The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great impor...The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great importance from the viewpoints of optimal design,manufacturing,use,and maintenance of gun and projectile.In this paper,the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi‐static and dynamic loading conditions.The quasi‐static engraving tests were performed on a CSS‐88500 electronic universal testing machine(EUTM)and a special gas‐gun‐based test rig was designed for dynamic impact engraving of the rotating bands.The mechanical behaviors of copper and nylon were investigated under strain rates of 10^(−3) s^(−1) and 2×10^(3) s^(−1) using an MTS 810 and a split Hopkinson pressure bar(SHPB),respectively.Morphologies of the worn surfaces and cross‐sectional microstructures were observed with scanning electron microscope(SEM)and optical microscope(OM).It was found that large deformation and severe friction occur during engraving.The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface.The structure of the rotating band and gun bore,band material,and loading rate have great effects on band engraving.The flow stress‐strain of the copper strongly depends on the applied strain rate.It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.展开更多
The nanoparticles of the hydrophobic drug of danazol with narrow size distribution are facilely prepared by controlled high-gravity anti-solvent precipitation （HGAP） process. Intensified micromixing and uniform nucl...The nanoparticles of the hydrophobic drug of danazol with narrow size distribution are facilely prepared by controlled high-gravity anti-solvent precipitation （HGAP） process. Intensified micromixing and uniform nucleation environment are created by the high-gravity equipment （rotating packed bed） in carrying out the anti-solvent precipitation process to produce nanoparticles. The average particle size decreases from 55 μm of the raw danazol to 190 nm of the nanoparticles. The Brunauer-Emmett-Teller （BET） surface area sharply increases from 0.66 m^2·g^-1 to 15.08 m^2·g^-l. Accordingly, the dissolution rate is greatly improved. The molecular state, chemical composition, and crystal form of the danazol nanoparticles remains unchanged after processing according to Fourier transform infrared （FTIR） and X-ray diffraction （XRD）, The high recovery ratio and continuous production capacity are highly appreciated in industry. Therefore, the HGAP method might offer a general and facile platform for mass production of hydrophobic pharmaceutical danazol particles in nanometer range.展开更多
A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(T...A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(Trad/s),which can be flexibly tuned with a mirror in the MI.Besides,its fold rotational symmetry structure is also changeable by controlling the difference from the topological charges of the pulse pair.Experimentally,we have successfully developed a twopetal lattice with a tunable rotating speed from 3.9 Trad/s up to 11.9 Trad/s,which is confirmed by our single-shot ultrafast frame imager based on noncollinear optical-parametric amplification with its highest frame rate of 15 trillion frames per second(Tfps).This work is carried out at a low repetition rate.Therefore,it can be applied at relativistic,even ultrarelativistic,intensities,which usually operate in low repetition rate ultrashort and ultraintense laser systems.We believe that it may have application in laser-plasma-based accelerators,strong terahertz radiations and celestial phenomena.展开更多
This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-MnCu/γ-Al_(2)O_(3)(Cat)in a rotating packed bed(RPB)for the first time.The results showed that the value of the overal...This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-MnCu/γ-Al_(2)O_(3)(Cat)in a rotating packed bed(RPB)for the first time.The results showed that the value of the overall decomposition rate constant of ozone(K_(c))and overall volumetric mass transfer coefficient(K_(L)a)are 4.28×10^(-3) s^(-1) and 11.60×10^(-3) s^(-1) respectively at an initial pH of 6,βof 40,Co3(g)of 60 mg·L^(-1)and Q_(L) of 85 L·h^(-1) in deionized water,respectively.Meanwhile,the K_(c) and K_(L)a values of Fenhe water are0.88×10^(-3) s^(-1) and 2.51×10^(-3) s^(-1) lower than deionized water,respectively.In addition,the K_(c) and K_(L)a values in deionized water for the Cat/O_(3)-RPB system are 44.86%and 47.41%higher than that for the Cat/O_(3)-BR(bubbling reactor)system,respectively,indicating that the high gravity technology can facilitate the decomposition and mass transfer of ozone in heterogeneous catalytic ozonation and provide some insights into the industrial wastewater.展开更多
A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and d...A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and density of flocs were investigated. The results show that under the new fluid conditions, the primary particles on the outer part of the formed flocs may be cut down and the flocs contract at the end of the original rotating direction; then fluid changes its rotating direction, an opposite shearing is imposed to the flocs and makes some primary particles slide along the floc surface, leading to a denser floc; meanwhile, the broken and unflocculated particles on the trajectory may have opportunities to penetrate into or cohere to the flocs. Compared with the conventional rotating flow, the new-designed flow pattern can not only keep the floc size (even enlarge the floc diameter if a suitable flow is chosen) but also increase the floc density effectively.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(NSFC)under Grant No.51175512.
