氢气/甲烷-空气爆轰波在含环形障碍物圆管内传播的试验研究

在内径48mm、长度5 800mm的含环形障碍物圆管内,进行了氢气-空气及氢气-甲烷-空气的爆轰波传播试验研究,确定了爆燃转爆轰(Deflagration-to-Detonation Transition,DDT)极限。环形障碍物阻塞比为0.56,间距分为两种,即S=D和S=2D,其中S为障碍物间距,D为管道内径。火焰的速度由安装在管道壁面上的光电二极管采集得到。试验测量得到的火焰为准爆轰或阻塞火焰。在S=2D情况下得到的火焰速度均比S=D情况下的火焰速度高,并且靠近DDT极限时速度波动更明显,表明在间距较大的情况下爆轰的重起爆循环周期更长,类似于"弛振爆轰"。对于氢气-空气,障碍物间距为D时在DDT极限处有d/λ1(富氧条件下d/λ=1.6,贫氧条件下d/λ=1.4),间距为2D时更容易形成爆轰的重起爆,在DDT极限处与准则d/λ≈1一致;对于氢气-甲烷-空气,甲烷的添加使爆轰更不稳定,对于两种间距的障碍物得到的DDT极限均有d/λ≈1(d和λ分别为障碍物内径和爆轰胞格尺寸)。说明障碍物间距对爆轰波传播有显著的影响,即间距的增大更有利于爆轰波的传播。为形成准爆轰,障碍物内径必须至少可以容纳一个爆轰胞格,同时障碍物间距足够大从而引起爆轰的重起爆。     

玻璃微球基乳化炸药及其在爆炸焊接中的应用

爆速是爆炸复合的主要参数之一。采用玻璃微球作为敏化剂和稀释剂,研究玻璃微球尺寸、含量对乳化炸药爆速的影响,然后调配爆速为2.230km/s的低爆速乳化炸药,利用铝蜂窝板配置蜂窝结构炸药,进行铝-钢复合板的爆炸焊接。试验结果表明:炸药密度随着玻璃微球含量的增加而减小;小尺寸玻璃微球含量(质量分数)小于2%或者大于35%时,乳化炸药发生拒爆现象;玻璃微球含量大于7%且小于35%时,炸药爆速随着玻璃微球含量的增大而减小。小尺寸(5~100μm)玻璃微球的敏化效果和调节爆速效果比大尺寸(70~200μm)玻璃微球好,铝蜂窝结构炸药用于铝-钢爆炸焊接可以获得良好的结合质量。     

基于环形自由面岩土高效爆破的研究与应用

针对岩石巷道掘进循环进尺慢,炮孔利用率低的问题,采用取岩芯技术在岩土中形成环形自由面,利用少量炸药即可达到高效爆破的效果。首先对取岩芯爆破模型进行数值模拟,对爆炸效果进行预估,并得到相关爆破参数;之后根据模拟结果进行爆破实验,制作两组水泥模型,分别模拟取岩芯爆破与传统爆破,在模型外部布置测振仪,测量爆炸过后模型的相关振动数据,并对两组模型的爆破效果与振动数据作出比较,得出取岩芯模型爆破效果及爆破振动要明显优于传统爆破模型。最后将该技术应用在某岩巷掘进现场进行爆破实验,取得成功。实验结果表明,利用取岩芯技术成形环形自由面进行爆破, 可以减少炮孔数, 降低炸药单耗,控制住爆破振动,提高爆破效率,达到高效爆破的目的,特别是该技术可应用于城市地下工程爆破。     

Construction of two-qubit logical gates by transmon qubits in a three-dimensional cavity

We report the implementation of qubit-qubit coupling in a three-dimensional(3 D) cavity, using the exchange of virtual photons, to realize logical operations. We measure single photon and multi-photon transitions in this qubit-qubit coupling system and obtain its energy avoided-crossing spectrum. With ac-Stark effect, fast control of the qubits is achieved to tune the effective coupling on and off and the state-swap gate (SWAP)~(1/2) is successfully constructed. Moreover, using two-photon transition between the ground state and doubly excited states, a kind of two-photon Rabi-like oscillation is observed. A quarter period of this oscillation corresponds to the logical gate (bSWAP)~(1/2), which is used for generating Bell states.(bSWAP)~(1/2) and (iSWAP)~(1/2) are the foundations of future preparation of two-qubit Bell states and realization of CNOT gate.     

