A compact Ka-band monolithic microwave integrated circuit(MMIC) voltage controlled oscillator (VCO) with wide tuning range and high output power,which is based on GaAs PHEMT process,is presented.A method is introduced...A compact Ka-band monolithic microwave integrated circuit(MMIC) voltage controlled oscillator (VCO) with wide tuning range and high output power,which is based on GaAs PHEMT process,is presented.A method is introduced to reduce the chip size and to increase the bandwidth of operation.The procedure to design a MMIC VCO is also described here.The measured oscillating frequency of the MMIC VCO is 36±1.2GHz and the output power is 10±1dBm.The fabricated MMIC chip size is 1.3mm×1.0mm.展开更多
Traditional mechanical rock breaking method is labor-intensive and low-efficient,which restrictes the development of deep resources and deep space.As a new rock-breakage technology,microwave irradiation is expected to...Traditional mechanical rock breaking method is labor-intensive and low-efficient,which restrictes the development of deep resources and deep space.As a new rock-breakage technology,microwave irradiation is expected to overcome these problems.This study examines the failure characteristics,weakening law,and breakdown mechanism of deep sandstone(depth=1050 m)samples in a microwave field.The macroscopic and microscopic properties were determined via mechanical tests,mesoscopic tests,and numerical simulations.Microwave application at 1000 W for 60 s reduced the uniaxial compressive strength of the sandstone by 50%.Thermal stress of the sandstone was enhanced by uneven expansion of minerals at the microscale.Moreover,the melting of some minerals in the high-temperature environment changed the pore structure,sharply reducing the macroscopic strength.The temperature remained high in the lower midsection of the sample,and the stress was concentrated at the bottom of the sample and along its axis.These results are expected to improve the efficiency of deep rock breaking,provide theoretical and technical support for similar rock-breakage projects,and accelerate advances in deep-Earth science.展开更多
A pressured microwave-assisted hydrolysis （PMAH） technique has been developed for hydrolyzing the crude glycyrrhizic acid （GA） extracted from licorice root to prepare glycyrrhetinic acid （GRA）. In order to optim...A pressured microwave-assisted hydrolysis （PMAH） technique has been developed for hydrolyzing the crude glycyrrhizic acid （GA） extracted from licorice root to prepare glycyrrhetinic acid （GRA）. In order to optimize the efficiency of PMAH, several experimental parameters were investigated, including liquid-solid ratio, hydrolysis time, sulfuric acid concentration and hydrolysis temperature. The optimized hydrolysis conditions were as follows：pressured microwave-assisted hydrolysis of crude GA for 21 min （taking 15 min to reach 150 ℃, and holding it for 6 rain） at 150 ℃ （at a radiation power of 450 W） in 3%-5% sulfuric acid solution with the liquid-solid （ml.g-1 crude GA） ratio of 25 ： 1. As a result of the considerable saving in time and higher product yields （up to 90%）, PMAH was proved more effective than conventional methods.展开更多
文摘A compact Ka-band monolithic microwave integrated circuit(MMIC) voltage controlled oscillator (VCO) with wide tuning range and high output power,which is based on GaAs PHEMT process,is presented.A method is introduced to reduce the chip size and to increase the bandwidth of operation.The procedure to design a MMIC VCO is also described here.The measured oscillating frequency of the MMIC VCO is 36±1.2GHz and the output power is 10±1dBm.The fabricated MMIC chip size is 1.3mm×1.0mm.
基金Projects(51822403,51827901)supported by the National Natural Science Foundation of ChinaProject(2018HH0159)supported by the Sichuan International Technological Innovation Cooperation,China。
文摘Traditional mechanical rock breaking method is labor-intensive and low-efficient,which restrictes the development of deep resources and deep space.As a new rock-breakage technology,microwave irradiation is expected to overcome these problems.This study examines the failure characteristics,weakening law,and breakdown mechanism of deep sandstone(depth=1050 m)samples in a microwave field.The macroscopic and microscopic properties were determined via mechanical tests,mesoscopic tests,and numerical simulations.Microwave application at 1000 W for 60 s reduced the uniaxial compressive strength of the sandstone by 50%.Thermal stress of the sandstone was enhanced by uneven expansion of minerals at the microscale.Moreover,the melting of some minerals in the high-temperature environment changed the pore structure,sharply reducing the macroscopic strength.The temperature remained high in the lower midsection of the sample,and the stress was concentrated at the bottom of the sample and along its axis.These results are expected to improve the efficiency of deep rock breaking,provide theoretical and technical support for similar rock-breakage projects,and accelerate advances in deep-Earth science.
基金Supported by the Yunnan Provincial Department of Education Key Foundation (07Z10311)
文摘A pressured microwave-assisted hydrolysis （PMAH） technique has been developed for hydrolyzing the crude glycyrrhizic acid （GA） extracted from licorice root to prepare glycyrrhetinic acid （GRA）. In order to optimize the efficiency of PMAH, several experimental parameters were investigated, including liquid-solid ratio, hydrolysis time, sulfuric acid concentration and hydrolysis temperature. The optimized hydrolysis conditions were as follows：pressured microwave-assisted hydrolysis of crude GA for 21 min （taking 15 min to reach 150 ℃, and holding it for 6 rain） at 150 ℃ （at a radiation power of 450 W） in 3%-5% sulfuric acid solution with the liquid-solid （ml.g-1 crude GA） ratio of 25 ： 1. As a result of the considerable saving in time and higher product yields （up to 90%）, PMAH was proved more effective than conventional methods.
