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
In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequen- tially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz...In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequen- tially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz-1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz-1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%-50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarel- ativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radi- ation loss in the THz range, although the modeled THz source area is 3-4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 10^33, 3.9 × 10^33 and 3.7 × 10^32 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 10^31, 2.1 × 10^31 and 5.2 × 10^31 erg estimated from soft X-ray GOES observations.展开更多
This letter presents the results of numerical simulations for phase-locked 2-D Joseph-son junction array oscillator. The simulation result shows that the junctions of 2-D array can mutually phase-locked in a considera...This letter presents the results of numerical simulations for phase-locked 2-D Joseph-son junction array oscillator. The simulation result shows that the junctions of 2-D array can mutually phase-locked in a considerable area if the parameters can be carefully selected. The oscillators are formed with up to 33 identical Nb/AIOx/Nb junctions, and the junctions are connected with Nb microstrip resonators. Optimum structure parameters for oscillator circuit design can be obtained with these simulation results.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
The forces acting on submillimeter spheres at the air-water interface are investigated theoretically and experimentally. To calculate the capillary force acting on the sphere, an iterative method is used to determine ...The forces acting on submillimeter spheres at the air-water interface are investigated theoretically and experimentally. To calculate the capillary force acting on the sphere, an iterative method is used to determine the immersing position of the liquid interface on the sphere for a given distance. Then the total forces acting on the sphere are considered. The scaling effects of the net force acting on the sphere at the air-water interface are demonstrated. For the experiments, the force-position relationship of microspheres is measured with a precise electronic balance. The results show that the evaporation of the liquid in the container affects the measuring results greatly under ambient conditions. After considering the evaporation compensation, there is a great agree- ment between the theoretical and experimental results. Obvious hysteresis phenomena of the force-distance curve during the emersion processes are also observed and explained.展开更多
The temporal evolution of a spectrum during a steeply rising submillimeter(THz) burst that occurred on 2003 November 2 was investigated in detail for the first time.Observations show that the flux density of the THz...The temporal evolution of a spectrum during a steeply rising submillimeter(THz) burst that occurred on 2003 November 2 was investigated in detail for the first time.Observations show that the flux density of the THz spectrum increased steeply with frequency above 200 GHz.Their average rising rates reached a value of 235 sfu GHz^(-1)(corresponding to spectral index α of 4.8) during the burst.The flux densities reached about 4 000 and 70 000 sfu at 212 and 405 GHz at the maximum phase,respectively.The emissions at 405 GHz maintained such a continuous high level that they largely exceeded the peak values of the microwave(MW) spectra during the main phase.Our studies suggest that only energetic electrons with a low-energy cutoff of~ 1 MeV and number density of ~ 10~6-10~8 cm^(-3) can produce such a strong and steeply rising THz component via gyrosynchrotron radiation based on numerical simulations of burst spectra in the case of a nonuniform magnetic field.The electron number density N,derived from our numerical fits to the THz temporal evolution spectra,increased substantially from 8 ×10~6 to 4 × 10~8 cm^(-3),i.e.,the N value increased 50 times during the rise phase.During the decay phase it decreased to 7 ×10~7 cm^(-3),i.e.,it decreased by about five times from the maximum phase.The total electron number decreased an order of magnitude from the maximum phase to the decay phase.Nevertheless,the variation in amplitude of N is only about one time in the MW emission source during this burst,and the total electron number did not decrease but increased by about 20%during the decay phase.Interestingly,we find that the THz source radius decreased by about 24%while the MW source radius,on the contrary,increased by 28%during the decay phase.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
We analyze large scale mapping observations of the molecular lines in the ^12CO(J= 2-1),^12CO(J=3-2),^13CO(J=2-1),and ^13CO(J=3-2) transition emissions toward the Cepheus B molecular cloud with the KOSMA 3mtel...We analyze large scale mapping observations of the molecular lines in the ^12CO(J= 2-1),^12CO(J=3-2),^13CO(J=2-1),and ^13CO(J=3-2) transition emissions toward the Cepheus B molecular cloud with the KOSMA 3mtelescope. The integrated intensity map of the ^12CO (J = 2 - 1) transition has shown a structure with a compact core and a compact ridge extended to the north-west of the core. The cloud is surrounded by an optically bright rim, where the radiation-driven implosion (RDI) may greatly change the gas properties. The intensities of the CO (J = 3 - 2) transition are higher than those of the CO (J = 2 - 1) transition along the rim area. We find characteristic RDI structure in position-velocity diagrams. Non-LTE large velocity gradient (LVG) model analysis shows that the density and temperature at the edge are higher than that in the center. Our results provide evidences that an RDI is taking place in the Cepheus B molecular cloud.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 the National Natural Science Foundation of China(Grant Nos.11333009 and 11573072)the"973"program(No.2014CB744200)
文摘In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequen- tially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz-1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz-1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%-50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarel- ativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radi- ation loss in the THz range, although the modeled THz source area is 3-4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 10^33, 3.9 × 10^33 and 3.7 × 10^32 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 10^31, 2.1 × 10^31 and 5.2 × 10^31 erg estimated from soft X-ray GOES observations.
