High-static-low-dynamic stiffness (HSLDS) vibration isolators have been demonstrated to be an effective means of attenuating low-frequency vibrations, and may be utilized for ship shafting applications to mitigate tor...High-static-low-dynamic stiffness (HSLDS) vibration isolators have been demonstrated to be an effective means of attenuating low-frequency vibrations, and may be utilized for ship shafting applications to mitigate torsional vibration. This paper presents the construction of a highly compact HSLDS torsional vibration isolator by connecting positive and negative stiffness components in paral lel. Based on mechanical model analysis, the restoring torque of negative stiffness components is de rived from their springs and connecting rods, while that of positive stiffness components is obtained through their circular section flexible rods. The quasizero stiffness characteristics of the HSLDS iso lator are achieved through a combination of static structural simulation and experimental test. The tor sional vibration isolation performance is assessed by means of numerical simulation and theory analy sis. Finally, the frequency-sweep vibration test is conducted. The test results indicate that the HSLDS torsional vibration isolator exhibits superior low-frequency isolation performance compared to its linear counterpart, rendering it a promising solution for mitigating low-frequency torsional vi bration in ship shafting.展开更多
An improved understanding of fatigue behavior of a cast aluminum alloy（2-AS5U3G-Y35）in very high cycle regime is developed through the ultrasonic fatigue test in axial and torsion loading.The new developed torsion f...An improved understanding of fatigue behavior of a cast aluminum alloy（2-AS5U3G-Y35）in very high cycle regime is developed through the ultrasonic fatigue test in axial and torsion loading.The new developed torsion fatigue system is presented.The effects of loading condition and frequency on the very high cycle fatigue（VHCF）are investigated.The cyclic loading in axial and torsion at 35 Hz and 20 kHz with stress ratio R=-1 is used respectively to demonstrate the effect of loading condition.S-N curves show that the fatigue failure occurs in the range of 105—1010 cycles in axial or torsion loading and the asymptote of S-N curve is inclined,but no fatigue limit exists under the torsion and axial loading condition.The fatigue fracture surface shows that the fatigue crack initiates from the specimen surface subjected to the cyclic torsion loading.It is different from the fatigue fracture characteristic in axial loading in which fatigue crack initiates from subsurface defect in very high cycle regime.The fatigue initiation is on the maximum shear plane,the overall crack orientation is on a typical spiral 45° to the fracture plane and it is the maximum principle stress plane.The clear shear strip in the torsion fatigue fracture surface shows that the torsion fracture is the shear fracture.展开更多
In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,...In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,and study n-tilting preenvelopes and n-cotilting precovers.展开更多
In the paper, we define（inco） project modules of relatively hereditary torsion theory τ by intersection complement of module and study their properties; secondly, we define the（inco） τ-semisimple ring by（inco）...In the paper, we define（inco） project modules of relatively hereditary torsion theory τ by intersection complement of module and study their properties; secondly, we define the（inco） τ-semisimple ring by（inco） τ-projective module and study their properties. When r is a trivial torsion theory on R-rood, we prove that R is a semisimple ring if and only if R is a（inco） semisimple ring and satisfies（inco） condition.展开更多
Torsional impact drilling is a new technology which has the advantages of high rock-breaking efficiency and a high rate of penetration(ROP).So far,there is no in-depth understanding of the rock-breaking mechanism for ...Torsional impact drilling is a new technology which has the advantages of high rock-breaking efficiency and a high rate of penetration(ROP).So far,there is no in-depth understanding of the rock-breaking mechanism for the ROP increase from torsional impact tools.Therefore,it has practical engineering significance to study the rock-breaking mechanism of torsional impact.In this paper,discrete element method(DEM)software(PFC2 D)is used to compare granite breaking under the steady and torsional impacting conditions.Meanwhile,the energy consumption to break rock,microscopic crushing process and chip characteristics as well as the relationship among these three factors for granite under different impacting frequencies and amplitudes are discussed.It is found that the average cutting force is smaller in the case of torsional impact cutting(TIC)than that in the case of steady loading.The mechanical specific energy(MSE)and the ratio of brittle energy consumption to total energy are negatively correlated;rock-breaking efficiency is related to the mode of action between the cutting tooth and rock.Furthermore,the ROP increase mechanism of torsional impact drilling technology is that the ratio of brittle energy consumption under the TIC condition is larger than that under a steady load;the degree of repeated fragmentation of rock chips under the TIC condition is lower than that under the steady load,and the TIC load promotes the formation of a transverse cracking network near the free surface and inhibits the formation of a deep longitudinal cracking network.展开更多
