Measurement of the Secondary Neutron Emission Differential and Double-Differential Cross Sections between 20 and 30 MeV

X. C. Ruan,G. C. Chen,H. X. Huang,X. Li,Y. B. Nie,B. Zhou,Z. Y. Ma,J. Bao,Q. P. Zhong,Z. Y. Zhou,H. Q. Tang,J. S. Zhang,C. L. Lan,Y. L. Zhang,Y. M. Li 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

More and more interests have been paid to the differential and double-differential neutron emission cross sections (DX and DDX) at above 20 MeV region in recent years. At the China Institute of Atomic Energy (CIAE), a program to measure the DX and DDX between 20 and 30 MeV neutron energy region has been carried out. The d-T reaction neutron source was used to produce the 20 - 30 MeV neutrons with a tritium gas target at the HI-13 tandem accelerator at CIAE. The time-of-flight(TOF) technique was used to measure the neutron energy from about 1 MeV to 30 MeV with 3 BC501A liquid scintillators (with a size of Φ180 ×100 mm). A preliminary measurement has been carried out for ^9Be at 22 MeV. The measured data were analyzed by detailed Monte-Carlo simulation to perform the multiple scattering, flux attenuation and finite geometry corrections. The experimental details, the data analysis, the progress, the results and the future plan will be presented in this report.

SHIFTING CONTROL OF AN AUTOMATED MECHANICAL TRANSMISSION WITHOUT USING THE CLUTCH

Z. ZHONG,G. KONG,Z. YU,X. XIN,X. CHEN 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.3

The automated mechanical transmission (AMT) is gaining popularity in the automotive industry, due to its combination of the advantages of mechanical transmissions (MT) and automatic transmissions (AT) in terms of fuel consumption, low cost, improved driving comfort and shifting quality. However, the inherent structural characteristics of the AMT lead to disadvantages, including excessive wear of the clutch plates and jerk and traction interruption during the shift process, that severely affect its popularity in the automatic transmission industry. The emerging technology of shifting control without the use of the clutch is a promising way to improve the shifting transients of AMTs. This paper proposes a control algorithm that combines speed and torque control of the AMT vehicle powertrain to achieve shifting control without using the clutch. The key technologies of accurate engine torque and speed control and rapid position control of the shift actuators are described in detail. To realize accurate engine speed control, a combined control algorithm based on feed-forward, bang-bang and PID control is adopted. Additionally, an optimized closed-loop position control algorithm based on LQR is proposed for the shift actuators. The coordinated control algorithm based on engine and shift actuator control is described in detail and validated on a test vehicle equipped with an AMT. The results show that the coordinated control algorithm can achieve shifting control without the use of the clutch to improve driving comfort significantly, reduce shift transients and extend the service life of the clutch.

Tokamak plasma disruption precursor onset time study based on semi-supervised anomaly detection

X.K. Ai,W. Zheng,M. Zhang,D.L. Chen,C.S. Shen,B.H. Guo,B.J. Xiao,Y. Zhong,N.C. Wang,Z.J. Yang,Z.P. Chen,Z.Y. Chen,Y.H. Ding,Y. Pan Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.4

Plasma disruption in tokamak experiments is a challenging issue that causes damage to the device. Reliable prediction methods are needed, but the lack of full understanding of plasma disruption limits the effectiveness of physics-driven methods. Data-driven methods based on supervised learning are commonly used, and they rely on labelled training data. However, manual labelling of disruption precursors is a time-consuming and challenging task, as some precursors are difficult to accurately identify. The mainstream labelling methods assume that the precursor onset occurs at a fixed time before disruption, which leads to mislabeled samples and suboptimal prediction performance. In this paper, we present disruption prediction methods based on anomaly detection to address these issues, demonstrating good prediction performance on J-TEXT and EAST. By evaluating precursor onset times using different anomaly detection algorithms, it is found that labelling methods can be improved since the onset times of different shots are not necessarily the same. The study optimizes precursor labelling using the onset times inferred by the anomaly detection predictor and test the optimized labels on supervised learning disruption predictors. The results on J-TEXT and EAST show that the models trained on the optimized labels outperform those trained on fixed onset time labels.