文摘This letter presents the results of numerical simulations for phase-locked 2-D Joseph-son junction array oscillator. The simulation result shows that the junctions of 2-D array can mutually phase-locked in a considerable area if the parameters can be carefully selected. The oscillators are formed with up to 33 identical Nb/AIOx/Nb junctions, and the junctions are connected with Nb microstrip resonators. Optimum structure parameters for oscillator circuit design can be obtained with these simulation results.
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.
基金Supported by the National Natural Science Foundation of China under Grant No 61005072the Self-Planned Task of State Key Laboratory of Robotics and System under Grant Nos SKLRS201501A04 and SKLRS201301A01
文摘The forces acting on submillimeter spheres at the air-water interface are investigated theoretically and experimentally. To calculate the capillary force acting on the sphere, an iterative method is used to determine the immersing position of the liquid interface on the sphere for a given distance. Then the total forces acting on the sphere are considered. The scaling effects of the net force acting on the sphere at the air-water interface are demonstrated. For the experiments, the force-position relationship of microspheres is measured with a precise electronic balance. The results show that the evaporation of the liquid in the container affects the measuring results greatly under ambient conditions. After considering the evaporation compensation, there is a great agree- ment between the theoretical and experimental results. Obvious hysteresis phenomena of the force-distance curve during the emersion processes are also observed and explained.
基金supported by the National Natural Science Foundation of China (Grant No.11333009)the National Basic Research Program of China (973 program,2014CB744200)
文摘The temporal evolution of a spectrum during a steeply rising submillimeter(THz) burst that occurred on 2003 November 2 was investigated in detail for the first time.Observations show that the flux density of the THz spectrum increased steeply with frequency above 200 GHz.Their average rising rates reached a value of 235 sfu GHz^(-1)(corresponding to spectral index α of 4.8) during the burst.The flux densities reached about 4 000 and 70 000 sfu at 212 and 405 GHz at the maximum phase,respectively.The emissions at 405 GHz maintained such a continuous high level that they largely exceeded the peak values of the microwave(MW) spectra during the main phase.Our studies suggest that only energetic electrons with a low-energy cutoff of~ 1 MeV and number density of ~ 10~6-10~8 cm^(-3) can produce such a strong and steeply rising THz component via gyrosynchrotron radiation based on numerical simulations of burst spectra in the case of a nonuniform magnetic field.The electron number density N,derived from our numerical fits to the THz temporal evolution spectra,increased substantially from 8 ×10~6 to 4 × 10~8 cm^(-3),i.e.,the N value increased 50 times during the rise phase.During the decay phase it decreased to 7 ×10~7 cm^(-3),i.e.,it decreased by about five times from the maximum phase.The total electron number decreased an order of magnitude from the maximum phase to the decay phase.Nevertheless,the variation in amplitude of N is only about one time in the MW emission source during this burst,and the total electron number did not decrease but increased by about 20%during the decay phase.Interestingly,we find that the THz source radius decreased by about 24%while the MW source radius,on the contrary,increased by 28%during the decay phase.
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.
文摘We analyze large scale mapping observations of the molecular lines in the ^12CO(J= 2-1),^12CO(J=3-2),^13CO(J=2-1),and ^13CO(J=3-2) transition emissions toward the Cepheus B molecular cloud with the KOSMA 3mtelescope. The integrated intensity map of the ^12CO (J = 2 - 1) transition has shown a structure with a compact core and a compact ridge extended to the north-west of the core. The cloud is surrounded by an optically bright rim, where the radiation-driven implosion (RDI) may greatly change the gas properties. The intensities of the CO (J = 3 - 2) transition are higher than those of the CO (J = 2 - 1) transition along the rim area. We find characteristic RDI structure in position-velocity diagrams. Non-LTE large velocity gradient (LVG) model analysis shows that the density and temperature at the edge are higher than that in the center. Our results provide evidences that an RDI is taking place in the Cepheus B molecular cloud.
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.