不同热处理状态下铝合金应变速率敏感性的研究

为研究不同热处理状态下AA6016铝合金板材的应变速率敏感性,针对1 mm厚的AA6016-T4和AA6016-T5两种不同热处理状态的铝合金板材,采用试验的方法获得不同应变速率下铝合金板材的应力应变数据,并进行试验结果的对比分析。结果表明,当应变速率为1730 s^-1时,AA6016-T5铝合金的抗拉强度为450 MPa,断裂应变为0.185;当应变速率超过1110 s^-1时,高应变速率下的断裂应变明显超过准静态下的断裂应变;当应变速率为1860 s^-1时,AA6016-T4铝合金的抗拉强度为245 MPa,断裂应变为0.235。对比分析表明,高应变速率下铝合金板材的抗拉强度比准静态下高;高应变速率下,随着应变速率增加,铝合金板材的塑性逐渐提高;AA6016-T5铝合金应变速率的敏感性明显高于AA6016-T4铝合金。

我国油菜生产现状、效益及提升策略

油菜是我国第一大自产植物油源,对确保食用油安全有着十分重要的作用。目前我国每年需进口大量食用油,自给率不足35%,因而大力发展油菜产业刻不容缓。基于国家统计年鉴资料,分析总结了2000—2018年油菜产业的发展情况,对影响油菜生产的成本及利润等方面情况进行分析,发现2000—2018年间我国油菜种植面积及产量基本保持稳定,在当前耕地面积有限的情况下,大力发展高油油菜是提高总产最有效的途径;2012年以来,净利润一直为负值,主要是肥料、人工投入及作业成本增幅过大所致。可通过发展油菜多用途等方法提高综合效益,增强农户生产积极性,促进油菜产业发展,确保我国食用油安全。

The Probe Transmission Spectra of^(87)Rb in an Operating Magneto-Optical Trap in the Presence of an Ionizing Laser

The influence of an ionizing laser on the pump-probe spectra of^(87)Rb over the transition 5^(2)S_(1/2),F=2→5^(2)P_(3/2),F'=3 is experimentally studied in an operating magneto-optical trap.These spectral features,including gain peak,a dispersion-like structure and absorption peak,become weak as the intensity of the ionizing laser increases.Moreover,the profiles of the absorption peak and gain peak vary as the ionizing laser intensity changes.Such results indicate that there is more than one component in the two features and that each component has different dependences on the number of^(87)Rb atoms.

Measurement of the Absolute Photoionization Cross Section for the 5P_(3/2) State of ^(87)Rb in a Vapor Cell Magneto-optic Trap

We report the measurement of the absolute photoionization cross section for the 5P_(3/2 )state of ^(87) Rb at wavelength of 473 nm,which results in the photoelectron energies of 33 meV above the ionization threshold,using cold atoms confined in a vapor-loaded magneto-optical trap.The 87Rb 5P_(3/2 )photoionization cross section at 473nm is determined to be σ_(PI) =10.5 ± 2.2 Mb.Considering the spatial distribution of the trapped atoms,the average intensity I_(PI) of the ionization laser seen by an atom in the MOT instead of ionizing laser intensity I_(PI) is used in our calculations for the photoionization cross sections.The excited state fraction is also accurately estimated using the latest experimental result.

Autoionizing Distribution of the Triply Excited Double Rydberg States in La Atom

The autoionization distribution of the triply excited double Rydberg states(TEDRS)5d5/2NLnl(N≤22;n≤50;L,l<4)of La has been investigated by using five-laser resonance excitation in combination with a method of sequential ionization by a pulsed electric field and a constant electric field.The experimental results exhibit that the La atoms in TEDRS predominantly single-autoionize to the ionic Rydberg states located in a few Rydberg manifolds.Furthermore,a difference of autoionization mechanisms between TEDRS above and those below the double ionization threshold is found.

The Inversionless Amplification in a Tripod System of SrRb Atoms in a Magneto-optical Trap

The probe transmission spectra around the atomic transition 52S1/2,F = 2 → 52P3/2,F = 2 of 87Rb are measured in a magneto-optical trap by adding a coupling field around the atomic transition 52S1/2, F = 2 → 52 P3/2, F1 = 2. The inversionless amplification is observed in the spectrum over the atomic transition 5 2 S1/2, F = 2 → 52pa/2, Fr = 2. The tripod eleetromagnetically induced transparency is proposed to account for the ampli- fication feature, in which population distributions among these related atomic levels play an important role.

半骺板阻滞术治疗儿童膝关节成角畸形的矫正速率与临床疗效分析

目的探讨半骺板阻滞术治疗儿童膝关节成角畸形的矫正速率及临床疗效。方法纳入自2016-03—2018-03采用8字形钢板半骺板阻滞术治疗的22例(36膝)膝关节成角畸形,膝内翻畸形6例(9膝),膝外翻畸形16例(27膝)。测量手术前后膝间距或踝间距、膝关节中心到下肢力线的距离、股胫角,计算矫正速率。结果22例均获得至少2年随访。膝内翻畸形患儿末次随访时膝间距、膝关节中心到下肢力线的距离、股胫角明显小于术前、术后1周和术后3个月,膝外翻畸形患儿末次随访时踝间距、膝关节中心到下肢力线的距离、股胫角均小于术前、术后1周和术后3个月,差异有统计学意义(P<0.05);患儿术前、术后1周、术后3个月上述指标比较差异无统计学意义(P>0.05)。膝内翻畸形患儿矫正速率为(0.32±0.12)°/月,膝外翻畸形患儿矫正速率为(0.48±0.09)°/月,术后9~12个月膝内翻与膝外翻畸形改善效果最明显。膝外翻畸形患儿的矫正速率明显高于膝内翻畸形患儿,差异有统计学意义(P<0.05)。结论半骺板阻滞术治疗儿童膝关节成角畸形效果满意,并发症较少,安全可靠,建议膝内翻畸形患儿矫正速率控制在(0.32±0.12)°/月,膝外翻畸形患儿矫正速率控制在(0.48±0.09)°/月。