The torsional characteristics of single walled carbon nanotube(SWCNT) with water interactions are studied in this work using molecular dynamics simulation method. The torsional properties of carbon nanotubes(CNTs) in ...The torsional characteristics of single walled carbon nanotube(SWCNT) with water interactions are studied in this work using molecular dynamics simulation method. The torsional properties of carbon nanotubes(CNTs) in a hydrodynamic environment such as water are critical for its key role in determining the lifetime and stability of CNT based nano-fluidic devices. The effect of chirality, defects and the density of water encapsulation is studied by subjecting the SWCNT to torsion. The findings show that the torsional strength of SWCNT decreases due to interaction of water molecules and presence of defects in the SWCNT. Additionally,for the case of water molecules encapsulated inside SWCNT, the torsional response depends on the density of packing of water molecules. Our findings and conclusions obtained from this paper is expected to further compliment the potential applications of CNTs as promising candidates for applications in nano-biological and nano-fluidic devices.展开更多
In this paper torsional deformation of the carbon nanotubes is simulated by molecular dynamics method. The Brenner potential is used to set up the simulation system. Simulation results show that the carbon nanotubes c...In this paper torsional deformation of the carbon nanotubes is simulated by molecular dynamics method. The Brenner potential is used to set up the simulation system. Simulation results show that the carbon nanotubes can bear larger torsional deformation, for the armchair type （10,10） single wall carbon nanotubes, with a yielding phenomenon taking place when the torsional angle is up to 63°（1.1rad）. The influence of carbon nanotube helicity in torsional deformation is very small. The shear modulus of single wall carbon nanotubes should be several hundred GPa, not 1 GPa as others reports.展开更多
For a hereditary torsion theory τ, this paper mainly discuss properties of A-τ-injective modules, where A is a fixed left R-module. It is proved that if M is an A-τ-injective, B is a submodule of A, then 1） M is A...For a hereditary torsion theory τ, this paper mainly discuss properties of A-τ-injective modules, where A is a fixed left R-module. It is proved that if M is an A-τ-injective, B is a submodule of A, then 1） M is A/B-τ-injective; 2） M is B-τ-injective when B is τ-dense in A. Furthermore, we show that if A1,A2,... An, are relatively injective modules, then A1 A2 ... An is self-τ-injective if and only if A1 is self-τ-injective for each i.展开更多
This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the prop...This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.展开更多
A high quality factor is preferred for a microresonator sensor to improve the sensitivity and resolution. In this paper we systematically investigate the performance of the microcantilever in different resonance modes...A high quality factor is preferred for a microresonator sensor to improve the sensitivity and resolution. In this paper we systematically investigate the performance of the microcantilever in different resonance modes, which are the first three flexural modes, the first lateral mode, and the first and the second torsional modes. An aluminum nitride-based piezoelectric cantilever is fabricated and tested under controlled pressure from an ultra-high vacuum to a normal atmosphere, using a custom-built vacuum chamber. From the experiment results, it can be seen that the torsional modes exhibit better quality factors than those of the flexural and lateral ones. Finally, an analytical model for the air damping characteristics of the torsional mode cantilever is derived and verified by comparing with experimental results.展开更多
The diagnosis of ovarian torsion(OT)in girls is challenging compared to that of testicular torsion in boys for many reasons,but it behooves the medical community to continue to strive to better identify this uncommon ...The diagnosis of ovarian torsion(OT)in girls is challenging compared to that of testicular torsion in boys for many reasons,but it behooves the medical community to continue to strive to better identify this uncommon but clinically important pathology^([1]) OT occurs when the ovary and associated structures rotate around its vascular pedicle,leading to eventually irreversible necrosis.^([2,3])Studies attempting to identify clinical features for early diagnosis have not reached a consensus on the best clinical predictors of this condition,making radiographic imaging of the ovaries even more crucial.^([4,5])展开更多
The thermoelastic effect of the suspension fibre in the torsion pendulum experiment with magnetic damping was studied.The disagreement in the oscillation periods was reduced by one order of magnitude through monitorin...The thermoelastic effect of the suspension fibre in the torsion pendulum experiment with magnetic damping was studied.The disagreement in the oscillation periods was reduced by one order of magnitude through monitoring the ambient temperature and thermoelastic correction.We also found that the period on uncertainty due to noise increases with the amplitude attenuation after thermoelastic correction.展开更多
Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with exc...Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.展开更多
