A Linear-Time Algorithm for Finding Induced Planar Subgraphs

In this paper we study the problem of efficiently and effectively extracting induced planar subgraphs. Edwards and Farr proposed an algorithm with O(mn) time complexity to find an induced planar subgraph of at least 3n/(d+1) vertices in a graph of maximum degree d. They also proposed an alternative algorithm with O(mn) time complexity to find an induced planar subgraph graph of at least 3n/(bar{d}+1) vertices, where bar{d} is the average degree of the graph. These two methods appear to be best known when d and bar{d} are small. Unfortunately, they sacrifice accuracy for lower time complexity by using indirect indicators of planarity. A limitation of those approaches is that the algorithms do not implicitly test for planarity, and the additional costs of this test can be significant in large graphs. In contrast, we propose a linear-time algorithm that finds an induced planar subgraph of n-nu vertices in a graph of n vertices, where nu denotes the total number of vertices shared by the detected Kuratowski subdivisions. An added benefit of our approach is that we are able to detect when a graph is planar, and terminate the reduction. The resulting planar subgraphs also do not have any rigid constraints on the maximum degree of the induced subgraph. The experiment results show that our method achieves better performance than current methods on graphs with small skewness

Anatomy of High-Performance GEMM with Online Fault Tolerance on GPUs

General Matrix Multiplication (GEMM) is a crucial algorithm for various applications such as machine learning and scientific computing, and an efficient GEMM implementation is essential for the performance of these systems. While researchers often strive for faster performance by using large compute platforms, the increased scale of these systems can raise concerns about hardware and software reliability. In this paper, we present a design for a high-performance GEMM with algorithm-based fault tolerance for use on GPUs. We describe fault-tolerant designs for GEMM at the thread, warp, and threadblock levels, and also provide a baseline GEMM implementation that is competitive with or faster than the state-of-the-art, proprietary cuBLAS GEMM. We present a kernel fusion strategy to overlap and mitigate the memory latency due to fault tolerance with the original GEMM computation. To support a wide range of input matrix shapes and reduce development costs, we present a template-based approach for automatic code generation for both fault-tolerant and non-fault-tolerant GEMM implementations. We evaluate our work on NVIDIA Tesla T4 and A100 server GPUs. Experimental results demonstrate that our baseline GEMM presents comparable or superior performance compared to the closed-source cuBLAS. The fault-tolerant GEMM incurs only a minimal overhead (8.89\% on average) compared to cuBLAS even with hundreds of errors injected per minute. For irregularly shaped inputs, the code generator-generated kernels show remarkable speedups of $160\% \sim 183.5\%$ and $148.55\% \sim 165.12\%$ for fault-tolerant and non-fault-tolerant GEMMs, outperforming cuBLAS by up to $41.40\%$.Comment: 11 pages, 2023 International Conference on Supercomputin

Corrosion Characteristics of Electrodeposited Ni Mo P Alloy Immersed in NaCl Solution

用失重法、阳极极化曲线、Ｘ光电子能谱（ＸＰＳ）以及俄歇电子能谱（ＡＥＳ）研究了电沉积ＮｉＭｏＰ合金镀层在５％ＮａＣｌ溶液中的腐蚀特性．非晶态ＮｉＭｏＰ合金镀层比晶态ＮｉＭｏＰ合金镀层有较低的腐蚀速度．阳极极化曲线表明，ＮｉＭｏＰ合金镀层中，镍的摩尔分数为０．７１９～０．８６８时，随镀层中磷含量的增加，腐蚀电位正移；而活化区的峰电流随镀层中钼含量的增加而增加．磷含量对活化区的峰电流以及钼含量对腐蚀电位的影响均很小．ＸＰＳ和ＡＥＳ分析指出，经５％ＮａＣｌ溶液中浸渍后，ＮｉＭｏＰ合金镀层表面形成厚度约为５０ｎｍ的氧化膜．这层氧化膜主要由Ｎｉ２Ｏ３，ＭｏＯ３和ＰＯ４３－等构成，其在电解质溶液和合金间起着阻挡层的作用．The corrosion characteristics of electrodeposited Ni Mo P alloy immersed in 5wt.% NaCl solution were investigated using immersion, anodic polarization curves, XPS and AES analysis. The corrosion rates of amorphous Ni Mo P alloys are lower than that of crystalline Ni Mo P alloys. Anodic polarization curve experiments show that for the electrodeposited Ni Mo P alloys, the nickel mol fraction of which has in between 0.719 and 0.868, the corrosion potential moves to positive with the increase of P content, and the peak current value of active region increase with the increase of Mo content in alloys, though the effects of P content on the peak current of active region and of Mo content on the corrosion potential are insignificant. XPS and AES analyses indicate that after immersion in 5wt.% NaCl solution, an oxidation film of about 50 nm in thickness is formed on the surface of Ni Mo P alloys. This oxidation film is composed of Ni 2O 3,MoO 3 and PO 3- 4, and acts as a barrier between the alloy and the electrolyte.作者联系地址：湖南师范大学化学系,天津大学应用化学系Author's Address: Department of Chemistry, Hunan Normal University, Changsha, Hunan, 410006 Yao Suwei Guo Hetong Department of Applied Chemistry, Tiangjin University, Tianjin, 30007