Temporal behaviour of open-circuit photovoltaic solitons

Based on the time-dependent band-transport model in a photorefractive medium, dark open-circuit photovoltaic (PV) solitons are investigated both theoretically and experimentally. Compared with those of the time-independent models, our theoretical results revealed that quasi-steady-state and steady-state PV solitons can both be obtained. Our results also revealed that when r < 1 (r is the normalized intensity at infinity), the full width at half maximum (FWHM) of solitons decreases monotonically to a constant value; when r > 1, however, the FWHM of solitons first decreases to a minimum before it increases to a constant value. Moreover, the FWHM of steady solitons decreases with increasing intensity ratio for r < 1, and increases with increasing intensity ratio for r > 1. We further observed dark PV solitons in experiments, and recorded their evolution. These results indicated that steady solitons can be observed at low optical power, while quasi-steady-state solitons can only be generated at higher optical power. Good agreement is found between theory and experiment.     

含铝纤维复合炸药的能量输出和力学强度

通过空中爆炸实验,研究了铝纤维对爆炸能量输出的影响,结果表明:wAl=0.20的TNT/Al,冲击 波压力峰值为TNT 的1.19倍,TNT 当量为TNT 的1.29倍;wAl=0.20的RDX/Al,冲击波压力峰值为 RDX的1.20倍,爆热为TNT的1.64倍,是RDX的1.31倍。通过抗压实验,研究了铝纤维对炸药力学强度 的影响,结果表明,铝纤维能增强TNT炸药的力学强度,破坏应力为6.8MPa,应变为0.043。铝纤维对炸药 能量和力学强度的双重增强特性,可以为现代高性能炸药设计提供参考。     

Incoherently coupled soliton pairs in nonlocal nonlinear media

We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright--bright, dark--dark, and gray--gray configurations. When the nonlocal nonlinearity is absent, these bright--bright and dark--dark soliton pairs are those observed previously in local Kerr-type nonlinear media. Our analysis indicates that for a self-focusing nonlinearity the intensity full width half maximum (FWHM) of the bright--bright pair components increases with the degree of nonlocality of the nonlinear response, whereas for a self-defocusing nonlinearity the intensity FWHM of the dark--dark and gray--gray pair components decreases with the increase in the degree of nonlocality of the nonlinear response. The stability of these soliton pairs has been investigated numerically and it has been found that they are stable.     

碳素基体固相微萃取吸附质的研制

研制了石墨型碳素基体固相微萃取吸附质,并以该新型固相微萃取装置联用气相色谱 电子捕获检测器分析水体中的有机农药。考察了吸附萃取时间及离子强度对分析结果的影响,并与商品装置进行了对比,结果表明其具有很好的应用前景。     

低碳烯烃高效分离新型多孔材料的研究进展

低碳烯烃(乙烯、丙烯等)作为石油化工的基本原料是现代化学工业的基石,也是我国国民经济发展的重要组成部分。然而,其生产过程常伴随着分离困难且能耗较高等问题。金属有机骨架(MOF)材料作为第三代新型多孔材料,因其具有高孔隙率、大比表面积、孔尺寸高度可调、结构多样等优点,在低碳烯烃分离领域表现出巨大的潜能。本文综述了MOF材料在低碳烯烃吸附分离领域的研究现状,包括MOF的分离机理和针对不同分离任务所采用的孔径调节、配体修饰、吸附位点构筑等策略,重点总结了本课题组近几年关于MOF在低碳烯烃分离方面取得的研究进展,并对未来的工业化应用进行了展望。     

基于自由振动的高速铁路简支梁桥共振与消振速度研究

为研究高速列车简支梁振动的问题,利用移动荷载列解析表达式的极限条件,推导了共振与消振速度。从自由振动幅值的角度,证明了桥梁振动主要由一阶模态贡献,且随着车速的增加,二阶模态对自由振动的贡献逐渐增大,而更高阶的模态贡献量可忽略不计。提高桥梁阻尼能起到抑振的作用,但会加剧车辆驶离桥后的自由振动。以20 m和32 m的两座简支梁桥为算例,从自由振动的幅值和相位出发,阐明了在特定的速度下,发生共振与消振的主要原因是轴载激励的自由振动之间出现叠加、抵消或抑制的现象。当共振速度与消振速度重合时,消振先于共振发生。比较移动轴载解析值与车-轨-桥耦合有限元模型的计算值,结果表明,移动轴载模型能有效预测桥梁的位移时程,但分析桥梁的加速度响应时,有必要考虑车-轨-桥之间的动力耦合效应。