Research on Video Smoke Recognition Based on Dynamic Image Segmentation Detection Technology
2019 12th International Conference on Intelligent Computation Technology and Automation (ICICTA)
The smoke feature recognition stage is a relatively core part. The quality of the smoke feature r... more The smoke feature recognition stage is a relatively core part. The quality of the smoke feature recognition algorithm directly affects the accuracy and real-time of the alarm. The existing smoke feature recognition methods are roughly classified into the recognition of color features, the identification of static features of smoke, and the identification of dynamic features of smoke. Experiments show that using the cumulative amount and the main motion direction to identify the combined motion history image and the constant distance to identify the characteristics of the smoke can get good results. Digital image processing technology and pattern recognition technology enable the system to sense where the human eye can perceive and detect fires based on the characteristics of the smoke image. In practical applications, video smoke detection only requires hardware devices such as cameras, and even the use of its own security surveillance camera, the hardware cost is very low; and the scope of use is very wide, basically no conditions are limited; portability is very good. This paper combines fire detection and recognition based on video images with visual attention mechanisms. Preprocessing the video image using the visual attention mechanism not only compensates for the shortcomings of the traditional fire detection method, but also significantly improves the speed and accuracy of fire detection and recognition.
The development of experimental techniques, in particular the emergence of the X-ray free-electro... more The development of experimental techniques, in particular the emergence of the X-ray free-electron lasers, allows one to register the scattering from an isolated particle and, thereby, opens a door to the study of a fine three-dimensional structure of non-crystalline biological objects by X-ray diffraction methods. The possibility to measure non-Bragg reflections makes experimental data mutually dependent and essentially simplifies the structure solution. The sampling of experimental scattering data to a sufficiently fine grid makes the structure determination equivalent to phasing of structure factor magnitudes for a 'virtual' crystal with extremely large solvent content. This makes density modification phasing methods especially powerful supposing the object envelope is known. At the same time, such methods may be sensitive to the accuracy of the predefined envelope and completeness of experimental data and may suffer from non-uniqueness of the solution of the phase problem. The mask-based approach is a preliminary phasing method that performs random search for connected object envelopes possessing of the structure factor magnitudes close to the values observed in X-ray experiment. The alignment and averaging of the phase sets corresponding to selected putative envelopes produce an approximate solution of the phase problem. Beside the estimation of unknown phase values this approach allows one to estimate the values of structure factor magnitudes lost in the experiment, e.g. those corresponding to beam-stop shade zone or to oversaturated reflections.
THE QUEST FOR A trans-CHELATING DIPHOSPHINE MOLYBDENUM COMPLEX
In the modern world, catalysts are essential in the synthesis of many compounds. Often, these are... more In the modern world, catalysts are essential in the synthesis of many compounds. Often, these are organometallic complexes, compounds with a central metal atom and bonded ligands. Before these catalysts can be implemented commercially, it is necessary for them to be synthesized and analyzed in a laboratory setting to fully understand their formation, structure, and properties. This study focuses on the synthesis of an octahedral trans-chelating diphosphine molybdenum complex, an organometallic complex with a central molybdenum atom, two phosphines linked by a carbon chain on opposite sides of the molecule, and carbonyl groups on the remaining peripheral atoms. We varied the lengths of carbon chain that were used to determine the range of carbon chain length that allowed for the isomerization of the cissubstituted molecule to the transisomer. The production of the molybdenum compound comprised of the initial formation of a cismolybdenum-dipiperidine complex followed by the replacemen...
for insights that improved the analysis. All remaining errors are our own. No external research s... more for insights that improved the analysis. All remaining errors are our own. No external research support was used to conduct this research. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The X-ray structure of compound (R,S)-17 S-38 17 d,e 11a MeOH-H 2 O (8:2), 18 h 92.5 a All the re... more The X-ray structure of compound (R,S)-17 S-38 17 d,e 11a MeOH-H 2 O (8:2), 18 h 92.5 a All the reactions were carried out with 1a (0.10 mmol), 2,2-diphenylglycine 19 (0.10 mmol), 11 (0.010 mmol for entries 1-3 and 6-9 and 0.0050 mmol for entries 4-5 and 10-17) in solvent (1.0 mL) at rt unless otherwise stated. b Isolated yield based on 1a. c Determined by chiral HPLC analysis of the corresponding methyl ester of 5a. d The reaction was carried out in MeOH-H 2 O (8:2) (0.5 mL). e HOAc (0.10 mmol) was added. S-4 Procedures for the Synthesis of Compound 13 (Scheme 2) Step i. Synthesis of compound 29 To a 1-L, three-neck, round-bottom flask equipped with a stirrer bar and a reflux condenser were added 3-bromo-2-methyl-5-nitropyridine (20.0 g, 92.2 mmol), iron powder (10.3 g, 184 mmol), ammonium chloride (24.6 g, 464 mmol), and MeOH (300 mL). After stirring at reflux overnight, the reaction mixture was concentrated to remove the methanol. To the flask was added EtOAc (500 mL). The mixture was submitted to filtration via a pad of Celite. The filtrate was concentrated via rotary evaporation under reduced pressure and then purified by column chromatography (ethyl acetate) to give compound 29 as a white solid (11.0 g, 64%).
Chiral Pyridoxal-Catalyzed Asymmetric Biomimetic Transamination of α-Keto Acids
Organic Letters, 2015
A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine ... more A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine and (S)-α,α-diarylprolinols. The pyridoxals exhibited good catalytic activity in an asymmetric transamination of α-keto acids with 2,2-diphenylglycine (7f) as the amine source to give various α-amino acids in 29-85% yields with 53-80% ee's. The current asymmetric transamination has successfully mimicked a complete biological transamination process characterized by two half-transaminations, a small chiral pyridoxal molecule acting as the catalyst, and enantioselective control.
Uploads
Papers by Ethan Liu