This paper studies the performance of a submillimeter wave antenna operating between frequencies 0.1 THz and 10 THz with a 4-cyano-4-pentylbiphenyl[5CB]substrate.Since the size and shape of the antenna impact its gain...This paper studies the performance of a submillimeter wave antenna operating between frequencies 0.1 THz and 10 THz with a 4-cyano-4-pentylbiphenyl[5CB]substrate.Since the size and shape of the antenna impact its gain/directivity,resonant frequency,bandwidth,and efficiency,the two antenna types considered in this paper are:(a)Rectangular Patch Antenna(RPA),and(b)Cylindrical Dielectric Resonator Antenna(CDRA).Here a submillimeter wave antenna is compared with a millimeter wave(a few GHz to 100 GHz)antenna.These popular mmwave antennas are chosen for the submillimeter wave antenna in order to understand changes in their performance as the result of changes in their geometrical shape.FEldberechnung bei Korpern mit beliebiger Oberflache(FEKO)software is used for the design and calculation of the Three-Dimensional(3D)ElectroMagnetic(EM)patterns.This paper also concentrates on the design and analysis of a massive submillimeter wave Multiple-Input Multiple-Output(MIMO)(8 by 8)RPA and CDRA.展开更多
The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S...The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S detector based on superlong SnO_(2)fibers.The submillimeter continuous fibers are deposited directly on ceramic tubes by in-situ electrospinning method and can keep morphology of fibers during calcination.By employing this technology,CuO-doped SnO_(2)fiber H_(2)S detectors are fabricated,and 10%atom CuO-doped SnO_(2)H_(2)S detector shows the highest response of 40 toward 1 ppm H_(2)S at 150℃while the response is only 3.6 for the H_(2)S detector prepared in traditional route.In addition,the in-situ electrospinning H_(2)S detectors show faster response and recovery compared to the H_(2)S detectors fabricated by the conventional way.The high and fast response of H_(2)S detectors based on in-situ electrospinning can be ascribed to the continuous fiber structure and CuO modification.The present in-situ electrospinning technology may provide a new strategy for the development of other gasdetectors and bio-detectors with fast and high response.展开更多
Friction stir lap welding was conducted on 2 mm + 2 mm sheets of aluminum alloy 2 A12-T4. The plunge depth(PLD) was designed as 2.45–2.58 mm, which was varied in submillimeters as 2.45, 2.50, 2.53, 2.55, and 2.58 mm,...Friction stir lap welding was conducted on 2 mm + 2 mm sheets of aluminum alloy 2 A12-T4. The plunge depth(PLD) was designed as 2.45–2.58 mm, which was varied in submillimeters as 2.45, 2.50, 2.53, 2.55, and 2.58 mm, and the axial force was recorded in the welding process. The results show that the PLD fluctuation in submillimeters causes significant variation in the axial force and affects the voids(i.e., Void I and Void II), hook, and effective sheet thickness(EST), among which Void I is the main factor that affects the EST. The fracture load–PLD function in the tensile shear test of the joints follows the rule of the EST–PLD function. An optimized PLD is approximately 2.55 mm, at which the EST reaches 1.71 mm, corresponding to a peak fracture load of 11.03 kN. Thus, a PLD of 2.55 mm is suggested with a tolerance of 0.02 mm, corresponding to a fracture load of 9.6–11.0 kN, i.e., within a fluctuation of 12%.展开更多
The most extensive survey of carbon monoxide(CO)gas in the Taurus molecular cloud relied on ^(12)CO and ^(13)CO J=1→0 emission only,distinguishing the region where ^(12)CO is detected without ^(13)CO(named mask 1 reg...The most extensive survey of carbon monoxide(CO)gas in the Taurus molecular cloud relied on ^(12)CO and ^(13)CO J=1→0 emission only,distinguishing the region where ^(12)CO is detected without ^(13)CO(named mask 1 region)from the one where both are detected(mask 2 region)(Goldsmith et al.2008;Pineda et al.2010).We have taken advantage of recent ^(12)CO J=3→2 James Clerk Maxwell Telescope observations,where they include mask 1regions to estimate density,temperature,and N(CO)with a large velocity gradient model.This represents 1395 pixels out of~1.2 million in the mark 1 region.Compared to Pineda et al.(2010)results and assuming a Tkin of 30 K,we find a higher volume density of molecular hydrogen of 3.3×10^(3) cm^(-3),compared to their 250-700 cm^(-3),and a CO column density of 5.7×10^(15)cm^(-2),about a quarter of their value.The differences are important and show the necessity to observe several CO transitions to better describe the intermediate region between the dense cloud and the diffuse atomic medium.Future observations to extend the ^(12)CO J=3→2 mapping further away from the ^(13)COdetected region comprising mask 1 are needed to revisit our understanding of the diffuse portions of dark clouds.展开更多