Testing the extreme weak gravitational forces between torsion pendulum and surrounding objects will indicate new physics which attracts many interests.In these measurements,the fiber alignment plays a crucial role in ...Testing the extreme weak gravitational forces between torsion pendulum and surrounding objects will indicate new physics which attracts many interests.In these measurements,the fiber alignment plays a crucial role in fulfilling high precision placement measurement,especially in measuring the deviation between the fiber and source mass or other objects.The traditional way of the fiber alignment requires to measure the component of the pendulum body and then transfer to the torsion fiber by some complicated calculations.A new method is reported here by using a CCD camera to get the projection image of the torsion fiber,which is a direct and no-contact measurement.Furthermore,the relative position change of the torsion fiber can also be monitored during the experiment.In our experiment,the alignment between the fiber and the center of the turntable has been operated as an example.Our result reaches the accuracy of several micrometers which is higher than the previous method.展开更多
The purpose of this paper is to calculate the torsional agility metric,the time-to-roll and capture a 90° bank angle change,using a simple pilot mathematical model obtained from simulator test. The metric mention...The purpose of this paper is to calculate the torsional agility metric,the time-to-roll and capture a 90° bank angle change,using a simple pilot mathematical model obtained from simulator test. The metric mentioned above is determined by the aircraft maneuverability and controllability,or the pilot ability to roll and capture quickly and accurately a bank angle. Therefore, the time-to-roll and capture a 90° bank angle change can be obtained by calculating the open loop process with limited maximum stick denflect velocity and the man-machine closed loop precise tracking control. Results show that the calculated values are quite consistent with the manned simulation data. The dteterioration of torsional agility while the aircraft is poor or very maneuverable can be explained. It is suggested that this approach could provide the basis for the approxi mate evaluation of aircraft torsional agility metric.展开更多
Based on statistical properties, two typical models are considered to calculate the uncertainties for some random noise sequences on the period extraction of a torsion pendulum, which is important and instructive in t...Based on statistical properties, two typical models are considered to calculate the uncertainties for some random noise sequences on the period extraction of a torsion pendulum, which is important and instructive in the measurement of gravitational constant G with the time-of-swing method. An expression of the uncertainty for the period measurement is obtained, which is dependent on the ratio ？t/（1/λ） where ？t is the interval of the sample time and 1/λ is the length of the correlation time. The result of processing experimental data shows that as the interval of the sample time ？t gradually shortens, the uncertainty of the period becomes smaller, and further when the ratio ？t/（1/λ） is less than 1, the uncertainty remains substantially unchanged.展开更多
文摘High-static-low-dynamic stiffness (HSLDS) vibration isolators have been demonstrated to be an effective means of attenuating low-frequency vibrations, and may be utilized for ship shafting applications to mitigate torsional vibration. This paper presents the construction of a highly compact HSLDS torsional vibration isolator by connecting positive and negative stiffness components in paral lel. Based on mechanical model analysis, the restoring torque of negative stiffness components is de rived from their springs and connecting rods, while that of positive stiffness components is obtained through their circular section flexible rods. The quasizero stiffness characteristics of the HSLDS iso lator are achieved through a combination of static structural simulation and experimental test. The tor sional vibration isolation performance is assessed by means of numerical simulation and theory analy sis. Finally, the frequency-sweep vibration test is conducted. The test results indicate that the HSLDS torsional vibration isolator exhibits superior low-frequency isolation performance compared to its linear counterpart, rendering it a promising solution for mitigating low-frequency torsional vi bration in ship shafting.
基金Supported by the National Natural Science Foundation of China(50775182)the Scientific Research Foundation for the Returned Scholars of the Ministry of Education of China~~
文摘An improved understanding of fatigue behavior of a cast aluminum alloy（2-AS5U3G-Y35）in very high cycle regime is developed through the ultrasonic fatigue test in axial and torsion loading.The new developed torsion fatigue system is presented.The effects of loading condition and frequency on the very high cycle fatigue（VHCF）are investigated.The cyclic loading in axial and torsion at 35 Hz and 20 kHz with stress ratio R=-1 is used respectively to demonstrate the effect of loading condition.S-N curves show that the fatigue failure occurs in the range of 105—1010 cycles in axial or torsion loading and the asymptote of S-N curve is inclined,but no fatigue limit exists under the torsion and axial loading condition.The fatigue fracture surface shows that the fatigue crack initiates from the specimen surface subjected to the cyclic torsion loading.It is different from the fatigue fracture characteristic in axial loading in which fatigue crack initiates from subsurface defect in very high cycle regime.The fatigue initiation is on the maximum shear plane,the overall crack orientation is on a typical spiral 45° to the fracture plane and it is the maximum principle stress plane.The clear shear strip in the torsion fatigue fracture surface shows that the torsion fracture is the shear fracture.