Clarifying the basic phase structure and magnetic behavior of directly quenched (Ce,La)2Fe14B alloys with various Ce/La ratios

X.F. Liao,L.Z. Zhao,J.S. Zhang,G. Ahmed,A.J. Khan,H.X. Zeng,H.Y. Yu,X.C. Zhong,Z.W. Liu,G.Q. Zhang 한국물리학회 2019 Current Applied Physics Vol.19 No.6

To improve the performance/cost ratio of NdFeB based permanent magnets, Ce or/and La substitutions for Nd have been suggested. To better understand the effects of these substitutions, the fundamental behavior of (Ce,La)-Fe-B alloys has to be clearly understood. Here, we reported a systematic investigation on the phase structure, microstructure, and magnetic properties of melt-spun (Ce,La)2Fe14B alloys. The results confirm that partial substitution of Ce by La can effectively enhance the hard magnetism and thermal stability of (Ce1- xLax)2Fe14B alloys, while over 80% La substitution leads to the decomposition of 2:14:1 phase. The lattice parameters a, c and the Curie temperature Tc of 2:14:1 phase increase linearly with the increasing La content. La substitution can effectively refine the grain, resulting in the enhancement of inter-grain exchange coupling. The (Ce0.7La0.3)2Fe14B alloy with a mean grain size of 25 nm exhibits high remanence, maximum energy product and intrinsic coercivity up to 0.69 T, 6.2 MGOe and 217 kA/m, respectively. The present work provides a good understanding on the melt-spun (Ce,La)-Fe-B system for further developing low cost rare earth permanent magnets.

Tensile and Creep Deformation of a Newly Developed Ni-Fe-Based Superalloy for 700 °C Advanced Ultra-Supercritical Boiler Applications

Y. Yuan,Z. H. Zhong,Z.S. Yu,H. F. Yin,Y. Y. Dang,X. B. Zhao,Z. Yang,J. T. Lu,J. B. Yan,Y. Gu 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.4

A new Ni-Fe-based superalloy, HT-X, has been developed for applications in 700 °C advanced ultra-supercritical (A-USC) boilers. The HT-X alloy is subjected to various heat treatments. Tensile tests are conducted at room temperature (RT), 700 °C and 750 °C. Creep tests are carried out under conditions of 700 °C/300 MPa and 750 °C/150 MPa. After aging treatment, the yield strength of the HT-X alloy at RT and 750 °C is 787 MPa and 624 MPa, respectively. When additional thermal exposure at 750 °C for 5400 h is applied, the yield strength is decreased to 656 MPa at RT and 480 MPa at 700 °C. For an aged specimen, the a/2<110> dislocation shearing process occurs when tensile testing is conducted at RT and 750 °C. As the γ' precipitate size increases in the specimen that is thermally exposed at 750 °C for 5400 h, Orowan bowing is the dominant dislocation process, and stacking faults develop in the γ' precipitates at both RT and 700 °C. Dislocation slip combined with climb is the dominant mechanism under the creep testing conditions. The factors that affect the mechanical properties and deformation mechanisms are discussed.

Thermal stability, magnetic and magnetocaloric properties of Gd55Co35M10 (M = Si, Zr and Nb) melt-spun ribbons

X.C. Zhong,D.L. Jiao,H. Zhang,W.Q. Qi,Z.W. Liu,R.V. Ramanujan 한국물리학회 2018 Current Applied Physics Vol.18 No.12

The thermal stability, magnetic and magnetocaloric properties of Gd55Co35M10 (M=Si, Zr and Nb) melts-pun ribbons were studied. The relatively high reduced glass transition temperature (Tx1/Tm > 0.60) and low melting point (Tm) resulted in excellent glass forming ability (GFA). The Curie temperatures (TC) of melt-spun amorphous ribbons Gd55Co35M10 for M=Si, Zr and Nb were 166, 148 and 173 K, respectively. For a magnetic field change of 2 T, the values of maximum magnetic entropy change (−ΔSM)max for Gd55Co35Si10, Gd55Co35Zr10 and Gd55Co35Nb10 were found to be 2.86, 4.28 and 4.05 J kg−1K−1, while the refrigeration capacity (RC) values were 154, 274 and 174 J kg–1, respectively. The RCFWHM values of amorphous alloys Gd55Co35M10 (M=Si, Zr and Nb) are comparable to or larger than that of LaFe11.6Si1.4 crystalline alloy. Large values of (−ΔSM)max and RC along with good thermal stability make Gd55Co35M10 (M=Si, Zr and Nb) amorphous alloys be potential materials for magnetic cooling operating in a wide temperature range from 150 to 175 K, e.g., as part of a gas liquefaction process.