This paper presents our investigation into a 220 GHz multicarrier highspeed communication system based on solid state transceivers.The proposed system has eased the demand of high sampling rate analog-to-digital conve...This paper presents our investigation into a 220 GHz multicarrier highspeed communication system based on solid state transceivers.The proposed system has eased the demand of high sampling rate analog-to-digital converter(ADC)by providing several signal carriers in microwave band and converting them to 220 GHz channel.The system consists of a set of 220 GHz solid-state transceiver with 2 signal carriers,two basebands for 4 GSPS ADCs.It has achieved 12.8 Gbps rate real-time signal transmission using 16QAM modulation over a distance of 20 m without any other auxiliary equipment or test instruments.The baseband algorithm overcomes the problem of frequency difference generates by non-coherent structure,which guarantees the feasibility of long-distance transmission application.Most importantly,the proposed system has already carried out multi-channel 8K video parallel transmission through switch equipment,which shows the multicarrier high-speed communication system in submillimeter wave has great application prospects.To the best of the authors’knowledge,this is the first all-solid-state electronics multicarrier communication system in submillimeter and terahertz band.展开更多
To investigate the effects of massive star evolution on surrounding molecules,we select nine massive clumps previously observed with the Atacama Pathfinder Experiment(APEX) telescope and the Submillimeter Array(SMA) t...To investigate the effects of massive star evolution on surrounding molecules,we select nine massive clumps previously observed with the Atacama Pathfinder Experiment(APEX) telescope and the Submillimeter Array(SMA) telescope.Based on the observations of APEX,we obtain luminosity to mass ratios Lclump/Mclump that range from 10 to 154 L_(⊙)/M_(⊙),where some of them embedded ultra compact(UC) H Ⅱ region.Using the SMA,CH3CN(12K-11K) transitions were observed toward nine massive starforming regions.We derive the CH3CN rotational temperature and column density using the XCLASS program,and calculate its fractional abundance.We find that CH3CN temperature seems to increase with the increase of Lclump/Mclump when the ratio is between 10 to 40 L_(⊙)/M_(⊙),then decrease when L_(clump)/M_(clump)≥ 40 L_(⊙)/M_(⊙).Assuming that the CH3CN gas is heated by radiation from the central star,the effective distance of CH3CN relative to the central star is estimated.The distance ranges from - 0.003 to - 0.083 pc,which accounts for - 1/100 to - 1/1000 of clump size.The effective distance increases slightly as Lclump/Mclump increases(Reff-(L_(clump)/M_(clump))0.5±0.2).Overall,the CH3 CN abundance is found to decrease as the clumps evolve,e.g.,XCH3CN -(L_(clump)/M_(clump))-1.0±0.7.The steady decline of CH3CN abundance as the clumps evolution can be interpreted as a result of photodissociation.展开更多
文摘This paper studies the performance of a submillimeter wave antenna operating between frequencies 0.1 THz and 10 THz with a 4-cyano-4-pentylbiphenyl[5CB]substrate.Since the size and shape of the antenna impact its gain/directivity,resonant frequency,bandwidth,and efficiency,the two antenna types considered in this paper are:(a)Rectangular Patch Antenna(RPA),and(b)Cylindrical Dielectric Resonator Antenna(CDRA).Here a submillimeter wave antenna is compared with a millimeter wave(a few GHz to 100 GHz)antenna.These popular mmwave antennas are chosen for the submillimeter wave antenna in order to understand changes in their performance as the result of changes in their geometrical shape.FEldberechnung bei Korpern mit beliebiger Oberflache(FEKO)software is used for the design and calculation of the Three-Dimensional(3D)ElectroMagnetic(EM)patterns.This paper also concentrates on the design and analysis of a massive submillimeter wave Multiple-Input Multiple-Output(MIMO)(8 by 8)RPA and CDRA.
基金supported by National Natural Science Foundation of China(51772082,51804106,51572078,51772086 and 51872087)。
文摘The fast and high response detection of neurotoxic H_(2)S is of great importance for the environment.In this paper,directly electrospinning technology on the ceramic tube is developed to improve the response of H_(2)S detector based on superlong SnO_(2)fibers.The submillimeter continuous fibers are deposited directly on ceramic tubes by in-situ electrospinning method and can keep morphology of fibers during calcination.By employing this technology,CuO-doped SnO_(2)fiber H_(2)S detectors are fabricated,and 10%atom CuO-doped SnO_(2)H_(2)S detector shows the highest response of 40 toward 1 ppm H_(2)S at 150℃while the response is only 3.6 for the H_(2)S detector prepared in traditional route.In addition,the in-situ electrospinning H_(2)S detectors show faster response and recovery compared to the H_(2)S detectors fabricated by the conventional way.The high and fast response of H_(2)S detectors based on in-situ electrospinning can be ascribed to the continuous fiber structure and CuO modification.The present in-situ electrospinning technology may provide a new strategy for the development of other gasdetectors and bio-detectors with fast and high response.