Probability Weighting Localization Algorithm Based on NLOS Identification in Wireless Network

In this paper, a localization scenario that the home base station (BS) measures time of arrival (TOA) and angle of arrival (AOA) while the neighboring BSs only measure TOA is investigated. In order to reduce the effect of non-line of sight (NLOS) propagation, the probability weighting localization algorithm based on NLOS identification is proposed. The proposed algorithm divides these range and angle measurements into different combinations. For each combination, a statistic whose distribution is chi-square in LOS propagation is constructed, and the corresponding theoretic threshold is derived to identify each combination whether it is LOS or NLOS propagation. Further, if those combinations are decided as LOS propagation, the corresponding probabilities are derived to weigh the accepted combinations. Simulation results demonstrate that our proposed algorithm can provide better performance than conventional algorithms in different NLOS environments. In addition, computational complexity of our proposed algorithm is analyzed and compared

Characterization of the complete chloroplast genome of Begonia handelii

Begonia is the fifth largest genus of angiosperms in the world, and Begonia handelii is a member of the Begonia(Begoniaceae), and is one of the few species with floral fragrance in this genus. However, the chloroplast genome structure and phylogenetic relationship of this species is still unclear. In this study, the chloroplast genome of B. handelii was sequenced by Illumina HiSeq X platform, and the phylogenetic relationship of this species in Begonia was analyzed with related species. The whole chloroplast genome of B. handelii is 169,406 bp in size, which consist one large single-copy region (LSC) with 95,403 bp, one small single-copy region (SSC) with 20,089 bp, and two inverted repeat regions (IR) with 26,957 bp. The GC content of this chloroplast genome is 35.6%. Moreover, 140 genes were found in the chloroplast of B. handelii, including 90 protein-coding genes, 8 rRNA genes, 42 tRNA genes. Phylogenetic analysis showed that B. handelii is closed to B. coptidifolia and B. pulchrifolia. This study lays the foundation for further research on the chloroplast genome evolution of B. handelii chloroplasts

Improved nonlinear optical properties of chalcogenide glasses in Ge-Sn-Se ternary system by thermal treatment

International audienceIn this work, a series of chalcogenide glass ceramics were prepared by thermal treating a precursor glass in molar composition of Ge20Sn5Se75 with different duration. X-ray powder diffraction (XRD) measurements showed the precipitation of nano-crystals belonging to GeSe2 and SnSe2 phases in the heat-treated glasses, which was confirmed by Raman spectra as well. The crystallization in glass matrix caused the variation of optical properties (i.e. Optical band gap, Urbach energy) due to localized field effect of the nano-crystals, while the infrared transmittance was kept unchanged. Third-order optical nonlinear properties of the precursor glass and glass ceramic samples were investigated by femtosecond Z-scan technique at telecom wavelength of 1550 nm. The maximum nonlinear refraction (γ) of the Ge-Sn-Se glass ceramics reached 5.319 × 10−16 m2/W, which is almost one order higher than that of the precursor glass, demonstrating the significant influence of nano-crystals on optical nonlinear property of the chalcogenide glasses