Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.A...Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.展开更多
The thin aluminum liners with an aspect ratio R/?r 1 have been imploded on the primary test stand(PTS) facility,where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present ...The thin aluminum liners with an aspect ratio R/?r 1 have been imploded on the primary test stand(PTS) facility,where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present azimuthally correlated perturbations in the liner implosions. The experiments show that at-10 ns before the stagnation, the wavelengths of perturbation are about 0.93 mm and 1.67 mm for the small-radius and large-radius liners, respectively. We have utilized the resistive magnetohydrodynamic code PLUTO to study the development of magneto-Rayleigh–Taylor(MRT) instabilities under experimental conditions. The calculated perturbation amplitudes are consistent with the experimental observations very well. We have found that both mode coupling and long implosion distance are responsible for the more developed instabilities in the large-radius liner implosions.展开更多
The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with an...The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.展开更多
The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standi...The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite.展开更多
In order to assess the effects of tuned mass dampers （TMDs） on wind actions, an aeroelastic model with a scale of 1：60 was constructed. Tests were performed in an atmospheric boundary layer wind tunnel to investiga...In order to assess the effects of tuned mass dampers （TMDs） on wind actions, an aeroelastic model with a scale of 1：60 was constructed. Tests were performed in an atmospheric boundary layer wind tunnel to investigate the buffeting response of the pylon with a TMD fixed by a wire rope instead of a spring. The model was tested under different levels of damping. The experimental and numerical results showed that with the TMD in the optimal condition, the buffeting response was reduced by 47%.展开更多
Fundamental power couplers are crucial components for feeding radio frequency power to accelerating cavities. Couplers must be tested and conditioned on a room-temperature test stand to evaluate and potentially improv...Fundamental power couplers are crucial components for feeding radio frequency power to accelerating cavities. Couplers must be tested and conditioned on a room-temperature test stand to evaluate and potentially improve their performance before being installed in an accelerating cavity. A new test system has been designed and is under construction at the institute of modern physics.For this test system, multiple conditioning modes, including the pulse mode, CW mode, and amplitude-sweeping mode, have been embedded in the low-level radio frequency system of the test stand. All of these conditioning modes can be run manually or automatically. In addition, a novel test cavity is proposed and has been designed, which facilitates non-contact conditioning and a multi-purpose test stand.展开更多
Background: This is the first study to publish the normative reference values for assessment of the level of muscular strength through the “standing long jump” test carried out on a large sample of Macedonian school...Background: This is the first study to publish the normative reference values for assessment of the level of muscular strength through the “standing long jump” test carried out on a large sample of Macedonian school children. The normative values encompass a wide span of years (6 - 18). Methods: The research was realized in a large sample of 12618 school children at the age of 6 to 18 years from Macedonia. The sample was divided in 14 groups, according to chronological age and each age group was divided into two subgroups according to the criteria of gender. For estimation of the morphologic characteristics, the following anthropometric measures have been applied: body height in standing position (cm), body weight (kg), as well as the body mass index (BMI). Children aged 6 or above were invited to take a standing long jump test. Results: Boys show statistically better results in all age categories in the standing long jump test than girls, and these differences become bigger with the increase of age, especially after the 14th year展开更多
文摘Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.11605013,11775032,11805019,and 11705013)
文摘The thin aluminum liners with an aspect ratio R/?r 1 have been imploded on the primary test stand(PTS) facility,where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present azimuthally correlated perturbations in the liner implosions. The experiments show that at-10 ns before the stagnation, the wavelengths of perturbation are about 0.93 mm and 1.67 mm for the small-radius and large-radius liners, respectively. We have utilized the resistive magnetohydrodynamic code PLUTO to study the development of magneto-Rayleigh–Taylor(MRT) instabilities under experimental conditions. The calculated perturbation amplitudes are consistent with the experimental observations very well. We have found that both mode coupling and long implosion distance are responsible for the more developed instabilities in the large-radius liner implosions.
文摘The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.
基金supported by the National Natural Science Foundation of China(Grant Nos.52278407 and 52378407)the China Postdoctoral Science Foundation(Grant No.2023M732670)the support by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation.
文摘The widespread utilisation of tunnel boring machines(TBMs)in underground construction engineering requires a detailed investigation of the cutter-rock interaction.In this paper,we conduct a series of largescale standing rotary cutting tests on granite in conjunction with high-fidelity numerical simulations based on a particle-type discrete element method(DEM)to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses.The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters.More specifically,the normal and rolling forces exhibit a positive correlation with penetration but are slightly influenced by the cutting radius.In contrast,the side force decreases as the cutting radius increases.Additionally,the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases.The cutter's relative effectiveness in rock breaking is significantly impacted by the penetration but shows little dependency on the cutting radius.Consequently,an optimal penetration is identified,leading to a low boreability index and specific energy.A combined Hertz-Weibull function is developed to fit the cutter-rock contact stress distribution obtained in DEM simulations,whereby an improved CSM(Colorado School of Mines)model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model.The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/simulations.The findings from this work that advance our understanding of TBM cutter performance have important implications for improving the efficiency and reliability of TBM tunnelling in granite.
基金The National Natural Science Foundation of China (Nos. 50808148 and 90815016)
文摘In order to assess the effects of tuned mass dampers （TMDs） on wind actions, an aeroelastic model with a scale of 1：60 was constructed. Tests were performed in an atmospheric boundary layer wind tunnel to investigate the buffeting response of the pylon with a TMD fixed by a wire rope instead of a spring. The model was tested under different levels of damping. The experimental and numerical results showed that with the TMD in the optimal condition, the buffeting response was reduced by 47%.
基金supported by the National Key Basic Research Program of China(973 Program)(No.2014CB845504)
文摘Fundamental power couplers are crucial components for feeding radio frequency power to accelerating cavities. Couplers must be tested and conditioned on a room-temperature test stand to evaluate and potentially improve their performance before being installed in an accelerating cavity. A new test system has been designed and is under construction at the institute of modern physics.For this test system, multiple conditioning modes, including the pulse mode, CW mode, and amplitude-sweeping mode, have been embedded in the low-level radio frequency system of the test stand. All of these conditioning modes can be run manually or automatically. In addition, a novel test cavity is proposed and has been designed, which facilitates non-contact conditioning and a multi-purpose test stand.
文摘Background: This is the first study to publish the normative reference values for assessment of the level of muscular strength through the “standing long jump” test carried out on a large sample of Macedonian school children. The normative values encompass a wide span of years (6 - 18). Methods: The research was realized in a large sample of 12618 school children at the age of 6 to 18 years from Macedonia. The sample was divided in 14 groups, according to chronological age and each age group was divided into two subgroups according to the criteria of gender. For estimation of the morphologic characteristics, the following anthropometric measures have been applied: body height in standing position (cm), body weight (kg), as well as the body mass index (BMI). Children aged 6 or above were invited to take a standing long jump test. Results: Boys show statistically better results in all age categories in the standing long jump test than girls, and these differences become bigger with the increase of age, especially after the 14th year
