采用液态源扩散法制备了双向型瞬变电压抑制二极管(Transient Voltage Suppressor Diode,简称TVS)器件。研究了扩散温度、扩散时间、电阻率、钝化保护等工艺参数对TVS器件电性能的影响。扩散温度、扩散时间的增加将使扩散结的结深增加;...采用液态源扩散法制备了双向型瞬变电压抑制二极管(Transient Voltage Suppressor Diode,简称TVS)器件。研究了扩散温度、扩散时间、电阻率、钝化保护等工艺参数对TVS器件电性能的影响。扩散温度、扩散时间的增加将使扩散结的结深增加;电阻率的提高及结深的增加,将使TVS器件的雪崩击穿电压增大;合适的钝化保护方法将有助于减小器件的反向漏电流。给出了电压和扩散时间之间的经验估算公式,该公式可用来指导得到希望的TVS目标电压档。据验算,该公式的误差在10%以内。展开更多
Ammopiptanthus mongolicus (Maxim.) Cheng f. is one of the evergreen shrubs in the desert region of China. In midday its leaves bear photon flux density over 1 500 μmol·m -2 ·s -1 at natural habit...Ammopiptanthus mongolicus (Maxim.) Cheng f. is one of the evergreen shrubs in the desert region of China. In midday its leaves bear photon flux density over 1 500 μmol·m -2 ·s -1 at natural habitat. They show the obvious phenomenon of photoinhibition. For the study of the effects of drought stress on the major protective mechanism against strong light in A. mongolicus leaves, the diurnal variations of photosynthetic rate and chlorophyll fluorescence parameters were investigated under natural conditions with portable photosynthetic measurement system (CIRAS_1) and portable fluorometer (MFMS_2). The experimental results showed that, under normal and drought stress conditions,the net photosynthetic rate ( Pn ), the primary maximum photochemical efficiency of PSⅡ ( Fv/Fm ) and the quantum efficiency of noncyclic electron transport of PSⅡ ( Φ PSⅡ ) decreased obviously at noon (Figs.2,3A,4B). In comparison with plants under normal condition, under drought stress minimal chlorophyll fluorescence ( Fo ) decreased at first and then increased (Fig.3A), non_photochemical quenching ( NPQ ) quickly increased and sustained at a higher level (Fig.4B). This indicated that the major photoprotective mechanism of A. mongolicus leaves was the xanthophyll cycle_dependent thermal energy dissipation under normal condition, while under drought stress, the major photoprotective mechanism was both the xanthophyll cycle_dependent thermal energy dissipation and the reversible inactivation of PSⅡ reaction center.展开更多
In this paper, we propose a cross reference method for nonlinear time series analyzing in semi blind case, that is, the dynamic equations modeling the time series are known but the corresponding parameters are not. ...In this paper, we propose a cross reference method for nonlinear time series analyzing in semi blind case, that is, the dynamic equations modeling the time series are known but the corresponding parameters are not. The tasks of noise reduction and parameter estimation which were fulfilled separately before are combined iteratively. With the positive interaction between the two processing modules, the method is somewhat superior. Some prior work can be viewed as special cases of this general framework. The simulations for noise reduction and parameter estimation of contaminated chaotic time series show improved performance of our method compared with previous work.展开更多
It is well-known that the IMC-PID controller tuning gives fast and improved set point response but slow disturbance rejection. A modification has been proposed in IMC-PID tuning rule for the improved disturbance rejec...It is well-known that the IMC-PID controller tuning gives fast and improved set point response but slow disturbance rejection. A modification has been proposed in IMC-PID tuning rule for the improved disturbance rejection. For the modified IMC-PID tuning rule, a method has been developed to obtain the IMC-PID setting in closed-loop mode without acquiring detailed information of the process. The proposed method is based on the closed-loop step set point experiment using a proportional only controller with gain K_(c0). It is the direct approach to find the PID controller setting similar to classical Ziegler-Nichols closed-loop method. Based on simulations of a wide range of first-order with delay processes, a simple correlation has been derived to obtain the modified IMC-PID controller settings from closed-loop experiment. In this method, controller gain is a function of the overshoot obtained in the closed loop set point experiment. The integral and derivative time is mainly a function of the time to reach the first peak(overshoot). Simulation has been conducted for the broad class of processes and the controllers were tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms, in order to obtain a reasonable comparison. The PID controller settings obtained in the proposed tuning method show better performance and robustness with other two-step tuning methods for the broad class of processes. It has also been applied to temperature control loop in distillation column model. The result has been compared to the open loop tuning method where it gives robust and fast response.展开更多
H. suaveolens （L.） Poit has been used in folk medicine revealing a wide pharmacological potential. This study aimed to evaluate the efficacy of the essential oil from 11. suaveolens leaves in inhibiting the growth o...H. suaveolens （L.） Poit has been used in folk medicine revealing a wide pharmacological potential. This study aimed to evaluate the efficacy of the essential oil from 11. suaveolens leaves in inhibiting the growth of A. flavus LM257 and synthesis of aflatoxins Bl and B2. The essential oil at 20, 40 and 80 laL/mL strongly reduced the biomass and spore germination ofA. flavus. A 100% inhibition was found at 40 μL/mL and 80μL/mL, while at 20 μL/mL the growth depressed over 50% for both tested parameters. The essential oil at all assayed concentrations totally inhibited the production of aflatoxin B1 and B2. From these results, the essential oil from 11. suaveolens leaves may be considered as an alternative and effective inhibitor ofA. flavus, in addition to offer some protective effect to the production of aflatoxins.展开更多
