• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.81-96
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• 2019

In this paper, a hybrid uncertain model is applied to system reliability based design optimization (RBDO) of trusses. All random variables are described by random distributions but some key distribution parameters of them which lack information are defined by variation intervals. For system RBDO of trusses, the first order reliability method, as well as monotonicity analysis and the branch and bound method, are utilized to determine the system failure probability; and Improved (${\mu}+{\lambda}$) constrained differential evolution (ICDE) is employed for the optimization process. System reliability assessment of several numerical examples and system RBDO of different truss structures are proposed to verify our results. Moreover, the effect of different classes of interval distribution parameters on the optimum weight of the structure and the reliability index are also investigated. The results indicate that the weight of the structure is increased by increasing the uncertainty level. Moreover, it is shown that for a certain random variable, the optimum weight is more increased by the translation interval parameters than the rotation ones.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.73.5-73.5
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• 2019

Studying the amount and kinematics of circumand intergalactic medium (CGM and IGM) is key to understanding the role of feedback and environment (cold streams and galactic winds) in the evolution of galaxies. In particular, $Ly{\alpha}$ emission line has been utilized to investigate the density structure and kinematics of the (most abundant) H I gas in the CGM and IGM around galaxies. Therefore, modeling $Ly{\alpha}$ radiative transfer through multiphase interstellar medium (ISM), CGM and IGM is crucial in understanding the galaxy evolution. As discussed in Kakiichi & Dijkstra (2018), most $Ly{\alpha}$ RT effects would occur on interstellar scales. This is because the main source of $Ly{\alpha}$ photons would be H II regions, which are in most cases, if not all, surrounded by "cold" photo-dissociation regions. However, most $Ly{\alpha}$ RT studies have been performed in the CGM and IGM environments with T ~ 10,000K. In this talk, we present how the $Ly{\alpha}$ RT effect in the cold ISM with T ~ 100 K regulates the $Ly{\alpha}$ spectral properties.

• Asian Journal of Innovation and Policy
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• v.7 no.3
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• pp.511-533
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• 2018

As the developed and developing economies make the transition to knowledge-based economies, the high-tech sector has been the primary engine in enabling this transformation. Given this context, the policy making and implementation abilities of the countries' local administration assume significance. This study therefore attempts to examine the policy evolution undertaken by China and India which resulted in the emergence of high-tech startup ecosystems in these countries. Further, using a theoretical framework for an ideal entrepreneurial ecosystem, it tries to understand the similarities and differences prevalent currently in the Indian and Chinese high-tech startup ecosystem. The results of the study indicate that although both the countries took different paths, from a macro-perspective, they follow the same pattern as observed in the US and Israel policy making - that of the change in the role of Government as a regulator to that of an enabler of the entrepreneurial ecosystem. The differences and similarities between the key entrepreneurial ecosystem components provide additional knowledge about the currently prevailing conditions of the ecosystem in these countries.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1294-1304
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• 2020

Objective: To determine whether T1 mapping could monitor the dynamic changes of injury in myocardial infarction (MI) and be histologically validated. Materials and Methods: In 22 pigs, MI was induced by ligating the left anterior descending artery and they underwent serial cardiovascular magnetic resonance examinations with modified Look-Locker inversion T1 mapping and extracellular volume (ECV) computation in acute (within 24 hours, n = 22), subacute (7 days, n = 13), and chronic (3 months, n = 7) phases of MI. Masson's trichrome staining was performed for histological ECV calculation. Myocardial native T1 and ECV were obtained by region of interest measurement in infarcted, peri-infarct, and remote myocardium. Results: Native T1 and ECV in peri-infarct myocardium differed from remote myocardium in acute (1181 ± 62 ms vs. 1113 ± 64 ms, p = 0.002; 24 ± 4% vs. 19 ± 4%, p = 0.031) and subacute phases (1264 ± 41 ms vs. 1171 ± 56 ms, p < 0.001; 27 ± 4% vs. 22 ± 2%, p = 0.009) but not in chronic phase (1157 ± 57 ms vs. 1120 ± 54 ms, p = 0.934; 23 ± 2% vs. 20 ± 1%, p = 0.109). From acute to chronic MI, infarcted native T1 peaked in subacute phase (1275 ± 63 ms vs. 1637 ± 123 ms vs. 1471 ± 98 ms, p < 0.001), while ECV progressively increased with time (35 ± 7% vs. 46 ± 6% vs. 52 ± 4%, p < 0.001). Native T1 correlated well with histological findings (R² = 0.65 to 0.89, all p < 0.001) so did ECV (R² = 0.73 to 0.94, all p < 0.001). Conclusion: T1 mapping allows the quantitative assessment of injury in MI and the noninvasive monitoring of tissue injury evolution, which correlates well with histological findings.