基金Supported by the 2018 Scientific Research Projects in Universities of Gansu Province(2018A-269)
文摘In this paper,we consider some generalizations of tilting torsion classes and cotilting torsion-free classes,give the definition and characterizations of n-tilting torsion classes and n-cotilting torsion-free classes,and study n-tilting preenvelopes and n-cotilting precovers.
基金Supported by the Science and Technology Develop Foundation of Jilin Science and Technology Department(20040506-3)
文摘In the paper, we define（inco） project modules of relatively hereditary torsion theory τ by intersection complement of module and study their properties; secondly, we define the（inco） τ-semisimple ring by（inco） τ-projective module and study their properties. When r is a trivial torsion theory on R-rood, we prove that R is a semisimple ring if and only if R is a（inco） semisimple ring and satisfies（inco） condition.
基金supported by the National Natural Science Foundation of China(Grant No.51674214)International Cooperation Project of Sichuan Science and Technology Plan(2016HH0008)+1 种基金Youth Science and Technology Innovation Research Team of Sichuan Province(2017TD0014)Applied Basic Research of Sichuan Province(Free Exploration-2019YJ0520)
文摘Torsional impact drilling is a new technology which has the advantages of high rock-breaking efficiency and a high rate of penetration(ROP).So far,there is no in-depth understanding of the rock-breaking mechanism for the ROP increase from torsional impact tools.Therefore,it has practical engineering significance to study the rock-breaking mechanism of torsional impact.In this paper,discrete element method(DEM)software(PFC2 D)is used to compare granite breaking under the steady and torsional impacting conditions.Meanwhile,the energy consumption to break rock,microscopic crushing process and chip characteristics as well as the relationship among these three factors for granite under different impacting frequencies and amplitudes are discussed.It is found that the average cutting force is smaller in the case of torsional impact cutting(TIC)than that in the case of steady loading.The mechanical specific energy(MSE)and the ratio of brittle energy consumption to total energy are negatively correlated;rock-breaking efficiency is related to the mode of action between the cutting tooth and rock.Furthermore,the ROP increase mechanism of torsional impact drilling technology is that the ratio of brittle energy consumption under the TIC condition is larger than that under a steady load;the degree of repeated fragmentation of rock chips under the TIC condition is lower than that under the steady load,and the TIC load promotes the formation of a transverse cracking network near the free surface and inhibits the formation of a deep longitudinal cracking network.
文摘The torsional characteristics of single walled carbon nanotube(SWCNT) with water interactions are studied in this work using molecular dynamics simulation method. The torsional properties of carbon nanotubes(CNTs) in a hydrodynamic environment such as water are critical for its key role in determining the lifetime and stability of CNT based nano-fluidic devices. The effect of chirality, defects and the density of water encapsulation is studied by subjecting the SWCNT to torsion. The findings show that the torsional strength of SWCNT decreases due to interaction of water molecules and presence of defects in the SWCNT. Additionally,for the case of water molecules encapsulated inside SWCNT, the torsional response depends on the density of packing of water molecules. Our findings and conclusions obtained from this paper is expected to further compliment the potential applications of CNTs as promising candidates for applications in nano-biological and nano-fluidic devices.
基金Project supported by the National Natural Science Foundation of China （Grant No 50405011） and the Natural Science Foundation of Heilongjiang Province of China （Grant No E0218）.
文摘In this paper torsional deformation of the carbon nanotubes is simulated by molecular dynamics method. The Brenner potential is used to set up the simulation system. Simulation results show that the carbon nanotubes can bear larger torsional deformation, for the armchair type （10,10） single wall carbon nanotubes, with a yielding phenomenon taking place when the torsional angle is up to 63°（1.1rad）. The influence of carbon nanotube helicity in torsional deformation is very small. The shear modulus of single wall carbon nanotubes should be several hundred GPa, not 1 GPa as others reports.
基金Supported by the National Natural Science Foundation of China(10571026)Supported by the Research Foundation of the Education Committee of Anhui Province(2006kj050c)Supported by the Doctoral Foundation of Anhui Normal University
文摘For a hereditary torsion theory τ, this paper mainly discuss properties of A-τ-injective modules, where A is a fixed left R-module. It is proved that if M is an A-τ-injective, B is a submodule of A, then 1） M is A/B-τ-injective; 2） M is B-τ-injective when B is τ-dense in A. Furthermore, we show that if A1,A2,... An, are relatively injective modules, then A1 A2 ... An is self-τ-injective if and only if A1 is self-τ-injective for each i.
文摘This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.
