Dynamic update of shortest path tree in OSPF

2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

An improved q-rrt*algorithm based on virtual light

The Rapidly-exploring Random Tree (RRT) algorithm is an efficient path-planning algorithm based on random sampling. The RRT Algorithm is a variant of the RRT algorithm that can achieve convergence to the optimal solution. However, it has been proven to take an infinite time to do so. An improved Quick-RRT*(Q-RRT*) algorithm based on a virtual light source is proposed in this paper to overcome this problem. The virtual light-based Q-RRT*(LQRRT*) takes advantage of the heuristic information generated by the virtual light on the map. In this way, the tree can find the initial solution quickly. Next, the LQRRT*algorithm combines the heuristic information with the optimization capability of the Q-RRT*algorithm to find the approximate optimal solution. LQRRT*further optimizes the sampling space compared with the Q-RRT*algorithm and improves the sampling efficiency. The efficiency of the algorithm is verified by comparison experiments in different simulation environments. The results show that the proposed algorithm can converge to the approximate optimal solution in less time and with lower memory consumption

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Age-hardening in Al alloys has been used for over a century to improve its mechanical properties. However, the lack of direct observation limits our understanding of the dynamic nature of the evolution of nanoprecipitates during age-hardening. Using in-situ (scanning) transmission electron microscopy (S/TEM) while heating an Al-Cu alloy, we were able to follow the growth of individual nanoprecipitates at atomic scale. The heat treatments carried out at 140, 160, 180 and 200 degrees C reveal a temperature dependence on the kinetics of precipitation and three kinds of interactions of nano-precipitates. These are precipitate-matrix, precipitate-dislocation, and precipitate-precipitate interactions. The diffusion of Cu and Al during these interactions, results in diffusion-controlled individual precipitate growth, an accelerated growth when interactions with dislocations occur and a size dependent precipitateprecipitate interaction: growth and shrinkage. Precipitates can grow and shrink at opposite ends at the same time resulting in an effective displacement. Furthermore, the evolution of the crystal structure within an individual nanoprecipiate, specifically the mechanism of formation of the strengthening phase,theta', during heat-treatment is elucidated by following the same precipitate through its intermediate stages for the first time using in-situ S/TEM studies

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Age-hardening in Al alloys has been used for over a century to improve its mechanical properties. However, the lack of direct observation limits our understanding of the dynamic nature of the evolution of nanoprecipitates during age-hardening. Using in-situ (scanning) transmission electron microscopy (S/TEM) while heating an Al-Cu alloy, we were able to follow the growth of individual nanoprecipitates at atomic scale. The heat treatments carried out at 140, 160, 180 and 200 °C reveal a temperature dependence on the kinetics of precipitation and three kinds of interactions of nano-precipitates. These are precipitate-matrix, precipitate-dislocation, and precipitate-precipitate interactions. The diffusion of Cu and Al during these interactions, results in diffusion-controlled individual precipitate growth, an accelerated growth when interactions with dislocations occur and a size dependent precipitate-precipitate interaction: growth and shrinkage. Precipitates can grow and shrink at opposite ends at the same time resulting in an effective displacement. Furthermore, the evolution of the crystal structure within an individual nanoprecipiate, specifically the mechanism of formation of the strengthening phase, θ′, during heat-treatment is elucidated by following the same precipitate through its intermediate stages for the first time using in-situ S/TEM studies

Loop Distribution and Fusion with Timing and Code Size Optimization for Embedded DSPs

International Conference on Embedded and Ubiquitous Computing (EUC 2005), Nagasaki, Japan,6-9 Dec 2005Loop distribution and loop fusion are two e.ective loop transformation techniques to optimize the execution of the programs in DSP applications. In this paper, we propose a new technique combining loop distribution with direct loop fusion, which will improve the timing performance without jeopardizing the code size. We .rst develop the loop distribution theorems that state the legality conditions of loop distribution for multi-level nested loops. We show that if the summation of the edge weights of the dependence cycle satis.es a certain condition, then the statements involved in the dependence cycle can be distributed; otherwise, they should be put in the same loop after loop distribution. Then, we propose the technique of maximum loop distribution with direct loop fusion. The experimental results show that the execution time of the transformed loops by our technique is reduced 21.0compared to the original loops and the code size of the transformed loops is reduced 7.0% on average compared to the original loops.Department of Computin

What Makes Theatrical Performances Successful in China's Tourism Industry?

This study aims to explore the factors affecting the success of a popular tourist product, namely, theatrical performance, within the context of China's tourism industry and develop a model based on previously successful productions. Using qualitative software, 22 Chinese-language articles on theatrical performances are analyzed to generate a list of success factors, classified as internal and external. The internal factors are storyline and performing, market positioning and marketing strategy, investment and financial support, operation and management, performing team, outdoor venue, indoor/outdoor stage supporting facilities, continuous improvement, and production team. The external factors are collaboration between cultural industries and local tourism, government support, privatization, and social and cultural effect. This study also provides suggestions for the future development of theatrical performances in China

Precise exogenous insertion and sequence replacements in poplar by simultaneous HDR overexpression and NHEJ suppression using CRISPR-Cas9

CRISPR-mediated genome editing has become a powerful tool for the genetic modification of biological traits. However, developing an efficient, site-specific, gene knock-in system based on homology-directed DNA repair (HDR) remains a significant challenge in plants, especially in woody species like poplar. Here, we show that simultaneous inhibition of non-homologous end joining (NHEJ) recombination cofactor XRCC4 and overexpression of HDR enhancer factors CtIP and MRE11 can improve HDR efficiency for gene knock-in. Using this approach, the BleoR gene was integrated onto the 3′ end of the MKK2 MAP kinase gene to generate a BleoR-MKK2 fusion protein. Based on fully edited nucleotides evaluated by TaqMan real-time PCR, the HDR-mediated knock-in efficiency was up to 48% when using XRCC4 silencing incorporated with a combination of CtIP and MRE11 overexpression compared with no HDR enhancement or NHEJ silencing. Furthermore, this combination of HDR enhancer overexpression and NHEJ repression also increased genome targeting efficiency and gave 7-fold fewer CRISPR-induced insertions and deletions (InDels), resulting in no functional effects on MKK2-based salt stress responses in poplar. Therefore, this approach may be useful not only in poplar and plants or crops but also in mammals for improving CRISPR-mediated gene knock-in efficiency