文摘采用液态源扩散法制备了双向型瞬变电压抑制二极管(Transient Voltage Suppressor Diode,简称TVS)器件。研究了扩散温度、扩散时间、电阻率、钝化保护等工艺参数对TVS器件电性能的影响。扩散温度、扩散时间的增加将使扩散结的结深增加;电阻率的提高及结深的增加,将使TVS器件的雪崩击穿电压增大;合适的钝化保护方法将有助于减小器件的反向漏电流。给出了电压和扩散时间之间的经验估算公式,该公式可用来指导得到希望的TVS目标电压档。据验算,该公式的误差在10%以内。
文摘Ammopiptanthus mongolicus (Maxim.) Cheng f. is one of the evergreen shrubs in the desert region of China. In midday its leaves bear photon flux density over 1 500 μmol·m -2 ·s -1 at natural habitat. They show the obvious phenomenon of photoinhibition. For the study of the effects of drought stress on the major protective mechanism against strong light in A. mongolicus leaves, the diurnal variations of photosynthetic rate and chlorophyll fluorescence parameters were investigated under natural conditions with portable photosynthetic measurement system (CIRAS_1) and portable fluorometer (MFMS_2). The experimental results showed that, under normal and drought stress conditions,the net photosynthetic rate ( Pn ), the primary maximum photochemical efficiency of PSⅡ ( Fv/Fm ) and the quantum efficiency of noncyclic electron transport of PSⅡ ( Φ PSⅡ ) decreased obviously at noon (Figs.2,3A,4B). In comparison with plants under normal condition, under drought stress minimal chlorophyll fluorescence ( Fo ) decreased at first and then increased (Fig.3A), non_photochemical quenching ( NPQ ) quickly increased and sustained at a higher level (Fig.4B). This indicated that the major photoprotective mechanism of A. mongolicus leaves was the xanthophyll cycle_dependent thermal energy dissipation under normal condition, while under drought stress, the major photoprotective mechanism was both the xanthophyll cycle_dependent thermal energy dissipation and the reversible inactivation of PSⅡ reaction center.
文摘In this paper, we propose a cross reference method for nonlinear time series analyzing in semi blind case, that is, the dynamic equations modeling the time series are known but the corresponding parameters are not. The tasks of noise reduction and parameter estimation which were fulfilled separately before are combined iteratively. With the positive interaction between the two processing modules, the method is somewhat superior. Some prior work can be viewed as special cases of this general framework. The simulations for noise reduction and parameter estimation of contaminated chaotic time series show improved performance of our method compared with previous work.
基金the support provided by King Abdulaziz City for Science and Technology (KACST) through the Science & Technology Unit at King Fahd University of PetroleumMinerals (KFUPM) for funding this work through project number 11-ENE1643-04 as part of the Notional Science Technology and Innovation Plan
文摘It is well-known that the IMC-PID controller tuning gives fast and improved set point response but slow disturbance rejection. A modification has been proposed in IMC-PID tuning rule for the improved disturbance rejection. For the modified IMC-PID tuning rule, a method has been developed to obtain the IMC-PID setting in closed-loop mode without acquiring detailed information of the process. The proposed method is based on the closed-loop step set point experiment using a proportional only controller with gain K_(c0). It is the direct approach to find the PID controller setting similar to classical Ziegler-Nichols closed-loop method. Based on simulations of a wide range of first-order with delay processes, a simple correlation has been derived to obtain the modified IMC-PID controller settings from closed-loop experiment. In this method, controller gain is a function of the overshoot obtained in the closed loop set point experiment. The integral and derivative time is mainly a function of the time to reach the first peak(overshoot). Simulation has been conducted for the broad class of processes and the controllers were tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms, in order to obtain a reasonable comparison. The PID controller settings obtained in the proposed tuning method show better performance and robustness with other two-step tuning methods for the broad class of processes. It has also been applied to temperature control loop in distillation column model. The result has been compared to the open loop tuning method where it gives robust and fast response.
文摘H. suaveolens （L.） Poit has been used in folk medicine revealing a wide pharmacological potential. This study aimed to evaluate the efficacy of the essential oil from 11. suaveolens leaves in inhibiting the growth of A. flavus LM257 and synthesis of aflatoxins Bl and B2. The essential oil at 20, 40 and 80 laL/mL strongly reduced the biomass and spore germination ofA. flavus. A 100% inhibition was found at 40 μL/mL and 80μL/mL, while at 20 μL/mL the growth depressed over 50% for both tested parameters. The essential oil at all assayed concentrations totally inhibited the production of aflatoxin B1 and B2. From these results, the essential oil from 11. suaveolens leaves may be considered as an alternative and effective inhibitor ofA. flavus, in addition to offer some protective effect to the production of aflatoxins.
