A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base ...A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm^2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic.展开更多
Laser beam welding is used to fabricate the 7A52 aluminum alloy plates.Effects of shielding gas and defocusing on porosities are investigated.Porosities are divided into hydrogen porosities and keyhole-induced porosit...Laser beam welding is used to fabricate the 7A52 aluminum alloy plates.Effects of shielding gas and defocusing on porosities are investigated.Porosities are divided into hydrogen porosities and keyhole-induced porosities.With the increasing flow rate of the front shielding gas,the porosity ratio firstly decreases,then increases.The porosity ratio is lowest under the flow rate of 25 L/min.When the flow rate is 30 L/min,the porosity ratio is higher because the large flow rate can affect the stability of the keyhole.The porosity ratio is also higher when the flow rate is less than 25 L/min because the protection is weakened.With the increase of the defocusing,the porosity ratio firstly decreases,then increases.When the defocusing is-2 mm,the porosity ratio is lowest.When the defocusing is more than 0 mm or less than-4 mm,the porosity ratio is higher due to the movement of the instable keyhole.展开更多
Wendelstein 7-AS (W7-AS) pertains to an advanced helical stellarator. A new fuelling method, the supersonic molecular beam injection (SMBI, named Gas Jet in Germany) system was installed in W7-AS in May 2001 as a coop...Wendelstein 7-AS (W7-AS) pertains to an advanced helical stellarator. A new fuelling method, the supersonic molecular beam injection (SMBI, named Gas Jet in Germany) system was installed in W7-AS in May 2001 as a cooperation research item co-supported by the National Nature Science Foundation of China and the Max-Planck Institute of Plasma Physics, Garching, Germany. The experiments of the gas jet with hydrogen or deuterium on W7-AS were implemented. The experimental results exhibit the following features such as high fuelling efficiency, stable high-density plasmas and reduction of the recycling fluxes from the vessel wall during injection. These crucial points show that the new fuelling method can be applied to long and stable discharges.展开更多
Aiming at the production of <sup>6</sup>He,<sup>8</sup>Li and <sup>7</sup>Be radioactive beams,various nuclear dataof d+<sup>6,7</sup>Li and d+<sup>9</sup>Be...Aiming at the production of <sup>6</sup>He,<sup>8</sup>Li and <sup>7</sup>Be radioactive beams,various nuclear dataof d+<sup>6,7</sup>Li and d+<sup>9</sup>Be reactions at incident energies spanning 0,1～30.0 MeV are obtained bycalculation with the distorted wave Born approximation,preequilibrium nuclear reaction andHauser-Feshbach（HF）theory.The cross sections of d+<sup>7</sup>Be reaction are also predicted.Theresults show that the experimental measurement for d+<sup>7</sup>Be reaction is feasible at HI-13 tandemaccelerator.展开更多
The mechanism of combination of Flow injection(FIA)and double beam of photometry and testing technique,together with the color reaction condition of 2-(4-bromo-2-carboxy phenylazo)-7-(2,4-dimethyl phenylazo)-1,8-dihyd...The mechanism of combination of Flow injection(FIA)and double beam of photometry and testing technique,together with the color reaction condition of 2-(4-bromo-2-carboxy phenylazo)-7-(2,4-dimethyl phenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid reacting with Barium,and the application in the determination of Barium in sinter have been studied.The analyses speed was 130～140 times/h,the Sensitivity was 1.6 times of the ordinary photometric method,the dynamic concentration range of bariumn was 0～1.1μg·mL-1which was in consistent with a Lamber-beer law.The experimental results was satisfactory.展开更多
3GPP标准在5G中引入了波束扫描和空域的维度,信道状态信息(channel state information,CSI)是UE上报给eNodeB的信道状态信息,信道状态信息参考信号(channel state information-reference signal,CSI-RS)是UE用来获取信道状态信息的参考...3GPP标准在5G中引入了波束扫描和空域的维度,信道状态信息(channel state information,CSI)是UE上报给eNodeB的信道状态信息,信道状态信息参考信号(channel state information-reference signal,CSI-RS)是UE用来获取信道状态信息的参考信号。终端接入时基站采用SSB波束轮发探测终端的最优波束,在终端接入后获取参考信号的配置信息后对信道状态信息进行反馈,基站采用CSI-RS波束轮发的最优波束。5G天线灵活配置波束个数并且兼顾水平维度、垂直维度的覆盖。结合广播波束发展、现网水平7波束面临的挑战,分析比较了水平7波束与1+X波束两种方案,并对两种方案进行测试分析。测试结果表明,1+X波束具有较水平7波束覆盖相当、控制干扰、降低资源开销和设备能耗的优势,结合自动优化工具的应用达到提升工作效率的效果。展开更多
Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy（BNCT） is investigated using a ^7Li（p,n）^7Be reaction. Design and optimization have been carried out for the target, cooling system,mode...Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy（BNCT） is investigated using a ^7Li（p,n）^7Be reaction. Design and optimization have been carried out for the target, cooling system,moderator, filter, reflector, and collimator to achieve a high flux of epithermal neutron and satisfy the IAEA criteria.Also, the performance of the designed beam in tissue is assessed by using a simulated Snyder head phantom. The results show that the optimization of the collimator and reflector is critical to finding the best neutron beam based on the ^7Li（p,n）^7Be reaction. Our designed beam has 2.49×109n/cm^2 s epithermal neutron flux and is suitable for BNCT of deep-seated brain tumors.展开更多
We report our progress in the high-temperature superconductor(HTS)Josephson junction fabrication process founded on utilizing a focused helium ion beam damaging technique and discuss the expected device performance at...We report our progress in the high-temperature superconductor(HTS)Josephson junction fabrication process founded on utilizing a focused helium ion beam damaging technique and discuss the expected device performance attainable with the HTS multi-junction device technology.Both the achievable high value of characteristic voltage V_(C)=I_(C)R_(N)of Josephson junctions and the ability to design a large number of arbitrary located Josephson junctions allow narrowing the existing gap in design abilities for lowtemperature superconductor(LTS)and HTS circuits even with using a single YBa_(2)Cu_(3)O_(7-x) film layer.A one-layer topology of active electrically small antenna is suggested and its voltage response characteristics are considered.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51677149)
文摘A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm^2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic.