文摘A high quality factor is preferred for a microresonator sensor to improve the sensitivity and resolution. In this paper we systematically investigate the performance of the microcantilever in different resonance modes, which are the first three flexural modes, the first lateral mode, and the first and the second torsional modes. An aluminum nitride-based piezoelectric cantilever is fabricated and tested under controlled pressure from an ultra-high vacuum to a normal atmosphere, using a custom-built vacuum chamber. From the experiment results, it can be seen that the torsional modes exhibit better quality factors than those of the flexural and lateral ones. Finally, an analytical model for the air damping characteristics of the torsional mode cantilever is derived and verified by comparing with experimental results.
文摘The diagnosis of ovarian torsion(OT)in girls is challenging compared to that of testicular torsion in boys for many reasons,but it behooves the medical community to continue to strive to better identify this uncommon but clinically important pathology^([1]) OT occurs when the ovary and associated structures rotate around its vascular pedicle,leading to eventually irreversible necrosis.^([2,3])Studies attempting to identify clinical features for early diagnosis have not reached a consensus on the best clinical predictors of this condition,making radiographic imaging of the ovaries even more crucial.^([4,5])
基金Supported by the National Natural Science Foundation of China under Grant No.19835040.
文摘The thermoelastic effect of the suspension fibre in the torsion pendulum experiment with magnetic damping was studied.The disagreement in the oscillation periods was reduced by one order of magnitude through monitoring the ambient temperature and thermoelastic correction.We also found that the period on uncertainty due to noise increases with the amplitude attenuation after thermoelastic correction.
基金financially supported by the National Natural Science Foundation of China(U2002213)the Creative Project of Engineering Research Center of Alternative Energy Materials&Devices,Ministry of Education,Sichuan University(AEMD202207)+7 种基金the Open Foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials of Guangxi University(2022GXYSOF10)the Guangdong Colleges&Universities Characteristic Innovation Project(2021KTSCX263)the Guangdong Education&Scientific Research Project(2021GXJK535)the Guangzhou Panyu Polytechnic Science&Technology Project(2021KJ01)the East-Land Middle-aged and Young Backbone Teacher of Yunnan University(C176220200)the Yunnan Applied Basic Research Projects(202001BB050006,202001BB050007)the Double Tops Joint Fund of the Yunnan Science and Technology Bureau and Yunnan University(2019FY003025)the Double First Class University Plan(C176220100042)。
文摘Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.
基金the National Natural Science Foundation of China(Grant No.11305057).
文摘Testing the extreme weak gravitational forces between torsion pendulum and surrounding objects will indicate new physics which attracts many interests.In these measurements,the fiber alignment plays a crucial role in fulfilling high precision placement measurement,especially in measuring the deviation between the fiber and source mass or other objects.The traditional way of the fiber alignment requires to measure the component of the pendulum body and then transfer to the torsion fiber by some complicated calculations.A new method is reported here by using a CCD camera to get the projection image of the torsion fiber,which is a direct and no-contact measurement.Furthermore,the relative position change of the torsion fiber can also be monitored during the experiment.In our experiment,the alignment between the fiber and the center of the turntable has been operated as an example.Our result reaches the accuracy of several micrometers which is higher than the previous method.
文摘The purpose of this paper is to calculate the torsional agility metric,the time-to-roll and capture a 90° bank angle change,using a simple pilot mathematical model obtained from simulator test. The metric mentioned above is determined by the aircraft maneuverability and controllability,or the pilot ability to roll and capture quickly and accurately a bank angle. Therefore, the time-to-roll and capture a 90° bank angle change can be obtained by calculating the open loop process with limited maximum stick denflect velocity and the man-machine closed loop precise tracking control. Results show that the calculated values are quite consistent with the manned simulation data. The dteterioration of torsional agility while the aircraft is poor or very maneuverable can be explained. It is suggested that this approach could provide the basis for the approxi mate evaluation of aircraft torsional agility metric.
基金supported by the National Natural Science Foundation of China(Grant Nos.11175160,11275075,and 11575160)
文摘Based on statistical properties, two typical models are considered to calculate the uncertainties for some random noise sequences on the period extraction of a torsion pendulum, which is important and instructive in the measurement of gravitational constant G with the time-of-swing method. An expression of the uncertainty for the period measurement is obtained, which is dependent on the ratio ？t/（1/λ） where ？t is the interval of the sample time and 1/λ is the length of the correlation time. The result of processing experimental data shows that as the interval of the sample time ？t gradually shortens, the uncertainty of the period becomes smaller, and further when the ratio ？t/（1/λ） is less than 1, the uncertainty remains substantially unchanged.
