Publications by authors named "Dongxian Geng"

Plant disease control mainly relies on pesticides. In this study, a series of coumarin derivatives containing hydrazone moiety were designed and synthesized. The synthesized compounds were characterized and used to evaluate the antifungal activity against four pathogens, Botrytis cinerea, Alternaria solani, Fusarium oxysporum, and Alternaria alternata.

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We present a cell-phone based polarized microscope for diagnosing malaria through hemozoin recognition over a wide field-of-view (FOV) accompanied with decent image performance. The system is constructed based on attachment method using a lens assembly as objective, two mobile phones and two linear polarizers. A ~0.

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In this report, we report a wide field-of-view (FOV) bright field (BF) microscope with compact and portable optical components, mechanically attached to the existing camera unit of the cellphone. A white screen displayed on a cellphone as the illumination source to pump the sample of interest uniformly for the purpose of the reduction in assembly complexity and alignment. It offers a large FOV of 4.

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A differential discrimination approach has been proposed in this paper to make fast discrimination from multi-returns in time-of-flight (TOF) systems. The time resolution of classical direct discrimination in a laser TOF system has been analyzed. A theoretical model of the differential discriminator has been established.

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Influence of high-repetition-rate noise on a range-gated laser ranging and tracking system (LRTS) is studied both theoretically and experimentally. The interference mechanism of high-repetition-rate noise on range gates is revealed. The interference effect, especially the effect caused by relative shift between signal and noise, is presented through theoretical analysis and numerical simulation.

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A free space duplex communication system with a single laser and a modulated retro-reflector is presented. A method to minimize the echo wave bit error rate (BER) of this system is proposed by setting the optimum threshold automatically based on the measured mean power and irradiance variances with log-normal distribution and the Bayes minimum classification error criterion. Experiments were taken at a distance of 1.

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