基金the National Natural Science Foundation of China(Grant No.51905273)Natural Science Foundation of Jiangsu Province(Grant No.BK20190472).
文摘Laser beam welding is used to fabricate the 7A52 aluminum alloy plates.Effects of shielding gas and defocusing on porosities are investigated.Porosities are divided into hydrogen porosities and keyhole-induced porosities.With the increasing flow rate of the front shielding gas,the porosity ratio firstly decreases,then increases.The porosity ratio is lowest under the flow rate of 25 L/min.When the flow rate is 30 L/min,the porosity ratio is higher because the large flow rate can affect the stability of the keyhole.The porosity ratio is also higher when the flow rate is less than 25 L/min because the protection is weakened.With the increase of the defocusing,the porosity ratio firstly decreases,then increases.When the defocusing is-2 mm,the porosity ratio is lowest.When the defocusing is more than 0 mm or less than-4 mm,the porosity ratio is higher due to the movement of the instable keyhole.
基金The project supported by the National Nature Science Foundation of China (Nos. 19775011 and 10075016) the China Nuclear Industry Science Foundation (No. 94C03033)
文摘Wendelstein 7-AS (W7-AS) pertains to an advanced helical stellarator. A new fuelling method, the supersonic molecular beam injection (SMBI, named Gas Jet in Germany) system was installed in W7-AS in May 2001 as a cooperation research item co-supported by the National Nature Science Foundation of China and the Max-Planck Institute of Plasma Physics, Garching, Germany. The experiments of the gas jet with hydrogen or deuterium on W7-AS were implemented. The experimental results exhibit the following features such as high fuelling efficiency, stable high-density plasmas and reduction of the recycling fluxes from the vessel wall during injection. These crucial points show that the new fuelling method can be applied to long and stable discharges.
基金The project supported by the Nuclear Industry Science Foundation of China
文摘Aiming at the production of <sup>6</sup>He,<sup>8</sup>Li and <sup>7</sup>Be radioactive beams,various nuclear dataof d+<sup>6,7</sup>Li and d+<sup>9</sup>Be reactions at incident energies spanning 0,1～30.0 MeV are obtained bycalculation with the distorted wave Born approximation,preequilibrium nuclear reaction andHauser-Feshbach（HF）theory.The cross sections of d+<sup>7</sup>Be reaction are also predicted.Theresults show that the experimental measurement for d+<sup>7</sup>Be reaction is feasible at HI-13 tandemaccelerator.
文摘The mechanism of combination of Flow injection(FIA)and double beam of photometry and testing technique,together with the color reaction condition of 2-(4-bromo-2-carboxy phenylazo)-7-(2,4-dimethyl phenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid reacting with Barium,and the application in the determination of Barium in sinter have been studied.The analyses speed was 130～140 times/h,the Sensitivity was 1.6 times of the ordinary photometric method,the dynamic concentration range of bariumn was 0～1.1μg·mL-1which was in consistent with a Lamber-beer law.The experimental results was satisfactory.
文摘3GPP标准在5G中引入了波束扫描和空域的维度,信道状态信息(channel state information,CSI)是UE上报给eNodeB的信道状态信息,信道状态信息参考信号(channel state information-reference signal,CSI-RS)是UE用来获取信道状态信息的参考信号。终端接入时基站采用SSB波束轮发探测终端的最优波束,在终端接入后获取参考信号的配置信息后对信道状态信息进行反馈,基站采用CSI-RS波束轮发的最优波束。5G天线灵活配置波束个数并且兼顾水平维度、垂直维度的覆盖。结合广播波束发展、现网水平7波束面临的挑战,分析比较了水平7波束与1+X波束两种方案,并对两种方案进行测试分析。测试结果表明,1+X波束具有较水平7波束覆盖相当、控制干扰、降低资源开销和设备能耗的优势,结合自动优化工具的应用达到提升工作效率的效果。
文摘Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy（BNCT） is investigated using a ^7Li（p,n）^7Be reaction. Design and optimization have been carried out for the target, cooling system,moderator, filter, reflector, and collimator to achieve a high flux of epithermal neutron and satisfy the IAEA criteria.Also, the performance of the designed beam in tissue is assessed by using a simulated Snyder head phantom. The results show that the optimization of the collimator and reflector is critical to finding the best neutron beam based on the ^7Li（p,n）^7Be reaction. Our designed beam has 2.49×109n/cm^2 s epithermal neutron flux and is suitable for BNCT of deep-seated brain tumors.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1603900)in part by the Russian Science Foundation(RSCF)(Grant No.19-72-10016-P).
文摘We report our progress in the high-temperature superconductor(HTS)Josephson junction fabrication process founded on utilizing a focused helium ion beam damaging technique and discuss the expected device performance attainable with the HTS multi-junction device technology.Both the achievable high value of characteristic voltage V_(C)=I_(C)R_(N)of Josephson junctions and the ability to design a large number of arbitrary located Josephson junctions allow narrowing the existing gap in design abilities for lowtemperature superconductor(LTS)and HTS circuits even with using a single YBa_(2)Cu_(3)O_(7-x) film layer.A one-layer topology of active electrically small antenna is suggested and its voltage response characteristics are considered.
