High-order harmonics q(ψ_(s))=1 energetic particle modes(EPMs)have been observed in toroidal plasmas experiments with neutral beam injection.To investigate these phenomena,linear properties and nonlinear dynamics of ...High-order harmonics q(ψ_(s))=1 energetic particle modes(EPMs)have been observed in toroidal plasmas experiments with neutral beam injection.To investigate these phenomena,linear properties and nonlinear dynamics of these EPMs driven by passing energetic particles(EPs)are studied via the global hybrid kinetic-magnetohydrodynamic code M3D-K.Simulation results demonstrate that passing EPs'effects on high mode-number harmonics(q(ψ_(s))=m/n=2/2,3/3,4/4)instability are more obvious than the q(ψ_(s))=1/1 mode,especially when q-profile is sufficiently flat in the core region.Furthermore,the effects of the pitch angleΛ_0 and beam ion pressure P_(hot)/P_(total)on the features of high n components are also analyzed specifically.It is found that there exists only one resonant condition for these EPMs.In the nonlinear phase,these high mode-number harmonics can induce significant energetic ions redistribution and chirping up phenomena,which differs from the classical fishbone excited by passing EPs.These discoveries are conducive to better apprehend the underlying physical mechanisms of the highorder harmonics driven by passing EPs.展开更多
We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye ...We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye form. A closed solution is impossible even if the equation is linear, because the Laplace transform of the memory kernel is a multi-value function. We use a numerical method to calculate the velocity correlation function of a force-free particle and the probability of a particle passing over the top of an inverse harmonic potential. We indicate the nonergodicity of the second type, i.e., the auto-correlation function of the velocity approaches to non-stationary at large times. Applied to the barrier passage problem, we find and analyse a resonant phenomenon that the dependence of the cutoff frequency is nonmonotonic when the initial directional velocity of the particle is less than the critical value, the latter is determined by the passing probability equal to 0.5.展开更多
The microstructure of the thin-walled tubes with high-strength aluminum alloy determines their final forming quality and performance. This type of tube can be manufactured by multi-pass hot power backward spinning pro...The microstructure of the thin-walled tubes with high-strength aluminum alloy determines their final forming quality and performance. This type of tube can be manufactured by multi-pass hot power backward spinning process as it can eliminate casting defects, refine microstructure and improve the plasticity of the tube. To analyze the microstructure distribution characteristics of the tube during the spinning process, a 3D coupled thermo-mechanical FE model coupled with the microstructure evolution model of the process was established under the ABAQUS environment. The microstructure evolution characteristics and laws of the tube for the whole spinning process were analyzed. The results show that the dynamic recrystallization is mainly produced in the spinning deformation zone and root area of the tube. In the first pass, the dynamic recrystallization phenomenon is not obvious in the tube. With the pass increasing, the trend of dynamic recrystallization volume percentage gradually increases and extends from the outer surface of the tube to the inner surface. The fine-grained area shows the states of concentration, dispersion, and re-concentration as the pass number increases. .展开更多
This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst inte...This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst interference may occur only on data symbols but not on pilot symbols, which means that interference information cannot be premeasured. To cancel the burst interference, we first revisit the uplink multi-user system and develop a matrixform system model, where the covariance pattern and the low-rank property of the interference matrix is discussed. Then, we propose a turbo message passing based burst interference cancellation(TMP-BIC) algorithm to solve the data detection problem, where the constellation information of target data is fully exploited to refine its estimate. Furthermore, in the TMP-BIC algorithm, we design one module to cope with the interference matrix by exploiting its lowrank property. Numerical results demonstrate that the proposed algorithm can effectively mitigate the adverse effects of burst interference and approach the interference-free bound.展开更多
During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well know...During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well known battle of ancient China because a commander of the Song army named Yang Ye(?-986)was really famous in both classical Chinese fictions and Chinese war history.He is the early protagonist of a famous Chinese classic fiction named The Romance of the Yang family’s generals(written in the 16th century,Ming Dynasty of China).The story of his family also appears in other novels.Besides,in history,he was a general who was active in the early stages of the war between Liao Dynasty and Northern Song Dynasty.The battle of Yanmen Pass(980)was one of the most important battles of Yang’s military career.His combat style especially his cavalry tactic can be summarized through researching this battle.展开更多
