Combined treatments of chitosan and sodium silicate to inhibit Alternaria alternata pathogens of postharvest winter jujube

Jingru Zhang,Xiaowen Cheng,Lulu Chang,Lele Zhang,Shaoying Zhang 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.4

Alternaria alternata is a pathogenic fungus thatinfects jujube fruit and leads to serious economic losses. Inthis paper, the antifungal activity of chitosan combinedwith sodium silicate against A. alternata in vitro andin vivo was investigated, and the possible antimicrobialmechanisms were explored. Results showed that the sporegermination and colony expansion of A. alternata weresignificantly inhibited by chitosan. Chitosan treatmentinduced the leakages of intercellular electrolytes, nucleicacids, and soluble protein of A. alternata. Meanwhile,chitosan damaged the cell morphology and membraneintegrity of A. alternata. The combination of chitosan andsodium silicate was more effective than chitosan alone. Inaddition, the effect of chitosan and sodium silicate couldsignificantly decrease natural rot rate and delay lesionexpansion of winter jujube. Collectively, chitosan combinedwith sodium silicate had the potential to controlpostharvest diseases of fruit caused by A. alternata.

Power output and efficiency of a negative capacitance and inductance shunt for structural vibration control under broadband excitation

Qureshi, Ehtesham Mustafa,Shen, Xing,Chang, Lulu The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

Structural vibration control using a piezoelectric shunt is an established control technique. This technique involves connecting a piezoelectric patch, which is bonded onto or embedded into the vibrating structure, to an electric shunt circuit. Thus, vibration energy is converted into electrical energy and is dissipated through a network of electrical components. Different configurations of shunt have been researched, among which the negative capacitance-inductance shunt has gained prominence recently. It is basically an analog, active circuit consisting of operational amplifiers and passive elements to introduce real and imaginary impedance on the vibrating structure. The present study attempts to model the behavior of a negative capacitance-inductance shunt in terms of power output and efficiency using circuit modeling software. The shunt model is validated experimentally and is used to control the structural vibration of an aluminum beam, connected to a pair of piezoelectric patches, under broadband excitation. The model is also used to determine the optimal parameters of a negative capacitance-inductance shunt to increase the efficiency and predict the voltage output limit of op-amp against the supply voltage.

An autonomous synchronized switch damping on inductance and negative capacitance for piezoelectric broadband vibration suppression

Qureshi, Ehtesham Mustafa,Shen, Xing,Chang, Lulu The Korean Society for Aeronautical and Space Scie 2016 International Journal of Aeronautical and Space Sc Vol.17 No.4

Synchronized switch damping (SSD) is a structural vibration control technique in which a piezoelectric patch attached to or embedded into the structure is connected to or disconnected from the shunt circuit in order to dissipate the vibration energy of the host structure. The switching process is performed by a digital signal processor (DSP) which detects the displacement extrema and generates a command to operate the switch in synchronous with the structure motion. Recently, autonomous SSD techniques have emerged in which the work of DSP is taken up by a low pass filter, thus making the whole system autonomous or self-powered. The control performance of the previous autonomous SSD techniques heavily relied on the electrical quality factor of the shunt circuit which limited their damping performance. Thus in order to reduce the influence of the electrical quality factor on the damping performance, a new autonomous SSD technique is proposed in this paper in which a negative capacitor is used along with the inductor in the shunt circuit. Only a negative capacitor could also be used instead of inductor but it caused saturation of negative capacitor in the absence of an inductor due to high current generated during the switching process. The presence of inductor in the shunt circuit of negative capacitor limits the amount of current supplied by the negative capacitance, thus improving the damping performance. In order to judge the control performance of proposed autonomous SSDNCI, a comparison is made between the autonomous SSDI, autonomous SSDNC and autonomous SSDNCI techniques for the control of an aluminum cantilever beam subjected to both single mode and multimode excitation. A value of negative capacitance slightly greater than the piezoelectric patch capacitance gave the optimum damping results. Experiment results confirmed the effectiveness of the proposed autonomous SSDNCI technique as compared to the previous techniques. Some limitations and drawbacks of the proposed technique are also discussed.

Power output and efficiency of a negative capacitance and inductance shunt for structural vibration control under broadband excitation

Ehtesham Mustafa Qureshi,Xing Shen,Lulu Chang 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.2

Structural vibration control using a piezoelectric shunt is an established control technique. This technique involves connecting a piezoelectric patch, which is bonded onto or embedded into the vibrating structure, to an electric shunt circuit. Thus, vibration energy is converted into electrical energy and is dissipated through a network of electrical components. Different configurations of shunt have been researched, among which the negative capacitance-inductance shunt has gained prominence recently. It is basically an analog, active circuit consisting of operational amplifiers and passive elements to introduce real and imaginary impedance on the vibrating structure. The present study attempts to model the behavior of a negative capacitance-inductance shunt in terms of power output and efficiency using circuit modeling software. The shunt model is validated experimentally and is used to control the structural vibration of an aluminum beam, connected to a pair of piezoelectric patches, under broadband excitation. The model is also used to determine the optimal parameters of a negative capacitance-inductance shunt to increase the efficiency and predict the voltage output limit of op-amp against the supply voltage.

An autonomous synchronized switch damping on inductance and negative capacitance for piezoelectric broadband vibration suppression

Ehtesham Mustafa Qureshi,Xing Shen,Lulu Chang 한국항공우주학회 2016 International Journal of Aeronautical and Space Sc Vol.17 No.4

Synchronized switch damping (SSD) is a structural vibration control technique in which a piezoelectric patch attached to or embedded into the structure is connected to or disconnected from the shunt circuit in order to dissipate the vibration energy of the host structure. The switching process is performed by a digital signal processor (DSP) which detects the displacement extrema and generates a command to operate the switch in synchronous with the structure motion. Recently, autonomous SSD techniques have emerged in which the work of DSP is taken up by a low pass filter, thus making the whole system autonomous or self-powered. The control performance of the previous autonomous SSD techniques heavily relied on the electrical quality factor of the shunt circuit which limited their damping performance. Thus in order to reduce the influence of the electrical quality factor on the damping performance, a new autonomous SSD technique is proposed in this paper in which a negative capacitor is used along with the inductor in the shunt circuit. Only a negative capacitor could also be used instead of inductor but it caused saturation of negative capacitor in the absence of an inductor due to high current generated during the switching process. The presence of inductor in the shunt circuit of negative capacitor limits the amount of current supplied by the negative capacitance, thus improving the damping performance. In order to judge the control performance of proposed autonomous SSDNCI, a comparison is made between the autonomous SSDI, autonomous SSDNC and autonomous SSDNCI techniques for the control of an aluminum cantilever beam subjected to both single mode and multimode excitation. A value of negative capacitance slightly greater than the piezoelectric patch capacitance gave the optimum damping results. Experiment results confirmed the effectiveness of the proposed autonomous SSDNCI technique as compared to the previous techniques. Some limitations and drawbacks of the proposed technique are also discussed.