文摘Friction stir lap welding was conducted on 2 mm + 2 mm sheets of aluminum alloy 2 A12-T4. The plunge depth(PLD) was designed as 2.45–2.58 mm, which was varied in submillimeters as 2.45, 2.50, 2.53, 2.55, and 2.58 mm, and the axial force was recorded in the welding process. The results show that the PLD fluctuation in submillimeters causes significant variation in the axial force and affects the voids(i.e., Void I and Void II), hook, and effective sheet thickness(EST), among which Void I is the main factor that affects the EST. The fracture load–PLD function in the tensile shear test of the joints follows the rule of the EST–PLD function. An optimized PLD is approximately 2.55 mm, at which the EST reaches 1.71 mm, corresponding to a peak fracture load of 11.03 kN. Thus, a PLD of 2.55 mm is suggested with a tolerance of 0.02 mm, corresponding to a fracture load of 9.6–11.0 kN, i.e., within a fluctuation of 12%.
基金the National Natural Science Foundation of China(NSFC,grant Nos.11988101,11725313,and U1931117)the International Partnership Program of Chinese Academy of Sciences(grant No.114A11KYSB20210010)supported by the Natural Science Foundation of Jiangsu Province(grant No.BK20201108)。
文摘The most extensive survey of carbon monoxide(CO)gas in the Taurus molecular cloud relied on ^(12)CO and ^(13)CO J=1→0 emission only,distinguishing the region where ^(12)CO is detected without ^(13)CO(named mask 1 region)from the one where both are detected(mask 2 region)(Goldsmith et al.2008;Pineda et al.2010).We have taken advantage of recent ^(12)CO J=3→2 James Clerk Maxwell Telescope observations,where they include mask 1regions to estimate density,temperature,and N(CO)with a large velocity gradient model.This represents 1395 pixels out of~1.2 million in the mark 1 region.Compared to Pineda et al.(2010)results and assuming a Tkin of 30 K,we find a higher volume density of molecular hydrogen of 3.3×10^(3) cm^(-3),compared to their 250-700 cm^(-3),and a CO column density of 5.7×10^(15)cm^(-2),about a quarter of their value.The differences are important and show the necessity to observe several CO transitions to better describe the intermediate region between the dense cloud and the diffuse atomic medium.Future observations to extend the ^(12)CO J=3→2 mapping further away from the ^(13)COdetected region comprising mask 1 are needed to revisit our understanding of the diffuse portions of dark clouds.
基金National Key R&D Program of China under Grant No.2018YFF0109702the National Natural Science Foundation of China under Grant No.61771116 and No.91738102.
文摘This paper presents our investigation into a 220 GHz multicarrier highspeed communication system based on solid state transceivers.The proposed system has eased the demand of high sampling rate analog-to-digital converter(ADC)by providing several signal carriers in microwave band and converting them to 220 GHz channel.The system consists of a set of 220 GHz solid-state transceiver with 2 signal carriers,two basebands for 4 GSPS ADCs.It has achieved 12.8 Gbps rate real-time signal transmission using 16QAM modulation over a distance of 20 m without any other auxiliary equipment or test instruments.The baseband algorithm overcomes the problem of frequency difference generates by non-coherent structure,which guarantees the feasibility of long-distance transmission application.Most importantly,the proposed system has already carried out multi-channel 8K video parallel transmission through switch equipment,which shows the multicarrier high-speed communication system in submillimeter wave has great application prospects.To the best of the authors’knowledge,this is the first all-solid-state electronics multicarrier communication system in submillimeter and terahertz band.
基金support from the National Natural Science Foundation of China (Grant Nos.W820301904 and 12033005)。
文摘To investigate the effects of massive star evolution on surrounding molecules,we select nine massive clumps previously observed with the Atacama Pathfinder Experiment(APEX) telescope and the Submillimeter Array(SMA) telescope.Based on the observations of APEX,we obtain luminosity to mass ratios Lclump/Mclump that range from 10 to 154 L_(⊙)/M_(⊙),where some of them embedded ultra compact(UC) H Ⅱ region.Using the SMA,CH3CN(12K-11K) transitions were observed toward nine massive starforming regions.We derive the CH3CN rotational temperature and column density using the XCLASS program,and calculate its fractional abundance.We find that CH3CN temperature seems to increase with the increase of Lclump/Mclump when the ratio is between 10 to 40 L_(⊙)/M_(⊙),then decrease when L_(clump)/M_(clump)≥ 40 L_(⊙)/M_(⊙).Assuming that the CH3CN gas is heated by radiation from the central star,the effective distance of CH3CN relative to the central star is estimated.The distance ranges from - 0.003 to - 0.083 pc,which accounts for - 1/100 to - 1/1000 of clump size.The effective distance increases slightly as Lclump/Mclump increases(Reff-(L_(clump)/M_(clump))0.5±0.2).Overall,the CH3 CN abundance is found to decrease as the clumps evolve,e.g.,XCH3CN -(L_(clump)/M_(clump))-1.0±0.7.The steady decline of CH3CN abundance as the clumps evolution can be interpreted as a result of photodissociation.