Objective:To explore the application effect of the blended education strategy based on the Learning Pass platform in the phase III cardiac rehabilitation of patients with coronary artery disease.Methods:90 patients di...Objective:To explore the application effect of the blended education strategy based on the Learning Pass platform in the phase III cardiac rehabilitation of patients with coronary artery disease.Methods:90 patients diagnosed with coronary artery disease in the Department of Cardiology of our hospital from January 2019 to January 2021 were selected and divided into the control group and the experimental group according to the method of randomized numerical table,with 45 cases in each group.Both the experimental group and the control group received pre-discharge cardiac rehabilitation education by conventional means.The control group received education and supervision information via WeChat after discharge,while the experimental group joined the Learning Pass platform to receive online and offline hybrid education and supervision,with online as the mainstay and offline as a supplement.The disease cognitive level,self-management skills,quality of life,medication adherence,and emotional status of the two groups were compared.Results:The disease cognitive levels in the experimental group were significantly higher than those of the control group(P<0.05);the scores of the experimental group in terms of quality of life,self-management skills,and medication adherence were significantly higher than those of the control group(P<0.05);and the scores of anxiety and depression in the experimental group were significantly lower than those of the control group(P<0.05).Conclusion:The blended education strategy based on the Learning Pass platform has a significant application effect in phase III cardiac rehabilitation of patients with coronary artery disease.It can improve patients’disease cognitive level,self-management skills,and quality of life,and provide a basis for improving patients’prognosis.展开更多
Based on the aerodynamics and vehicle dynamics, the aerodynamic performances and vehicle dynamic characteristics of two high-speed trains passing each other on the ground, embankment and bridge are studied. Firstly, a...Based on the aerodynamics and vehicle dynamics, the aerodynamic performances and vehicle dynamic characteristics of two high-speed trains passing each other on the ground, embankment and bridge are studied. Firstly, a train aerodynamic model and a vehicle dynamic model are established. Through the simulation of the two models, the pressure waves, aerodynamic forces, and vehicle dynamic responses are obtained. Then, the pressure waves and aero- dynamic forces on different foundations are compared. The results show that the variation trends of pressure wave and aerodynamic forces of trains passing each other on different foundations are almost similar. The peak-to-peak differ- ences in pressure wave and aerodynamic force are below 4% and 3% in three cases in open air. Besides, the differences of security indexes, including coefficient of derailment, wheel unloading rate, the wheelset lateral force, and the wheel- rail vertical force, are below 2% among the three cases; the differences of comfort indexes, including the lateral acceleration and the vertical acceleration, are also below 2%. It is concluded that the dynamic performances of trains pass- ing each other are influenced little by different foundations in open air.展开更多
Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on...Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.展开更多
Adiabatic response effects on high-frequency flshbone instability driven by passing energetic ions are studied.With flnite orbit width effects,the adiabatic contributionδW_(hf)is derived analytically for purely passi...Adiabatic response effects on high-frequency flshbone instability driven by passing energetic ions are studied.With flnite orbit width effects,the adiabatic contributionδW_(hf)is derived analytically for purely passing energetic ions.By approximating the adiabatic contribution to the flrst order of the reverse aspect ratioε,we derive one of its analytic expressions,which is expected to be more accurate than that in a previous work(Graves J P 2004 Phys.Rev.Lett.92185003).For high-frequency flshbone instability,nonadiabatic response is usually dominant over adiabatic response,but under certain circumstances the latter plays an important role,comparable to the former.With a more generalized distribution function by introducing Gaussian-type factors representing their pitch and radial dependences and using a slowing-down equilibrium distribution for the energy of energetic ions,numerical analysis indicates that the adiabatic contribution is conducive to stabilization of the mode and causes a decrease in mode frequency.In addition,we flnd that the adiabatic contribution has a weak stabilizing effect on the flshbone instability when the flnite orbit width effect is taken into account.We further analyze the dependence of the adiabatic contribution on the characteristic parameters of the distribution function.When the neutral beam has either a larger deviation from the plasma axis or a larger radial proflle,the adiabatic contribution has a more evident effect on the flshbone instability.When the neutral beam has a relatively small critical energy,the adiabatic contribution has a greater effect on the mode instability.展开更多
Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear observations.Currently,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate ...Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear observations.Currently,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been proposed.For SBL,it has accurate performance with robustness while its computational complexity is high due to matrix inversion.For AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS problem.To overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)prior.Simulation results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.展开更多
On January 7, 2015 the project "Study on the technology formanufacture of high-spheroidicity FCC catalysts "undertakenby the SINOPEC Research Institute of Petroleum Processing(RIPP) has passed the technical apprai...On January 7, 2015 the project "Study on the technology formanufacture of high-spheroidicity FCC catalysts "undertakenby the SINOPEC Research Institute of Petroleum Processing(RIPP) has passed the technical appraisal organized by theScience and Technology Division of the Sinopec Corp.展开更多
Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy p...Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10<sup>-5</sup>). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.展开更多
基金supported by National Key R&D Program of China(Nos.2019YFE03050002,2018YFE0310400,and 2022YFE03040002)National Natural Science Foundation of China(Nos.12005003 and 11975270)Science Foundation of Institute of Plasma Physics,Chinese Academy of Sciences(No.DSJJ-2022-04)。
文摘High-order harmonics q(ψ_(s))=1 energetic particle modes(EPMs)have been observed in toroidal plasmas experiments with neutral beam injection.To investigate these phenomena,linear properties and nonlinear dynamics of these EPMs driven by passing energetic particles(EPs)are studied via the global hybrid kinetic-magnetohydrodynamic code M3D-K.Simulation results demonstrate that passing EPs'effects on high mode-number harmonics(q(ψ_(s))=m/n=2/2,3/3,4/4)instability are more obvious than the q(ψ_(s))=1/1 mode,especially when q-profile is sufficiently flat in the core region.Furthermore,the effects of the pitch angleΛ_0 and beam ion pressure P_(hot)/P_(total)on the features of high n components are also analyzed specifically.It is found that there exists only one resonant condition for these EPMs.In the nonlinear phase,these high mode-number harmonics can induce significant energetic ions redistribution and chirping up phenomena,which differs from the classical fishbone excited by passing EPs.These discoveries are conducive to better apprehend the underlying physical mechanisms of the highorder harmonics driven by passing EPs.
文摘We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye form. A closed solution is impossible even if the equation is linear, because the Laplace transform of the memory kernel is a multi-value function. We use a numerical method to calculate the velocity correlation function of a force-free particle and the probability of a particle passing over the top of an inverse harmonic potential. We indicate the nonergodicity of the second type, i.e., the auto-correlation function of the velocity approaches to non-stationary at large times. Applied to the barrier passage problem, we find and analyse a resonant phenomenon that the dependence of the cutoff frequency is nonmonotonic when the initial directional velocity of the particle is less than the critical value, the latter is determined by the passing probability equal to 0.5.
文摘The microstructure of the thin-walled tubes with high-strength aluminum alloy determines their final forming quality and performance. This type of tube can be manufactured by multi-pass hot power backward spinning process as it can eliminate casting defects, refine microstructure and improve the plasticity of the tube. To analyze the microstructure distribution characteristics of the tube during the spinning process, a 3D coupled thermo-mechanical FE model coupled with the microstructure evolution model of the process was established under the ABAQUS environment. The microstructure evolution characteristics and laws of the tube for the whole spinning process were analyzed. The results show that the dynamic recrystallization is mainly produced in the spinning deformation zone and root area of the tube. In the first pass, the dynamic recrystallization phenomenon is not obvious in the tube. With the pass increasing, the trend of dynamic recrystallization volume percentage gradually increases and extends from the outer surface of the tube to the inner surface. The fine-grained area shows the states of concentration, dispersion, and re-concentration as the pass number increases. .
基金supported by the National Key Laboratory of Wireless Communications Foundation,China (IFN20230204)。
文摘This paper investigates the fundamental data detection problem with burst interference in massive multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) systems. In particular, burst interference may occur only on data symbols but not on pilot symbols, which means that interference information cannot be premeasured. To cancel the burst interference, we first revisit the uplink multi-user system and develop a matrixform system model, where the covariance pattern and the low-rank property of the interference matrix is discussed. Then, we propose a turbo message passing based burst interference cancellation(TMP-BIC) algorithm to solve the data detection problem, where the constellation information of target data is fully exploited to refine its estimate. Furthermore, in the TMP-BIC algorithm, we design one module to cope with the interference matrix by exploiting its lowrank property. Numerical results demonstrate that the proposed algorithm can effectively mitigate the adverse effects of burst interference and approach the interference-free bound.
文摘During the war between Liao Dynasty(907-1125)and Northern Song Dynasty(960-1127),there was a classic battle that happened in Yanmen Pass(located in today’s Dai County,Xinzhou,Shanxi Province,China).It was a well known battle of ancient China because a commander of the Song army named Yang Ye(?-986)was really famous in both classical Chinese fictions and Chinese war history.He is the early protagonist of a famous Chinese classic fiction named The Romance of the Yang family’s generals(written in the 16th century,Ming Dynasty of China).The story of his family also appears in other novels.Besides,in history,he was a general who was active in the early stages of the war between Liao Dynasty and Northern Song Dynasty.The battle of Yanmen Pass(980)was one of the most important battles of Yang’s military career.His combat style especially his cavalry tactic can be summarized through researching this battle.
