEE

HTS high Q resonant controller

High Tc superconductor (HTS) technology has been used to develop an advanced high Q resonant circuit and its devices. With a HTS, a very high Q circuit can be achieved; consequently special aspects such as high voltage generation and high current control can be theoretically and practically realized. Theoretical study has been carried out, as well as a practical approach has been made for the concept verification. This paper describes the theory of this high Q resonant circuit and the operational principle of its high voltage generation and current control

Characterization of the thermoelastic martensitic transformation in a NiTi alloy driven by temperature variation and external stress

In order to test the concept of the physics of dissipation during first-order phase transitions in solids, we measured the internal friction (Q-1) and the relative shear modulus (μ) during a thermoelastic martensitic transformation in a NiTi alloy. We adopted two approaches: temperature variation and application of external stress. This investigation of internal friction was carried out with various vibration frequencies ω, temperature variation rates Ṫ, and strain variation rates ɛ̇. The index l (coupling factor between phase interface and oscillating stress) and index n (rate exponent for the effective phase transformation driving force) have been calculated from the experimental data for each case and the values of l and n are about the same in the two (doped) NiTi samples, irrespective of whether the phase transition is driven by a temperature variation or stress induced process. We compare the values of n and l for the NiTi samples with that of the other samples (VO2 ceramics and FeMn alloys), reinforcing the previous physical interpretations of these indices. We believe the indices n and l are indeed fingerprints of first-order phase transitions in solids.published_or_final_versio

Low-loss narrowband filtering switch based on coaxial resonators

© 2013 IEEE. In this paper, a narrowband filtering switch with low loss and high selectivity is presented based on coaxial resonators for the first time. PIN diodes mounted on the printed circuit boards are embedded into a coaxial filter to enable ON and OFF states. In the ON-state, the PIN diodes are turned OFF, which do not introduce the loss and affect the linearity. Two transmission zeros are generated by a novel feeding structure, which improves the skirt selectivity. In the OFF-state, the PIN diodes are turned on. Then, lumped capacitors are loaded to the coaxial resonators so that the resonant frequencies of the resonators are changed. The passband at the operating frequency cannot be formed, resulting in high isolation. For demonstration, the coaxial-resonator-based filtering switch is designed and fabricated. Good agreement between simulated and measured results verifies the proposed ideas. Comparison with other reported filtering switches is given. The proposed filtering switch shows the advantages of high Q-factor, relatively compact size, and wide stopband responses, which is attractive in wireless systems

Narrowband Single-Pole Double-Throw Filtering Switch Based on Dielectric Resonator

© 2001-2012 IEEE. In this letter, a narrowband single-pole double-throw (SPDT) filtering switch based on dielectric resonators (DRs) is presented. It consists of two DRs shared by two channels for size reduction. Printed circuit boards are embedded in the metal cavity to integrate the PIN diodes. The switching between two channels is enabled by controlling the PIN diodes connected to the two output feeding lines. The electromagnetic field distributions of the DR at the TE -{11\delta } mode are studied to control the coupling between the DR and two output feeding lines. When one channel is on, the PIN diode for this channel is turned off, which does not introduce loss and affect the linearity. For the off-state channel, isolation is obtained by controlling the coupling between the DR and output feeding line, which is considerably enhanced. For demonstration, the DR filtering SPDT switch is implemented. The measured results exhibit that the proposed filtering SPDT switch has narrow bandwidth, low loss, high isolation, and high linearity

Recent changes of water discharge and sediment load in the Yellow River basin, China

The Yellow River basin contributes approximately 6% of the sediment load from all river systems globally, and the annual runoff directly supports 12% of the Chinese population. As a result, describing and understanding recent variations of water discharge and sediment load under global change scenarios are of considerable importance. The present study considers the annual hydrologic series of the water discharge and sediment load of the Yellow River basin obtained from 15 gauging stations (10 mainstream, 5 tributaries). The Mann-Kendall test method was adopted to detect both gradual and abrupt change of hydrological series since the 1950s. With the exception of the area draining to the Upper Tangnaihai station, results indicate that both water discharge and sediment load have decreased significantly (p<0.05). The declining trend is greater with distance downstream, and drainage area has a significant positive effect on the rate of decline. It is suggested that the abrupt change of the water discharge from the late 1980s to the early 1990s arose from human extraction, and that the abrupt change in sediment load was linked to disturbance from reservoir construction.Geography, PhysicalGeosciences, MultidisciplinarySCI(E)43ARTICLE4541-5613