• Carbon letters
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• v.12 no.4
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.

• Geomechanics and Engineering
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• v.10 no.3
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• pp.325-334
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• 2016

Rock salt is a near-perfect material for gas storage repositories due to its excellent ductility and low permeability. Gas storage in rock salt layers during gas injection and gas production causes the stress redistribution surrounding the cavity. The triaxial cyclic loading and unloading tests for rock salt were performed in this paper. The elastic-plastic deformation behaviour of rock salt under cyclic loading was observed. Rock salt experienced strain hardening during the initial loading, and the irreversible deformation was large under low stress station, meanwhile the residual stress became larger along with the increase of deviatoric stress. Confining pressure had a significant effect on the unloading modulus for the variation of mechanical parameters. Based on the theory of elastic-plastic damage mechanics, the evolution of damage during cyclic loading and unloading under various confining pressure was described.

• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.557-566
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• 2019

The reservoir basin bedrock produced significant impact on the long-term service safety of super-high arch dams. It was important for accurately identifying geomechanical parameters and its evolution process of reservoir basin bedrock. The deformation modulus mechanism research methods of reservoir basin bedrock deformation modulus for super-high arch dams was carried out by finite element numerical calculation of the reservoir basin bedrock deformation and in-situ monitoring data analysis. The deformation modulus inversion principle of reservoir basin bedrock in a wide range was studied. The convergence criteria for determining the calculation range of reservoir basin of super-high arch dams was put forward. The implementation method was proposed for different layers and zones of reservoir basin bedrock. A practical engineering of a super-high arch dam was taken as the example.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1480-1489
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• 2024

Displacement cascade behaviors of Ti-6Al-4V alloys are investigated using molecular dynamics (MD) simulation. The embedded atom method (EAM) potential including Ti, Al and V elements is modified by adding Ziegler-Biersack-Littmark (ZBL) potential to describe the short-range interaction among different atoms. The time evolution of displacement cascades at the atomic scale is quantitatively evaluated with the energy of primary knock-on atom (PKA) ranging from 0.5 keV to 15 keV, and that for pure Ti is also computed as a comparison. The effects of temperature and incident direction of PKA are studied in detail. The results show that the temperature reduces the number of surviving Frenkel pairs (FPs), and the incident direction of PKA shows little correlation with them. Furthermore, the increasing temperature promotes the point defects to form clusters but reduces the number of defects due to the accelerated recombination of vacancies and interstitial atoms at relatively high temperature. The cluster fractions of interstitials and vacancies both increase with the PKA energy, whereas the increase of interstitial cluster is slightly larger due to their higher mobility. Compared to pure Ti, the presence of Al and V is beneficial to the formation of interstitial clusters and indirectly hinders the production of vacancy clusters.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7547-7552
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• 2014

The mir-155 family is not only involved in a diversity of cancers, but also as a regulator of the immune system. However, the evolutionary history of this family is still unclear. The present study indicates that mir-155 evolved independently with lineage-specific gain of miRNAs. In addition, arm switching has occurred in the mir-155 family, and alternative splicing could produce two different lengths of ancestral sequences, implying the alternative splicing can also drive evolution for intragenic miRNAs. Here we screened validated target genes and immunity-related proteins, followed by analyzation of the mir-155 family function by high-throughput methods like the gene ontology (GO) and Kyoto Eneyclopedin of Genes and Genemes (KEGG) pathway enrichment analysis. The high-throughput analysis showed that the CCND1 and EGFR genes were outstanding in being significantly enriched, and the target genes cebpb and VCAM1 and the protein SMAD2 were also vital in mir-155-related immune reponse activities. Therefore, we conclude that the mir-155 family is highly conserved in evolution, and CCND1 and EGFR genes might be potential targets of mir-155 with regard to progress of cancers, while the cebpb and VCAM1 genes and the protein SMAD2 might be key factors in the mir-155 regulated immune activities.