7,487 research outputs found

    Control energy of complex networks towards distinct mixture states

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    Controlling complex networked systems is a real-world puzzle that remains largely unsolved. Despite recent progress in understanding the structural characteristics of network control energy, target state and system dynamics have not been explored. We examine how varying the final state mixture affects the control energy of canonical and conformity-incorporated dynamical systems. We find that the control energy required to drive a network to an identical final state is lower than that required to arrive a non-identical final state. We also demonstrate that it is easier to achieve full control in a conformity-based dynamical network. Finally we determine the optimal control strategy in terms of the network hierarchical structure. Our work offers a realistic understanding of the control energy within the final state mixture and sheds light on controlling complex systems.This work was funded by The National Natural Science Foundation of China (Grant Nos. 61763013, 61703159, 61403421), The Natural Science Foundation of Jiangxi Province (No. 20171BAB212017), The Measurement and Control of Aircraft at Sea Laboratory (No. FOM2016OF010), and China Scholarship Council (201708360048). The Boston University Center for Polymer Studies is supported by NSF Grants PHY-1505000, CMMI-1125290, and CHE-1213217, and by DTRA Grant HDTRA1-14-1-0017. (61763013 - National Natural Science Foundation of China; 61703159 - National Natural Science Foundation of China; 61403421 - National Natural Science Foundation of China; 20171BAB212017 - Natural Science Foundation of Jiangxi Province; FOM2016OF010 - Measurement and Control of Aircraft at Sea Laboratory; 201708360048 - China Scholarship Council; PHY-1505000 - NSF; CMMI-1125290 - NSF; CHE-1213217 - NSF; HDTRA1-14-1-0017 - DTRA)Published versio

    Effect of honeycomb core under hypervelocity impact: numerical simulation and engineering model

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    Abstract Honeycomb sandwich panels (HC/SP) are the most common used structures for space vehicle. Under the threat of meteoroid and space debris, the distribution of the fragments produced in a hypervelocity impact event on HC/SP is critical to the vulnerability assessment of space vehicle. CISAS developed an engineering model to describe fragments clouds propagating inside spacecraft in consequence of space debris impact on HC/SP. In this model, the effect of the honeycomb core was modeled by an empirical corrective factor, which was not related to the physical of the impact. To improve this model, a new model to describe the effect of the honeycomb core was developed. In the new model, the honeycomb core was equaled to multi-parallel thin plates, which can represent the discontinuity of honeycomb core without complex boundary. Based on the knowledge of hypervelocity impact on a simple thin plate and approximation supported by numerical simulation results, the model was deduced. The coefficient of the model was fitted by the numerical simulation results

    Attention guided global enhancement and local refinement network for semantic segmentation

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    The encoder-decoder architecture is widely used as a lightweight semantic segmentation network. However, it struggles with a limited performance compared to a well-designed Dilated-FCN model for two major problems. First, commonly used upsampling methods in the decoder such as interpolation and deconvolution suffer from a local receptive field, unable to encode global contexts. Second, low-level features may bring noises to the network decoder through skip connections for the inadequacy of semantic concepts in early encoder layers. To tackle these challenges, a Global Enhancement Method is proposed to aggregate global information from high-level feature maps and adaptively distribute them to different decoder layers, alleviating the shortage of global contexts in the upsampling process. Besides, a Local Refinement Module is developed by utilizing the decoder features as the semantic guidance to refine the noisy encoder features before the fusion of these two (the decoder features and the encoder features). Then, the two methods are integrated into a Context Fusion Block, and based on that, a novel Attention guided Global enhancement and Local refinement Network (AGLN) is elaborately designed. Extensive experiments on PASCAL Context, ADE20K, and PASCAL VOC 2012 datasets have demonstrated the effectiveness of the proposed approach. In particular, with a vanilla ResNet-101 backbone, AGLN achieves the state-of-the-art result (56.23% mean IoU) on the PASCAL Context dataset. The code is available at https://github.com/zhasen1996/AGLN.Comment: 12 pages, 6 figure