文摘Objective:To explore the application effect of the blended education strategy based on the Learning Pass platform in the phase III cardiac rehabilitation of patients with coronary artery disease.Methods:90 patients diagnosed with coronary artery disease in the Department of Cardiology of our hospital from January 2019 to January 2021 were selected and divided into the control group and the experimental group according to the method of randomized numerical table,with 45 cases in each group.Both the experimental group and the control group received pre-discharge cardiac rehabilitation education by conventional means.The control group received education and supervision information via WeChat after discharge,while the experimental group joined the Learning Pass platform to receive online and offline hybrid education and supervision,with online as the mainstay and offline as a supplement.The disease cognitive level,self-management skills,quality of life,medication adherence,and emotional status of the two groups were compared.Results:The disease cognitive levels in the experimental group were significantly higher than those of the control group(P<0.05);the scores of the experimental group in terms of quality of life,self-management skills,and medication adherence were significantly higher than those of the control group(P<0.05);and the scores of anxiety and depression in the experimental group were significantly lower than those of the control group(P<0.05).Conclusion:The blended education strategy based on the Learning Pass platform has a significant application effect in phase III cardiac rehabilitation of patients with coronary artery disease.It can improve patients’disease cognitive level,self-management skills,and quality of life,and provide a basis for improving patients’prognosis.
基金supported by the National Natural Science Foundations of China (Nos. 50823004 and 50821063)the "Eleventh Five-year Plan" National Science and Technology Support Plan(No. 2009BAG12A01-C09)
文摘Based on the aerodynamics and vehicle dynamics, the aerodynamic performances and vehicle dynamic characteristics of two high-speed trains passing each other on the ground, embankment and bridge are studied. Firstly, a train aerodynamic model and a vehicle dynamic model are established. Through the simulation of the two models, the pressure waves, aerodynamic forces, and vehicle dynamic responses are obtained. Then, the pressure waves and aero- dynamic forces on different foundations are compared. The results show that the variation trends of pressure wave and aerodynamic forces of trains passing each other on different foundations are almost similar. The peak-to-peak differ- ences in pressure wave and aerodynamic force are below 4% and 3% in three cases in open air. Besides, the differences of security indexes, including coefficient of derailment, wheel unloading rate, the wheelset lateral force, and the wheel- rail vertical force, are below 2% among the three cases; the differences of comfort indexes, including the lateral acceleration and the vertical acceleration, are also below 2%. It is concluded that the dynamic performances of trains pass- ing each other are influenced little by different foundations in open air.
文摘Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.
基金supported by National Natural Science Foundation of China(No.11975068)by the National Key R&D Program of China(No.2019YFE03030004)。
文摘Adiabatic response effects on high-frequency flshbone instability driven by passing energetic ions are studied.With flnite orbit width effects,the adiabatic contributionδW_(hf)is derived analytically for purely passing energetic ions.By approximating the adiabatic contribution to the flrst order of the reverse aspect ratioε,we derive one of its analytic expressions,which is expected to be more accurate than that in a previous work(Graves J P 2004 Phys.Rev.Lett.92185003).For high-frequency flshbone instability,nonadiabatic response is usually dominant over adiabatic response,but under certain circumstances the latter plays an important role,comparable to the former.With a more generalized distribution function by introducing Gaussian-type factors representing their pitch and radial dependences and using a slowing-down equilibrium distribution for the energy of energetic ions,numerical analysis indicates that the adiabatic contribution is conducive to stabilization of the mode and causes a decrease in mode frequency.In addition,we flnd that the adiabatic contribution has a weak stabilizing effect on the flshbone instability when the flnite orbit width effect is taken into account.We further analyze the dependence of the adiabatic contribution on the characteristic parameters of the distribution function.When the neutral beam has either a larger deviation from the plasma axis or a larger radial proflle,the adiabatic contribution has a more evident effect on the flshbone instability.When the neutral beam has a relatively small critical energy,the adiabatic contribution has a greater effect on the mode instability.
基金supported by NSFC projects(61960206005,61803211,61871111,62101275,62171127,61971136,and 62001056)Jiangsu NSF project(BK20200820)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX210106)Research Fund of National Mobile Communications Research Laboratory.
文摘Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear observations.Currently,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been proposed.For SBL,it has accurate performance with robustness while its computational complexity is high due to matrix inversion.For AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS problem.To overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)prior.Simulation results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.
文摘On January 7, 2015 the project "Study on the technology formanufacture of high-spheroidicity FCC catalysts "undertakenby the SINOPEC Research Institute of Petroleum Processing(RIPP) has passed the technical appraisal organized by theScience and Technology Division of the Sinopec Corp.
文摘Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10<sup>-5</sup>). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.