Influence of crystallization treatment on structure, magnetic properties and magnetocaloric effect of Gd71Ni29 melt-spun ribbons

X.C. Zhong,H.Y. Yu,Z.W. Liu,R.V. Ramanujan 한국물리학회 2018 Current Applied Physics Vol.18 No.11

The influence of crystallization treatment on the structure, magnetic properties and magnetocaloric effect of Gd71Ni29 melt-spun ribbons has been investigated in detail. Annealing of the melt-spun samples at 610 K for 30 min, a majority phase with a Fe3C-type orthorhombic structure (space group, Pnma) and a minority phase with a CrB-type orthorhombic structure (space group, Cmcm) were obtained in the amorphous matrix. The amorphous melt-spun ribbons undergo a second-order ferromagnetic to paramagnetic phase transition at 122 K. For the annealed samples, two magnetic phase transitions caused by amorphous matrix and Gd3Ni phases occur at 82 and 100 K, respectively. The maximum magnetic entropy change (–ΔSM)max is 9.0 J/(kgˑK) (5T) at 122 K for the melt-spun ribbons. The values of (–ΔSM)max in annealed ribbons are 1.0 and 5.7 J/(kgˑK), corresponding to the two adjacent magnetic transitions.

Investigation on the Unlubricated Sliding Tribological Properties of Ti–20Zr–6.5Al–4V Alloy at Elevated Temperatures

H. Zhong,L. Q. Yang,Y. Yue,C. P. Zhang,F. X. Jin,M. Gu,M. Z. Ma 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.12

In this study, unlubricated sliding friction and wear properties of a recently-developed TiZr-based alloy (Ti–20Zr–6.5Al–4V, TZ20 hereafter) were tested at elevated temperatures ranging from room temperature to 673 K. After the tribologicaltests, worn surface and cross-section of TZ20 alloy were analyzed to illustrate its wear behavior. The results showed that thewear rate was increased firstly with the ambient temperature, which then decreased when the temperature exceeded criticaltransition temperature (473 K). Also, the dominant wear mechanisms changed from adhesive wear at room temperature toabrasive wear at 473 K, and then to mild abrasive wear at highest ambient temperature of 673 K. The variations of wearbehaviors could be attributed to tribo-oxide layer formed during sliding process. At ambient temperature of 673 K, the tribooxidelayer formed on the surface was thicker and more compact, and showed more obvious protective role on tribologicalproperties of TZ20 alloy.

100KW DC Arc Plasma of CVD System for Low Cost Large Area Diamond Film Deposition

Lu, F.X.,Zhong, G.F.,Fu, Y.L.,Wang, J.J.,Tang, W.Z.,Li, G.H.,Lo, T.L.,Zhang, Y.G.,Zang, J.M.,Pan, C.H.,Tang, C.X.,Lu, Y.P. The Korean Ceramic Society 1996 The Korean journal of ceramics Vol.2 No.4

In the present paper, a new type of DC arc plasma torch is disclosed. The principles of the new magnetic and fluid dynamic controlled large orifice long discharge tunnel plasma torch is discussed. Two series of DC Plasma Jet diamond film deposition equipment have been developed. The 20kW Jet equipped with a $\Phi$70 mm orifice torch is capable of deposition diamond films at a growth rate as high as 40$\mu\textrm{m}$/h over a substrate area of $\Phi$65 mm. The 100kW high power Jet which is newly developed based on the experience of the low power model is equipped with a $\Phi$120 mm orifice torch, and is capable of depositing diamond films over a substrate area of $\Phi$110 mm at growth rate as high as 40 $\mu\textrm{m}$/h, and can be operated at gas recycling mode, which allows 95% of the gases be recycled. It is demonstrated that the new type DC plasma torch can be easily scaled up to even higher power Jet. It is estimated that even by the 100kW Jet, the cost for tool grade diamond films can be as low as less than $4/carat.

SYSTEMATIC SYNTHESIS METHOD AND PROTOTYPING OF FIXEDAXLE VEHICULAR ELECTRIFIED MECHANICAL TRANSMISSION

H. ZHANG,Z. ZHONG,X. CHEN 한국자동차공학회 2015 International journal of automotive technology Vol.16 No.4

In the process of mechanism creative design, structure synthesis is the primary and the most important issue. This paper proposes a systematic and automatic synthesizing method of fixed-axle gear sets by means of morphological analysis. And the process is implemented to synthesize Electrified Mechanical Transmission (EMT) schemes which are parallel hybrid electric transmission composed of fixed-axle gear sets. First, independent design parameters as well as feasibility constraints and consistency conditions are defined by analyzing the structure and functions of EMT. According to these boundary conditions, structure variables such as the quantity of components and their connection relationship are solved. Then, the scheme quantity of each structure type is synthesized. Secondly, based on the abstraction of practical mechanisms with topology models, the corresponding adjacency matrixes are derived, and they are used to filtering unqualified schemes and retrieve all potential transmission paths of the remaining schemes. These potential transmission paths are further used to find out the layout and operating mode of each scheme. Finally, all schemes satisfying the structural and functional requirements are synthesized. For example, one EMT prototype is built based on one of the final schemes found and an ICE car is modified to adapt to such transmission. Vehicle test results verify the effectiveness and feasibility of the chosen transmission scheme.