文摘The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great importance from the viewpoints of optimal design,manufacturing,use,and maintenance of gun and projectile.In this paper,the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi‐static and dynamic loading conditions.The quasi‐static engraving tests were performed on a CSS‐88500 electronic universal testing machine(EUTM)and a special gas‐gun‐based test rig was designed for dynamic impact engraving of the rotating bands.The mechanical behaviors of copper and nylon were investigated under strain rates of 10^(−3) s^(−1) and 2×10^(3) s^(−1) using an MTS 810 and a split Hopkinson pressure bar(SHPB),respectively.Morphologies of the worn surfaces and cross‐sectional microstructures were observed with scanning electron microscope(SEM)and optical microscope(OM).It was found that large deformation and severe friction occur during engraving.The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface.The structure of the rotating band and gun bore,band material,and loading rate have great effects on band engraving.The flow stress‐strain of the copper strongly depends on the applied strain rate.It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.
基金Supported by the National High Technology Research and Development Program of China (2006AA030202)the Talent Training Program of Beijing (2007B022)
文摘The nanoparticles of the hydrophobic drug of danazol with narrow size distribution are facilely prepared by controlled high-gravity anti-solvent precipitation （HGAP） process. Intensified micromixing and uniform nucleation environment are created by the high-gravity equipment （rotating packed bed） in carrying out the anti-solvent precipitation process to produce nanoparticles. The average particle size decreases from 55 μm of the raw danazol to 190 nm of the nanoparticles. The Brunauer-Emmett-Teller （BET） surface area sharply increases from 0.66 m^2·g^-1 to 15.08 m^2·g^-l. Accordingly, the dissolution rate is greatly improved. The molecular state, chemical composition, and crystal form of the danazol nanoparticles remains unchanged after processing according to Fourier transform infrared （FTIR） and X-ray diffraction （XRD）, The high recovery ratio and continuous production capacity are highly appreciated in industry. Therefore, the HGAP method might offer a general and facile platform for mass production of hydrophobic pharmaceutical danazol particles in nanometer range.
基金supported by the National Natural Science Foundation of China(Nos.61775142,61705132,61490710 and 61827815)China Postdoctoral Science Foundation(No.2017M612726)+1 种基金Shenzhen Basic Research Project on Subject Layout(No.JCYJ20170412105812811)Fund of the International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology,Shenzhen University(No.2DMOST2018019)。
文摘A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(Trad/s),which can be flexibly tuned with a mirror in the MI.Besides,its fold rotational symmetry structure is also changeable by controlling the difference from the topological charges of the pulse pair.Experimentally,we have successfully developed a twopetal lattice with a tunable rotating speed from 3.9 Trad/s up to 11.9 Trad/s,which is confirmed by our single-shot ultrafast frame imager based on noncollinear optical-parametric amplification with its highest frame rate of 15 trillion frames per second(Tfps).This work is carried out at a low repetition rate.Therefore,it can be applied at relativistic,even ultrarelativistic,intensities,which usually operate in low repetition rate ultrashort and ultraintense laser systems.We believe that it may have application in laser-plasma-based accelerators,strong terahertz radiations and celestial phenomena.
基金supported by the Specialized Research Fund for Sanjin Scholars Program of Shanxi Province(201707)Key Research&Development Plan of Shanxi Province(201903D321059)+2 种基金Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20200004)Transformation and Cultivation Projects of Scientific and Technological Achievements in Universities of Shanxi Province Institutions(2020CG040)the China National Key Project of Science and Technology “Major Science and Technology Program for Water Pollution Control and Treatment”(2018ZX07601001)。
文摘This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-MnCu/γ-Al_(2)O_(3)(Cat)in a rotating packed bed(RPB)for the first time.The results showed that the value of the overall decomposition rate constant of ozone(K_(c))and overall volumetric mass transfer coefficient(K_(L)a)are 4.28×10^(-3) s^(-1) and 11.60×10^(-3) s^(-1) respectively at an initial pH of 6,βof 40,Co3(g)of 60 mg·L^(-1)and Q_(L) of 85 L·h^(-1) in deionized water,respectively.Meanwhile,the K_(c) and K_(L)a values of Fenhe water are0.88×10^(-3) s^(-1) and 2.51×10^(-3) s^(-1) lower than deionized water,respectively.In addition,the K_(c) and K_(L)a values in deionized water for the Cat/O_(3)-RPB system are 44.86%and 47.41%higher than that for the Cat/O_(3)-BR(bubbling reactor)system,respectively,indicating that the high gravity technology can facilitate the decomposition and mass transfer of ozone in heterogeneous catalytic ozonation and provide some insights into the industrial wastewater.
文摘A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and density of flocs were investigated. The results show that under the new fluid conditions, the primary particles on the outer part of the formed flocs may be cut down and the flocs contract at the end of the original rotating direction; then fluid changes its rotating direction, an opposite shearing is imposed to the flocs and makes some primary particles slide along the floc surface, leading to a denser floc; meanwhile, the broken and unflocculated particles on the trajectory may have opportunities to penetrate into or cohere to the flocs. Compared with the conventional rotating flow, the new-designed flow pattern can not only keep the floc size (even enlarge the floc diameter if a suitable flow is chosen) but also increase the floc density effectively.
