75 research outputs found
Performance Measurement of Vietnamese Publishing Firms by the Integration of the GM (1,1) Model and the Malmquist Model
Background: In the new technology context, the publishing industry cannot continue to maintain its business operations and to develop relying solely on traditional product offerings, such as books, magazines, and newspapers. There needs to be an expansion into innovative products, such as e-books, micro-publishing, and websites. Objectives: The paper addresses the factors influencing financial reports of Vietnamese publishing firms using two methodological approaches, namely the Grey first-order one variables (GM,1,1) model in the Grey theory and the Malmquist model in the data envelopment analysis (DEA). Methods/Approach: The GM(1,1) model predicts the future period of 2020–2023 based on the historical time series analysis. The Malmquist model presents catch-up, frontier-shift, and Malmquist Productivity Index (MPI) in whole terms. Results: The analysis provides an overview of the publishing industry in Vietnam. The final empirical results show that twelve companies reached a production efficiency higher than 1 and fourteen companies are expected to attain a productivity score higher than 1. Conclusions: Only a few firms do not need to change significantly; however, the remaining firms must re-evaluate their current operations
DOLABRANE-TYPE DITERPENOID AND LIGNAN CONSTITUENTS FROM THE STEM BARKS OF CERIOPS DECANDRA (GRIFF.) W. THEOB.
Three dolabrane-type diterpenoids (1‒3) and a lignan derivative (4) were isolated from a methanolic extract of C. decandra stem barks using various chromatographic separations. Their structures were elucidated to be tagalsine X (1), tagalsin P (2), ent-5α,2-oxodolabr-3-ene-3,15,16-triol (3), and (+)-pinoresinol (4) by detailed analysis via spectroscopic techniques (1D, 2D NMR, and ESI-MS data) as well as comparison with those reported. This is the first report of compound 4 from the Ceriops genus
A Simple Linear Time Algorithm for Computing a 1-Median on Cactus Graphs
We address the problem of finding a 1-median on a cactus graph. The problem has already been solved in linear time by the algorithms of Burkard and Krarup (1998), and Lan and Wang (2000). These algorithms are complicated and need efforts. Hence, we develop in this paper a simpler algorithm. First, we construct a condition for a cycle that contains a 1-median or for a vertex that is indeed a 1-median of the cactus. Based on this condition, we localize the search for deriving a 1-median on the underlying cactus. Complexity analysis shows that the approach runs in linear time
FPGA-Based Multiple DDoS Countermeasure Mechanisms System Using Partial Dynamic Reconfiguration
In this paper, we propose a novel FPGA-based high-speed DDoS countermeasure system that can flexibly adapt to DDoS attacks while still maintaining system performance. The system includes a packet decoder module and multiple DDoS countermeasure mechanisms. We apply dynamic partial reconfiguration technique in this system so that the countermeasure mechanisms can be flexibly changed or updated on-the-fly. The proposed system architecture separates DDoS protection modules (which implement DDoS countermeasure techniques) from the packet decoder module. By using this approach, one DDoS protection module can be reconfigured without interfering with other modules. The proposed system is implemented on a NetFPGA 10G board. The synthesis results show that the system can work at up to 116.782 MHz while utilizing up to 39.9% Registers and 49.85% BlockRAM of the Xilinx Virtex xcv5tx240t FPGA device on the NetFPGA 10G board. The system achieves the detection rate of 100% with the false negative rate at 0% and false positive rate closed to 0.16%. The prototype system achieves packet decoding throughput at 9.869 Gbps in half-duplex mode and 19.738 Gbps in full-duplex mode
Design and performance analysis of a mechanically coupled spring compliant to out-of-plane oscillation
In this paper, a spring system symmetrically arranged around a circular plate compliant to out-of-plane oscillation is proposed. The spring system consists of single serpentine springs mutually coupled in a plane. Three theoretical mechanical models for evaluating the stiffness of the spring system are built, which are based on the flexural beam, Sigitta, and serpentine spring theories and equivalent mechanical spring structure models. The theoretically calculated results are in good agreement with numerical solutions using the finite element method, with errors less than 10% in the appropriate dimension ranges of the spring. Compared to similar spring structures without mechanical coupling, the proposed mechanically coupled spring shows advantage in suppressing the mode coupling
Phenolic compounds from leaves of Amensiodendron chinese (Sapindaceae)
From the ethyl acetate extract of the leaves of Amensiodendron chinense (Merr.) Hu (Sapindaceae), we isolated three known phenolic compounds: 4-hydroxy-3-methoxybenzaldehyde (1), methyl 3,4-dihydroxybenzoate (2), and 3,4-dihydroxybenzoic acid (3). We elucidated their chemical structures from the spectral data and compared them with those reported in the literature.3 hợp chất phenolic được phân lập từ cao chiết ethyl acetate của lá thuộc loài Amensiodendron chinese (Merr.) Hu (Sapindaceae) bao gồm : 4-hydroxy-3-methoxybenzaldehyde (1), methyl 3,4-dihydroxybenzoate (2), 3,4-dihydroxybenzoic acid (3). Cấu trúc hóa học được xác định dựa vào dữ liệu phổ và so sánh với tài liệu tham khảo
LIGNANS FROM LEAVES OF AMESIODENDRON CHINENSE AND THEIR CYTOTOXIC ACTIVITY
ABSTRACTFrom leaves of Amesiodendron chinense (Mer.) Hu four lignans (+)-aptosimon (1), (+)-isolariciresinol (2), (-)-cleomiscosin A (3), and (-)-cleomiscosin C (3) were isolated. Their structures were determined by spectroscopic analysis including MS, 1D and 2D NMR as well as by comparison with reported data in literature. All compounds were evaluated for cytotoxic activities against five human cancer cell lines, KB, SK-LU-1, MCF-7, HepG-2, and SW-480. They showed weak cytotoxic activity on five tested human cancer cell lines with IC50 values ranging from 32.61 to 95.18 µg/ml
Green synthesis and crystal structure of 3-(benzo-thia-zol-2-yl)thio-phene.
The title compound, C11H7NS2, was prepared in high yield (87%) using a solvent-free microwave-assisted synthesis. The structure shows whole-mol-ecule disorder with occupancies for two orientations (A and B) of 0.4884 (10) and 0.5116 (10), respectively. The thio-phene and benzo-thia-zole rings are almost planar and make dihedral angles of 10.02 (18) and 12.54 (19)° for orientations A and B, respectively. Slipped π-π stacking between the aromatic rings, together with C-H⋯π, C-H⋯S and C-H⋯N inter-actions, result in a herringbone motif in the crystal packing
Crystal structure of <i>N</i>-(4-oxo-2-sulfanyl-idene-1,3-thia-zolidin-3-yl)-2-(thio-phen-3-yl)acetamide.
The title compound, C9H8N2O2S3, crystallizes with two mol-ecules (A and B) in the asymmetric unit. Both have similar conformations (overlay r.m.s. deviation = 0.209 Å) and are linked by an N-H⋯O hydrogen bond. In both mol-ecules, the thio-phene rings show orientational disorder, with occupancy factors of 0.6727 (17) and 0.3273 (17) for mol-ecule A, and 0.7916 (19) and 0.2084 (19) for mol-ecule B. The five-membered rings make an angle of 79.7 (2)° in mol-ecule A and an angle of 66.8 (2)° in mol-ecule B. In the crystal, chains of mol-ecules running along the a-axis direction are linked by N-H⋯O hydrogen bonds. The inter-action of adjacent chains through N-H⋯O hydrogen bonds leads to two types of ring structures containing four mol-ecules and described by the graph-set motifs R44(18) and R42(14)
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