第1个回答 2011-06-15
Abstract: With the development of science and technology, electronics, electronic measuring a vast number of electronic journalists must master the means of measurement accuracy and functional requirements have become more sophisticated, we design a microcontroller based DC digital voltmeter.
This paper describes high-precision digital voltmeter using ADC0809 A / D converter circuit, the use of LED digital display module display. First described in detail a digital voltmeter, digital voltmeter and then about the design of hardware and software design, including data acquisition circuit, analog-digital conversion circuit and display circuit specific design. Through the MCU AT89S52 and A / D converter ADC0809 complete data conversion and transmission, the core of the system. Expounded the principle of ADC0809 and voltage sampling circuit, A / D converter circuit, the reference power supply circuit, reset circuit, clock circuit and so circuit specific design. Software design includes a main program, analog-digital conversion process and display program design, program flow diagram is given.
Finally, according to the system software and hardware design debugging. Verified by the commissioning of the system meets the design requirements, high accuracy, high sensitivity, performance, reliable, simple, low cost.
Keywords: microcontroller; voltage sampling; A / D conversion
第2个回答 2011-06-15
我有偿翻译,专业翻译文献!
第3个回答 2011-06-15
The tomato is a kind of antioxidant activity
Pick to
This subject is the tomato skins as raw material, with ascorbic acid, citric acid as controls, with Fenton reaction produces hydroxyl radicals (• OH), adjacent pyrogallol from oxidation reaction to produce superoxide anion radical (O2-•) for test model, and the ultraviolet spectrophotometer to measure eggplant is a kind of hydroxyl radicals, superoxide anion radical scavenging effect; For the substrate to lard, use the oven storage method to determine the POV values of grease, study the purple tomato is a kind of to grease the antioxidant activity. The experimental results show that: eggplant is a kind of the above free radicals are clear roles of free radical scavenging effect (than citric acid, ascorbic acid, and remove effect with the increase of the concentration enhancement, when concentration is greater than 0.5 g / 100 ml of free radical scavenging capacity, OH stable; Superoxide anion of free radical scavenging effect than citric acid, ascorbic acid, best inhibition rate was 91%, 0.6 g/when the concentration of 100 ml after, to adjacent pyrogallol since the oxidation of inhibition become stable; Restrain the degree of lipid peroxidation than citric acid and ascorbic acid, in 0.7 g/ml concentrations, synergistic effect be more stable.
Keywords: purple tomato skin red pigment; Hydroxyl radicals; Adjacent pyrogallol; Grease POV values; Oxidation stability
第4个回答 2011-06-22
Abstract: With the development of science and technology, electronics, electronic measuring a vast number of electronic journalists must master the means of measurement accuracy and functional requirements have become more sophisticated, we design a microcontroller based DC digital voltmeter.
This paper describes high-precision digital voltmeter using ADC0809 A / D converter circuit, the use of LED digital display module display. First described in detail a digital voltmeter, digital voltmeter and then about the design of hardware and software design, including data acquisition circuit, analog-digital conversion circuit and display circuit specific design. Through the MCU AT89S52 and A / D converter ADC0809 complete data conversion and transmission, the core of the system. Expounded the principle of ADC0809 and voltage sampling circuit, A / D converter circuit, the reference power supply circuit, reset circuit, clock circuit and so circuit specific design. Software design includes a main program, analog-digital conversion process and display program design, program flow diagram is given.
Finally, according to the system software and hardware design debugging. Verified by the commissioning of the system meets the design requirements, high accuracy, high sensitivity, performance, reliable, simple, low cost.
Keywords: microcontroller; voltage sampling; A / D conversion