    Injector Design Tool Improvements: User's manual for FDNS V.4.5

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    The major emphasis of the current effort is in the development and validation of an efficient parallel machine computational model, based on the FDNS code, to analyze the fluid dynamics of a wide variety of liquid jet configurations for general liquid rocket engine injection system applications. This model includes physical models for droplet atomization, breakup/coalescence, evaporation, turbulence mixing and gas-phase combustion. Benchmark validation cases for liquid rocket engine chamber combustion conditions will be performed for model validation purpose. Test cases may include shear coaxial, swirl coaxial and impinging injection systems with combinations LOXIH2 or LOXISP-1 propellant injector elements used in rocket engine designs. As a final goal of this project, a well tested parallel CFD performance methodology together with a user's operation description in a final technical report will be reported at the end of the proposed research effort

    UV Finite Brane Decay

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    The decay of an unstable D-brane via closed string emission and open string pair production is considered in subcritical string theory with a spacelike linear dilaton. The decay rate is given by the imaginary part of the annulus, which has ambiguities corresponding to the choices of incoming closed and open string vacua. An exact expression for the full annulus diagram is computed with a natural choice of incoming vacua. It is found that the ultraviolet divergences present in critical string theory in both of these processes are absent for any nonzero spacelike dilaton. Implications for the vexing issue of the tachyon dust are discussed.Comment: 21 pages, 3 figures, minor changes, changed to JHEP styl

    Investigating the maxillary buccal vestibule

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    AbstractBackground/purposeImproper assessment of the maxillary buccal vestibular space can contribute to the fabrication of maxillary dentures with inadequate buccal flange extensions. The purpose of this study was to determine whether a significant difference existed between the anatomic dimensions of the buccal vestibules and the corresponding buccal flanges of maxillary complete dentures in an edentulous population.Materials and methodsThe anterior, middle, and posterior depth and width of the maxillary buccal vestibules in 100 randomly selected subjects were measured with a periodontal probe. Corresponding measurements of the buccal flanges of the subjects' existing dentures were recorded. The differences between buccal vestibule widths and depths and denture flange widths and lengths were statistically compared according to site.ResultsThe difference in the mean depth between the vestibules and the flanges in the posterior area (6.4 mm and 10.3 mm, respectively) was approximately 38% (P < 0.001). The difference in the mean width between the vestibules and the flanges in the posterior area (3.3 mm and 7.9 mm, respectively) was approximately 58% (P < 0.001).ConclusionThe study revealed statistically significant differences between the anatomic depth and width of the buccal vestibules and the corresponding flange dimensions of the existing dentures

    Spontaneous regression of advanced hepatocellular carcinoma: a case report

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    Spontaneous regression of advanced hepatocellular carcinoma is extremely rare. A 66-year-old Taiwanese male patient with liver cirrhosis related to chronic hepatitis C presented with hepatocellular carcinoma with portal vein thrombosis. At first, he refused curative therapy, except for silymarin medicine. Spontaneous regression of hepatocellular carcinoma occurred with a decline in tumour size and tumour marker in imaging studies. The patient agreed to undergo surgery approximately 14 months after presentation because of no further decrease in tumour size and an increase in tumour marker in the imaging studies. The resected tumour was hepatocellular carcinoma with portal vein thromboses. Presently, the patient is alive and in good condition without any symptoms or tumour recurrence. We concluded that this was a rare case of spontaneous regression of advanced hepatocellular carcinoma

    Two new species of Scytinostroma (Russulales, Basidiomycota) in Southwest China

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    Two new species of Scytinostroma viz. S. acystidiatum and S. macrospermum, are described from southwest China. Phylogeny based on ITS + nLSU dataset demonstrates that samples of the two species form two independent lineages and are different in morphology from the existing species of Scytinostroma. Scytinostroma acystidiatum is characterized by resupinate, coriaceous basidiomata with cream to pale yellow hymenophore, a dimitic hyphal structure with generative hyphae bearing simple septa, the absence of cystidia, and amyloid, broadly ellipsoid basidiospores measuring 4.7–7 × 3.5–4.7 μm. Scytinostroma macrospermum is characterized by resupinate, coriaceous basidiomata with cream to straw yellow hymenophore, a dimitic hyphal structure with generative hyphae bearing simple septa, numerous cystidia embedded or projecting from hymenium, and inamyloid, ellipsoid basidiospores measuring 9–11 × 4.5–5.5 μm. The differences between the new species and morphologically similar and phylogenetically related species are discussed
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